Maintenance of Horticultural Equipment

Maintenance of Horticultural Equipment

P.A. REYNOLDS

BIOTECH BOOKS

Maintenance of Horticultural Equipment

"This page is Intentionally Left Blank"

Maintenance of Horticultural Equipment

by P.A. REYNOLDS

BIOTECH

2009

Biotech Books Delhi - 110 035

©Reserved First Indian Impression 2009

ISBNlO 81-7622-204-6 ISBN13 978-81-7622-204-4

Published by

BIOTECH BOOKS 1123/74, Tri Nagar, DELHI - 110 035 Phone: 27383999 e-mail: [email protected]

Showroom

4762-63/23, Ansari Road, Darya Ganj, NEW DELHI -110 002 Phone: 23245578, 23244987

Printed at

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PRINTED IN INDIA

INTRODUCTION NEVER has there been so

much equipment on the farm, the nursery and the smallholding. That equipment must be kept in good order if production costs are to be kept down. On every holding there should be someone who understands engines, general machinery, electricity, water installations and carpentry. His knowledge need not be profound, but he must know how to use tools. Here, then, is a practical guide to the maintenance of equipment.

"This page is Intentionally Left Blank"

CONTENTS IN T R 0 I) I (' 1 J 11 '\

page :,

1. OPERA TlNG COSTS

II

Operating costs of a two-wheeled tractor-types of horticul tural tractor-single-wheeled-two-wheeled-thrce- and four-wheeled-tracklayers.

2. CHOOSING A MACHINE

18

How to choose a motor cultivator-adaptability-buying a second-hand machine.

3. THE WORKSHOP

24

Your workshop and its equipment-engineering and woodworking tools-how to use a hacksaw-files and filing-spanners-drills and drilling-how to solder-hard soldering-brazing-riveting-thread cutting-grinding wheels.

4. ENGINES

41

How an engine works-four-stroke engines-two-stroke engines-principles of carburation-the fuel systemengine governors-principles of ignition-sparking plugs -ignition testing-air cleaners-adjusting a carburettor.

5.

MORE ABOUT ENGINES

60

Decarbonising a two-stroke-decarbonising a four-stroke -adjusting engine governors--engine timing-servicing data for ViIliers and J.A.P. engines.

6. TRANSMISSION Transmission-methods of drive-roller chain adjustment and repair-ditferential gears-hub ratchets-dog clutches -centrifugal clutches-clutch relining-belt drive and belt clutches and their adjustment-tube repairing.

7.

IMPLEMENT MAINTENANCE

Sharpening cultivators, disc harrows, etc. Rotary scythes, lawn mowers and cutter bars-sharpening a lawn mower-cutter bar maintenance-rotary hoe maintenance, etc. -rust prevention-broken bolts-sprayer maintenance.

72

8

CONTENTS

8. DIESEL ENGINES

page 94

Diesel engines-care and maintenance-bleeding the fuel system-installing a stationary engine-fuel filters-the Lister diesel.

9.

ELECTRICITY

99

Small electric generating plants-wind-driven generators -Iow voltage generators-clectrical terms explainedhow to wire a house and buildings for electric Iight-care of dynamos-battery maintenance-mains supplies.

10. WATER SUPPLIES

113

Water supplies-shallow well pumps-centrifugal pumps -pistons-glands-deep bore pumps and their maintenance-stationary engines-belts and pulleys-belt joining and lacing-pipe work, etc.

11. BOILERS AND OIL BURNERS

124

Maintenance of boilers and oil burners.

12. BRICK AND CONCRETE WORK

127

Brick and concrete work-lime mortar-cement mortarmixing cement and concrete-cutting bricks-bricklaying -concrete and breeze blocks-plugging brickworkcutting glazed earthenware pipes.

13. WOODWORKING

134

Woodworking tools-how to sharpen a saw, chisel and plane-setting a plane-how to plane-making a sawing stool-woodworking joints and how to make them-nails -screws-making an extension ladder-making gates-preserving wooden posts.

14. ROOFS AND BUILDINGS

151

Roofs and buildings-bracing a shaky building-making a shed-cutting asbestos cement sheets-fixing asbestos sheets-roofing with felt-repairing a torn roof-painting -glazing, etc.

15. SOME USEFUL ODD JOBS

159

Sharpening shears and scissors-repairing a cracked petrol pipe-oil lamps and heaters-maintenance of pressure lamps, blowlamps and flame guns-oil drum as an engine cover-repairing galvanised tanks-fitting new handles to forks, spades and axes, sharpening auger and centre bits-oilstones-truing up a grindstone, etc. INDEX

181

ILLUSTRATIONS I. Using a hacksaw

page 169

2. The Surform plane

169

3. Drill grinding gauge

31

4. Riveted joints

36

5. A simple four-stroke engine

41

6. A mushroom valve

42

7. The principle of a carburettor

4S

8. A simple carburettor 9. Banjo coupling and filter gauze 10. Villiers Mk. 10 engine and governor

11. Villiers engine governor weights

45 169 170 47

12. Two modem types of sparking plug

170

13. Contact breaker of Wico flywheel magneto

171

14. Contact breaker of Villiers flywheel magneto

171

J 5. Fabric type air cleaner on J.A.P. engine

172

16. Zenith Model12T carburettor 17. Adjusting Amal carburettor on Gem Rotavator

S6 172

18. The Villiers industrial engine carburettor

59

19. Throttle slide on Villiers Mk. 25C engine

173

20. Two-stroke engine with cylinder removed

173

21. Removing rings from piston

173

22. Parts of Villiers engine

174

23. Valve chamber of Villiers four-stroke

174

24. Flywheel magneto armature plate

17S

25. Governor linkage on J.A.P. 2A engine

175

26. Governor adjustment on a J.A.P. engine

176

27. Wico Type A magneto

176

28. Wico Type A magneto contact breaker

176

29. Parts of a roller chain 30. Repairing roller chains 31. Servicing Trusty dog clutch 32. Drive lay-out on Howard Bantam

74 76

177 80

10

ILLUSTRATIONS 33. Adjusting belt tension on Howard Bantam 34. Clutch adjustment on B.M.ll. Hoemate

page 177 177

35. Drake & F1etcher Model L.O. pump

178

36. The Lister Diesel

178

37. Insta1lation of Lister Diesel

179

38. Compression ratio change-over valve on Lister

98

39. A simple lighting circuit

101

40. Lighting circuit

102

41. Methods of fixing electrical cables

104

42. Common type of fuse holder

180

43. Parts of water pump gland

180

44. Belt fastener

119

45. How to lace a leather belt

120

46. Pipe fittings for water supplies

121

47. Making a sawing stool

139

48. Woodworking joints

141

49. Lap joint

142

SO. Making an extension ladder

146

51. Ironwork for extension ladder

147

52. Construction details of wooden gate

148

53. Bracing roof raftel'S

152

54. Tool for cutting asbestos sheet

180

55. Details of a modem blowlamp

163

56. Oil drum as an engine cover

164

57. Fitting-a new handle to a spade or fork

166

CHAPTER 1

Operating Costs grower is at some time or other confronted with the problem of mechanisation. He is urged to buy a motor cultivator, to go in for heated glasshouses or for an elaborate system of irrigation. Advertisements extol the virtues of the latest appliances and imply that prosperity is bound to follow their purchase. Perhaps it will, but not just by writing out a cheque. When you buy any piece of equipment you pay in advance for a service. Whether the particular service turns out to be good or bad depends upon three things: whether you have made a wise choice; whether you make full and proper use of that service; and whether you maintain the equipment in good order throughout its life. Suppose you contemplate buying a motor cultivator, how do you know if it will justify its cost? And even when that point has been settled you still have to discover which machine is the best for your purpose. Finally you need to know how to keep it running. A motor cultivator can easily do five times as much work as you can do by hand, but a cultivator will not do everything nor will it always do the job quite so well as a skilled man. Crop production includes the following operations: EVERY

1. 2. 3. 4. 5.

Digging or otherwise loosening the soil. Preparing a seed bed from rough land. Sowing seeds Qr transplanting seedlings. Keeping down weeds by hoeing. Carrying manures, fertilisers, tools and produce.

You might add to this list spraying and dusting. Possibly there will be hedges to trim as well. A small garden tractor will do these tasks (with the exception of transplanting) a great deal easier and quicker than you can, and even were the above the only things a machine can do, its purchase would in many cases be justified. But the modem light tractor can do much more. With suitable equipment it will CUt 11

12

MAINTENANCE OF HORTICULTURAL EQUIPMENT

grass, mow lawns, pull a roller, haul a 10ad€f
13

OPERATING COSTS

particularly the blades of rotary hoes, but the total yearly figure ought not to amount to more than £2, particularly if you carry out the maintenance work yourself. For the most part only a few minutes' attention a week is necessary but to allow for the larger jobs I will assume that maintenance averages one hour a week. At 3s. an hour the annual total for this is £7 16s. Od. From personal experience I find this ample and it usually includes replacements, but let us put down £10. The last item to be considered is that of the wages of the operator and these ought to be included even if the owner uses the machine himself. On the same basic wage figure the total for 520 machine hours is £78. Thus to put these in tabular form we get an all-in operating cost of: £ s. d. Depreciation on capital outlay 10 0 0 16 0 0 Petrol and oil Maintenance and repairs 10 0 0 Operator's wages 78 0 0

114 0 0 If .this appears to be rather a substantial sum remember that what a machine does in a year would cost £390 if done by hand. Nevertheless it must be clearly understood that this saving of £286 is affected only if the operator spends the time he is not using the machine in doing other useful work. Looked on as a substitute for personal labour a motor cultivator is an expensive plaything. Should the outfit be required to do the jobs given on pages 11-12 considerable additional expense is involved although the amount should also be reckoned in terms of labour saved. Here is list a of prices of the equipment made for one machine:

3 ft. grass cutter 2 ft. grass cutter 20 in. lawn mower (including purchase tax of £7 148. 8d.) Electric hedge trimmer Trailer (71 cwt. capacity) Tipper truck

£ s. d. 21 10 0 20 10 0

29 0 0 32 10 0 39 10 0 24 0 0

14

MAINTBNANCB OF HORTICULTURAL BQUIPMBNT

Water pump (600 gallons per hour) Hay sweep Snowplough 16 in. logging saw Seeder Sprayer Plant pot washer

£ 27 10 13 19 11 69 10

s. d. 10 5 0 0 10 10 15

0 0 0 0 0 0 0

Similar tools for other makes are approximately the same price. If, then, the initial outlay of £100 seems to you to be too high, remember that it is possible to undertake work for neighbours and so help considerably to repay the cost. There are many growers who have paid for their machines in a few months by doing this. But do remember that the figure of 4s. 5td. is the exact cost per hour-as near as ·we can get it-of operating a £100 outfit. If other appliances are used adjustments should be made to this figure. Remember, too, that nothing has been included for profit or to cover unexpected difficulties or breakdown, so base your charges accordingly. Ifyou are asked to quote a price for a job bear in mind that a breakdown or other holdup adds to your expenses. And do not forget that it takes time to get a machine and its equipment to the site and back again. Keep an eye, too, on the wages rates for it may be that even by the time you read this, my figure of 3s. an hour might be too low. If any reader feels that the lump sum outlay of even £65 is likely to put too much strain upon his resources, there are such things as hire-purchase and second-hand machines. A new outfit can be obtained by paying 25 per cent down and the balance at £1 a week. Some interest has to be paid if this type of transaction is resorted to, but the scheme has its advantages. For instance it would assist to cultivate land this year and so perhaps give a useful profit that would otherwise be lost. The fact, too, that £1 a week has to be paid might have the effect of making one think again of undertaking work for neighbours and so earn extra money that way as well. With regard to second-hand machines, there are generally plenty of them on offer at prices to suit all pockets, but before you go out to buy, read pages 21 to 22 very carefully. Once you have made up your mind to buy a cultivator the next

OPERATING COSTS

15

step is to see what machines are available. There are singlewheeled, two-wheeled, three- and four-wheeled and tracklayer models, each possessing advantages over the others.

SiDgle-wheeled Cultivators From I to 2! h.p. are popular with many growers because they can be used between rows of tall plants, the machines being narrow in width. A low centre of gravity is necessary otherwise the machine will be awkward to handle. The ideal position for the engine is of course near the centre of the land wheel, but this offers considerable difficulties in manufacture, and it certainly adds to the cost. The best known example of this design is the Gravely. The engine of this cultivator is actually on one side of the land wheel, the gearing in the centre and the carburettor and clutch on the other side. In several other makes the engine is set just over and in front of or slightly behind the land wheel. Frequently $e fuel tank is above the engine, thus giving the machine a somewhat top-heavy appearance. Most of these outfits are, however, reasonably easy to control. Single-wheeled machines are designed mainly for inter-row cultivation and not usually for much else. But some of them will operate a small plough and pull up to three seeders. The Gravely will plough, seed, cultivate, disc, hoe and harrow. The Colwood will take attachments for lawn mowing, grass cutting (that is tall grasses), seeding, hedge trimming and fertiliser spreading. There is also a 5 cwt. truck attachment in addition to the usual cultivating tools. One model Colwood is designed for rotary hoeing. Many users of single-wheelers have carried out ingenious adaptations and produced an outfit capable of work that no other tractor can do. Two-wheeled Machines These range in power from 1 to 7 h.p. and form the most popular class. The chief advantages are that the two wheels giv~ stability, ease of handling and greater adaptability. Moreover a low centre of gravity is more easily obtained because the engine can often be placed almost at axle height. It is true that they cannot be used on some crops, but there is usually sufficient ground clearance to enable them to straddle plants which are not too

16

MAINTBNANCH OF HORTICULTURAL BQUIPMBNT

advanced in growth. The land wheels are frequently adjustable along the axle. It is desirable on the whole that two-wheelers should have a wider speed range than the single-wheeler and in consequence one finds a few with change-speed gear-boxes. A low gear is essential for ploughing and the heavier forms of cultivation, while a higher speed is desirable for lighter work such as hoeing and scuffiing. It is generally possible to tow even a loaded trailer on the highest gear of all. Nevertheless very satisfactory work can be done with a single-speed inaChine which, incidentally, is cheaper to manufacture. Machines of 4 h.p. and above mostly have twoor three-speed gear-boxes, and a few of them can reverse. These bigger tractors are at their best when cultivating upwards of three acres, and particularly when there is a good area devoted to one crop. A 1 h.p. machine will cultivate up to two acres without difficulty, some being in regular use on bigger areas. There comes a point, however~ when extra power is well worth the additional cost. Indeed it is unwise to have too small an outfit. In the twowheeler class are the majority of the rotary hoes, these range in power from 2 to 7 h.p. We will return to these presently.

Tbree- and Four-wheelers A number of manufacturers who began by making twowheeled tractors have gone over to the production of three- and four-wheeled units because many operators demanded seating accommodation. Of these the most popular are: Gunsmith 6 h.p. air-cooled single cylinder Trusty Steed 6 h.p. air-cooled single cylinder Gamer 10 h.p. air-cooled twin There are also a number of "light" tractors with four-cylinder water-cooled engines. The term "light" is clearly relative. Tracklaying Machines The Ransomes M.G. and the Bristol are popular with market gardeners, fruit growers and even with those who cultivate really large acreages. The advantages of this type are that they can travel over soft ground without becoming bogged, are extremely manreuvrable and can carry out neariy every kind of cultivation

OPERATING COSTS

17

work. But they are the tools of the specialist grower, and I am confining myself chiefly to small acreage equipment. As we have seen, a 1 h.p. cultivator will work two or at most three acres. Above that it is advisable to go in for something more powerful. A rough but useful guide is to reckon 1 h.p. per acre above two; for example, use a 3 h.p. machine on three acres, a 5 h.p. machine on five acres and so on. But there is no sharp dividing line. Although the size of your land must influence your choice, it is not the only consideration. Very heavy soil needs a more powerful tractor than does light land. Hills, too, make a difference and so does the type of crops grown. Where intensive cultivation is followed, such as when growing flowers, a narrow machine might be far more useful than a wide one, so long as the ground has been well cultivated first. Do not overlook these things. And when at last you reach the conclusion that this or that power is required, make sure quite that you select the right machine for your purpose. This subject is gone into fully in the next chapter.

2

CHAPTER 2

Choosing a Machine going any further it is necessary to decide which form of cultivation you intend to adopt, i.e. ploughing or rotary hoeing. Both methods have proved effective and so long as one looks after the land's humus content, either method gives excellent results. But it must be confessed that the plough type machine can usually be fitted with a wider variety of implements, and this might be of great importance where cash is limited. All the same, the majority of rotary hoes can be made t6 take ordinary hoes, ridgers and sprayers, although the machine itself is generally less handy for cartage work. No doubt this matter will receive the attention of manufacturers before long. The question of machine adaptability is a vital one for singlehanded growers. Within reason, the more uses to which a machine can be put, the greater is its value in terms of labour saving. The lower, too, are its running costs-for remember that annual depreciation remains whether the outfit is used for ten minutes or ten hours a day. On the other hand to rely completely on a single engine means that a breakdown can upset the whole routine, and that a big repair j0b requiring a week or more to perform can be a serious hindrance. The more you rely upon your cultivator the more careful should you be over its maintenance. There is one other aspect of adaptability to consider, namely the ease with which the various implements are attached and removed. I have found that in an endeavour to rival their competitors, one or two tractor manufacturers have produced equipment requiring all sorts of rods and brackets and clips. On a few makes it is necessary to dismantle a large part of the machine itself in order to attach something which, at best, is only used for short periods at a time and is, in consequence, rather a makeshift affair. When one realises that nearly every light tractor has a power unit m8de either by Villiers or J.A.P., and that all the manuraC'tur\.'r of the machine has to do is to design a frame for it, it is :-trange that not more attention is not given to tool design and

BEFORE

18

CHOOS ING A MACH INE

19

methods of attaching them. The ease with which implements arc fitted is so important a matter that I would rather forego the use of one or two appliances than spend an hour or two attaching them. Of course, when an attachment can be put on arid left in place for a week or more it doesn't matter so much, but for most of us a few hours' work with one implement meets our needs, and back we go to another tool. To make a wise choice, then, begin by concentrating upon the work the machine will have to do. Write down a list of essential jobs and include desirable features such as two-speeds, reverse gear, etc. Then make a second list putting in it all the less vital tasks, and possibly sundry features of a desirable but less essential character. Your two lists might, for example, be as under. List No. 1.

List No. 2.

Plough (or rotary hoe) Toolbar Sprayer Grass mower Two-speed gearbox Trailer Power take-off pulley Seeder Hedge trimmer Saw bench

Instead of ploughing you might favour rotary cultivation but feel that a machine which can do both is desirable. In that case, put both on your list. Some might consider cartage work less necessary than a power take-off pulley. So make out your own lists and do not hurry over them, 'otherwise you might regret your haste. Visualise yourself doing a whole year's work on your holding, and you will be surprised at the number of tasks in which a tractor can help you. Having made your lists send for descriptive leaflets of all the light tractors. I say "all" advisedly, for it may well happen that an entirely new model is on the way, one that will solve many of your problems. Names and addresses of the various manufacturers are found in advertisements in the various gardening and horticultural papers. You can also get most of them by visiting an Agricultural Show. Sort your catalogues out and put into a pile all the machines

20

MAINTENANCE OF HORTICULTURAL EQUIPMENT

which come into your selected power range. Go through each one carefully and put on one side all those relating to machines which do not cater for your essential needs. Of the balance, sort out those which, besides doing the jobs in your list No. 1, also cover most of the tasks in list No. 2. By this time you will have reduced the number considerably. Do not consider price at this stage for you must be more concerned with the machine itself, An extra few pounds, even if it is over your original limit, might be money well spent, for it could result in a saving far in excess of the expenditure. Again go through these leaflets, studying the illustrations. Look for snags. Ask yourself why this manufacturer failed to say anything about the ease of tool changing, or why that one concentrates upon one feature and ignores others. There is a reason for these exclusions and for that emphasis. Now you are getting down to the heart of the problem, so write and ask for a demonstration on your own land of two or three possible outfits. Ask the agent to bring with him the various implements and attachments you intend eventually to buy. You might find he is unable to bring some of them, but this may be because they take so long to fit that he doesn't want to tackle the job. You can draw your own conclusions. As each implement is demonstrated use the machine yourself and note how it handles, how easy (or difficult) it is to turn or to control. See how the tools are adjusted. Note how long it takes to remove them and fit another. Do not be put off with an airy: "Oh, it takes less than three minutes-it's so simple that I won't bother to do it now." A salesman who really believes in the products he sells will gladly do all the tool changing you want. If you are interested in a trailer, try this, too, and do not forget to load it to the capacity the maker says it will carry. You might find he has been a bit optimistic or has based his calculations when pulling the load along a nice level road. Do not be led away to order the first machine demonstrated even if it does appear to meet your needs. The next one might suit you better or be easier to handle. After all, it is your money and it is up to you to spend it to the best advantage. It is only fair to point out, however, that many salesmen are genuinely interested in the land and will do all possible to see that a purchaser is completely satisfied. From such salesmen a

CHOOSING A MACHINE

21

great deal can be learned, for these know exactly how an imple~ ment ought to be adjusted to suit the different soils. They will provide valuable hints concerning lay-out and planting distances. They can even give you the names and addresses of the best suppliers of seeds and plants, and help with suggestions for marketing one's produce. Some will even tell you not to buy this or that implement just yet because it is still not quite satisfactory. Make friends of these men. You will not regret it. Similarly there are some manufacturers whose sole aim it is to make the best tractor for the small farmer. These will employ practical men-practical growers-and will have their own land to cultivate. Finally, do not buy any equipment you do not need at the moment-or, say, that you will not be needing this season. Prices are falling a little, and anyway you might discover another way of doing the job. Turning now to second-hand machines, it has been said with a good deal of truth that the best way to learn all about a car is to buy an old one. It also applies to a motor cultivator. But those who go in for power cultivation usually do so with a view to profit, so the choice of a machine is a more serious matter. Much of what I have said about choosing a new tractor applies equally to a used one, but whereas a new machine carries a guarantee ( and in any case can be expected to be free of defects) a second-hand outfit might easily turn out to be a dead loss. First, then, select the type of tractor best suited to your needs, then watch the advertisements for one of that model. If you buy from a firm of agricultural engineers the price will be higher than if from a grower, but at least you will know that the engineer has discovered and remedied the more serious defects. He might even have completely overhauled it and be prepared to give a shortperiod guarantee. But buying from another grower is a different proposition. He will naturally dwell on the outfit's good qualities to such an extent that you might well wonder why he wants to sell it. Remember, however, that many a real bargain can be obtained in this way. If you call, by appointment, to see a machine, casually put your hand on the engine. If it is warm the chance~ are that it is a difficult starter and has been made ready for your visit. Not that

22

MAINTENANCE OF HORTICULTURAL EQUIPMENT

hard starting is a serious fault for there are many ways of curing .it easily, as you will see when you read Chapter 4. All the same a man who does not see that his engine starts easily is likely either to be ignorant of engines-in which case he has probably neglected this one-or he is the type who is careless. The results are the same. If you can, take with you someone who really understands engines, but failing that, carry out a few tests yourself. Begin by checking the compression. To do this pull the starter cord slowly. There should be an appreciable resistance. It will be greater if the engine has been warmed up first. Sometimes, however, a valve in a four-stroke engine sticks open, especially if the machine has not been used for some considerable time. There will be no compression, then, of course. A little paraffin oil generally frees a stuck valve if poured into the spark plug hole and left for a few minutes. If compression is sound, take hold of the starter pulley or one of the pulleys on the other end of the crankshaft, and shake it. An up-and-down movement, however small, denotes loose bearings, but there is always some end-play which can be ignored. Look for signs of oil leakage but remember that a wipe over with a cloth soon destroys this evidence. Some people view a very clean machine with suspicion, and there is often good reason for doing so. Start the engine, let it warm up and then open the throttle. Bumps, thumps and knocks mean that a major overhaul will shortly be necessary. An engine should speed up quickly and without hesitation. If it does not it is likely that the carburettor is out of adjustment. Too rich a mixture revealed by black exhaust smoke or a sooty plug are matters which can be remedied quickly, so do not pay over-much attention to them. One cause of sluggishness, however, is a choked exhaust, and that again is something which can easily be cured. It does indicate that the machine has not been decarbonised for a long time, so take that into account when naming your price. Spitting when the throttle is opened quickly is likely due to too weak a mixture, and if this has been going on for a long time it is rather more serious for it results in burned-out valves and plug points. You can check the latter and if they look as if they have been burned in a very hot fire, be careful. Next look at the nuts and bolts. If these show signs of careless

CHOOSING A MACHINE

23

handling, i.e. badly fitting spanners having been used, or maybe a monkey-wrench instead of a spanner, you will know that the owner is no mechanic and that the machine has almost certainly received rough treatment. Take out the dipstick, if the engine is a four-stroke, and look at the oil on it. If it is black then it has not been changed for a long time, or possibly the cylinder is worn. 01). the other hand clean oil might show that the seller has also read this! If you sniff the oil, however, and find it has a nasty, burned smell, suspect cylinder wear and lower your price. Chains should be inspected, too, also the sprockets, for a sprocket with well-worn teeth tells its own tale. Tight chains place a very heavy strain upon bearings, so look out for them. Read the chapter on transmission and chains and you will get some more useful hints. Test the tractor in all gears; note any faults in the clutch and throttle controls and if possible do a bit of cultivating, etc., to check the power output. Examine all the implements for misuse or neglect and then, taking everything into consideration, make your offer fit the probable exp""1se of putting the whole outfit into a serviceable condition.

CHAP TER 3

The Workshop DIREC TL Y a machine or other piece of equipment is made, it starts to deteriorate. The rate of deterioration is speeded up by neglect and reduced in propor tion to the care bestowed upon it. Time spent on maintenance is therefore time spent profitably, at any rate until the equipment reaches the stage when further attention is not economic. This being so it is up to every property owner to prolong the effective life of his plant and machinery and to do so as cheaply as possible. Nearly all th( equipment used on a holding can be kept in sound and workable condition by an ordinary handyman. There is work, naturally, needing highly skilled workmanship, and no attempt is made here to steer work away from the craftsman. But it is'foolish to send for a skilled man if you or an employee can do it equally well and much more cheaply. If you have read the Introduction to this book you will remember that several trades were mentioned. Each of these trades has its own special tools, some of which you will need. You will also need a workshop. Even a small shed is valuable, but try to get something large enough -to take a good sized bench, accommodate your tools, the various bits and pieces of implements and all the oddments required for the repair work. If possible have a place that is big enough to take your tractor. See that the building is weatherproof, not only on account of your tools, but because dryness provides more comfort. The floor must be level and hard and there should be plenty of natural light even when the door is shut. On occasion you may have to work after dark, so if you use oil lamps be sure to leave the engine fuel tank outside and drain all petrol from the carburettor. A strong, firm bench is essential. It should be at least 6ft. long, 2ft. wide, and at a height convenient to suit you. From 30 to 33 in. is about right for the average man. Make the top of stout planks at least an inch thick and clamped tightly together to prevent nails and small oddments falling through. Next fit a good vice; the engineer's type is the best for all round work although if

24

THE WORK SHOP

25

much carpentry is contemplated it is better not to have anything which projects above the bench top. Fix the vice so that long pieces of metal or wood held in it can protru de through the doorway. Just as import ant as the bench are shelves and racks for tools, spare parts, tins of nails, scr~ws, washers, nuts and bolts as well as materials such as paint, putty and so on. It is surprising how much of this one collects in a year or two. If your roof is a strong one it can carry a number of hooks for various oddments. One never seems to have too many tools. A full list of requirements would probably stagger the beginner, but an enormous amoun t of work can be done with a few simple hand tools plus ingenuity. Below is a brief list of items indispensable to the man who undertakes the maintenance of his tractor and other mechanical equipment. No doubt you already have some of them. Engineer's vice Hamm er Hacksaw with adjustable frame and 12-in. blades Pliers Screwdrivers, 8 in. and lOin. Adjustable spanner, 12 in. Stilson wrench or large footprints Files: 1 each second cut and smooth, 10 in. flat Set of Whitworth open-ended spanners, 1 in. to tin. Breast drill (although a carpenter's brace can be used for many jobs) Twist drills, l in. to i in. rising in 64ths Centre punch Tinman's snips Soldering iron (i or i lb.) solder and flux Blowlamp Oilcan As time goes on and you acquire more skill you will probably buy a small grinding wheel and maybe acquire or make one or two cold chisels. For woodwork you will require: Claw hammer Rip saw Tenon saw Chisels, i in. to i in. Oilstone or carborundum stone

26

MAINT ENANC E OF HORTI CULTU RAL EQUIP MENT

Mallet Ratchet type brace Twist bits, set i in. to 1 in. (although twist drills can often be used instead) Pincers Spokeshave or Surform tool (described on page 28) Jack plane Smoothing plane Saw sharpening file Saw set Steel square Again it is likely that you will have several of these. Owning tools is one thing and using them correctly is another. If you watch a skilled man at work you will notice that he works with the minimum expenditure oflabo ur yet gets the best possible results. That is what you should aim at. A hammer, for instance, is not simply a tool with which to hit things -it is a scientifically designed appliance with a handle to match the weight of the head. "Chok ing", or holding the hammer shaft close to the head, means extra work and loss of effect. Hold the hammer near the end of the shaft and direct each blow intelligently and with the right amoun t of force, remembering always the type of material you are striking. Blows should be light on brittle substances like cast iron, and moderate on non-ferrous materials such as brass,. copper and aluminium. Usually it is wise when working on these soft and brittle metals to interpose something to take the shock and prevent damage. Engineers either use what is called a drifta bar of copper about 6 in. long and of a diameter suitable for the job-o r they use a rubber or hide hammer. Hacksaw This tool is used for sawing metals. It consists of a frame to hold a thin blade of tempered steel. Blades are inserted in the frame with the teeth pointing towards the frame tip and then drawn taut with a thumb-screw. The tension of the blade is important, for if it is slack the blade will snap the first time it is used, while a blade that is too tight needs very careful handling. Correct tension must be found by trial and error. Blades are made in different lengths but engineers usually prefer the 12 in. Some blades have thirty teeth to the inch, others have fewer. Twenty is best for general work.

THE WORK SHOP

27

When sawing, hold the work firmly in a vice so that the cut is as near to the vice jaws as possible; this prevents chattering and saves blades. The left hand should grasp the frame end as shown in Fig. 1. Tilt the tool slightly downwards at the front end and maintain that angle throughout the cut. On the forward stroke press down a little with both hands, but release the pressure on the return stroke. Saw at the rate of between 40 and 50 strokes a minute. If you work faster than this the blade will get hot and some of the teeth will snap. Should it be necessary to make a saw cut in a bolt head in order to use a screwdriver, put two blades in the frame for this will give the wide slot necessary. Broken blades can be used for a variety of purposes, especially if mounted in an Eclipse holder. When sawing angle iron start sawing at the apex, and to saw through tubing do not attempt to cut right through, but turn the tube from time to time. These hints prevent broken blades. To saw thin metal, clamp it between two pieces of wood and cut through all three together.

Files and Filing Files are tools well worth looking after, and being made of cast steel they are somewhat brittle. Never drop them or throw them carelessly on the bench. There are several grades of file, those with many teeth to the inch for finishing or fine work, and those with only a few large teeth for removing metal quickly. Here is a list which will help you to choose a file for a particular job. 100 teeth per inch Dead smooth 50-60 per inch Smooth 40 per inch Second cut 30 per inch Bastard 25 per inch Middle 20 per inch Rough Each is obtainable in various lengths and section. There are flat, half round, triangular and square section files. Some have parallel sides and others have tapered. Then there are some which have one edge without any teeth at all. For general work you will need rough, bastard and smooth. Get a half-round rough, twelve inches long, and the other two of the flat type. Store files in a rack at the back of the bench. The file handle

28

MAINT ENANC E OF HORTI CULTU RAL EQUIP MENT

will hold the tool in place. A length of leather strap nailed up to form pockets makes another useful holder. In a damp workshop it is better to wrap the files in a cloth and put them on a shelf or in a cupboard. There is an art in using a file and it is an art worth acquirin~. First grip the work firmly in the vice, then stand in front of it with the feet well apart, one foot in front of the other. Grip the file handle with one hand and put the other on the tip of the file so that the ball of the thumb can be used to apply pressure. With small files this is of course not possible, and in this case take the file tip between the thumb and finger (thumb on top). Lay the file on the work and push steadily forward, applying a light pressure to the tool. Keep the file level throughout the stroke and release the pressure as the file is drawn back. When it is necessary to remove a lot of metal quickly, such as when roughing out a job, use the curved side of a half-round rough file; it cuts quickly and does not clog. Best of all, however, use a Surform tool. This is available either in the form of a plane (hence it has been included in the list of carpentry tools) or of a file. The cutting blade is a thin, hard strip of steel not unlike a file but it is perforated to allow the chippings of metal or wood to get away quickly. In either holder, this blade will rapidly cut all soft non-ferrous metals such as aluminium, copper, brass and so on, and it will also deal effectively with mild steel. Tests have. shown that whereas an engineer's rough file takes off i in. of aluminium, the Surform removes I! in. in the same time. On copper the amounts are approximately i in. with the file and It in. with the Surform. On wood the difference is even greater. Fig. 2 shows plane type, but the same blade fits either frame. Filing should be done at the same rate as hacksawing, namely from 40 to 50 strokes a minute. There is no need to lift the file right off the work on the return stroke; as a matter of fact the light rubbing helps to clear the file teeth, but if you find that on soft metals the teeth of the file do fill up, clear them with a strip of file card obtainable from any ironmonger. This is a fabric backing with short lengths of stiff wire woven in. Tack or glue a strip of the card on to a piece of wood and it will last much longer and be easier to use. Rubbing a piece of chalk over a file before starting to work results in reducing the effective depth of the teeth and a shallower cut is obtained. It thus acts as

THE WORK SHOP

29

a smoother file. Use a new file on soft metals first, going on to harder metals once the teeth have worn a little. Cutting is not so fast, of course, but the files last longer. It is sometimes necessary to file down the end of a round rod in order to reduce its diameter and at the same time leave a shoulder. A simple method is to slip a washer over the rod, then grip the rod in the vice so that the washer rests against the vice jaws. The washer prevents the vice being damaged and at the same time it helps to form the shoulder. Give round or half-round files a slight turn in a clockwise direction as you push forward on the cutting stroke. This speeds up filing and prevents the teeth clogging.

Pliers Pliers should be used only for holding small parts and for cutting thin wire. They should not be used to unscrew tight nuts or on thick, tough wire. Nuts on which pliers have been used soon lose their corners and make the effective use of a spanner impossible. Screwdrivers Screwdrivers are all too often used as chisels but a blow from a hammer generally means a split handle. Keep screwdrivers for their designed work and make sure that they are in a fit condition to perform it. Many people grind the blade to a taper, but this is wrong. The slot in the head of a screw has parallel sides and the driver blade should be ground to suit. Make the sides of the blade parallel for about a quarter of an inch and even if it is too small for the screw slot there will be no damage as there is no tendency for the driver to ride out of the slot as it is twisted. Spanners Considerable force sometimes has to be used when tightening or loosening nuts, hence cheap spanners are generally a waste of money. Good quality spanners, provided they are used intelligently will last a lifetime. The main abuse suffered by these tools occurs through using the wrong size. A well-fitting spanner will actually scrape off the paint from the nut yet not be so tight that it has to be tapped or hammered on. You will save yourself a lot of time and much money if you follow this rule, to say nothing about skinned knuckles.

30

MAINTENANCE OF HORTICULTURAL EQUIPMENT

Shifting spanners have tnelr uses, but a good mechanic seldom uses this tool. It is difficult to get the jaws tight enough round the nut, and the very nature of the design makes it easy for the jaws to spring apart at the tips, giving the same effect as a badly fitting spanner of the orthodox type. Never use a monkey wrench or a Stilson on a nut unless you have decided that the nut is to be discarded. It is true that a Stilson has a tremendous grip, and it is a most useful tool for removing very tight nuts-but in the main keep your Stilson for pipe work. Rusted nuts can nearly always be loosened by applying one of the proprietary easing fluids, and if this fails, it is often less dangerous to one's hands to split the nut with a cold chisel. If the surrounding metal is soft, make a saw cut down the side of, but not touching, the thread, when the judicious use of .a cold chisel will spread the nut open to fall clear.

Drilling Sooner or later you will need to make holes in metal. Special carbon steel drills, known as twist drills, are used for the purpose. Start by marking the exact centre of the hole with a centre punch-a round steel rod ground to a tapering point. Apply the punch to the right spot and hammer the end to make an indentation. This keeps the drill from wandering, as the drill itself has no point. If you require a hole bigger than i in. you will usually find it easier first to drill a small hole, say 1- in., when the larger drill will cut faster. Apply a fair pressure, but not too much on thin drills or they will break. If you are using a hand drill, turn the handle as fast as you can, for most of the drills sold today are of the high speed variety. Be careful not to alter the angle once the drill has entered the metal, and keep just enough pressure to get a good cut. The life of a drill will be lengthened and the work of cutting made easier if a lubricant is used. For aluminium apply paraffin; for copper, mild steel, wrought iron and malleable iron use soapy water. Cast iron needs no lubricant at all, nor does brass. When you approach the end of the metal and the point of the drill just starts to show through, ease the pressure. In course of time your drills will need sharpening. The best thing is to take them along to a garage where a skilful touch upon a fast grinding wheel quickly restores the cutting edge. If,

31

THE WORK SHOP

-. -.

-.

'j-, I

/

I

-'r---

... /

?9

t

I

FIG.

3

however, you have a grinder of your own, experiment with an old drill before touching your better ones. The aim is not only to get a keen cutting edge but also to provide a clearance, which means grinding back from the cutting edge. The correct angle for general drilling work is 59 degrees, see Fig. 3. It is easy enough to make a small gauge out of a piece of tin. Soldering Every handyman should learn how to join metals with solder. The process is quite easy so long as (1) the metals to be joined are clean, (2) the iron is well-tinned and (3) the iron is sufficiently hot. First of all make sure that the surfaces to be joined fit reasonably close, for solder in thick masses has very little strength. Next remove dirt, grease or rust from the areas to be joined. Do this by filing, scraping or rubbing with emery cloth. A single spot of grease or dirt will weaken the joint. The "bit" or copper head of a soldering iron serves two purposes; one is to hold sufficient heat to raise the temperature of the parts to be joined and keep the solder molten. In order to transfer this heat, the tip of the copper bit is filed to provide two or four flat surfaces, one of which must make reasonably good contact with the areas to be joined. The second function of the iron is to assist in spreading the solder over the prepared surfaces, and this requires a clean iron with the point well tinned. Tinning an iron consists of heating it until it will melt solder, removing impurities from the surface to be tinned, and applying the tinning

32

MAINT ENANC E OF HORTI CULTU RAL EQUIP MENT

material. Tinsmiths once used a special mixture of tin and lead which melted at a higher temperature than ordinary solder (which contains a smaller proportion of tin) but since electric irons came in the one grade of solder only is generally used. So to tin your iron, heat it then rub the tip on to emery cloth (or file it) then dip in flux which has the effect of excluding the air, which causes oxidation. Solder applied then flows on to the prepared tip. Spreading is helped if the tip is wiped with a piece of clean dry rag. The clean ~urfaces that are to be joined must also be given a coating of flux, although there are on the market special solders with a flux core. Heat the iron again until it melts solder at a touch. Apply to the job and apply solder, when the metal will melt and flow over the prepared surfaces. Hold the surfaces together until the solder sets, and the job is done. It is clear that a small-headed soldering iron is no use on a large article because insufficient heat is available in the copper and the iron cools too quickly. I,.ight irons are, of course, used for radio work in which mainly thin wires are soldered. Where mains electricity is available the heat is maintained by the element, so there is no need to have a large mass of copper. If ever you have to repair by soldering any closed vessel that has contained petrol, e.g. a tractor fuel tank, be sure to get all the petrol, and petrol fumes, out before applying heat. Drain the tank, then fill it with paraffin oil. Drain this out. Paraffin is less volatile than petrol and it will not explode with the heat of an iron. Some people prefer to be safer still, and fill the tank with water, but the last few drops are difficult to get out. Owing to the large area of a fuel tank and the consequent rapid dispersal of heat, a big iron should be used. When soldering electric cables or other electric fittings, use a paste flux such as "Fluxite", for many of the liquid fluxes contain a corrosive that will subsequently weaken the joint. Always wipe a soldered joint clean when it has cooled. Of late years there has been much development as far as solders and fluxes are concerned, one outstanding achievement being that of a solder paint. This is a semi-fluid mixture of powdered solder and a flux. After the initial cleaning, solder paint is applied with a brush, the parts fitted together and heat applied while the parts are held together. One of the many

THB WORK SHOP

33

advantages of solder paint is that its application is under more contro l than ordinary solder so that a neater job results. The method, too, is economical of solder and of time. Solder paint may be obtain ed from all good tool shops. Other useful products are cored solder wire, solder cream and a dozen or two different kinds of solder for special jobs. There is, too, an aluminium solder, but this should not be used for vessels which have to hold water.

Hard Soldering It often happens that ordinary solder does not make a strong enough job. Fuel pipe nipples which are subject to vibration are a case in point. Hard or silver solder is' considerably stronger, but a different technique has to be used. First of all get some of the solder from a jeweller or from a good ironmonger. At the chemists get some powdered borax. To hard solder a nipple to a pipe, first clean both the pipe and the union thoroughly and make sure that they fit closely together. This is essential because, first, it is easier to make a good joint and, second, the solder is expensive. Cut a narrow strip of the solder and wrap it loosely round the pipe. Once round is sufficient. Slide the solder up the pipe away from the join. Mix a little borax with water and apply the flux with a small brush to the surfaces to be joined. Fit the nipple over the pipe, apply a little more flux at the join, then warm up the pipe and nipple. Now slide the solder down the pipe until it rests on the nipple. Keep the flame of the blowlamp going until the solder melts, then allow to cool. Done carefully itl this way the joint will never break. Hard solder can be used for making repairs which are practically invisible.

Brazing Large joints are often brazed. This consists of joining the two parts with brass. The process is much the same as hard soldering but considerably more heat is necessary. An ordinary blowlamp is hardly big enough for this work and generally a special brazing lamp is used. As a number of these lamps have been sold as government surplus a few hints on brazing might be useful. The parts to be joined should be made to fit reasonably closely, and both surfaces must be well cleaned. It is of course necessary 3

34

MAINT ENANC E OF HORTI CULTU RAL EQUIP MENT

that they be held in contact during brazing, and .often this is done by binding them with wire or using some form of clip or holder. The flux is borax and water, which is applied to the joint. Heat the parts gently to drive away the moisture. ijecause considerable heat is required to melt the spelter, build a hearth of coke breeze, fire-resisting brick or asbestos blocks. Do not use pieces of asbestos cement sheet for these will explode violently and shoot all over the place when heated. Pile the coke, etc., round the job and then raise the metal to almost white heat. The spelte r-in granular form- is put into some of the flux and then applied to the job with an old hacksaw blade, stirring the mixture until the spelter melts and flows into the join. Remove the blowlamp and allow the job to cool. File or grind off surplus brass to make a neat job. Riveting Many articles can be repaired cheaply or made from odd scraps of metal joined together by riveting. The process consists of overlapping the pieces to be joined, drilling holes at specified intervals and clamping the pieces firmly together with rivets carefully burred over. To make a sound lap joint the rivets must be selected according to the materials with which they are used, bearing in mind any particularly heavy strains the joint is likely to undergo. Rivets are obtainable in copper, brass, aluminium, iron and so on, and in a variety of thicknesses, lengths and styles of head. Except when joining thick iron plates, copper, brass or aluminium will generally be found the most useful. The question of rivet diameter is important, and a sound rule to get the right ones for a particular job is to measure the thickness of the two plates and divide this by three-quarters; thus if the two plates are together ! in. thick, use a iIr-in. rivet. Next mark the position for the rivet holes. In a single lap joint the centre of each hole should be not less than twice the rivet diameter from the edge of the sheet, so that with i-in. sheets there should be i in. from the rivet to the edge. As to distance apart, we again use the rivet diameter as a guide, and the spacing should if possible be four diameters. Having selected the rivets and marked out the position for the holes, clamp the two sheets together in the required position

THB WORK SHOP

3S

and drill through both at once to ensure proper register. The in snugly hol~ should be of a size that permits the rivet to slide but not be loose. Insert a rivet and inspect the projectitl'g portion for length. Just enough should be left to form a good head and, although there is no rule as to the amount, I usually find that if the amount projecting is about equal to the diameter of the rivet, it is not far out. If the rivet is too long it will bend over and make an unsightly, as well as weak, joint. If cut too short there will not be enough to make a good head which again means that the joint will be weak. Replace the rivet and turn the job over, putting the rivet head on a firm surface such as an anvil or a vice. Take a hammer and strike the projecting rivet squarely and firmly one blow to spread the rivet above the hole and hold the sheets reasonably :firmly together. Now turn the hammer over so that the ball e!ld comes into use, and strike the rivet all round the projecting part, working round and round. Direct the blows towards the centre (not vertically downwards) to make a round and well-shaped clinching head. The object is to shape the head with the minimum number of blows, for "repeated hammering makes the rivet brittle. Do not hammer heavily or for too long as this will draw the plates so tightly together that they will buckle. In view of all this, practise on odd scraps before tackling a proper job. There are several ways of joining metal sheets by riveting, for if it is not possible to overlap them and make a strong enough joint, butt the two together and rivet a strip across both of them, using, of course, a double row of rivets. This is known as a single butt joint see (a), Fig. 4. To get even more strength a strip may be used each side, this making a double strap cover joint as in (b). In either case observe the directions given about spacing, etc. For the majority of jobs a snap head rivet is suitable, this having one end like a half ball (and you make a similar one on the other end when you hammer over). Others have countersunk heads but these are generally used when the metal plates are comparatively thick or when projecting heads are inconvenient. A countersunk headed rivet is frequently the best to use when fitting handles to spades and forks- at least they save a deal of filing.

36

MAINTENANCE OF HORTICULTURAL EQUIPMENT

Useful repairs may be done with fiat-headed copper rivets so long as the joint does not have to suffer too much strain. These rivets are obtainable in solid, hollow, and bifurcated types but the solid are the best for general use. Bifurcated rivets do not hold so well or for so long as solid ones. Copper rivets are used

(a)

(b)

FIG.

4

to join leather belts, and in this case it is necessary to slip a copper washer over the rivet before clinching it. When patching a tank, get someone to hold a heavy hammer on the rivet head as you burr the other end over, or the metal plates will be buckled. One last point: should you be using brass sheet, anneal it first because it will harden up as it is hammered. Heat to a cherry red and plunge into water. This, incidentally, is opposite to the annealing of steel, for sudden cooling makes steel brittle. Steel is softened by heating, then allowing it to cool slowly. Loose Nuts

One trouble frequently encountered with farm machinery is that nuts work loose, bolts wobble in their holes and the thread becomes so damaged that the nut cannot be screwed down tight again. An excellent tool for re-forming these threads has recently been put on the market. It comprises two hard steel plates, hinged at one end and threads tapped in a row along the join. Tore-form a thread it is only necessary to open the hinge, "put the damaged bolt in the correct half-die, close the hinge tightly and then unscrew the bolt. The one tool takes bolts of the following sizes: t, fir, i, t, iIr, t, and! in. Models are

*,

THE WORKSHOP

37

available for Whitworth, B.S.F. and A.N.F. threads. It is a tool well worth having, but note that it will not cut new threads on a plain bar, nor is it effective if the whole of a bolt thread is badly damaged. In these conditions it is necessary to use proper thread-cutting dies. Two types of die are available, one consisting of two halves set in a frame, and the other a circular piece of steel not unlike a round nut. The thread in these is usually tapered so that it gradually finds its way along the bolt as the die itself is turned. Use plenty of oil when cutting threads and do not try to cut too quickly. Dies nearly always have some form of adjustment, so that the finished size of the thread is not produced until the die has been run along the rod once or twice. Do not use a die on a rod which is too thick for it for this nearly always results in a badly cut thread. Keep the clearance holes in the die free of cuttings and a perfect thread will result. Special die nuts are available for running down the threads of cylinder head bolts. They are used with a spanner. Thread Cutting

Cutting internal threads is done with taps which are fluted steel rods, tapered and with a hardened thread. These tools generally have a square top, and are turned by a tap wrench. The hole in which a thread is to be cut must be the right size. If it is too small the tap will break, and if too large the thread will not be the right depth and thus have little strength. A book of engineers' tables gives the correct sizes, but here are a few of the most commonly used: Thread (Whitworth) 1 in. -Is- in.

tin.

ts- in. ~

4

.

l1l •

Size of hole for tapping. Drill 11 (0·191) .. D (0·246) .. N (0·302) .. S (0·348) .. ts- in.

Taps are usually in sets of three. The first is more tapered than the other two and it is used to cut a fairly shallow thread at the top of the hole. Insert the tap, apply a little oil and affix the wrench. This is a bar flattened in the middle and punched with a hole to fit the square top of the tap. It is unsafe to use any other

38

MAINTENANCE OF HORTICULTURAL EQUIPMENT

turning implement owing to the difficulty in holding the tap square to the job. With one hand on each end of the bar, apply a light pressUre and turn slowly. The tap will gradually feed itself into the hole as it cuts the shallow thread. If great resistance is felt it is a sign that the hole is too small and a continuance of tapping will break the tool. Run the first tap right down, then remove it. The second tap has less taper than the first but it cuts a slightly deeper thread. Use as described above and do not forget the oil. The final tap is parallel except for the first thread or two and it finishes the thread to the correct size. In a properly tapped hole the right size of bolt or screw will turn in easily and neither bind nor be slack. It is worth while learning how to cut threads properly and to have in the tool box a set of dies and taps for the most commonly used nuts and bolts on your machinery. Grinding Wheels

One ofthe most frequently needed tools in the farm workshop is the grinding wheel. An abrasive wheel is actually a circular holder for millions of tiny cutting teeth, each one being really a minute chisel which pares shavings from the metal being ground. As with all other cutting tools, the edges in time become worn and dulled, and when an abrasive "tooth" becomes blunt, the strain on its anchorage'increases and the tooth is broken out, leaving a new one to carry on the work. Here area few general working hints that will be found useful: 1. Do not expect one wheel to do every job equally well. 2. If a wheel is not satisfactory it can often be made so by changing its speed. 3. When a wheel glazes it is an indication that it is too hard. If it wears rapidly it is too soft. 4. As a wheel wears down, its speed should be increased, otherwise it may appear to be s6ft towards the centre. 5. The work rest should be close to the wheel face to prevent the work from catching between the wheel and the rest. 6. Keep the wheel true by using a dressing tool or diamond. 7. Never force work against a cold wheel as the sudden heating may cause the wheel to break.

THE WORKSHOP

39

8. See that the machine is firmly fixed and does not vibrate, also that the bearings are not unduly loose. Keep the bearings well oiled. 9. Wheels should not be forced on to the spindle, but be an easy, sliding fit. 10. On power-driven machines particularly, the spindle should be threaded left or right hand so that the wheel-tightening nuts will tend to tighten as the spindle revolves. Principles of Mechanics The possession of all the tools mentioned so far, and even the ability to use them with reasonable skill, does not turn one into a qualified mechanic, any more than the possession of a field and some seeds makes one a good grower. Something else is required. Just as the grower must have some understanding of the soil, of the nature of plants and their individual needs, so must the would-be mechanic possess a certain appreciation of the principles upon which he works. Every machine and every piece of equipment is based upon certain "Laws of mechanics", and the successful maintenance of machinery presupposes an understanding of them. This may sound rather alarming, but it is really quite simple. All constructions, whether of wood or of metal, are fitted together, and usually the principle of the wedge is involved. When a screw is turned, all that happens is that the threads of the screw are pressed tightly against similar threads made in the wood. It is the friction between the screw and the wood which prevents the two from separating. Similarly with a nut and bolt. A nut stays on the bolt because of friction. It is to increase that friction that a spring washer is put under a nut for, if the nut works loose, the spring washer operates to increase the friction and to reduce the tendency for further movement. You may have noticed that some bolts have "coarse" threads (i.e. but few turns to the inch) whereas others have "fine" threads, or many turns to the inch. It is not by mere chance that the thread of a bolt used to secure a cylinder head to the cylinder has more turns to the inch than a bolt used to clamp a bracket. Within limits, the finer the thread the tighter can the parts be clamped together, and certainly there is less chance of the nut shaking loose. But there comes a point when the threads are so

40

MAINTENANCE OF HORTICULTURAL EQUIPMENT

close together that they lose strength, hence it is easier to "strip" the threads from a fine-threaded bolt than it is from a coarse one. To counteract this, stronger metals are frequently used, particularly where very tight clamping is necessary. That is why cylinder head and similar bolts are made of high tensile steel. You probably begin to understand now why some bolts break when you apply excessive leverage on the nut-the bolt is simply pulled apart by the strain. If you glance at a set of spanners you will notice that they vary in length-the small one being the shortest. If, then, in an endeavour to prevent a nut from unscrewing, you slip a tube over the end of the spanner and use plenty of force, you are in danger of over-straining the bolt, and although it might not snap immediately, it may be so badly strained inside that it will break before long. Three things have been mentioned: friction, wedges and leverage, and if you examine any piece of machinery you will find that these three principles are utilised. Even in a simple glued joint in woodwork, friction is involved, for although there may be no screws, the glue resists separation because the particles adhere closely and dislike the friction involved when being torn apart. And what holds a nailed joint? Simply friction between the nail and the wood. Bear these things in mind as you' work, and before starting on a job just think out the principles involved. It will not be long before you begin to appreciate not only the tools you use, but the details of the construction upon which you are working. And as a result, you will turn out better work and, in time, become a sound mechanic.

CHAPTER 4

Engines the beginner an engine is a complicated affair, mysterious, and at times exasperating. But every part of it is essentially simple. Fig. 5 shows some of the parts. (1) is the cylinder, a cast iron or steel barrel polished smooth inside. (2) is the cylinder top or head. In some engines the cylinder and head are all in one

TO

FIG. 5

piece. (3) is the piston, an inverted cup of cast iron or aluminium alloy. (4) is a steel bar called a gudgeon pin which rests in the walls of the piston and passes through the upper end of the rod (5). The lower end of this rod-the connecting rodencircles a cranked shaft to which is attached a heavy flywheel. If the piston is pushed downwards the connecting rod turns the cranked shaft and the flywheel. The force which pushes the piston down is some form of oil product which is burned inside the cylinder. The burning is started when the piston is at the top of its compression stroke, and the combustion of the fuel 41

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MAINTENANCE OF HORTICULTURAL EQUIPMENT

produces a quantity of gas under high pressure. This forces the piston down, turns the flywheel and drives machinery. To ignite the fuel an electric spark is made to occur in the cylinder top when the air/fuel mixture is under compression. The spark is produced by a machine called a magneto. The fuel has to be mixed with a large quantity of air before it will bum properly, and the device which measures and mixes them in the correct proportions is called a carburettor. Thus, provided an engine is mechanically sound, an adequate spark occurs at the right time, and the air /fuel mixture is correct, then the engine will start and run. The air/fuel mixture enters the cylinder through a valve which opens as the piston descends and closes when the downward movement is finished. As the piston rises again it compresses the mixture and the electric spark ignites the fuel and forces the piston down again. This time another valve opens and the upstroke of the piston forces the burned gases out of the cylinder. There are thus four operations-induction, compression, firing and exhaust-these FIG. 6 forming what is known as the four-cycle principle. Fig. 6 shows a typical valve. It is made of high quality steel to withstand hammering and the heat of combustion. The valve is shaped like a mushroom and the bevelled edge makes a gastight seal. A photograph of a valve in an engine is on page 174. The valve stem slides in a guide and a spring closes the valve when the cam no longer forces it open. In some engines the valves are placed side by side in a part of the cylinder casting, and in others they are in the cylinder head. A great deal of the efficiency of an engine depends upon the valves, for unless they are really gas-tight some of the compression is lost and the engine cannot develop its full power. Attached to the engine crankshaft is a gear-wheel which meshes with another on a shaft. This shaft carries the valveoperating cam, an oval-shaped piece of metal. Both the inlet

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and the exhaust valves open once every two revolutions of the crankshaft. Just when the piston begins to descend on its inlet s~oke the cam lifts the inlet valve off its seat. The descending piston lowers the air pressure in the cylinder so that the air outside, being at a higher pressure, rushes in. The opening is connected to the carburettor, and air and fuel enter together. When the piston reaches the bottom of the inlet stroke the cam allows the valve to be closed by the spring. Compression and firing strokes follow, and then it is the turn of the exhaust valve. This operates in exactly the same way except that it opens a little before the piston reaches the bottom of its stroke and it closes just about the top of the exhaust stroke, when the inlet valve once more opens. Although the head of each valve makes contact with the burning fuel the inlet is cooled to some extent by the incoming mixture. The exhaust gases, however, pass right round the exhaust valve head, which often becomes red hot. There is one other aid to the retention of compression and that is the piston ring. This is in effect a cast iron ring of slightly larger circumference than that of the cylinder. The ring is, however, cut so that when the two ends are closed the diameter is the same as that of the cylinder. Thus the ring, which tries to regain its original diameter, presses lightly against the cylinder walls and prevents the escape of the gases. Piston rings rest in grooves in the piston walls and are often prevented by small pegs from moving round the grooves. The object of this is to prevent the ring openings (for usually there are three rings on a piston) coinciding and so allowing the escape of gas. Two-strokeEngines Another and very popular type of engine is that known as the two-stroke. We have seen that in the engine previously -described the complete cycle of operations requires two complete revolutions of the crankshaft, but in the two-stroke the four requisites of induction, compression, firing and exhaust take place during one revolution. Assume that the piston is at the bottom of its stroke. As it rises it creates a partial vacuum in the crankcase and a mixture of air and fuel (the fuel in this engine is petrol to which some lubricating oil has been added) enters the crankcase. At the same time the ascending piston is also compressing the previous

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charge of fuel in the cylinder. Thus in this single movement of the piston we have two out of the four essential operations, induction and compression. When the piston reaches the top of its stroke a spark occurs, the fuel is ignited, and down comes the piston on its power stroke. As it descends the piston uncovers an opening in the cylinder wall, an opening which leads down to the crankcase, so that the piston forces the fuel mixture up a tube (called the transfer port) and into the cylinder itself. By this time the combustion of the previous charge is complete so that· the new charge is not ignited. The fresh charge enters the cylinder under partial compression and forces the spent gases out through another opening (the exhaust port) which has been uncQvered by the piston. This engine therefore has no valves. The cycle is now complete-induction and compression on the upstroke of the piston and firing and exhaust on the downstroke. Every time the piston reaches the top the mixture is fired, giving the two-stroke a "purring" sound compared with the spaced bang of the four-stroke. The two-stroke has very few moving parts, hence it is cheaper to manufacture than the four-stroke; moreover it is smaller and lighter for equal power. It is, however, less economical of fuel. If you have followed me so far you will be able to understand the rest of the engine's equipment and before long have the ability to diagnose'those troubles which are so mysterious to the uninitiated. Common to both types of engine are two instruments, the carburettor and the magneto. A carburettor, as we have seen, is a device which mixes air and fuel in the correct proportions needed. This is important for if there is too much fuel to air we have what is called a "rich" mixture and this causes an engine to run badly, to acquire a great deal of soot and carbon and to exude a black smoke from the exhaust. On the other hand if the mixture contains less petrol than it should the mixture is "weak". This makes an engine get too hot, loose power and, if carried to excess, stop running. Fig. 7 shows the principle of a carburettor; the drawing is of a simple spray of the type used domestically for spraying tlykiller. When the pump handle is pushed in a stream of air is forced over the top of a small tube, the lower end of which is

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FIG. 7

immersed in liquid. The rush of air carries with it the air in the vertical tube and this is followed by the liquid. Thus what eventually issues from the instrument is a mixture of air and liquid, the latter in the form of a spray. A similar but more elaborate device is fitted to an engine. From Fig. 8 you will be able to recognise the principle in application. Petrol flows by gravity from the fuel tank into the float chamber. When the chamber is nearly full the float closes a valve and cuts off the supply. The level of the fuel in the chamber is then roughly the same as the top of the jet. As air passes into the engine it flows round the jet carrying with it some fuel in the form of a spray. The size of the jet and the speed of the air flow both affect the quantity of fuel reaching the engine, and in most light tractor engines there is a means of altering the jet size.

FIG. 8

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MAINTENANCE OF HORTICULTURAL EQUIPMENT

The air is made to travel quickly by passing it through a restriction called a choke tube (seen shaded in the illustration). The fastest speed is reached as it passes through the narrow part of the choke, hence the top of the jet is put at that point. There is no need for me to complicate matters by explaining everything about a carburettor, but you !will need to know how to clean and adjust these instruments. Dirt sometimes finds its way into a petrol tank and to prevent it reaching the jet-which is a very small hole-one or more filters are used. Usually there is one in the fuel pipe where this joins the carburettor. On the end of the pipe is a brass "banjo" coupling inside which is cut a groove. Petrol flows down the pipe into this groove and through a small drum-shaped filter made of a very fine mesh wire gauze. Fig. 9 shows this coupling unscrewed. The bolt which secures the coupling is hollow and the fuel passes through the filter and inside the bolt to the float chamber. Note the gauze and the fibre washers. One of these washers must be each side of the banjo before the bolt is tightened. In spite of this filter, however, dirt and sometimes water get into the float chamber. To remove this the chamber must be taken off and the float removed. Fig. 10 shows the carburettor of a Villiers four-stroke engine. Unscrew the long cap nut at the bottom, then the fibre washer, the hexagon nut, and another fibre washer. The float chamber will then come away. When" replacing do not forget the washers. When the cap is removed a small brass screw and lock-nut are seen. Do not touch these for the screw is the adjustment for the jet. Adjustment of the mixture strength is dealt with on pages 56-59. The purpose of the coil spring and the angle arm are a part of the governor mechanism. Many, but not all, light tractors have a governor which automatically adapts the speed of the engine to the load imposed upon it. The principle of governors is quite simple. Encircling a part of the crankshaft is a gear-wheel which engages with another, the axle of which is fastened to the crankcase. Fastened to this second wheel are two lugs which carry a pair of pivoted weights, see Fig. 11. As the engine revolves these two weights move outwards by centrifugal force and in doing so they move a small rod. By a system of linkages the throttle of

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the carburettor is opened or closed according to the movement of this rod, and adjustment is provided to limit the maximum throttle opening. The angle lever in Fig. 10 is, at its upper end, attached to the throttle, and the spring closes the throttle when the engine speed falls. It will be seen that not only can the tension of the spring be altered by lengthening or shortening the support screw, but the leverage exerted on the angle arm be varied by engaging the spring in one of a number of holes.

FIG. 11

Increasing the tension on the spring increases the maximum speed of the engine, but altering the position of the bottom of the spring affects the speed range between no load and full load, as well as changing the normal load speed. Further information on governor adjustment is given on page 67. Light tractors fitted with a governed engine do not therefore require a hand throttle control, although on some makes there is a governor over-riding device. The B.M.B. Hoemate is an example of this. Two-stroke engines are not generally governed.

Ignition The ignition system is probably the most mysterious part of an engine, although it is by no means difficult to understand.

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Let US begin with a simple statement: magnetism produces electricity, and electricity produces magnetism. This is not Completely accurate but it is near enough for our purpose. A magneto has a magnet and as every schoolboy knows invisible lines of force called "flux" or "magnetism" pass from one pole of the magnet to the other. If a bar of iron is put between the poles the flux will pass through it more easily than through air. If a coil of insulated wire is wound on to the iron bar the magnetism in the bar induces a current of electricity in the coil, the current being induced not simply by magnetism but by changing magnetism-a movement of it. If it were possible to switch the flow of magnetism on and off we should find that the current of electricity in the coil flows when the magnetism is switched on, ceases during the steady magnetic flow, and starts again when the switch is turned off. It is a part of the job of a magneto to produce this change of magnetism. This it does very simply for the iron core and coil are fixed, and the magnet goes round and round it-at least this is what happens in the flywheel type of magneto commonly used on small engines. You will remember I said that electricity produces magnetism; the current in our coil produces some, too. Now over the top of this first coil is wound a second coil, this consisting of half a mile or more of very thin, insulated copper wire. When a current flows through the first coil a magnetic field is set up around it. It might help to imagine this as a little cloud of magnetic flux. This cloud moves extremely rapidly around the windings of the second coil and the movement produces a high pressure current in that coil. The faster the movement-either inwards or outwards-the stronger- is the current in "the second coil. In addition to having this stronger current we must see that it arrives at exactly the right moment, which is when the mixture in the engine cylinder has been compressed and the piston ready to descend on its power stroke. This timing is controlled by an engine controlled device which switches off the current in the first winding and produces a collapse of the magnetism surrounding the coils. That switch is known as the contact breaker, and there is an illustration of one on page 171.

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Sparking Plugs The function of a sparking plug is to provide a gap across which the electric current can jump. One side of this gap must be insulated from the other. A sparking plug, then, consists of a metal body which is screwed into the cylinder head and which carries one side (or point) of the gap, the other side, or point (surrounded by insulating material which not only supports it but is able to withstand the effects of considerable heat) being placed a definite distance from the first. Fig. 12 shows a sparking plug in pieces. In order to flow, an electric current must have a path; moreover that path must be adequately fenced in or the current will escape. The electricity from the magneto flows through the rubber-insulated high tension cable to the terminal on the top of the plug insulator, down the central electrode, across the gap to the other "point" attached to the plug body, and back through the metal parts of the engine to the magneto. It is essential that no conductor of electricity bridges the gap between the points or covers the insulator, hence the need for cleaning carbon from the inside of the plug body. It is also essential that if the plug is of the kind which can be taken to pieces for cleaning, the seal between the insulator and the plug body must be gas-tight. If you have followed me so far you can begin to look upon various engine faults with understanding. It is clear that unless the contact breaker points are clean the electricity cannot flow and so no spark will reach the plug. The contact breaker of the Wico magneto, fitted to J.A.P. engines and to many others, is shown in Fig. 13. The two metal contacts which are usually but erroneou.sly referred to as points, are marked "A" and "B" in the picture. Contact "A" is fastened to a rocker arm pivoted at "C". At "D" there is a hard fibre pad. This pad rubs on a metal band secured to the crankshaft. This band is called the cam, and it has a projection on it which at the right time presses on to the fibre pad, separates the contacts, and, as I have explained, results in a spark appearing at the plug points. It is important that the contacting surfaces of the breaker switch are kept clean and flat. A simple but none the less effective method of cleaning is to slip a piece of stout brown paper between them, letting the contacts close on to it, and then pulling 4

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MAINTENANCE OF HORTICULTURAL EQUIPMENT

the paper out. It might be necessary to do this two or three times. To adjust the gap rotate the engine until the points are wide op~n, then slacken the screw marked "E" in Fig. 13. Turn screw "F" until the correct thickness gauge slides comfortably in without being slack or forcing the contacts farther apart. Tighten "E". The screw "F" has an eccentric head so it doesn't matter which way it is turned. Fig. 14 shows the Villiers contact breaker. This operates on exactly the same principle but the method of adjustment is a little different. Set the points fully open as described above, then slacken the screw "A". The plate "B" has now been loosened and may now be moved on its pivot. This can be done with a screwdriver. Use the feeler gauge as above and when the gap is correct, tighten "A" securely. It is always advisable to check the gap once more after tightening the locking screw in case movement of the contact plate has taken place. Looking for trouble

Engines fail to start for a variety of reasons, but assuming that there is no mechanical breakage-and this is unlikely if the machine was last stopped in the normal manner-it is a good plan to adopt a definite routine check. In this way the fault will be located fairly quickly. But before going into the question of fault finding it is as well to have a few hints about starting. An engine and its components might be in perfectly good condition but fail to start. This happens more in cold weather than in warm. When the crankshaft of an engine is turned very slowly the magneto might not produce a sufficiently good spark to ignite the mixture in the cylinder. In very cold weather engine oil coagulates and this makes it difficult to get the desired speed with a starter rope. A change to thinner oil helps considerably. Again, too rich a mixture will prevent an engine starting, and overflooding of the carburettor due to too much use of the "tickler" will cause this. It is seldom necessary to flood the carburettor at all, for if the petrol is turned on and one then sees to the oiling of the machine, the float chamber will be full by the time you are ready. Flooding wastes petrol, anyway. Now for a quick check-up. There must of course be fuel in the tank. Next press the tickler. The sole reason for using the tickler

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is to test the fuel flow, it being nearly always possible to tell by sound if the fuel is in the float chamber. Prove this for yourself by operating the tickler and then turning on the fuel. If you listen you will note a different sound as the petrol enters the float chamber. If operating the tickler produces no result you should first see that the fuel tap is turned on (and this is not quite so silly a suggestion as it seems). If no flow, slacken the banjo coupling nut, Fig. 9. If petrol is in the pipe it will drip from the loosened joint, but if there is none in the float chamber turn . off the fuel, remove the gauze filter from the banjo coupling and inspect it for dirt. A quick on-and-off flick of the petrol tap will show if the pipe is choked. It is, as you see, simply a matter of elimination. To clean a filter wash it thoroughly in petrol or paraffin oil. Do not dry it with a rag or pieces of fluff will adhere; just shake the gauze and replace it. It is seldom that the jet becomes choked but if it does consult the index which will tell you where to look for further instruction. Assuming for the moment that the fuel system is in order the next step is to test the ignition. Remove the sparking plug, reattach the high tension cable, then lay the plug on the engine so that the terminal does not touch any metal part. Use the starter cord and watch the plug points. If the ignition is in reasonably good order there will be a spark. Failure here might mean that the plug itself is faulty or that the magneto is not giving a spark. This can be tested by removing the cable from the plug and holding the end of the lead about l to iir in. from the cylinder, then use the starter cord. If a spark occurs this time the magneto is all right but the plug is not. Don't forget to hold the high tension cable by its insulation or you will get a shock. Most of the sparking plugs used on horticultural tractors are of the detachable type, i.e. they can be taken apart for cleaning. Lightly grip the body of the plug in a vice and, using a wellfitting box spanner, unscrew the gland nut, see Fig. 12. The insulator can now be lifted out. Scrape the inside of the plug body to remove carbon deposit, clean the central electrode; and wipe the insulation with a petrol damped rag. There is a small copper washer inside the plug body to act as a seal between the body and the insulator. Be careful not to damage this washer. When the plug is clean reassemble it, tightening the

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MAINTENANCE OF HORTICULTURAL EQUIPMENT

gland nut firmly. It is possible that the gap between the electrodes will have altered so check this with a feeler gauge. One of these is generally supplied in the tractor tool kit. The usual gap is 0·018 in. but on some engines a smaller or larger gap is recommended. To adjust, bend the outer electrode inwards (a light tap with a spanner or something else that is hard will do this). Never try to bend the central electrode or the insulation win crack. Test the plug again as previously described and if it now sparks replace it and start the engine in the usual way. These two faults constitute the most common causes of trouble. Difficult Starting of a Two-stroke It sometimes happens that a two-stroke engine defies all one's attempts to start it. Usually this occurs if the clutch has been let in too suddenly and the engine stalled. The trouble is due to an excess of fuel in the crankcase, and this must be removed. There are three ways of doing it. The first is to turn off the petrol, remove the sparking plug, and use the starter cord at least half a dozen times. This is, however, not infallible and it can be tiring. The second method is to shut off the petrol and then take out the small plug screwed into the crankcase. Unfortunately on some engines this is difficult to get at. With this plug out, use the starter cord and the excess fuel will be blown out. The third method, and I consider this the best, is to turn off the fuel, then slacken the nut under the float chamber of the carburettor and let the fuel drain out. Tighten the nut again, and use the starter cord. Directiy the engine runs-and it will-turn on the fuel quickly. I have never known this to fail on my Villiers two-stroke, but not all carburettors are so easy to empty. So far, then, we know how an engine works and we have learned about the main starting troubles. The next step is to look after it properly.

Lubrication The purpose oflubrication is to prevent rubbing metallic parts making actual contact. This requires a high quality oil that will retain the essential film in conditions of great heat, pressure, and cold. Hence it is very unwise to use cheap oils. The fact that a lubricant is marked "S.A.E. 40", for example, is no indication

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of its quality but only that it flows at a certain rate at a certain temperature. It can easily happen that an oil will do this at the specified temperature but possess very imdesirable characteristics at higher or lower temperatures. Always use oils marketed by firms of repute. You cannot do better than follow the recommendations of the engine manufacturers in this respect. Store oil in tins which have a cap or stopper, and always wipe off spilled oil. If this is not done grit will get on to it and when the can is used again some of the contaminated oil will find its way into the engine and cause excessive wear. Attention to small matters such as this make all the difference to the life of an engine. If you pour oil into a measure drain the can after use or invert it over a tray. Oil containers should whenever possible be stored in a cupboard and the door kept shut. The same pr/'cautions should be observed with tins of grease. On four-stroke engines regularly check the oil level in the sump and add as needed. The engine instruction book should tell you how frequently the oil ought to be changed. This is best done at the end of the day's work for the oil is more fluid and drains away easily. Two-stroke engines are generally lubricated by the petroil system, i.e. a quantity of oil is mixed with the petrol before the tank is filled. Thorough mixing is necessary. Villiers and most other two-strokes require half a pint of oil to a gallon of petrol, but the B.M.B. Hoemate needs less-one third of a pint to a gallon. This is because this engine has ball bearings. Never vary the two quantities and always use the grade recommended by the engine maker. It is now time to go a little deeper into our subject and to describe various other components. AirOeaners Every gallon of petrol an engine uses has to 00 mixed with something like nine thousand gallons of air to provide the correct mixture strength. This air contains many impurities, some of them consisting of particles of silica, one of the hardest substances known. It is therefore necessary, if engine wear is to be kept to a minimum, to make the air as clean as possible. To do this filters are u~ed. Some of them cohsist of a perforated metal cannister containing a pad of cotton. This is very effective but in

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course of time the cotton becomes loaded with dust and must be cleaned. Remove the cannister, wash it in petrol and then dip it in thin oil. Allow this to drain before replacing. There is a filter with a detachable element, see Fig 15. Unscrew the cannister top, lift out the filter element and treat as above. A third type is known as the oil-washed or oil-bath. In this the air first passes through a gauze screen which removes straw particles and the like. The air then goes down a tube and impinges upon a bath of oil. The heavier bits of material are retained by the oil and sink to the bottom. The air (which travels fairly fast owing to the suction of the engine) then passes upwards through gauze screens. It is by now rather oily and the dirt sticks to the screens which' themselves are usually surrounded by a mist of oil. Dirt is carried down into the container and the clean air passes int" the carburettor. Pad type cleaners need washing every 100 working hours, but the oil bath type needs only to be topped up occasionally, although after 100 hours (and this period has to be shortened in very dusty-weather) the dirty oil should be drained out, the container cleaned, and new oil inserted. A choked filter greatly restricts the flow of air and may alter the mixture strength. Carried to excess this choking will eventually stop the engine. _ More about Sparking Plugs You have been told how to clean and adjust the points of a sparking plug but it does not necessarily follow that the plug will fire. To obtain satisfactory service it is necessary to fit the correct type, for by no means will even the best of makes function properly under all conditions. Although the internal combustion engine is a "heat" engine the operating temperatures vary widely and depend upon the grade of fuel used, the compressfon ratio, and the adjustment of the carburettor. There are many engines-notably those which run on vaporizing oil-which need a plug maintained at a temperature sufficient to bum any fuel or oil off the points. Others require a plug which dissipates heat very rapidly in order to prevent the points themselves burning away. Generally speaking, a cold plug (Le. one which rapidly dissipates heat) has a low insulator seat. This means that the seating between the insulator and the plug body is set fairly close to the

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actual point of firing. A hot plug, on the other hand, has the seating well away from the plug points. Attention to this matter will make all the difference to the performance of an engine and the life of the plug. One would scarcely imagine that the way in which a plug is screwed into the engine would affect the running of the machine, but it is most important that every plug should have its copper washer between the body and the cylinder because this plays an important part in the dissipation of heat. It is a fact that some 80 per cent of the heat is dispersed through this medium. A plug should always be tightened down properly to prevent gas leakage past the threads and hinder the cylinder walls and fins from playing their part in cooling. When buying a new plug either look up the model and make recommended in your engine handbook or ask your supplier to consult the plug charts supplied to him by the various manufacturers. These charts name every make of tractor and give the correct plug (of all makes) to use. It is a good plan always to have a spare plug in store. The condition of the plug is often an indication of the condition of the engine. A sooty or oily plug shows that either the carburettor needs adjustment or that the cylinders are worn. The first ,would occur if the mixture were too rich. Worn cylinders cause over-oiling of plugs. If an engine does not stop when the ignition is switched off, pre-ignition is the cause and is due to the incandescence of the plug points, of carbon, or even of the plug hole threads. Too weak a mixture causes pre-ignition, so will an overheated valve. Yet another cause is a faulty washer or gasket, both of which mean a gas leak and reduced dissipation of heat. Carburettor Adjustments Small engines are fussy about the strength of mixture, but carburettor adjustments have to be made carefully or the engine will not run at all. The principle of all carburettors is the same no matter what make but there are differences in design which alter the method of tuning. The three most common carburettors used on horticultural tractors and small stationary engines are the Villiers, the Zenith and the Amal, there being several different models in each make.

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Zenith Model12T This is used on J.A.P. Model2A engines. Fig. 16 shows two views of this instrument and here is an explanation of the numbers:

12

'.1

5-~.,.-

16

14-~J

i

7

_.__.__._.__._.J FIG. ]6

1. 2. 3. 4. 5. 6. 7. 8.

Banjo coupling on fuel pipe Gauze filter Needle and seating valve Float chamber Float Main jet discharge tube Choke or strangler Butterfly throttle

9. 10. 11. 12. 13. 14. 15. 16.

Throttle operating lever Throttle stop screw Tickler Main jet adjusting screw Slow running tube Float chamber drain tap Carburettor bowl Washer

Fuel enters by the banjo coupling and passes through the gauze filter then down past the needle seating valve into the float chamber. As the float rises and falls so it shuts and opens this valve. When there is suction in the inlet pipe of the engine, fuel passes through the main jet (12) and out through the discharge tube (6). The volume of mixture entering the engine is controlled by the butterfly throttle. To adjust the main jet slacken the nut surrounding the jet needle and turn the needle anti-clockwise to make the jet larger and .so enrich the mixture. Never alter the jet .

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withou t very good reason and, when you do, turn the screw only 1 in. at a time. Always adjust a carbur ettor for fast runnin g before touchi ng the slow runnin g adjustm ent. First decide what has to be done. A rich mixtur e produc es black smoke from the exhaus t and causes the rapid format ion of carbon in the cylinder. Slacke n the nut and turn the screw (12) a little at a time until the black smoke ceases. Then open the throttl e quickly. If the engine speeds up quickly you have probab ly obtain ed the right mixtur e strengt h but if there is a pause before ,it speeds up the mixtur e is a little on the weak side in which case open the jet a shade more. It is a matter of getting a balanc e between the two. When possible adjust a carbur ettor while the engine is under load but if this cannot be done try the machin e on the land and note how it behaves. If it lacks power open the jet a little more but be careful not to get black smoke from the exhaust. As for the slow- runnin g adjustm ent, start by turning the throttl e stop screw (10) clockwise to increase the engine speed, then gradua lly turn it in the opposi te directi on until the engine turns over at about 600 r.p.m. This is very difficult to guess so just carry on until the engine ticks over steadily and does not stop when the throttl e is closed. It might be necessary to increase this idling speed in cold weather. Should you find it difficult to adjust the idling speed examine the gasket between the float chamb er and the barrel or main casting of the carbur ettor, also that between the carbur ettor and the .cylinder flange for if either of these is defective it will upset the adjustm ent. Amal, type 225/3 (Howa rd Gem ID) Consu lt Fig. 17. "A" is the adjusta ble main jet; "B" the throttl e stop screw and "C" the air adjusti ng screw for slow runnin g. Turnin g "A" in a clockwise directi on reduces the mixtur e strength. Start the engine and very slowly screw in the main jet "A" by turning it in a clockwise directi on until the engine falters, then turn it back a shade. It might be necessary to open the jet a little more when the machin e is put to work. If spittin g back occurs it is a sign that the mixtur e is too weak, in which case open the jet. To adjust for slow runnin g screw in the throttl e stop "B" to make the engine run on the fast side when the air screw "C" is

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MAINT ENANC E OF HORTI CULTU RAL EQUIP MENT

screwed. right in. Turn the throttle stop out a little to slow up the speed., then open the air screw until the engine runs faster again. Repeat the adjustments on "B" and "C" until the engine idles steadily with the smallest throttle opening. Sometimes, when the throttle is opened slowly there is a dead spot and the engine .falters and perhaps stops. To cure this turn in "C" a little. If this does not cure it, bring "C" back to the previous setting and then give a little more petrol by very slightly unscrewing the main jet "A". You may find that a little adjustment of both "A" and "C" is necessary, but endeavour to overcome the trouble at "C". Villiers Two types of Villiers carburettor are dealt with here, that fitted to the Mk. 10 industrial engine (used for water pumping, for driving small trucks, and occasionally on a light tractor) and the Mk. 25C which is found on the Howard Bantam Rotavator and a few other such machines. In neither case is there any separate adjustment of the air flow for slow running, hence tuning is easy. Right at the bottom of the float chamber on the Mk. 10 ~burettor (see Fig. 18) is a cap nut. When this is removed the main jet adjusting screw is exposed. To alter the mixture strength slacken back the lock-nut and turn the screw inwards to weaken the mixture and outwards to enrich it. If the original setting has been disturbed, or the needle has been removed to clear a choked jet, it is best to slacken the lock-nut well down the thread and then turn the screw clockwise as far as it will go. This closes the jet completely. Do this carefully and without using force or the needle might be damaged. Now slacken back the screw from two to two and a half turns, and start the engine. Run until warm and then turn the screw in or out until the engine runs smoothly. Next run the engine without load and turn the throttle adjusting screw a little so that it just bears lightly on the carburettor lug. This screw is near the top of the carburettor, and it has a small spring behind it. When the engine runs steadily and does not change speed (or "hunt" ), tighten the lock-nut at the jet adjuster, taking care not to move the screw. To check the work allow the engine to get cold, then start it again. If you find that the choke has to be kept closed for several

ENGINE~

59

FIG. 18

minutes before the engine is running smoothly, then the setting is rather too weak and the jet screw should be turned out slightly. Replace the screw cap. Fig 19. shows part of the Mk. 25C carburettor. The throttle assembly has been removed by unscrewing the knurled ring. To alter the amount of fuel the small screw shown at "A" must be turned. This screw is right in the centre of the throttle slide. Turning this screw clockwise lowers the needle and weakens the mixture. Make half a turn at a time, then replace and run the engine. Reference has already been made to black exhaust smoke, and if you did not read about it, turn back to the notes on the Zenith 12T.

CHAPTER 5

More about Engines of the results of combustion is the formation of a carbon deposit. This attaches itself to the cylinder head, the piston crown, and round the valves (or ports if a two-stroke). It will also get into the piston ring grooves and prevent them doing their work properly; forms on the underside of the piston crown, and also in the exhaust pipe and silencer. The presence of this carbon has the effect of slowing up heat dissipation, causing pre-ignition, and generally reducing power output. It is therefore necessary at specified intervals to dismantle part of the engine and remove the deposit. The frequency with which this should be done depends to some extent upon the completeness of combustion, and as far as two-stroke engines are concerned the recommended period is after every 200 hours of service. This gent
Villiers Two-stroke Decarbonising is by no means a difficult task, and it is certainly one not to be ftightened about. So long as you observe carefully the instructions given here the result will be completely satisfactory. By far the longest part of the job is that of removing sundry parts and fittings so as to get at the engine. Prepare by getting together a few tools-spanners, pliers, screwdriver and so on, and then a quantity of clean rags, a tin of paraffin oil and a brush. A few extra things will be needed for a four-stroke engine but these will be dealt with later. Whether or not you have to remove the fuel tank depends upon the make of machine, but in any case disconnect the fuel pipe, take off the carburettor and also the silencer. The sparking plug must be removed, then the engine cowl. This is usually held in place by two bolts screwed into the top of the cylinder and by three set screws spaced round the magneto back plate. 60

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Remove the· four nuts from the base of the cylinder and then raise the cylinder without turning it. Hold the connecting rod as you lift the cylinder to prevent the piston falling against the crankcase when the cylinder is free. As you know, two-strokes have ports instead of valves, and these ports are uncovered by the piston. It is therefore essential to stop the rings from rotating in their grooves, otherwise the ends would catch in the port edges and break. That is why the rings are stepped and a small peg is fastened in the piston. If the cylinder is twisted as it is raised the rings might break. Fig. 20 shows the engine with the cylinder removed. Note the ends of the rings and the peg in each groove. These are seen more clearly in Fig. 21. Thoroughly scrape the carbon from inside the combustion chamber, using a long screwdriver for the purpose. If you can polish the surface with a piece of fine emery cloth so much the better. Scrape the carbon from the ports and then wash the cylinder in paraffin oil to remove all traces of carbon dust. If you are doing the job in the middle of your busy season you need not remove the piston from the connecting rod, although this ought to be done once every year. Assuming for the moment that this is to be left until next time, wrap a piece of clean rag round the connecting rod to prevent carbon dropping into the crankcase, then scrape and polish the top of the piston. Examine the piston rings and if any are stuck in their groove it will be necessary to free them. This is a delicate job for the rings are brittle. Start by cutting three strips of tin or thin copper about fs in. wide and 3 in. long. Insert one under the end of the top ring and slide it round the piston a little way. Insert the second strip and move both round, keeping them an inch or two apart. Then put in the last strip and space the others so that the ring is raised from its groove and can be pushed off the piston. Repeat with the other. Fig. 21 shows the strips in position and the top ring ready to come off. Scrape the ring grooves carefully and rub them clean with a paraffin-damped rag. Handle the rings themselves very carefully and lightly remove the carbon. If you decide to remove the carbon from the under side of the piston you can leave the cleaning of the top until the piston has

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MAINT ENANC E OF HORTI CULTU RAL EQUIP MENT

been removed. First note which way round the piston is fitted in other words, which side is the deflector. The slopmg side is towards the -exhaust. The gudgeon pin is a light push fit in the cylinder walls and is held in plaCe by two circlips, one at each end. Clean away the carbon from one of them and then with a small pair of tapernosed pliers grasp the protruding ears of the ci£clip and press them together. The clip can then be taken out of its groove. The two ends of a circlip are seen in Fig. 21. The gudgeon pin can now be pushed out from the opposite side. If you have any difficulty over this, get someone to hold the piston while you tap the gudgeon pin lightly with a small hamm er-but do not forget to interpose a drift of soft metal or hard wood. Remove the other circlip and clean away all carbon. Scrape the underside of the piston crown. Piston rings should be replaced with the help of the tin strips, although with careful handling it is possible to do without them. In this case; put one ring on from the piston top and the other from the bottom to save having to make a jump over a groove. Note the position of the step in the rings for this has to fit round the small peg in the piston. Lubricate the gudgeon pin before replacing it, and secure the circlips in their grooves. To replace the cylinder smear some lubricating oil inside it, then hold the piston in one hand and with the fingers press the ends of the top ring together. Turn the cylinder the right way round and lower it on to the piston until the top ring is safely inside· the barrel, then grip the ends of the second ring and let the cylinder downover this too. Do not twist the cylinder at any time. On some engines there is a gasket between the cylinder flange and the crankc ase-se e that this is sound. Screw the cylinder nuts down :firmly. Decarbonising provides a good opportunity to clean the contact breaker points and adjust the gap. On some models of this engine the starter pulley forms part of a cone-shaped casting secured by two set screws. If these are removed the breaker may be reached through the spokes of the flywheel. On other models a dust cover is fastened by three screws. How to service the breaker points was described on page 49. Clean out the carburettor and the silencer before replacing

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them. Tighten all nuts securely and make sure that no leakages can occur through the joints. Villiers Mk. 10, 20 and 25

In addition to the tools and cleaning materials mentioned earlier, get some valve grinding abrasive. This may be bought as a powder or as a paste. Buy two grades, one coarse and the other fine. Sometimes it is possible to buy a tin with a double c01ll,partment, one grade being in each. Fig. 22 shows a Mk. 10 engine with the cowl, etc., removed. Remove the bolt shown at "A", and the two nuts "B", when the carburettor can be taken off. If the screw "C" is taken out access to the valve springs is obtained when the plate is removed. Take off the silencer. There are six nuts holding down the cylinder head, unscrew these and take off the head. With the aid of a valve spring compressor, lift the springs and remove the retaining collars, thus releasing the valves. Scrape the deposit from the cylinder head, from the piston top, and round the valve pockets. This piston is of aluminium alloy and it is better to use a soft scraper-e.g. a piece of copper -to clean it. Lift out the valves, polish the stems with a strip of fine emery cloth, and clean out the valve guides. Fig. 23 shows one of the valves removed. Note the cotter. To grind the valves smear a little of the coarse compound on to the valve face. If you have the powder abrasive, mix with it a few drops of lubricating oil. Insert the valve into its correct guide and rotate it backwards and forwards with the screwdriver, using only a light pressure. Occasionally lift the valve and give it a slight turn before lowering it. When you no longer feel the abrasive cutting into the surfaces take the valve out and wipe both the face and the seating. Grinding should be continued until there is a grey ring right round the valve face. This ring does not have to be the full width of the face, but it must go right round. Wipe both surfaces clean and finish off by using the fine grade of abrasive. Treat the other valve in the same way. If you ~nd that the surfaces are badly pitted the best thing is to get a garage mechanic to grind them on an electric machine. Take the cylinder along as well and he will see that the whole job is done properly.

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MAINT ENANC E OF HORTI CULTU RAL EQUIP MENT

Smear a little oil on the valve stems when they are ready to be replaced, but do not at the moment put the springs back, Lightly tap each valve down on to its seating and then check the tappet clearance. The correct gap is between 0·006 in. and 0·010 in. Insert the feeler gauge and if the gap is less than 0·006 in. take the valve out and with a smooth file carefully trim a little metal off the stem. If you grip the valve in a vice to do this, be sure to use lead vice clamps or the stem will be scored. File the end flat and square, then test again. When the clearance is correct replace the springs and the retaining collar. It might not be necessary to remove the cylinder barrel and attend to the piston rings, but do this every second time you decarbonise. The barrel is held by four nuts, and the piston secured in exactly the same way as on the two-stroke. Treat the rings in the same manner as described earlier. Attend to the contact breaker points, and adjust the gap to 0·015 in. As with the two-stroke, clean the carburettor, silencer, etc. Both of the engines dealt with so far are of Villiers manufacture, and both have the same type of flywheel magneto. It will probably be necessary in course of time to do more than clean and adjust the contact breaker points, for new ones might have to be fitted, or perhaps the condenser will need renewing. In order to get at the armature plate the flywheel must be taken off. This is held in place by a large nut of special design, for in addition to securing the flywheel the nut also acts as a puller. Because the flywheel is not keyed to the crankshaft, the nut is very tight, and a special spanner is made for it. There are on the market some stout box spanners made for 18 mm. sparking plugs, and these fit the nut perfectly. Apply the spanner and strike the bar with a hammer to turn the nut in an anti-clockwise direction. Once loosened, the nut will turn about twice and then stop. It is at this point that the nut starts to act as a puller, and if it is further unscrewed it will gradually draw the flywheel off the shaft. The magneto armature (or back) plate is seen in Fig. 24. Fitting new contact points is simple and a glance will show how the old ones are removed. In the somewhat unlikely event of a condenser breaking down, a new one must be fitted. The condenser is attached to the

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underside pf the contact breaker box and is held in position by the studs which attach the breaker box to the armature plate. To remove the box, undo the two nuts at the back of the plate. If your engine is a Mk. 10 one of these nuts is sunk into a deep recess and a slim box spanner is needed. This nut is actually a cap nut and beneath it is a soft copper washer, the purpose of which is to prevent oil from the inside of the engine from escaping into the condenser box. Next unsolder the primary lead at the high tension coil and remove the box. There are two studs which secure the condenser in place, so take these out. Next remove the screw which holds the lead or wire to the condenser. This wire will have to be unsoldered and drawn through the hole in the box. A sign that a condenser is faulty is that the contact breaker points are badly burned. The engine will also be hard to start. When replacing the flywheel it will be necessary to retime the magneto. First wipe the tapered end of the crankshaft and the corresponding taper inside the cam of the flywheel clean and dry. Slip the flywheel on the shaft and lightly screw up the centre nut, turn the flywheel on the shaft until the timing ma:k (an arrow) stamped on its rim coincides with a similar mark on the edge of the magneto back plate, then hold the flywheel in this position and tighten the nut. If this is done correctly the contact points begin to open when the piston is /2 in. before top dead centre on the two-stroke, and fs in. on the fourstroke. Check this when the starter pulley is turned, then finally tighten the nut by hitting the tommy bar of the spanner with a hammer. On J.A.P. engines, the flywheel is keyed to the crankshaft, so the timing is not upset when the flywheel is taken off. As there is no drawer-nut on this engine, get someone to pull the flywheel forward while you tap the end of the crankshaft with a lead hammer or a mallet. Do not use an ordinary hammer unless you interpose a block of wood or a soft metal drift between the shaft and the hammer, otherwise the thread will be damaged. Condenser replacement on the Wico magneto is easier than that on the Villiers, for it is only necessary to remove the contact breaker connection strip and the primary connection from the 5

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MAINTENANCE OF HORTICULTURAL EQUIPMENT

live end of the condenser and to take out the two screws holding the condenser clamp. Overhauling a J.A.P. Model2A Engine

The full sequence of operations for dismantling this engine is given below, and the procedure is more or less the same for most other makes. Disconnect high tension cable from sparking plug. Remove sparking plug. Remove petrol pipe. Remove petrol tank, complete with brackets and straps. Remove cowl, drawing high tension cable through rubber grommet. Remove breather box and baffle. Remove magneto flywheel, using special extractor supplied for this purpose. Remove high tension cable clip. Remove cylinder head and valve box cover. Remove magneto and felt sealing ring, first disconnecting cutout wire. Remove aluminium bearing plate (6 nuts). Disconnect governor control spring, remove throttle link and throttle lever from carburettor, and from external end of governor rod. Unscrew carburettor from inlet pipe. Remove governor rod bush from crankcase. Remove camwheel bolt, camwheel, cam lever bolt, and cam levers. Remove pinion with special extractor supplied for this purpose, together with governor weight rings. Remove governor sleeve and spring. Remove engine base with oil trough. Remove split pins from big end bolts of connecting rod. Remove nuts and big end cap from connecting rod. Remove connecting rod and piston complete by drawing upwards through cylinder. Remove rings from piston, one circlip and gudgeon pin. Compress valve springs with collars and remove cotters. Remove crankshaft from crankcase. To reass~mble the engine, reverse the above procedure. The chief thing to bear in mind when dismantling any engine

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is that great care must be used. Think out what has to be done, then use correctly fitting spanners. When possible replace all -nuts on their bolts so that they are not lost. Put all gaskets in a box. As each part is removed, clean it ready for reassembly and, if a part seems complicated, make a rough drawing before unscrewing anything. This is particularly necessary when dismantling the governor linkage and springs. With regard to governor adjustment, manufacturers seldom give detailed information, merely saying that nothing should be disturbed unless it is absolutely necessary. This advice is of little value if you only hear of it after you have removed some of the parts. The illustration on page 170 will be of assistance here with regard to Villiers four-strokes, and Fig. 25 shows the arrangement on the J.A.P. Model 2A. On larger J.A.P. engines, however, the governor mechanism is hidden. Nevertheless, the principle is much the same in all engines. Fig. 26 is a photog raph of the governor contro l on a larger model J.A.P. The knurled screw "A" is locked by the nut "B" which has to be slackened before any adjustment can be made. Turnin g the knurled screw clockwise increases the· governed speed for this action alters the pressure on an internal coiled spring. Any adjustment which strengthens the effect of the governor spring results in a speeding up of the engine before the governor takes effect. On the Villiers engine, the governed speed can be altered by screwing the nut" A" (see Fig. 10) down the rod, and tightening the nut "B", this having the effect of increasing the spring tension. There is, however, anothe r adjustment, for if you look at the bottom of the spring you will see that it is hooked into the second hole from the left. Where, however, the load is a fluctuating one, such as is encountered when operating a piston type water pump, more even running is secured if the spring is hooked in the end hole. This increases the leverage on the bent arm. On the J.A.P. engine (see Fig. 25) the tension of the spring is increased by slackening the set screw "A", moving the short lever to the left and tightening the screw again. Similar provision for damping out fluctuations is provided by the holes into which the other end of the spring is hooked. But do not forget that erratic running under load can be caused by an incorrect air ffuel mixture.

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Servicing Inform ation for .l.A.P. Engines Mode1 2A. 98 c.c. Valve clearances: Exhau st 0·008 in. Inlet 0·008 in. Inlet valve opens 8° before T.D.C . Magne to: Wico flywheel. Magne to timing : 30° before T.D.C . Contac t breake r gap: 0·018 in. Sparki ng plug: 14 mm. Gap 0·018 in. Carbur ettor: Zenith 12T. Sump capaci ty: I pint. Model 4/2. 245 c.c. Valve clearances: Exhau st 0·010 in. Inlet 0·008 in. Inlet valve opens 17° before T.D.C . Exhau st valve opens 48° before T.D.C . Magne to: Wico Type A.516BZ. Magne to tUning: 25° before T.D.C . Contac t breake r gap: 0·015 in. Sparki ng plug: 14 mm. Champ ion LlO. Gap 0·020 in. Carbur ettor: Zenith 24T-2. Sump capaci ty: 1 quart. Model 4/3. 288 c.c. Valve clearances: Exhau st 0·010 in. to 0·012 in. Inlet 0·008 in. Inlet valve opeJls 17° before T.D.C . Exhau st valv
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Model 6. 588 c.c. Valve clearances: Exhaust 0·020 in. Inlet 0·010 in. Inlet valve opens 17° before T.O.C. Exhaust valve opens 48° before T.O.C. Magneto: Wico Type A.576BZ. Magneto timing: 20° before T.O.C. Contact breaker gap: 0·015 in. Sparking plug. 14 mm. Champion LlO. Gap 0·020 in. Carburettor: Zenith 24T-l. Sump capacity: 3 pints. Model 55. 824 C.c. (Two cylinder) Valve clearances: Exhaust 0·020 in. Inlet 0·010 in. Inlet valve opens 17° before T.O.C. Exhaust valve opens 48° before T.O.C. Magneto: Wico Type A.937BZ. Magneto timing: 20° before T.O.C. Contact breaker gap: 0·015 in. Sparking plug: 14 mm. Champion LIO. Gap 0·020 in. Carburettor: Zenith 24T-2. Sump capacity: 6 pints. A Wico Type A magneto is illustrated in Fig. 27. It is fitted with an impulse coupling which gives a high density spark for starting, achieved in the following manner. When the engine is rotated by hand (or starter motor) the magneto armature is held still, but at the moment a spark is due at the sparking plug a trip is released and, by means of a spring, the armature is turned rapidly. The fact that the magneto is being operated at a much greater speed than the engine results in a strong spark-considerably stronger than would be produced were the two machines run at the same speed. Once the engine has started, the impulse coupling goes out of commission and the speed of armature rotation is half that of the engine crankshaft. Engines fitted with this device should not be run continuously at less than 165 r. p.m., otherwise the impulse coupling trips all the time and consequently wears rapidly. Replacing this type of magneto correctly is a little puzzling if the work has not been done before. First remove the contact breaker cover and then hold the impulse lever so that it does not engage with the impulse stop. The lever in question projects

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MAINTENANCE OF HORTICULTURAL EQUIPMENT

through the coupling, see "A", Fig. 27. Now turn the magneto shaft in an anti-clockwise direction until the contact breaker points begin to open. Next turn the engine crankshaft until the piston is approximately i in. before top dead centre on the compression stroke (both valves will be closed). Couple up the magneto, making sure that the lugs engage properly. Check the alignment of the drive by turning the engine crankshaft a few times before the magneto is finally secured. If you are renewing any of the securing bolts, be sure they are not too long and bottom in the tapped holes before the head grips. Fig. 28 shows the contact breaker of this magneto. To adjust the contact gap, turn the engine until the points are fully open, then slacken the screw "A" and turn screw "B" until the correct gap is obtained, then tighten "A". Information on cleaning points is given elsewhere. These magnetos have two spring-type oilers and after every 200 hours fill either one with Wakefield Castrolite lubricant. The rocker cam is lubricated from a small pad. This should be removed after each 1,000 working hours and a quantity of summer grade motor transmission grease (no other) kneaded into it. The impulse coupling should be flushed out with paraffin oil if the trip arm fails to engage or disengage, or if the mechanism becomes clogged with dirt. Do not let any paraffin enter the magneto. Servicing Information for Villiers Engines Mk. 10. 98 c.c. Valve clearances: Inlet and Exhaust 0·006 in. to 0·010 in. Magneto: Villiers flywheel type. Ignition timing: is in. before T.D.C. Contact breaker gap: 0·012 in. to 0·016 in. Sparking plug: 18 mm. long reach Lodge CB3. Gap 0·020 in. Carburettor: Villiers. Sump capacity: 1 pint. Mk. 20. 206'5 c.c. Valve clearances: Inlet and Exhaust 0·006 in. to 0·010 in. Magneto: Villiers flywheel type. Ignition timing: -i\ in. before T.D.C. Contact breaker gap: 0·012 in. to 0·016 in. Sparking plug: 18 mm. long reach Lodge CB3. Gap 0·020 in. Carburettor: Villiers. Sump capacity: 1 quart.

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Mk. 25. 256·5 c.c. Valve clearances: Inlet and Exhaust 0·006 in. to 0·010 in. Magneto: Villiers flywheel type. Ignition timing: is in. before T.D.C. Contact breaker gap: 0·012 in. to 0·016 in. Sparking plug: 18 mm. long reach Lodge CB3. Gap 0·020 in. Carburettor: Villiers. Sump capacity: 1 quart. Note: To time the valves on these engines, rotate the cam shaft gear until the centre punch mark coincides with a similar mark on the other gear-wheel.

CHAPTER 6

Transmission POWER from horticultural tractor engines is transmitted to the land wheels in various ways. Usually there is a combination of two or more of the following: belts, roller chains, gear-wheels, shafts. Because an internal combustion engine develops low power when it is turning slowly some form of reduction gear is used so that although the engine may be run at two or three thousand revolutions a minute, the land speed of the machine is something less than three miles an hour. Drive is in two or more stages. The first of these might be by Vee belt from the engine to a shaft; the second stage by roller chain to a gear-wheel and from that througH more gear-wheels to the axle of the machine. In another cultivator we might find that the first drive is by chain to a clutch, then through a gear-box, and then by chain or gearing to the wheel axle. On yet another we find a direct drive by shaft to a centrifugal clutch, and from that through gear-wheels or perhaps a worm reduction drive to the land wheels. More and more light tractors, however, use a Vee belt for the initial drive. This method has several advantages for it is simple, cheap, and flexible; moreover it eliminates the need for an elaborate clutch. The belt is normally slack but it is tightened to transmit power by the pressure of a free-running wheel called a jockey. This is controlled from the handlebars of the machine. Thus when the lever is operated the belt is made to bed down into the pulley grooves and take the drive by friction. Moving the control lever in the opposite direction slackens the belt, and drive ceases. This might appear to be a crude method but it is most satisfactory in practice. If, for instance, there is a sudden and additional load imposed upon the cultivating tools (such as would happen when they encounter a buried rock) the belt slips provided it is not being run too tightly, thus protecting the engine and implements from injury. Belts which are used as clutches do not, of course, last as long as those which merely 72

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drive, but no one can grumble at twelve month s' service from a belt which costs but a few shillings. Operators can do much to lengthen the life of belts, many of which are run too tight. So long as they transmit the norma l power without slipping, it is uneconomical to run them tighter for it only means that the belt will stretch rapidly and wear more quickly. The advice given by the majority of light tractor makers is to tighten the adjuster until the belt can be pressed down a distance of about one inch at a point midway between the pulleys, but of course much depends upon the spacing of the pulleys and how much pressure is used. Even to give a figure in pound s is not much help for who can judge this with accuracy? One could use a spring balance but these are notoriously unreliable. The safest plan is to tighten the belt until it no longer slips under normal load. Both fiat and Vee belts deteriorate if oil is allowed to remain on them, and water is likely to rot the fabric. So keep belts dry and clean. Never leave a belt tightened when the machine is not at work, although the advice is difficult to follow if the belt is used to drive the dynamo of a lighting plant. But when possible slacken a belt when it is not required to drive. In winter it is a good plan to hang belts in a dry place. Metho ds of joining fiat belts used on some stationary engines are given on page 118. Chains With regard to chains, these have a very long life if they are cleaned and oiled regularly. Chains are often totally enclosed and run in an oil bath. This is undoubtedly preferable but it adds to the cost of the machine, also to the time required for servicing. A few machines have chains which are exposed to dust, dirt and weather, and regular attention is here most necessary.. A broken chain means a laid-up machine so it pays to keep chains in good condition. Fig. 29 shows the parts of a modem roller chain. Note the hardened steel bearing pins, the bush and the roller. Strictly speaking a chain ought to be washed at the end of a day's work, a counsel of perfection indeed. All the same do not let mud dry on a chain if you can help it. A swill with water and the application of a brush will do no harm so long as the chain is well lubricated internally. Do not be afraid to apply oil generously

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for althou gh some of it will fly off as the chain revolves, a good deal will work its way into the rolling parts. Occasionally take the chain off, wash it in paraffin oil and then dip it in engine oil. If you can leave it in either the paraffin or the oil bath all night, so much the better. Many chains are fastened by spring clips which have open ends. To remov e one

HARDENED STEEL BEARING PIN HARDENED STEEL BUSH STEEL

FIG. 29

of these clips insert the point of a screwdriver or similar tool under one side of the spring and prise the end out of the groove of the bearin g pin. When replacing a clip see that the closed end lies·in the direction of rotatio n. Anoth er type of fastening consists of a long split pin which is pushed throug h a hole drilled in the bearin g pin. The life of any chain may be lengthened considerably if it is run at the correc t tension. There should be an up-and -down movement of about one inch at a point midwa y between the two chain sprockets. This amoun t is for sprockets set two feet apart, and a slightly lesser amoun t of play is needed when the sprockets are closer. Never run a chain too tight or it will wear out rapidly

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and the sprocket bearings will be overloaded. On the other hand, if a chain is too loose it might jump the sprocket teeth and break. Various methods of tension adjustment are used, but when it is necessary to move a component bodily, see that the sprockets do not get out of alignment. One check of this is to put a straightedge across the two sprockets-it should touch at all four points, i.e. the inner and outer edges of both sprockets. Another check is to examine the inside of the side plates of the chain. If one plate shows considerable wear then the sprockets are not parallel or in line. To make· a sound repair to a chain it is advisable to use a bearing pin extractor which simplifies the removal of outer links. The tool is very simple to use, for after it has been positioned correctly the pin is pressed away from the plate merely by turning a tommy bar. When both pins on the same link are thus pressed, the plate comes off. These pins cannot be used again, however, and a new outer link must be fitted. Two kinds are available, one designed for speedy but temporary repair in the field, and the other for a permanent repair. For this the pins have t~ be peened over after the side links are put on. Lay the chain on an anvil or other hard surface and then use a special tool called a fetching-up punch. This forces the plate close to the shoulders of the pins. Mter that, rivet the pins with a light hammer. Fig. 30 shows at (a) the parts to be removed when a roller or inside link is broken, (b) the link for a temporary repair (c) a new inner link, and (d) the repaired chain. After much service chains and sprockets reach the point where they should be discarded. One useful test for wear is to remove the chain from the machine, lay it on a.fiat surface and pull it out straight. Then measure its length. Now push the ends together so as to take out the play in all the links, then measure again. It will probably be best to start at one end and work along to the other, closing the links together as you proceed. If there is half an inch or more difference between the two measurements it is time to fit a new chain. Never fit a new chain to old sprockets otherwise after half an hour's running the new chain will have stretched considerably and might even be almost as bad as the old one; certainly it will be strained. If new sprockets are fitted to an old chain it is likely that the links will jump the teeth, when there will be a jam followed probably by breakage.

76

MAINT ENANC E OF HORTI CULTU RAL EQUIP MENT

(a)

(b)

(c)

COIII1U}' of RoIoId cl Co","lrY Chain Compony LImited

FIG. 30

When chains run in an oil bath it is essential that sufficient oil

is maintained in the bath, so occasionally look for signs ofleak -

age due to a broken gasket or a lost bolt. In the absence of a proper gasket, make one out of stout brown paper, and seal it wj.th gold size. To cut the gasket first clean the surfaces to be joined, then lay the paper on the most convenient of the two surfaces. Rub a finger round the outside edge to mark it, and cut carefully with scissors. If the cover is an aluminium casting the judicious use of a light tack hamm er will cut the paper exactly to size. Repeat on the inner edge and then cut the bolt holes with the ball-end of the hamm er or punch them out with a bolt. It is a good plan to cut one hole, insert a bolt, and then work at the other end of the gasket, inserting bolts as the work proceeds. This prevents the paper from moving. Put a coating of gold size or other similar material on both of the surfaces, apply the gasket, attach the cover, and then leave it to set before filling with oil.

Dift"erential Gears An examination of light tractor specifications shows that a few two-wheelers have a differential gear which gives positive drive to both wheels when the machine is turning a corner or being steered straight ahead. Its chief disadvantage apart from the high manufacturing cost is that if one wheel slips or spins on a muddy patch, the outfit comes to a halt. This can be overcome

TRANSMISSION

77

by fitting a differential lock which acts as if both wheels are rigidly attached to a single axle, in which case if one wheellooses its grip the other will propel the tractor. Such a device is on the Gem rotary hoe, for engaging the rotor gear also locks the differential.

Hub Ratchets A good many machines are fitted With wheel hub-ratchets: these operate in much the same way as the free-wheel on a bicycle. A positive forward drive is given to the wheels when the machine is proceeding in a straight line, but when turning a corner the ratchet on the inside wheel comes into operation. The drive is then on the outside wheel only. As soon as a straight course is again steered, drive is resumed on both wheels. The system has one disadvantage, for if the machine has to travel down a steep hill, both ratchets over-run and the operator has to hold it back. When, however, he is sitting on a laden trailer things are apt to become exciting, for not all trailers have efficient brakes. One or two manufacturers fit a ratchet lock device so that either or both wheel ratchets are put out of operation when desired, but as this necessitates stopping the machine and inserting a pin into the ratchet, one soon gets tired of it and learns the art of dodging obstructions when travelling fast. There are a few machines which have neither of these fitments, both wheels being secured to a single axle. The disadvantage here is felt when turning corners, for one has to lug the machine round with locked wheels. Actually this is not so bad as it sounds, for the only cultivators I know with this form of drive have close-set wheels, and when the machine is on the move, no difficulty at all is experienced on turns. It is only when the wheels are spaced more than a foot or so apart that the drag is noticeable. Gear and shaft transmission require no attention other than oiling. Clean out oil cups occasionally and, if grease nipples are fitted, make sure they are clear and that the grease really does go where it should. New nipples are cheap compared with shafts and bearings. It may happen that due to some irregularity the gun cannot make proper contact with the nipple and grease spurts out, but if you put a piece of rag over the nipple before applying the gun the leakage can often be prevented. The grease is, of course, forced through the cloth.

78

MAINTENANCE OF HORTICULTURAL EQUIPMENT

Clutches Various types of clutches are used on small machines, and in addition to the jockey pulley type already described there are dog clutches, centrifugal clutches, and car type plate clutches. In a dog clutch slots in a collar engage with projections in another collar, thus there is either a positive and sudden engagement or there is none at all. A clutch of this type is naturally unsuitable for linking engine power directly with tractor transmission. It can be used, however, to engage and disengage shafts or gears, both of which are stationary and then driven through a more gradual engagement type of clutch. On the Trusty tractor there is a centrifugal clutch on the engine and two dog clutches on the secondary shaft. The machine must be stationary. when the dog clutches are engaged. As a rule these clutches require no attention or even lubrication although the operating meChanism needs oil. Fig. 31 shows the countershaft of the Trusty. The large chain sprocket in the bottom left-hand corner is driven from a small sprocket behind the centrifugal clutch. The countershaft is splined (i.e. grooved) and one of the two parts of each dog clutch is free to slide along it, although it has to rotate with the shaft. The other half of the dog is secured to the chain sprocket on the right of the picture. Each sliding dog is operated by a lever, and friction between this and the dog is borne by two bronze segments shown at "A" in the picture. To replace these segments remove the nut from the bolt "B", release the old segments and slip new ones in their place. These segments must be kept well lubricated. A centrifugal clutch operates in much the same way as the brake shoes of a car. The engine crankshaft carries a shoe assembly and as the engine speed rises the shoes are flung outwards by centrifugal action until they rub against the inside of a "brake drum" which, as we have seen, has attached to it a chain sprocket. Eventually the shoes press so hard against the drum that they rotate it, thus driving the machine through the dog clutches. As soon as the engine speed falls to a certain point the shoes close in a little and come away from the drum, which then ceases to turn. To renew the linings of these shoes, either obtain a new pair from the manufacturer (in which case the fabric will be drilled

TRANSMI<:SJON

79

ready for the rivets) or from a garage. In this event the lining will probably be cut from a roll. The garage man will fit it for a shilling or two but if you prefer to do the job yourself, proceed as follows. Carefully measure the length and width of the old lining and add an eighth of an inch to its thickness to allow for the wear that has taken place. Buy the lining and a supply of rivets. Warm the fabric to make it bend easily, then shape it over the shoe. Clamp it in position with a few fretwork or other small clamps, then drill down the rivet holes right through the lining. When this is done countersink each h<.>le on the face of the lining which comes into contact with the drum. This can be done with a large twist drill or with a carpenter's countersink bit. Grip a piece of mild steel rod in the vice to act as an anvil. Now insert a copper rivet through the lining and the shoe. Punch the head well into the countersink. Insert another rivet opposite it and knock this down too. Turn the shoe over and lay the rivet head on your anvil and peen the end over with a light hammer. Strike the rivet squarely to begin with for this will spread it to completely fill the hole and also give a slight bulge to the end. Finish off with oblique blows until you have formed a neat p.ead. Repeat with the rest of the rivets. Finish off the job by chamfering off the ends of the lining for a distance of about an inch. This will ensure a smooth engagement.

Bantam Drive The method of drive on the Rotavator Bantam embodies Vee belt, shaft, a spur gear type of gear-box, and worm gears. Fig. 32 shows the genera1lay-out. The engine is at the front and is mounted on a hinged frame which swings from one side to the other when the clutch control lever is operated. When the lever is pulled up the engine moves to the right and the belt is tightened. A double pulley is fitted to the rear end of the engine crankshaft, one pulley being larger than the other. According to which of these pulleys carries the belt, so the speed of the drive shaft is affected. This shaft carries another double pulley, and in the illustration the "high belt gear" is in operation. The drive shaft carries a worm drive to a two-speed gear-box and thence to the land wheel axle. The wheels are attached to a single axle and rotate together at all times. The main drive shaft

80

MAINTENANCE OF HORTICULTURAL EQUIPMENT

is carried on towards the rear of the machine and terminates in a dog clutch, the other half of which is attached to the rotor shaft unit. There are therefore four land speeds, two for each belt speed, and two rotor speeds. As to belt adjustment (in this case clutch adjustment) this is

I

I

I

Engine I

-

.::::::::;.

~

~

~

~

/ ' l\~/

::::~ ~

/

~

/

~

/

V~\ ~

~ ~

I

~

~

~

~

-

FIG. 32

/

~

~

-

~

TRANSMISSION

81

done by turning a screw which has the effect of moving the engine frame a little more to one side. Tightening the screw (see Fig. 33) moves the engine to the right and takes up some of the slackness in the belt. On the B.M.B. Hoemate the clutch is in the form of a jockey pulley. To adjust the belt tension slacken the set screw shown at "A" in Fig. 34 and slide the collar up the clutch control rod. If necessary the top collar can be moved away from the spring. Tighten the set screws firmly.

Tyres Buying new tyres is a costly business today but much can be done to postpone the day of replacement. The chief cause of deterioration is under-inflation, for when a tyre is run too soft the flexing of the cover walls tends to separate the fabric from the rubber bonding, and a blow-out will occur when thc tyre is pumped up hard. Under-inflation also causes the cover to creep round the rim and this will sometimes tear out a valve. It is always a wise plan to fit dust caps to the valves for they not only serve to retain the pressure but they keep dust from the valve seating. If no cap is used dirt is bound to prevent the valve from doing its work properly. If you find your tyres going soft, start by testing the valves. You can do this by putting a drop of water 011 the valve stem and seeing if the bubble increases in size. Less refined people like myself use spittle which always seems to give better results. Often the application of the pump will reseat the valve and make it airtight, but as a rule it is better to fit a new valve core. Buy a box of five from your garage man and keep them in your tool shed. Punctures seldom occur, but when they do, make a sound repair if only to save the trouble of doing the job again. Tilere are two methods of mending a tube, vulcanising and patching. The former means taking the tube to a garage. but caretul patching is alnwst as good, for tractor tyres do not ha\e to put up \vith the ~ame strains as those on a car. Be very careful how you use tyre le\ ers or you may ruin the tube completely. The tyre bead is un~tret('habk, being made of wire, but the ""ell of the rim is smallcl in diam",ter than is the outside edge, so push a part of the bead down into the well, then get the opposite edge over the rim. ()

82

MAINT ENANC E OF HORTI CULTU RAL EQUIP MENT

Once you have found the puncture wipe round the damaged area with a petrol damped rag, then roughen with sandpaper an area extending for about an inch all round the puncture. Within reason, the rougher the surface the better the repair. Apply a thin coating of rubber solution and leave it for several minutes to dry. Most patches come off because they are put on too soon. Apply a second coat and when this appears dry cut a piece of patching material slightly smaller than the solutioned area. Strip off the linen covering, and without touching the prepared surface, put the patch centrally over the injury and press it well down. Replace the tube carefully. A little air pumped into it will assist matters. It is quite easy to replace a valve that is torn out, although if the stem is of rubber, get a new one. Repair the damaged tube by patching, then put the new valve in a new place just as if it were a patch. But don't forget to cut a hole for the air to enter, and to see that you don't cover it with the stem flange. If the tube has a split, trim the edges with scissors and remove all jagged fragments. To prevent a slit from extending press the end between the thumb and finger and cut out the end of the tear with scissors. This will leave a small round hole. Do this at each end, then repair as described.

CHAPTER 7

Implement Maintenance maintenance is just as important as keeping the tractor in good order. Tools that are looked after properly serve both to lessen the work of the tractor and increase the quality of the job done. Fortunately it takes very little time to keep implements clean and sharp, and for the most part few tools are required other than spanners and a grindstone or a file. All implements become blunt after a season or two's wear, and the speediest way to sharpen them is on a grindstone. Doubleended, or reversible cultivators should be sharpened on the outside of the curve, i.e. the underside when they are on the tool standards. Whenever possible follow the original grinding angle. Cultivator points can either be ground or drawn to a point by a blacksmith-unless you have your own forge and anvil. There comes a time, of course, when the cultivator has worn so much that it has to be discarded because the tool standards must be set so low as to impose a great strain on the standard and the tool-bar frame. If the point is drawn under heat, remember to retemper the metal again by heating about two inches of the tip to a dull red and then plunging it into water. Be careful not to make the point hotter than red heat as the metal will be too hard if quenched then. Disc harrows should be dismantled and each disc sharpened oil the concave side. Mowing attachments are now available for the majority of horticultural tractors for the grassing down of orchards is becoming popular. There are three types of grass cutters; the ordinary lawn mower, the rotary scythe and the cutter bar. Lawn mowers can be adapted for use behind or in front of motor cultivators, but on the whole, smallholders, nurserymen and growers do not use this type much because they are only affective if the grass is cut very frequently, the design of the mower being such that it will not deal well with long grass. Rotary scythes are available either as self-contained machines having their own engine, or as an attachment to a light tractor.

IMPLEMENT

S3

84

MAINTENANCE OF HORTICULTURAL EQUIPMENT

The cutting mechanism is simple for it merely consists of a few triangular blades (of exactly the same type as fitted to the cutter bar) attached to a steel disc. This disc is rotated by engine power and it is upon the speed with which the blades strike the grass that the quality of the work depends. Cutter bars operate on a different principle, being, in fact, exactly the same as that of the large cutters used by farmers at haymaking time.

Lawn Mowers IT the machine is a self-contained unit, the engine will in all probability be a two-stroke, but whether it is this or a fourstroke, the information given in Chapters 4 and 5 will enable the operator to maintain it in sound condition. As far as the cutting mechanism is concerned it is not generally advisable for the amateur to sharpen the knives because these are best done on a special machine. Nevertheless the cutting qualities of the machine can be improved by less costly means. As you will remember, engine valves are ground in with an abrasive paste, and the same material can be used on mower blades. First of all clean the blades thoroughly and then adjust the bottom plate (which is actually a knife) so that it makes light contact with each of the blades when the rotor is slowly turned by hand. Now spread a little of the abrasive paste on to the knives (lower one as well). If you have only powdered abrasive, put some oil on the bottom blades and then sprinkle the powder on to it. Now rotate the blades quickly in the reverse direction to that of the normal cutting. It might be necessary to remove one of the gear-wheels to do this, but it all depends upon the type of machine. Continue grinding until each blade rubs lightly and evenly against the bottom cutter and has a sharp edge then thoroughly wash the abrasive from the machine. It should be possible to cut a piece of paper in a mower, the rotating blade and the lower blade working as a pair of scissors. Putting the rest of the machine into good order is merely a matter of cleaning, oiling and adjusting, and by this time you should be able to do this without difficulty.

Rotary Scythes The best way to sharpen the triangular blades is to remove them

IMPLEMENT MAINTENANCE

85

and bolt them to a piece of wood which is then gripped in a vice. The cutting edge may be restored with a file. See that the original cutting angle is preserved. The maintenance of engines and driving belts has already been covered.

Cutter Bars This type of implement is really like a gigantic pair of hair clippers. The main frame consists of a steel slide to which are attached a number of fingers or guides and often, but not always, an equal number of ledger plates. These form half the cutting mechanism and act as a half-scissor. Sliding backwards and forwards over the ledger plates are the knives which are riveted to a steel bar. Before using a machine that has been stored, take out the knife blade and clean both the blade and the main frame of the cutter. Then remove rust with fine emery cloth. Generally speaking the fingers should be reasonably sharp and pointing straight to the front, and although this is less necessary on a farm mower driven by a big tractor it is advisable to reduce the friction as much as possible when the power unit is a small one. Fingers are generally bolted to the main bar, so any bent ones should be removed and straightened on an anvil with a hammer. When ledger plates are fitted they are riveted in place, so check for looseness. It is not advised to tighten up loose rivets but to renew them. Grind or file the cutting edges of each ledger, keeping to the original angle. On the B.M.B. Hoemate and some other makes of cutter bar there are no ledger plates so it is most essential that the cutter knives are kept sharp. Knives are invariably riveted to their bar, and if any are loose file off the rivet heads, punch them out and insert new ones. The knife bar is held in position in the cutter by clips bolted to the main frame, and if these clips are damaged, either reset them or fit new ones. If bending is resorted to see that each clip has a clearance of about -h in. Some clips are of cast iron and these will not bend although possibly one may break. Fit another. Freedom of movement of the knife is of course essential but there must never be too much play. If the blade itself is bent remove it and straighten it on an anvil, tapping the bulges with a hammer. Twisted bars can be corrected in the same way.

86

MAINTENANCE OF HORTICULTURAL EQUIPMENT

When sharpening blades always keep to the original angle, for if the cutting bevel is made wider the knife will nick easily, and if too narrow the cutting will be impaired. Sharpen each blade so that the point is always in the centre. Use great care when sharpening knives as it is easy to gash the hand deeply. Clamp the knife firmly and use a,1ong file. It is a good plan to fit a guard of some sort on the file blade to protect the left hand. A strip of old rubber tube wound on a few inches from the outer end of the blade and fastened with wire or string will give some protection and a stout glove will also help. Most agricultural engineers have special mower grinding stones, but these are rather expensive. Once the blade is sharp and it slides smoothly in the guides, give some attention to bearings. On some machines there is no provision for adjustment, but on others, sliding collars or shims take up play. Clean out all oil holes and lubricate the bearings, working each one until the oil penetrates freely. The last job is to see that the knife travels the correct distance along the guides. Attach the implement to the tractor but do not fit the driving belt. Turn the belt pulley slowly in the operating direction and watch the knives. They should travel from the centre of one finger to the centre of the next and then back again. If the point of the knife blade does not reach the middle of the finger, make the adjustments recommended by the manufacturer of the cutter. Usually it is a question of altering the length of a connecting rod, but there are other methods. Always operate a cutter bar by hand before engaging power as this procedure prevents breakage should there be tightness m an obstruction. If your mower is of the side type it is essential that the bar is dead square with the line of travel. Different makes have different adjustments, so follow the instruction book in this respect. Mter mowing is finished clean the implement carefully, oil the bearings and, if the machine is to be stored, coat the knives and other bright parts with a rust preventive. This will keep the metal safe from the effects of weather for several months. It is usually best to remove the knife and store it separately, for the preparations named above are slightly sticky. A wipe over with a paraffin damped rag will remove the coating and leave the metal bright and clean.

IMPLEMENT MAINTENANCE

87

Rotary Hoe Unit Whether your machine is designed specially for rotary hoeing, or whether you have a separate rotary hoeing attachment, the unit must be considered as an implement needing periodical attention. It is not always realised that on low-powered machines overloading must be avoided. Bent blades, tight bearings due to lack of lubrication, loose hoes, and a choked shield all have the effect of increasing the demands upon the engine. At intervals through the season, remove the unit, clean it and put it on a bench for inspection. Test the security of each blade by checking the tightness of the bolts. Use a good ring spanner or a well-fitting double-ended spanner on blade nuts, for they must be drawn up tight. Fit spring washers under the nuts if any are missing. Pay particular attention to the bolts securing the hoes at the outer ends of the rotor shaft, for if these work loose they can cause a good deal of damage. When in the field, a loose outer bolt generally makes itself heard by a knocking sound. Stop immediately this is noticed and tighten the bolts, pulling them up tightly by using a hammer on the end of the spanner. Bent hoe blades cause considerable drag. Some machines are provided with a tool for straightening blades, but it is not always possible to use it when the rotor is attached. Take these bent blades off and straighten them in a vice or on an anvil. The useful life of rotor blades varies considerably and is dependent upon the type and condition of soil cultivated. They cab usually be used, however, until they are worn down to an inch in width, although on hard ground it might be advisable to fit new blades and to keep worn ones for an emergency or for soft ground. If you should remove all the blades at one time be sure that the new ones are fitted correctly, i.e. that the sharpened edge and not the back of the blade strikes the ground first; it is easy to make a mistake and have to do the work again. See, too, that the blades point in the correct direction, otherwise the rotor shaft will be out of balance and the quality of the work will be affected. Keep the ends of the rotor shaft free of grass, weeds, etc., for these have a habit of winding themselves around so tightly that they can actually stop the engine. Strawberry runners and bindweed are two offenders in this respect. Pay attention to the oiling

88

MAINTENANCE OF HORTICULTURAL EQUIPMENT

and do not postpone it. All rotors should be lubricated before starting the day's work. Wheel Bearings

Implements and machinery use many types of wheel bearings ranging from the simple axle shaft running in a hole bored in the wheel hub to ball or roller bearings with oil seals and lubricating nipples. A point frequently overlooked by users is that a wheel is not only intended to revolve on its shaft but should do so without undue side play. Because of the conditions in which farm implements operate, regular attention should be given to these bearings. With a plain bearing, play can only be fully removed by truing the axle end in a lathe and fitting a bush in the wheel hub-a job for the trained engineer. Sometimes, however, a certain amount of the play can be taken out by adding washers, the object being to lessen the gap between the wheel hub and the securing pin. A nail is often used as a "temporary" fastener, but always put a washer behind it. If the play is excessive a thick washer can be made from a piece of gas pipe. Rust Prevention

Two-fifths of farm machinery troubles, repairs, and the need for replacements are attributable to rust. The tractor itself is in fairly constant use and is less affected, but the plough, discs, cultivators, the seeder and mower are only used intermittently and are more often than not left out in the open. Within a few days rust forms. Rust is not static, for a coating will slowly but surely get thicker and thicker until working parts become immovable; metal is literally eaten away, and the time comes when it will no longer stand the strain for which it was designed. Mter considerable research a number of compounds have been produced which not only prevent rust formation but which are easily applied to all machinery. More than one compound is available according to the degree of protection required. Ensis 256 has the property of displacing water from metal surfaces, leaving a protective film which will last for several months. This fluid can be used on disc and tined cultivators, mouldboards.

IMPLEMENT MAINTENANCE

89

coulters and landslides of ploughs-in fact any farm machinery. A single coating of 256, brushed or sprayed on, will actually pu~h away all water and leave the metal partially protected. A second coat applied in two days' time will finish the job. When the machine is needed it is only necessary to wipe the protected parts with a paraffin damped rag and the metal will be bright and clean. For those appliances which have to be left completely in the open air for several months, the 256 is first applied and then a solid compound (No. 352) put on. These two together will give protection for a year or more. It is estimated that a year's protection can be given to an implement at the cost of from 1 to I! pints of fluid. Ensis oil (452) for using inside engines which are to be laid up is sold in 5 gallon drums at 6s. Od. per gallon. No. 256 at 6s.3d. per gallon in 5 gallon drums, and the solid compound No. 352 costs 6s.4d. per 7 lb. tin. They are made by Shell-Mex and B.P. Ltd., and can be obtained through any of their agents. Most of the oil companies market similar products.

Broken Bolts Too much force when tightening or attempting to unscrew a rusty bolt sometimes results in the head being twisted off. First of all apply some easing fluid to the thread, then, if the position of the bolt allows it, use two hacksaw blades in the frame and cut a slot in the projecting stud. If a screwdriver will not loosen it, try a screwdriver bit in a carpenter's brace. If this fails, use a small pipe wrench. Sometimes the bolt breaks off flush, but try to turn it using a centre punch and hammer. If this fails, get a screw extractor from your tool shop. This is a hard and tapered screw with a steep, left-hand thread. It will be necessary to drill a hole down the broken bolt to a depth of about half an inch. The extractor is then screwed in, and as it is turned it will usually loosen the bolt. Do not forget to apply an easing fluid or, if that is not available, some paraffin oil. As a last resort, the bolt will have to be drilled out. If this is done very carefully and the right-sized drill used, it might be possible to use the old threads again by clearing them with a set of taps.

90

MAINTENANCE OF HORTICULTURAL EQUIPMENT

Sprayers

The principle of most crop sprayers is that a fluid is forced at high pressure through one or more small apertures, emerging in the form of a mist. The suburban gardener uses a small handoperated double-acting pump which draws the fluid from a bucket and forces it by direct pressure through the nozzle. Those with larger areas go in for the knapsack type which comprises a small tank, inside which is a pump. Air pressure sends the liquid along a short length of hose and through one or possibly two small nozzles on a tubular lance. Similar in principle are those sprayers designed for the market gardener who has but an acre or two, for the somewhat larger tank is mounted on wheels and the spray boom is set horizontally and carries three or four nozzles. Next come the engine-driven pump models with a larger tank and wider spray boom, and these are followed by bigger outfits still, the power being from a tractor P.T.O. shaft. Finally there are huge machines with 500-gallon tanks and pumps driven by engines of 20 h.p. or more. The periods during which spraying can be carried out are very limited, depending upon the stage of growth of the crop and also upon weather conditions. It is thus essential that the equipment be ready for use at a moment's notice, for a hold-up can be a costly business. And not only must the plant itself be in perfect order but it is vital to ensure that the liquid to be sprayed is free from solid impurities. A spray plant, then, comprises a power unit, a pump, a container, pipe lines and nozzles. Sufficient information has already been given in this book to enable the power unit to be maintained properly, and the chapter on water pumps will also prove useful. The Drake and Fletcher "L.O." pump illustrated in Fig. 35 is actually a shallow well water pump. Owing, however, to the corrosive nature of many of the fluids used, frequent inspection of pump leathers and glands is necessary. Here, then, are the maintenance instructions for this particular pump. Referring to the illustration, "0" is an oil box and it should be topped up with engine oil. There are wicks inside the box which carry the lubricant to oil holes. See that these wicks are not disturbed. Two connecting rods are on this pump -one of them is marked "R". On the big end of each, at "G"

IMPLE MENT MAINT ENANC E

91

is a greaser which should be kept filled and the cup given a turn every three hours. The small ends of the connecting rods have oil holes; add a few drops of engine oil to these every three hours. Apply grease daily to the driving gears, and fill the gear shaft bearing greaser, giving the cap of this a turn every three hours. The method of repacking and adjusting glands has been dealt with on page 115, to which reference should be made. If the pump has been used for lime sulphur and has been in store for some time, renew the gland packings for the sulphur will have set solid and caused the gland to bind on the plunger. The gland adjusting nuts are shown at "N". Should it be necessary to remove the valves, take off the two caps "C", the gear bracket "B" and the plug "P". There is no need to take off the connecting rods, but after removing the four fixing nuts the countershaft "S" can be rotated to push the bracket off the studs and allow it to be lifted clear. Remove the complete valve cages with the special spanner supplied with the pump. The strainer on the end of the suction pipe must be entirely immersed in the fluid and all joints in the pipe kept tight. Knapsack. Sprayers

These are very popula r among those with only small areas devoted to fruit. The principle by which they operate is essentially the same as that of the larger units, and very much the same maintenance instructions apply. As with all sprayers, it is the washers which give the most trouble. Leather and leather composition dry out and crack, and natural rubber deteriorates when it is in contact with grease or oil. It is therefore advisable to test for leaky joints, using plain water, before starting out to spray. Spare washers should always be on hand, and those which have dried or cracked should be renewed. It is often possible to revive leather washers by soaking them in soapy water and then kneading a little grease into them. If the washers are removed at the end of the spraying season and kept in Vaseline (petroleum jelly) or in engine grease, their life will be lengthened. Manufacturers are now endeavouring to replace leather and rubber washers with oil-reSisting materials. Nozzles wear in course of time, and this means both increased consumption of material and a change in the size of the droplets

92

MAINT ENANC E OF HORTI CULTU RAL EQUIP MENT

which may be detrimental to the quality of the work. Users should be on the watch for this increase and change, renewing thtUets when necessary. With regard to the general maintenance of sprayers, one cannot do better than follow the advice of Shell Chemicals Ltd., who have issued a useful booklet on the subject. Here, for instance, are their recommendations for DAILY routine: At the end of each day's spraying drain the tank, taking care that in the case of poisonous sprays such as DNOC and DNPB, there is no contamination of ponds and streams or formation of pools from which livestock might drink. Wash the tank out with clean water and spray a quantity throug h the booms and nozzles. If the machine has been used for acid spraying, neutralise any acid residue by means of a solution containing 2 lb. of washing soda to 10 gallons of water. Follow this by a rinse of clean water. If frost is expected at night, drain the pump and the spray lines. (Note that in the Drake and Fletcher pump, Fig. 35, there are four drain taps marked "i)". An alternative is to remove the plugs, there being one tap or plug at the gear end of the pump and three taps or plugs at the other end. Drain from each of the four places. Start the engine and let it run for about half a minute as this will help in drying out the pump.) Clean the filters if necessary. If the tank is 1iIIed with water overnight, DO NOT add the spray chemical until ready to start spraying in the morning. When changing from one material to another, the tank, booms and nozzles should be washed as described above, and acid residues removed with a soda solution. All traces of growthregulating weed killers must be removed before using an insecticide or fungicide on crops which would be susceptible to the previous material. The washing solution should in this case be 20 lb. soda to 100 gallons of water. When washing out a sprayer make sure that every path that the liquid can take is traversed by the cleaning material. It might be desirable to loosen the relief valve spring to ensure that there is a sufficient flow throug h the valve to flush it clear. It is always advisable, when putting a sprayer away at the end of the season, not only to thoroughly clean the appara tus as described above, but to wash it out with 2 quarts of Shellestol mixed with 100 gallons of water. Shellestol is a chemical neutral

IMPLEMENT MAINTENANCE

93

liquid sold primarily as a spreader and wetter for use with insecticides and fungicides, but it is also an excellent detergent for spraying machinery. It mixes readily even with hard water. At the beginning of the spraying season, check all washers and renew any that have perished. Check, too, the hose connections. Finally, thoroughly wash the machine out again with water or with the Shellestol solution. If any parts of the apparatus have been treated with Ensis fluids as a protection against rust, wash them with paraffin oil. After washing valves with paraffin, rinse them with Shellestol and water. Dusting Machines Daily: Lubricate the bearings using the correct grade of lubricant as recommended by the manufacturer of the implement. Fill the dust hopper and make sure that pieces of sacking and labels do not get into the hopper. At the end of each day's work empty the hopper and remove any pieces of odd material such as bag string, which have wrapped themselves round the agitator. Cover the hopper with a waterproof material so that it will be dry in the morning. Clean dust from the fan, and clear the flexible pipes. Keep a lookout for oil leaks in seams, or serious clogging may occur. At the end of the season, clean the machine down thoroughly, lubricate all bearings and store the outfit in a dry place. Rubber belts should be taken off and stored carefully.

CHAPTER 8

Diesel Engines diesel engines are becoming popular for such jobs as water pumping, driving generators for lighting and power plants and operating barn machinery. Despite their high initial cost they possess a number of advantages, such as low operating cost, high power output, and extraordinary reliability. In a diesel engine air only is compressed in the cylinder but to a much greater degree than is the fuel in a petrol engine. High compression raises the temperature considerably, the air becoming hot enough to ignite the oil fuel which is sprayed into the cylinder by a fuel injection system when the piston is at the top of the compression stroke. These engines require no sparking plug, no magneto, and no carburettor. There are a number of different makes of diesel engines suitable for farm work, the power range being from 3 h.p. upwards, but here we will discuss the Lister Model 3/1 (Le. 3 h.p., single cylinder), a water cooled engine. Diesels are not high speed engines for the maximum number of revolutions per minute seldom exceeds 2,000, which is about half that of the petrol engine. The Lister 3/1 has an operating speed of 600 to 650 r. p.m. and comes into the medium speed range. It is this speed range which determines the type of lubricant used, and the use of the correct oil is most important. Ordinary oils should never be used. Special diesel lubricants usually contain detergents, and only the brands recommended by the engine manufacturer should be used. If an engine has been run on a "straight mineral oil". i.e. one containing no detergents, and the newer oils are to be used, it is advisable to drain the sump and thoroughly clean before the first filling of detergent oil, which should be used for a period of 150 hours only. This is because the older oils did not keep the passage ways clean, and the detergents soften up this deposit which is carried back into the sump. After this 150 hour period the sump should again be drained and cleaned. From then on, the newer oils will run for the full period of 500 hours. SMALL

DIESEL ENGINES

95

The filters must receive frequent attention during this changeover period. Should you find that you have to change from one brand of oil to another-even if both are detergent oils-do not mix them, but drain the sump and refill with the different brand. It sometimes happens that oils which come from different countries will react upon each other. By far the most important thing as far as users are concerned is cleanliness of the fuel. Not only must this be of the right type (and vaporising oil will NOT do), but it must be well filtered. When it is realised that a spot smaller than a pin head is injected through a minute nozzle and that a single speck of dirt can stop the engine, it will be appreciated that every precaution must be taken when handling and storing the fuel. The storage tank should be under cover to prevent the ingress of rain or dust, and a funnel with a filter must always be used. In addition to this the draw-off cock from the tank should be set a little above the bottom of the container to allow any sediment or impurities to settle at the bottom. Frequently tanks are designed with a sloping bottom and a sediment drain plug fitted at the lowest point. Galvanised tanks and pipes should not be used. It is absolutely necessary that no air gets into the engine fuel pump or pipes: if it does, the whole of the system must be bled. Bleeding is also necessary if the engine tank has been allowed to run dry. Refer to Fig. 36. First fill the tank and then prime the fuel filter by undoing the vent screw on the filter top. Leave this open until all the air is released and the fuel emerges without bubbles. Tighten the screw. Next put the governor hand lever to the "Stop" position and disconnect the fuel pipe from the delivery valve holder on the fuel pump. Remove the delivery valve holder and spring and slightly raise the valve from its seat. Hold it up and let the fuel flow until it contains no bubbles, then lower the valve and replace the holder and spring. Tighten down. Now reconnect the fuel injection pipe and loosen the inject"r union. Put the governor hand lever in the "Start" position and crank the engine by hand until the oil flows freely from the injector union. Finally tighten the union and crank the engine again until there is a creaking or buzzing noise in the injector pipe. This denotes that fuel is being injected. Never at any time allow the nozzle to spray fuel oil on to the hand for the pressure

96

MAINTENANCE OF HORTICULTURAL EQUIPMENT

is so great that the liquid will be driven through the skin. Medical treatment will then be necessary. Although diesels are extremely reliable, occasionally a fault may develop in the fuel pump. This might take the form of a complete or a partial stoppage, or even an intermittent supply reaching the nozzle. First check that there is fuel in the tank. A choked fuel pipe or a dirty filter will also prevent flow and so too will an air lock. If the delivery valve remains open remove it and examine the face of the valve, the seating, and the guide. If any damage is seen replacements must be fitted. Check, too, for leaky joints in the pressure system. If the engine emits a black smoky exhaust, looses power, knocks, overheats, or there is a noticeable increase in the fuel consumption, the injector nozzle requires attention. These nozzles should not, however, be interfered with but left to the service engineer. In fact you should touch nothing but the pump delivery valve, or change the nozzle if you have a spare. You will find that pretty well all troubles encountered may be traced to dirty fuel, and after you have had to bleed the system a few times you will be more careful. Practically all diesel engines used in this country are cooled by water, the method being either by radiator and fan (as in a car), or by tank. Usually the water is circulated by thermo-syphon, an automatic action caused by the hot water from the cylinder head rising and being replaced by cooler water from the bottom of the tank. To facilitate this circulation the tank should be raised as shown in Fig. 37. Note that the bottom connection from the engine to the tank is level and that the top pipe slopes upwards all the way. In the illustration the engine fuel tank is clamped to the cooling tank. Even when the cooling tank has been fitted as described, it is as well to make sure occasionally that the water really does circulate. This is done by feeling the bottom hose after the engine has run for a short time, for the water should be warm. Care must be taken to prevent anything choking the pipes. In frosty weather drain the water from the engine and pipes by turning the threeway tap so that although the jacket is drained, water still remains in the tank. If the water used for cooling is hard it will sooner or later form a deposit inside the cylinder jacket and impair the cooling.

DIESE L ENGIN ES

97

There are propri etary fluids for removing this scale, but a good substitute so long as the deposit is not too thick is to fill the jacket with a solution of boiling water and soda (1 i lb. soda to l.gallon water). Let this remain in for some time-s everal hours if possib le-the n drain out and flush with cold water. Where radiato r and fan cooling is used make sure that the engine room has plenty of ventilation, for not only does the engine itself need a lot of air, but there must be a good circulation through the radiator. Keep the header tank filled to within 2 in. of the filler, and attend to any leaky hose connections immediately. See that the fan belt is tight enough, and after every 1,000 hours or running, regrease the fan hub bearings. Observe the usual precautions against frost either by draining the jacket or using an anti-freeze solution. The air filter of these engines is suitable for all ordinary conditions but where there is considerable dust it is advisable to fit an oil-bath cleaner of the type described in Chapter 4. The engine manufacturer or his agent will advise as to the right size. Felt type cleaners should NOT be washed in diesel fuel but in paraffin oil, and even then the filter must be allowed to dry before it is refitted. Make sure that all the filter connections are air-tight. Lister engines have a compression ratio change-over valve which permits a high ratio to be used for starting, and a lower one for normal running. This valve is seen in Fig. 38. The fuel injector nozzle is in a small chamber, and from this a narrow tube connects with a second or auxiliary chamber. When the valve is screwed in, the auxiliary chamber is sealed off and the high compression ratio is in operation, but unscrewing the valve allows the compressed air to occupy more space, with consequent lower pressure. Screw the valve in when starting or running on a light load. Never put this valve in the half-way positi on-it must either be right in or right out. If it is necessary to remove this valve, first unscrew the fuel pipe from the injector, and unscrew the nut for releasing the auxiliary chamber. This will withdraw the outer half of the chamber. Take care of the thin copper washer. The other half of the chamber may be removed by engine compression, but first drive a hard wooden plug into the i-in. dia. hole in the centre to prevent leakage, then replace the outer parts. Put the valvl! 7

98

MAINT ENANC E OF HORTI CULTU RAL EQUIP MENT

FIG. 38

in the "out" position and, with the outer combu stion chamb er nut screwed into the head three or four turns, crank the engine. The purpos e of these actions is to prevent the inner part of the auxiliary chamb er being ejected too violently. To extract the valve unscrew the small nut in the centre of the handwheel and unscrew the shaft. Take care of the spring, the spring washer, and the woodruff key. After decarbonising the engine, set the valve tappet clearances to 0·017 in. in the inlet valve and 0·032 in. for the exhaust. These clearances are measured when the engine is cold.

CHAPTER 9

Electricity ALTHOUGH mains electricity supplies are spreading across the country there are many districts which win not be reached for several years. Nevertheless that is no reason why country folk should not enjoy the advantages of this form of lighting, and this chapter tells you something about electricity, about small generating plants and how to wire a house. Sufficient current for lighting, running a vacuum cleaner and an electric iron may be obtained from quite sman plants. There is, for instance, a wind-driven generator giving 500 watts (this term will be explained later); there are several petrol engined plants of equal or greater capacity, some diesel engined outfits, and a few which may be run on paraffin or tractor vaporising oil. Some plants require storage batteries, others do not, but when batteries are used the lights may be switched on at any time without the need to start the engine. There are plants which automaticany start running when any switch is put on, and which stop when the last lamp is switched off, but naturally this type is rather more expensive.

Wind-driven Plants The best known example of this type is the Freelite, obtainable with either a 12-volt or a 24-vo]t dynamo. The former costs £58 and the latter £74. The mast is extra, a metal one being about £20. A wooden pole is of course much cheaper. The Freelite consists of the dynamo, propeller, fittings for attaching the dynamo to the masthead, batteries, half-a-dozen switches, a dozen insulators, lamp holders, six lamps, and a switchboard incorporating a cut-out, main switch, fuse, and ammeter, etc. One should never buy a wind-driven plant unless there is a fairly constant and reasonably strong wind supply available; to put one in a sheltered valley is a waste of money. Usually the dealer will be quite honest about this and will advise you to employ other means if he thinks the wind is insufficient in the 99

100

MAINTENANCE OF HORTICULTURAL EQUIPMENT

chosen spot. Winds are, as a matter of fact, very deceptive and even what is considered a good situation might turn out to be the reverse in practice. In areas where the wind is intermittent but is strong when it does come, I advise getting large capacity batteries for these might keep one supplied for a month or so. On my own holding I found that despite being 500 feet above sea level, in an exposed situation and having a 50-ft. mast well away from trees or buildings I am forced to have a petrol engine and another dynamo to keep my batteries charged. When you come to have dealings with electricity you will encounter such terms as "volts", "amperes" and "watts". Before an electric current can flow there must be some pressure behind it, just as with water, and the word for electrical pressure is "volt". By "amperes" we mean quantity. Every current must have both quantity and pressure although perhaps you will seldom hear the word "ampere". You will, however, meet the term "watts" whenever you go to buy an electric bulb. By "watt" is meant the actual power of the lamp and the figure is obtained by mUltiplying amperes and volts together. One can, for example, have a 12-volt current of 2 amperes, and a lamp which consumes this amount of electricity is rated at 24 watts. Lamps can be obtained for voltages of 6, 12,24,32,50, 110 and 230, so if the voltage of your lighting plant differs from that of your local mains supply it is necessary to state the voltage required. The dynamo of a Freelite can generate 500 watts an hour and. the set could keep twenty 12-volt 24-watt lamps burning at full power. It is clear, however, that unless the wind is blowing strongly and the dynamo is charging to its maximum capacity, current will be drawn from the batteries if all these lamps are alight. With this type of plant it is as well to be moderate in one's demands. Engine-driven Plants Yardley Wavis Ltd., of Shrewsbury, market a useful generator set for low voltage lighting, and a brief description might be of interest. The engine is a Villiers Mk. 10 four-stroke. The generator can be obtained for voltages of 12, 24 or 32. Engine and dynamo are mounted on a flat steel bed-plate fitted with rubber feet to prevent creeping. The complete machine weighs 83 lb.

ELE CTR ICIT Y

101

side of the generator and The control panel is mounted on the out, an ammeter, a field it contains the battery charging cutswitch, and electrically resistance, the push-button starting terminals. The cut-out is an controlled solenoid and the out put to prevent the current in the automatic switch, its purpose being dynamo when the engine batteries from flowing back into the solenoid controls the engine stops or is running very slowly. The t when the plant is running throttle according to the load, so tha noid automatically opens and lights are also being used, the sole rate. If the lights are g the throttle to increase the chargin little to compensate for the switched off, the throttle is closed a els can be supplied for operating on decreas~d load. All the mod petrol). paraffin oil (although they start on ts with higher voltages There are, of course, generating plan sley supply them in of Dur and a much bigger output. Listers output is, on one model, voltages of 110, 200/240 and 400. The ther it is 6 kilowatts. ano 3 kilowatts (i.e. 3,000 watts), and on ous electric motors vari run These generators are big enough to lighting, cooking ry, hine for water pumping, operating bar n mac and so on. Wiring ises for electric lighting, It is by no means difficult to wire prem work should be done by a but when mains supplies are used, the qualified contractor.

FIG. 39

prising the source of Fig. 39 shows a simple circuit, com e lamp, a switch, and the sup ply -in this case a bat tery -th complete circuit or pat h is wires. When the switch is closed, a Any number of lamps and provided and the lamp will light. h one must be a complete switches can be installed, but eac

102

MA INT ENA NCE OF HO RTI CUL TUR AL EQU IPM ENT

FIG. 40

circuit as will be seen from Fig. 40. Closing any one or more of these switches will light the corresp onding lamp. The wires used to convey electric cur rent are made of copper, for this metal does not offer so much resistance as, for example, iron. Resistance to the flow produc es heat, and for tha t reason the "element" in an electric fire is made of iron. This, as you know, gets red hot. The wire or filament in an electric bul b offers a bigger resistance still, and it becomes white hot, hence the illumination. Obviously, then, it is necessary to make sure tha t the wires are capable of carr ying the tota l amo unt of current used. Wiring is roughly divided into two classes, the first being called cable, and the second flex. Cables are used to car ry the current from the intake switchboar d to the various ceiling roses, switches and power points. Flex is used to connect the ceiling roses to the lamps. Thus unless flex is to be used for running an electric iron, it can be quite tlrin as it seldom has to carry more than 2 amperes. But it does have to bea r the weight of the lamp holder, bulb and shade. A flex suit able for all general purposes usually has up to 14 strands of thin copper wire and will sup por t a weight of 3 lb. Cables, however, have to car ry a greater loa d for they may have to supply the current for a doz en or more lighting points. To select you r cable size, estimate the power of every bulb you will use on any one circuit and wor k out the tota l amperage ass urin g tha t all the lamps will be swi tched on at one time. The following table will help you to sele ct the right size: SIZE

1/0·036 will carry 1/0·044 will carry 3/0·029 will carry

AMPERES

4·1 6·1

7·8

to3

ELE CTR ICIT Y SIZE

3/0·036 will carry 7/0·029 will carry 7/0·036 will carry 7/0·044 will carry 7/0·052 will carry 7/0·064 will carry

AMPERES

12·0 18·2 24·0 31·0 37·0 46·0

ber of wires and their The figures denoting size give the num nds, each 0·029 in. in n stra diameter, thus a 7/0·029 cable has seve with insulating material ered cov are nds stra diameter. The main with tape, plastic, rubber which may be of rubber covered k outer casing of tougher covered with lead or rubber with a thic ainable with two sets of rubber. Many of these cables are obt g insulated from the bein wires ins ide -ea ch set, of course, les. cab n twi as wn kno other. These are cables through metal Very often it is necessary to run the y in damp places this has pip ing -or con dui t-an d particularl the moisture. For the most to be screwed together to keep out ber-sheathed cable will be part, however, a good tough rub perfectly efficient. necessary to have cables In wiring for low voltage current it is rwise by the time the othe , which do not unduly restrict the flow have dropped so will sure electricity reaches the lamp the pres it is advisable on reas t tha much tha t the light will be dim. For to plan your wiring carefully. oard and batteries use Fro m the dynamo to the switchb sists of seven strands con , 7/0·064 cable which, as we have seen This wire has to carry the of wire, each 0·064 in. in diameter. larger section than the remaximum current, hence it is of batteries have to supply mainder. The cables leading from the and although it is unlikely current for every lamp and appliance, it is better to use a good tha t everything will be used at once, e wires (for there are two sized cable, say 7/0·044. It is from thes individual light, so from h of them) tha t current is drawn for eac O·0 64- to the switches e-l/ wir the 7/0·044, connect thinner roses to the lamp holders, and ceiling roses. Fro m the ceiling no wires can be at any time twin flex is used. It is thus seen tha t sible voltage reaches the overloaded and tha t the highest pos lamps. e of cable, the next step Having, then, decided upo n the typ

104

MA INT ENA NCE OF HO RTI CU LTU RA L EQU IPM ENT

is to investigate the methods of fixi ng it. If the wiring is to be put into tubing or conduit, a clip known as a saddle will be "needed. This is screwed into a bea m or a wooden plug. Lat h and plaster walls present some difficulty in this respect, and it might be desirable to use a lighter form of wiring. Con dui t is generally used in new hou ses for it can be built into the wall and covered with plas ter. In old farmhouses this is not generally possible, but cable tha t is attached to a wall can be quite inconspicuous if it is neatly fixed and put close to doo r posts, etc. Cables for gro und floo r ceiling roses should be attached as neatly as possible, but for upp er floors it might be possible to run con dui t on top of the joists so tha t it is not visible from the roo m itself.

COIlduit sadd le

flxtid

C4h1esa&ile

FIXed

FIG. 41

mD/eel;" fixed

IInf/ xeti clip

Ordinary cotton-covered and rub ber-covered cables are fastened either with saddles or clip s. Fig. 41 shows the three types mentioned. The saddle is ~ene rally used for twin cable, but clips are quite satisfactory and a little cheaper. Rub ber covered cable (known as T.R.S. or tou gh rubber-sheathed) is cheaper tha n lead-covered wire and installing con dui t is the most expensive of all. In every electrical installation it is desirable to have one or more safety devices to prevent the wir es overheating as the result of a sho rt circuit. Thu s the cur ren t is mad e to pass thro ugh a sho rt length of special wire tha t hea ts up mu ch mo re rapidly tha n the cables, so tha t in the event of an overload the fuse wire melts and cuts off the current. Fus e wire is held in porcelain fittings, one of which is shown in Fig . 42. The whole fitting can be withdrawn from clips for inspecti on or replacement of the fuse wire.

ELE CTR ICIT Y

105

le fuse is sufficient, but In low voltage bat tery systems a sing s there sho uld be several. on high voltage and mains installation r of mai n fuses (one for the There would, for example, be a pai negative or retu rn wire) at positive or live wire and one for the stro ng enough to carry the the switchboard. These would be the lamps and oth er equipfull loa d of cur ren t required for all have a set of smaller fuses ment. It is generally convenient to and 10 or 15 amp. for fires, (5 amp. carrying capacity for lighting se, however, are not essenetc.) for each floor of the house. The them, not necessarily the tial, although convenient. By fitting r in the event of a "bl ow n" whole of the lights will go oht togethe y even only a par t of it. fuse, but only one floor, or possibl e you r premises for high Assuming tha t you inte nd to wir a 3 or 6 kilowatt pla nt at voltage cur ren t drawn, say, from st appropriate.place for the 230 volts, begin by selecting-the mo . Nea r by you must affix a main cables to enter the building s are fastened. Hav e two boa rd on which the switch and fuse rd so tha t the cables can slats screwed to the bac k of the boa the switch. come behind it and through holes to combined switch and fuse ad" ncl You will need to buy an "Iro e voltage and amperage if uni t tha t will carry the app rop riat Ma ny of these switchboxes one is not provided with the plant. as a rule the cover can not are now mad e of plastic material, and been switched off. Cur ren t be removed until the cur ren t has the switch thro ugh terminals, from the supply line is connected to e for each cable) to oth er and it passes thro ugh the fuses (on r domestic or oth er wiring. terminals from which it goes to you us suppose tha t you are For the purpose of illustration, let cable. If you strip the out er using tou gh rubber-sheathed twin le you will see tha t one wire insulation from one end of the cab oth er in black. No te this as is covered in red insulation and the hal f to three-quarters of an it will affect you r wiring. Bare from a small circle. Thr oug h this inch of the wire and ben d it to form ays ben d the wire so tha t circle is put the terminal screw. Alw the wire rou nd the terminal. tightening the screw tends to wra p s, keeping the wire straight At intervals affix the cable with clip tha t it fits snugly into corners and neat. Do not let it sag, and see rtly reach a poi nt where a and rou nd beams. Yo u will sho lamp. There are two ways bra nch mu st be mad e to a switch and to insert wha t is called a of making this branch-off. One is

106 MA INT ENA NCE OF HO RTI CUL TUR AL EQU IPM ENT junction box, and the other is to atta ch the branch lines to the cable. wire by twisting and soldering. A junction box (or join t box) consist s of a number of encased terminals. The main wire is attache d to two of them which are connected internally to others, and it is from these tha t the branch line goes. The main line the n goes on to the next box, and so on. Remember tha t when affi xing wires to a terminal, there must be no loose ends or "wh iskers". Wrap the wire well round the terminal and see tha t not a single stra nd can touch any par t other than the terminal. The second method of joining disp enses with boxes. The insulation is stripped from a par t of the cable and the wires laid bare. The branch wires are then bar ed at the ends and wound tightly rou nd the main wire, red to red and black to black. It is best to clean the wires by scraping the m with a knife, or rubbing them with a piece of sandpaper as this ensures better contact. Next solder each join t carefully. Unl ess this is done, corrosion will be set up and in a year or two trouble will result. Do not use an acid type of flux, but get a tin of "Fluxite" or something similar. Have the iron hot and mak e sure tha t the solder really flows well into the joint. Wipe the finished job with a rag and then bind it carefully with insulating tape. Apply enough tape to provide proper insulation, and be sure tha t all the bared wire is covered. For neatness, the two joints can then be bound together with tape and a clip affixed either side. Assuming tha t you have now fixe d the main cable to the farthest point and attached your bra nch lines let us go back to the first of these branches. Yo u hav e a length of twin wire (1/0'064), one red and the other blac k. You may, of course, have two single wires, and on the who le this might work out better. You must now decide where the ceil ing rose and the switch are to be fixed. Ceiling roses and swi tches are screwed to wooden blocks which are fastened to a woo den joist or to a wall. With a light hammer, tap the ceiling gen tly and you will be able to tell by the sound when you meet a hidd en joist. Mark the spot. The wooden blocks are usually circ ular and are recessed at the back. Start by boring a hole through the centre to take the fixing screw (probably a 1i-in. No. 8 will be large enough). Countersink the hole on the polished side of the block so tha t the fitting

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will lie flush. Next (assuming that your wires are not coming through the ceiling) cut a slot through the rim of the block for the cable to pass into the recess, then drill two more holes for the cables to come through the block. Take a ceiling rose and unscrew the cover. Inside will be seen two terminals with flat-headed screws and two small screws projecting from brass tubing. Slacken these small screws, put the rose centrally on the block and push a thin bradawl down each tube to mark the block. Now drill a hole at each mark so that the wires can come through the block into the fitting. Prepare another block for the switch. One of your branch wires (the red one) must go down the wall to the switch, but the black wire' must run along to the ceiling rose. A third wire must join the other terminal of the rose to the other terminal of the switch. Thus, single cable for these branch lines will be easier to handle than twin. Remember always to connect the red wire to the switch. Cut the cables so that an inch or two can protrude through the holes in the blocks. Attach the switch block firmly to the wall at the required height. Trim back the insulation from the end of each wire and slide the wires into the brass tubes of the switch. They should come through and stick out. Pull on each wire and push the switch back against the block and then tighten the small screws to grip the wires firmly. Screw the switch to the block, snip off the projecting ends of the cable, and affix the switch cover. Run the loose wire up the wall alongside the other one and on to the ceiling rose, and fix the rose in a similar manner to that described. Attach twin flex to the ceiling rose and lamp holder. A useful means of testing the continuity of your wiring is to employ a small battery. say one from a car or motor-cycle and a lamp of the same voltage. Take out the main fuses and attach the battery to the output side of the fuse box terminals (i.e. the side to which your house wiring is connected). Your test lamp is probably too small for your house lamp holders, so attach a small holder to a short piece of flex and then to a standard adaptor. If this adaptor is put into each of the house lamp holders in turn, the lamp should light when the appropriate switch is pressed down. If all is satisfactory, remove your test battery, replace the

108 MAINT ENANC E OF HORTI CULTU RAL EQUIP MENT main fuses, put bulbs of the required size in the various rooms. and start up your plant. When your supply is from the mains it is strongly advised that the house wiring be done by a qualified electrician, it being necessary for reasons of safety to "earth " the system. "Earthing" means the provision of a path for the current to escape by in the event of a fault in the wiring or in a fitting. Without an adequate earth one may receive a severe shock -sever e enough to be fatal on occasion. Should, for instance, one of the wires touch any metal part such as a lamp holder, electric iron, or fire frame, then anyone touching those parts will provide a path for the current which passes through the body to earth. If, however, the metal parts are already connected to earth, then the current will flow direct and no shock wil1 be felt. Particularly where a high voltage supply is installed, make it a rule never to attempt any alterations or repairs without first switching the current 0.0' at the main switch. . Fuses do not require any attention but sometimes a faulty lamp will cause the wire to melt. A new wire can be put in quite easily. First turn the current off at the main switch, then pull each fuse from its clips and inspect it. When the broken one has been found, slacken the two screws and remove the pieces of melted wire. Insert a new length and clamp the ends under the screws. Replace the fuse and switch on the current. Be sure to use the correct size of wire. Spare wire is obtainable in three sizes- 5, 10 and 15 amp.- and each piece is wound on to a card and clearly marked. If a fuse blows frequently, do not fit a thicker wire, but find the cause of the trouble. It may be that a cable has frayed and is touching another. If one light only goes out, the fault might be in the lamp or in the holder, so first put in another bulbone you know is sound. If this does not light, switch off the current and inspect the lamp holder. If you look into it you will see two spring-loaded plungers designed to carry the current to the contacts on the lamp. Sometimes these plungers stick or the springs weaken. Take the holder off the wires, dismantle it and apply a tiny spot of oil to the plungers. If a spring is weak, a new holder will have to be fitted. When replacing the holder be sure that the wire is properly secured and that there are no loose ends to give further trouble. If you find that the wire itself

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is dirty or corroded, scrape it lightly with a knife before fitting it to the holder. Switch springs sometimes break, but the most common source of trouble in switches is dampness or corrosion. A .little oil on pivot pins helps a lot. Apply it with a feather. Generator Care Apart from the engine there are two parts of a generating set which need attent ion-th e dynamo and the batteries. One of the most common causes of a dynamo failing to function is the accumulation of dirt or dust between the brushes and the commutator. The zone of contac t is never very large, and it is obvious that reduction of this area will adversely affect the work of the machine. Cleanliness is therefore an essential feature. The majority of dynamo brushes are made in varying degrees .:If hardness according to the work they have to perform. The harder carbons have the greater resistance to wear, but unfortunately their electrical resistance is also higher. It is important, therefore, when replacing brushes, to obtain if possible those specified for the dynamo in question. Brushes that are. badly worn may cause sparking at the commutator, with consequent loss of output. It is also import ant that brushes should be so fitted that they slide freely in their holders, while not being so free that they vibrate when the dynamo is running. A simple metho d of bedding in dynamo brushes is by encircling the commutator with fine glasspaper (rough side outwards) and pressing the brushes on to this while the armatu re is being slowly revolved. A .few turns should suffice to produce a slightly concave bearing surface on each brush, thus ensuring the maximum zone of contact. Trouble is sometimes caused by faulty insulation between the brush holder and the dynamo body. A short here can easily be discovered with the aid of a flash lamp battery and bulb, one of the leads from the battery being made to touch the dynaino body, while the other with bulb in circuit is in contact with the brush holder; if the bulb lights, the insulation is imperfect. Shorts are frequently caused by accumulations of carbon dust, which should be removed. Where plaited copper wires are employed as leads, care should be taken to ensure that they do not contact the body of the dynamo, and that they are firmly attached to

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MAINT ENANC E OF HORTI CULTU RAL EQUIP MENT

their proper terminals. It is not always fully appreciated that loose connections always mean increased resistance. Brush and gear faults can thUS'be summarised as follows: Brushes imperfectly bedded in. Brushes sticking in holders. Loose holders or brush rigging. Poor brush connections. Weak or broken springs. Worn brushes. Faulty insulation of brush holders. Brush "pigtails" touching the frame of the dynamo. Defective terminal insulation. The comm utator should obviously be bright and cIeap, the copper segments standing out above the insulation separating them. Should the segments be so worn that the mica insulation stands "proud ", it can be cut away with a small slotting saw. The copper segments should never be allowed to become pitted or scored, but where this has occurred, the comm utator can often be cleaned up by the aid of fine glasspaper glued to the edge of a piece of wood scooped out to conform to the arc of the commutator. When using this method it is a wise precaution to insert some old brushes, as otherwise particles of the abrasive may embed themselves in the proper brushes and cause rescoring. Be sure to remove all traces of dust from the dynamo before running it.

Batteries The modem storage battery is a very interesting piece of equipment, for it changes an electric current into chemicals and then changes chemicals back into an electric current. This transformation is accomplished by water, sulphuric acid and lead which, in the language of the chemist are H 0, H S0 , and 2 Pb respectively. A simple battery, then, consists of2 an 4 acidproof container and two or more plates of lead immersed in a water /acid mixture known as electrolyte. What happens when a charge of electricity is sent into the battery is that certain chemicals leave the lead plate into which the current first passes, go through the electrolyte, and attach themselves to the other plate. Thus the structure of the two plates undergoes a chemical change. During this process the

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water in the electrolyte is gradually consumed and the liquid becomes more acid. When, however, electricity is taken from the battery, the chemical action is to all intents and purposes reversed and so a discharged battery reverts to its former chemical state and the electrolyte loses some of its acidity and, in fact, becomes lighter in density. The process of charge and discharge is much more complicated than I have described here, but it is essential to realise that unless the chemical changes take place without opposition, the battery cannot do its work properly and the lighting will suffer. Keep the battery in good condition by regularly-and this means weekly-checking its electrical, external, mechanical and physical condition and correcting any faults discovered. The electrical condition means the degree of chemical change from that of the discharged state or, in other words, whether or not the battery is "charged". One can either use an instrument called a voltmeter or (which is preferable) a device which measures the density of the electrolyte. This instrument is called a hydrometer. A voltmeter is a mechanical device which indicates electrical pressure and the action of charging a battery really creates a difference in electrical pressure between the two lead plates (or the two groups of lead plates). In a fully charged battery the voltmeter should give a reading of 2·2 per cell, thus a 6-volt battery consists of three cells each with a 2·2-volt pressure, or 6·6 volts in all. A 12-volt battery when fully charged should give a reading of 13 volts. It must be understood that merely putting the meter test prongs to the battery terminals is not a sound test of the condition of the battery, and that it is necessary that the battery be discharging some of its current. Make your voltmeter test when the lights are on, and if the accumulator is in a charged condition the voltmeter will read 2 volts per cell. If the reading is lower the battery is not fully charged. A reading of 1·8 volts per cell indicates a discharged battery. A much more reliable test is made with a hydrometer. We have already seen that in a fully charged cell the electrolyte becomes more acid, and this means that it is heavier or denser than when the cell is discharged. By putting a float into the electrolyte it is easily possible to ascertain the density or specific

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MAINTENANCE OF HORTICULTURAL EQUIPMENT

gravity, noting how much of the float is above the level of the liquid. Hydrometers therefore consist of a glass float weighted with shot at one end, and a scale at the upper end. The float is contained in a larger glass cylinder which has a rubber ball at the top. At the bottom is a length of rubber tubing. The tubing is inserted in the electrolyte and the bulb squeezed and released. This draws a certain amount of the liquid into the tube and the float rises according to the density. The float is generally marked with three coloured bands, the lowest white or yellow, the middle blue and the uppermost red. Very often there will also be a scale with numbers reading 1100, 1150, 1200, 1250 and 1300, the high figure being at the bottom of the scale. When a battery is fully charged the density of the electrolyte is between 1275 and 1300 (actually 1·275 and 1'300, but the decimal point is usually ignored). Thus if, when a test is made, the float rises until the 1200 mark is level with the liquid, we know that the battery is only half charged. If the reading is 1300 then the battery is fully charged. It should be clear now that any interference with the electrolyte, such as adding more acid or water, will render the hydrometer reading false. But the water in the mixture does evaporate and must be replenished. When it is seen that the level of the fluid falls below the top of the battery plates, simply add distilled water to cover the plates by 1 in. Clean rainwater can be used, but it must not have come into contact with iron (as would be the case were it collected via an iron gutter into a water butt, or collected in an iron tank). Never use any other than distilled or clean rainwater or the battery will be ruined because ordinary water contains impurities, iron and so on. Bear in mind the fact that the electrolyte in a flat or discharged battery will freeze in very cold weather and burst the case, whereas if the battery is fully charged it will suffer no harm from any temperature we are likely to experience in this country.

CHAPTER 10

Water Supplies farms and smallholdings water is obtained from a variety of sources: streams, ponds, shallow and deep wells or perhaps from the Water Board's mains. Many people are forced to spend a good deal of cash in having a bore hole drilled, and the depth of this may be anything from 30 to 500 or more feet. Except when one has a mains supply, engine and pipe line maintenance costs fall upon the owner or tenant, hence the need for a knowledge of pumps, pipe work, and a certain amount of plumbing. Exchequer grants are available towards the cost of water, but there are snags. It might be, for example, that your estimate for sinking a bore hole and erecting a pump and engine comes to, say, £200. You calculate that if you can get a grant for half this amount you can stand the rest. The authorities, however, have their own views on the matter. It generally turns out that you have to install an elaborate system of irrigation or possibly equally elaborate drinking trough lay-out, your own simple scheme being set aside as of no importance. A further source of worry is that no one knows what the final cost might be, for boring difficulties can push up the bill in an alarming manner. One bore hole I had went down to a depth of over 350 ft., and with the pump (but no engine) the cost was £350. Another went to 92 ft. and cost £325, chiefly because the borer struck a patch of loose sand. This necessitated the insertion of about 80 ft. of steel tubing at over £1 per foot. I had expected this job to cost £150 at most. With regard to the type of pump to buy, the safest thing is to consult a pump manufacturer, and he will want to know the answer to such questions as:

ON

1. 2. 3. 4. 8

Quantity of water required (in gallons per day or per hour). Source (stream, well or bore hole). Diameter of bore hole. Storage tank capacity. 113

114 MA INT ENA NCE OF HO RTI CUL TUR AL EQU IPM ENT

5. Frequency with which pumping can be carried out. 6. If electricity supply is available, whether mains or private supply; the voltage, and whether A.C . or D.C. 7. If engine, whether petrol, vaporis ing oil or diesel engine is required. If the level in your well is not more tha what is known as a shallow well pum n 25 ft. below ground, p can be used. In this the pump is above ground, the water bein But when the water level is at a greater g drawn up by suction. depth, a deep well pump has to be used. The pump in this type is immersed in the water but operated from above gro und. There are deep well pumps which have both pump and mo tor (electric) completely immersed. The size of pump required natu rally depends upon the quantity of water needed, and as a rough guide, the average, ignoring irrigation purposes, is said to be 20 gallons per person per day, and 30 gallons per day for a cow to run a pump continuously, so as . One would not expect the time of operation is shortened, so the output of the pum p must be increased. My own pump, used for domesti c capacity of 140 gallons per hour, and purposes only, has a our daily consumption is approximately 60 gallons. My storage capacity is 150 gallons, so I usually pump about every oth er day, the pump running for about three-quarters of an hour. On many farms and holdings, wat er is drawn from a river or pond by a portable pump, the modern type comprising a set of rotating vanes inside a specially shaped casing. This is for shallow work only. By far the more common, howeve r, are piston type pumps fixed permanently above or by the side of a well, and used for domestic purposes. A crankshaft turn operates a small connecting rod which ed by engine power is attached to a crosshead sliding in an open-ended cylinder. Screwed into the crosshead is a plunger rod which passes thro ugh a sealed bearing called a gland. On the end of the plunge r rod are two cup leathers working in a cylinder. These leathers draw the water from the well and pump it through pipes to the storage tank. A pump gland has to prevent water from esca ping through the plunger rod bearing and this is achieved by surrounding the rod with a

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sleeve of flexible material known as packing, generally a fabric impregnated with graphite or some other lubricant and made in the form of rings or string. There are three parts to a gland (see Fig. 43). On the right is the stuffing box through which the rod slides. In the nriddle is the packing and on the left is the gland nut. The purpose of this nut is to squeeze the packing so that it tightens on to the plunger rod and so prevents the escape of water. A gland should never be so tight that it binds on the rod and hinders its sliding action, but it must, of course, prevent water escaping. In practice, a gland should allow a small amount of water to pass, as this acts as a lubricant for the rod. . Mter a time the packing becomes hard so that further tightening of the gland nut has no effect. At this stage the packing must be renewed. To do this, unscrew the gland nut (on some pumps this "nut" is in the form ~f a flange secured by bolts) and take out the old packing. It is necessary that every piece is removed. When the stuffing box is clear, the new packing is inserted. This is sometimes supplied in the form of split rings which are twisted open, closed round the shaft and then pressed into place. The recommended procedure is to tighten the gland nut after each ring has been put round the shaft, for this ensures the ring being pressed in evenly. The gland nut is slackened, the next ring put on and then turned round so that the two openings of the rings do not coincide. Press the second ring in with the gland nut as before. Repeat with the third ring. The gland should not, as has been said, be tightened too much, and the usual practice is to run the pump, tighten the gland nut until no water emerges, and then check from time to time, tightening the gland until the packing has bedded in properly. Where gland-packing string (tallow hemp) is used, it is wound round the shaft and cut off when the stuffing box will hold no more. In this case the string is usually pressed in carefully with a piece of wood. Cup leathers on water pumps are in pairs placed back to back so that there is a pumping action on each stroke. (In a bicycle pump there is only one leather as the pump has a one-way action only.) The pump rod is threaded and the arrangement of parts is: nut, washer, cup leather, washer, cup leather, washer, nut. Sometimes there are lock-nuts at either end in addition.

116 MAINT ENANC E OF HORTI CULTU RAL EQUIP MENT

Leathers are treated with oil when being shaped, and they usually last a considerable time. When fitting new leathers, be careful not to pucker them when inserting them into the cylinder. Wh~n pumps are used for hot water, the cups are usually made of rubber or a special composition. Deep bore pumps are generally of the piston type, although where mains electricity is available and the bore hole is not too costly, an entirely submerged centrifugal pump together with a direct-coupled electric motor is sometimes preferred. Bore holes for these units, however, have to be of a larger diameter than for piston pumps, and the extra cost is likely to.be substantial. A more common arrangement is for the pump to be submerged and operated by wooden rods connected to the pump head, the unit comprising gears (generally tQta11y enclosed in an oil bath) driven by a belt. Pump heads are frequently bolted to a heavy plate attached to a concrete block cast round the borehole tube, the same plate usually carrying the engine. One of the most essential things after the pump has been erected is to enclose the whole unit in a draught- and frost-proof shed. The pump house should be large enough for working round the plant, and it should contain a window or two. As it will be necessary on occasion to lift the pump to replace washers, arrange for some form of hinged cover (or detachable skylight) in the roof to allow the rods to project as the pump is lifted. Servicing engineers usually have a strong tripod which they erect over the well head, but unless the building is small it might not be possible for the tripod to straddle it. In this case, provide a stout beam to which blocks and tackle can be attached. A corrugated iron or asbestos cement sheet building will need to be lined with· Essex board or something similar. Make sure that the doors fit snugly, for a cold North-Easter soon finds the gaps and crevices. Even then it is advisable to guard against excessive frost by lagging all above-ground piping. Felt, straw and sacking are all useful, so is an enclosing box of wood filled with sawdust. On some makes of pump, drain taps are provided for use in frosty weather. It is necessary with such pumps to have some water available for priming the pump and for refilling the engine hopper. Apart from the engine and belt, the only points on the pump

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head which need attention are the gears and the gland. Check the oil level in the gear-box every month and top up to the required level, using the recommended brand of lubricant. If the oil becomes thin or dirty, drain and renew. Information on gland packing has already been &iven. If a pump ceases to deliver water while the engine is running, some obstruction such as sand, etc., has probably got under a valve. It can usually be removed by opening the engine throttle and thus speeding up the pump. Water hammer is caused by a lack of air in the air chamber, and the remedy is to stop the pump and remove the air chamber to empty it of water. Before starting the engine in very cold weather, make sure that the pipes have not frozen and that there is no ice on the plunger. Check by removing the belt and turning- the pulley several times by hand. If the engine is started up and the belt tightened when the pump is frozen, something is certain to break. A kettleful of hot water poured over the suspected pipe and round the plunger rod is most effective, but always engage the belt drive very slowly so that should the pipes not be clear, the belt will slip. All water piping that runs underground from the pump to the house or storage tank should be buried from 18 in. to 2 ft., and all piping above ground well lagged. Most small water pumps are belt driven, the Vee belt generally being supplied when one orders a pump and engine as a complete unit. It frequently happens, however, that for the sake of reducing the initial outlay, a second-hand engine is obtained, when the method of drive- adopted is generally by flat belt of the woven cotton variety. In using this type of drive several things must be considered, the first of which is the size of the driving pulley in relation to that of the driven. Water pumps do not run at a high speed, for seldom is the actual number of strokes more than 90 per minute. There is always some gearing between the pump pulley and the plunger shaft, this gearing allowing for a pulley of, say, 10 in. diameter being driven at 360 r.p.m. Engines, however, run much faster, so the driving pulley on the crankshaft must be much smaller than that on the pump. Nevertheless too small a driving pulley reduces the friction between the pulley and the belt. This can, however, be overcome to some extent by using a wide pulley.

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Assuming that you have purchased the pump unit and the recommended speed of the pulley is 360 r.p.m., the size of the driving pulley can be calculated from the following formula: Speed of follower dia. of driving pulley dia. of follower Speed of driver = The follower in our case is the pulley on the water pump, and this we know has a diameter of 10 in. Assuming that our engine is governed to run at 1,000 r.p.m., we now get 360 _ dia. of driving pulley (unknown) 1,000 dia. o{follower or 360 x 1,000= 10 If x divided by 10 equals 360 divided by 1,000, then x equals 360 mUltiplied by 10 and divided by 1,000, giving us 3·6 in. as the diameter of the pulley that must be used on the engine. Pulleys are not, however, made in tenths of an inch, so one would use a 4-in. pulley as being the most suitable. The formula given will come in handy should you need to calculate the size of a pulley on an attachment driven from the power take-off shaft of your tractor. Having obtained and fitted the driving pulley make sure that both the driving and the driven pulleys are in alignment, otherwise the belt will not stay on. Use the method given on page 15, for aligning chain sprockets. The next step is to measure the length of belt required, so run a steel tape or a piece of strong cord over both pulleys and deduct one per cent from the figure thus obtained to make sure of a tight contact. Turning now to the piece of belting, first see that the end is cut squarely across, for a fraction of an inch of error has the effect of lengthening one side of the belt, causing it to run off the pulleys. Use a carpenter's try-square to mark off the cut. Use the square again after marking off the length of belt required. If fastener bolts are used, measure first the exact distance between the bolt centres, see Fig. 44. Halve this amount and pencil a line that distance from the belt end and parallel to the cut. Drill the bolt holes on this line so that when the fasteners

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I .1

I I I

I 1 I

e9 FIG. 44

are fitted the two ends of the belt butt closely together. Any gap allowed gives rise to weakness and the belt will eventually pull through to the edge. Make sure that the drill is exactly the same size as the fastener bolts and clamp the upper half of the fastener down securely, but not tightly enough to distort the belt face. If the belt is to be laced with a leather thong use similar care in cutting square, then punch the holes. Do not use a penknife to cut them. The number of holes, of course, depends upon the width of the belt and also upon its operating speed, for the greater the speed the more power it has to transmit. For light belt work, such as driving a water pump or charging a dynamo, four holes per belt end are sufficient. Punch these as shown in Fig. 45 (a). This is known as single lacing; (b) shows the outside of the belt and the method of lacing. The numbers at the holes indicate the order of putting the thong through. For moderate duty, increase the number of holes in each belt end to eight, putting a row of four near the cut end, then three, and finishing with a single hole still farther back and in the centre. Follow the same principle when lacing. Holes should be -fir in. for a i-in. thong. Make sure that the thong ends are fastened securely. They can be tied in a knot if no idler pulleys are used. Although not shown in the illustration, I have found that a slight cut made in each end of the thong, rather in the form of a "nick", will act in much the same way as a fish-hook barb and prevent the thong coming back through the hole. Alligator fasteners are not often used on farms but they do provide a sound and simple join. They consist of a pair of toothed strips of metal bent to a V shape. Mter squaring up the belt end, place a fastener so that the row of pointed teeth is parallel with the belt end, then lightly hammer the teeth down. When the other end has been similarly treated, mate up the two

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MAINT ENANC E OF HORTI CULTU R.AL EQUIP MENT

r (a)

FIG. 45

(b)

fastener ends and insert the metal rod supplied. In an emergency, a headless nail will do. Pipe Work Metal piping has a variety .of uses on farms, nurseries and other holdings and every mechanic will, sooner or later, have to effect repairs or alter existing installations if not to design and erect new ones. Many of your engineering tools can be used but if a fair amoun t of work has to be undert aken the following additio nal items will be needed. It might be possible to hire them from an ironmo nger or a plumber. 1. Pipe wrenches (at least one). 2. Pipe cutter. 3. Pipe vice. 4. Dies and taps. With a little ingenuity two pipe wrenches and your worksh op lice will eliminate item 3 on the list, and a hacksa w can be used instead of a pipe cutter. Item 4 is expensive, so either hire them or get your threads cut by a plumber. Galvanised pipe is used for

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122 MAINT ENANC E OF HORTI CULTU RAL EQUIP MENT most purpos es (althou gh not for piping diesel fuel). It should certain ly be used for a water supply system. Pipes are design ated by their inside diamet er. When an elbow has to be screwed on, the inside diamet er of this must accord ingly be approx imatel y the same size as the outside of the pipe. A i-in. elbow therefo re has an inside diamet er of about i in. In additio n to right-a ngle bends, tee socket s and connec ting sleeves, there is a big array of fitments. Study Fig. 46 for it will help you to simplify the task of erectio n. By careful planni ng it is often possibl e to elimina te many fittings. Measu re up every job carefully to avoid unnece ssary cutting , for a pipe that is an inch short might necess itate replace ment or the purcha se of extra fittings. If you are measu ring a pipe that is to fit into a given place, do not forget that one end will have to screw into some fitting or other, so take this into accoun t. Mark the point of cut with a triangu lar file-it not only makes a readily seen notch but provid es a start for your hacksa w. Do not use heavy pressu re when hacksa wing pipe and have the blade a little tighter in the frame than usual. The pipe-cu tting tool leaves a smooth er end than the hacksa w but it forms a burr inside the tube; this should be remove d as it impede s the flow of water. Cuttin g thread s on pipes is similar to that on rods, but as a rule the thread cut does not exceed the thickness of the die by more than a thread or two. The reason for this is that pipe threads are usually tapered so that the joint will pull up tightly. There are occasions, however, when a long thread is require d, but here the thread s are paralle l. Use plenty of oil when turning the die. When a mains water supply is used for irrigati on it is worth consid ering having it run to the centre of one's field so that subseq uent and overgr ound piping is kept to the minim um. All above- ground pipe should slope down from the supply , for the pipes can then be draine d in frosty weathe r. If a section of pipe formin g part of a perma nent installa tion bursts as the result of freezing, saw the defective section throug h, when the two parts can be unscre wed withou t disturb ing the rest of the piping. To replace , use two lengths of pipe and join them with a union. Pipe thread s should be given a coat of paint or some other materi al before the joints are screwed up. If the installa tion is not

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permanent, however, a mixture of grease and graphite is better, for after a time paint sets very hard. Do not pull the joints up too tight; the taper threads and jointing material will prevent leakage. For domestic installations there are available copper pipes with threadless joints. The various 'bends, tees and so on have a lining of solder at their ends and the tubing is simply cut to length and pushed into the fitting. The application of a blowlamp flame melts the solder and seals the joint. IT a lead pipe freezes and splits, a temporary repair can be made directly a thaw comes by first turning off the water and draining the pipe, then using a light hammer to draw the edges of the split together. When this has been done, apply a coat of paint and then bind the pipe with two or three layers of tape, preferably painted. Secure the end with string and give the whole a further coat of paint. Allow this to get dry if you can, although the water can be turned on at once if necessary. In this case turn the main cock on only a small amount to keep the pressure low. Get a plumber to effect a proper repair as soon as you can. It is sometimes necessary to run a branch line from an existing installation, and undoubtedly the quickest method of doing this is to use a pipe saddle. This consists of a metal flange curved to fit snugly round the pipe to which it is clamped by a U bolt. The pipe is then drilled through the hole in the flange, and as this hole is already threaded, additional piping, taps, etc., are screwed in. Pipe saddles are obtainable in sizes from! in. to 6 in. Several different types of shut-off valves, gate valves and taps (faucets) are obtainable. A stop-and-waste cock, for instance, is a useful fitting for a mains supply, for when the cock is turned off the contents of the pipe from that point onwards can be drained off as a safeguard against freezing. Common taps or f~ucets have a rubber or leather disc as a water seal. To renew this when it breaks or wears, unscrew the top of the tap with a spanner, lift it out and a short brass rod called a jumper will be found inside. The lower end of this forms a circular plate, beneath which is the tap washer secured by a nut. A complete jumper and washer is obtainable, but the separate washers are cheaper.

CHAP TER 11

Boilers and Oil Burners MAINT ENANC E work "on horticu ltural heating plant is largely a matter of comm on sense. In the main it is unwise to go beyond the instruc tions given by the manuf acturer , for not only might the plant be put out of action, but valuable crops be ruined . Instruc tions natura lly vary accord ing to individual makes, but below are the mainte nance jobs which are within the capabilities of the average boiler attend ant using KinneIl equipment.

Boilers Examine all brickw ork, and repair where necessary to ensure air-tightness. Regula rly clean the tubes of tubula r boilers during the heating season to mainta in the efficiency ofheat transmission. Clean the flue up-tak e or smoke-pipe at least once every season to mainta in a good boiler draugh t. Renew immed iately any damag ed tubes. (Special breakd own tubes are available for this purpos e.) Inspec t the valve rubber s of screwdown contro l valves, and renew those which are faulty. Repac k glands if leaky. Circulators Grease the bearings of electric motors accord ing to the maker 's instructions. Repac k glands of water pumps , adjust the tension of driving belts and renew those which are worn. Forced-draught Fans Grease motor bearings. Paint the sheet metal fan casings.

l1nderfeedStokers Grease or oil motor bearings. Blowo ut dust from retort via the blow-o ut tube. Clean the hopper , firepot and tuyeres at the end of the season and leave them free of fuel. Paint where necessary.

Oil Burners Grease or lubrica te the motor bearings and regularly clean nozzles and ignitio n points, also the filters in the oil feed line and 124

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in the burner. Be sure to draw off water from the oil storage tank at intervals and, when taking in a fresh load of oil, allow the disturbed sludge to settle for an hour before restarting the burner. Paint the outside of the oil tank every year. Regularly clean the stem of the flamestat to keep it free of soot. Steam Heating Plants Regularly Clean the strainers fitted to the steam traps, and renew parts when necessary both of the steam traps and of the steam and condense valves. General

All valves on hot water or steam heating pipes should be operated occasionally when the plant is not in regular use, so as to ensure freedom of movement. If air cocks are fitted instead of open vent pipes, open them occasionally to keep the heating system free of air. Open vent pipes should be examined from time to time, and obstructions removed. Every season carefully check the levels of heating pipes and mains. Hot water piping should have a rise and fall on flows and returns of not less than 1 in. in 10ft. With regard to automatic light oil burners, such as the Nu-Way, here again, the user is not advised to go beyond the following instructions. When oil is delivered, shut off the burner and do not switch on again until the new fuel has been allowed to settle in the tanks for an hour. The oil filter element should be cleaned once a month. At the beginning of the heating season, remove the filter bowl and drain it. There should be no need to alter the setting of the air damper, for it is adjusted correctly by the installing engineer, but where adjustment is clearly necessary, set the damper so that there is a slight haze from the top of the chimney stack. Get the engineer to check the setting next time he calls. Similarly, the boiler flue damper must not be altered except by a qualified man. Should any attention to the burner be necessary, always switch off the current first. A burner that will not start is probably due to one or more of the following: (1) The control circuit is not "calling for heat", i.e. the instruments should be set above the actual temperature or pressure. (2) The thermostat in

126 MAINTENANCE OF HOR.TICULTUR.AL EQUIPMENT the flue (the fluestat) might be stuckin the hot position, in which case press the button on the back of the instrument to reset it. If a flame-eye-a photo-electric cell operated by the light from the flame-is fitted; make sure that its window is clean. (3) When examining the flame-eye, check that the cover screws are firmly and evenly tightened. (4) The burner may have locked out, this being indicated by the red lamp in the control box being alight. If this has happened, press the reset lever. Check the main fuses. A b1J!D.er which starts, but fails io light is probably due to a choked nozzle. To rectify this, remove the inspection cover at the back of the burner and disconnect the electrode bus-bars from the transformer terminals (two nuts on the right-hand side of the air tube). Undo the oil pipe union at the draught tube, then withdraw the complete nozzle assembly. If a copper nozzle shield is fitted, remove it. Take out the nozzle and strip it into its three parts, screen, core and body. Wash all these in paraffin oil or hot water. Never use a pin or other hard instrument to clean the orifice and grooves. A sharpened match will usually do the trick. When the nozzles have been cleaned, reassembled and replaced, check the electrodes for adjustment, following carefully the maker's instructions. If. a burner starts and lights correctly, then locks out after running for half a minute or so, it is likely that the fluestat needs cleaning. This instrument is removed by slackening the securing pin in the brass flange. Mter cleaning, press the reset button on the back of the instrument. The formation of carbon in the combustion chamber is generally due to a partial blockage in the nozzle. When removing the carbon deposit take care not to damage the lining of the combustion chamber. Clean the nozzle as described above. At the end of the season, switch off the current; close the oil stop valve at the tank and near the burner; open the boiler doors; take out the fluestat and clean it carefully; then clean the boiler flues.

CHAPTER 12

Brick and Concrete Work or later you will need to undertake some brickwork and to put down concrete paths. You might decide to build a wall or two, erect a permanent shed, build a glasshouse on a brick and concrete foundation, or make concrete gate and fence posts. But whether you use bricks or cement blocks, the material which fastens them together is mortar, and to learn how to make this properly is essential. Two kinds of mortar are employed, one made of builders' sand and lime, called lime mortar, and the other of sand and Portland cement. Lime mortar is the cheaper of the two but it takes longer to make. One big advantage of lime mortar, however, is that brickwork cemented with it can be dismantled and the bricks used again. In the country it is sometimes possible to buy bricks that have been used to build a barn or cottage. Old mortar can be removed from the bricks fairly easily with a chopper or similar tool. To make lime mortar, measure out 1 part lime to 4 parts sand. Put the sand on to a large mixing board or flattened sheet of corrugated iron. Spread the sand so that it forms a ring, then tip the lime in the middle. Add water, and in an hour or two the lime will have slaked and it can be worked into a smooth paste with a shovel. The sand is then mixed with it and the mass allowed to stand for two or three days before using. Hydrated lime can be used, but it is more expensive. It does not, however, need slaking. Cement mortar consists of Portland cement and sand, the proportion for brickwork being 1 part cement to 6 parts sand. To mix, tip the measured quantity of sand on to the board, add the cement and mix very thoroughly. Good mixing is the secret of good cement making. Work round and round the heap, shovelling the sand to the middle and keep on until the whole is a uniform grey and there are neither lumps of sand nor any uncoated sand left. Water is then sprinkled on from a can with a rose, and the whole again mixed thoroughly. Cement for SOONER

127

128 MAINTENANCE OF HORTICULTURAL EQUIPMENT brickwork should not be so thin as to run, nor so dry that any of the cement is in powder form. The same two ingredients, plus what is termed "aggregate" make concrete, a rock-like material used for wall foundations, paths and so on. The proportions must, however, be varied according to the use for which the concrete is required. Here is a short guide to proportions: Cement Aggregate Sand (sack) (Cu. ft.) (Cu. ft.) Floors from '2 in. to 4 in. thick, fence posts. 1 3 11 Foundations for walls and engines. 1 21 4-: Thick floors, steps, paths, water tanks, etc. 1 21 3 Note that the sand and aggregate are measured in cubic feet and that a sack of cement weighs 1 cwt. All sand, whether required for cement or concrete, must be sharp and contain no dirt, clay or vegetable matter. Aggregate is very much coarser than sand and it can consist of pebbles, crushed stone, broken bricks or clinker, pieces not to be larger than 2 in. in diameter. This should also be clean and free from impurities. Portland cement must be fresh and dry, so do not buy more than you need for the job. Water used for the mixes must also be clean and free from vegetable matter, and to that end it is not recommended that pond water be used. The quantity needed for concrete must be measured carefully, for too much weakens the cement and too little results in a crumbly mass which does not hold together. For a really strong concrete mixture, 1 gallon to every 10 lb. of cement is required, but for foundation work twice the quantity of water can be used. Incidentally, a gallon of water weighs 10 lb. To ensure the proper quantities of solids it pays to knock up a measuring box of stout wood. The inside dimensions of a box to take half a cubic foot are of course 12 in. by 12 in. and 6 in. deep. Make the box strong by binding the corners with hoop iron straps. Water is best measured in a watering can, these generally being marked with their capacity. Use the rose as this prevents the formation of lumps and makes the mixing easier.

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Having decided upon the proportions of ingredients for your concrete, tip the measured quantity of sand on to your board, hollow it out in the middle and add the right amount of powdered cement. Then take the shovel and mix as previously described. Next tip on the measure of aggregate and once more mix thoroughly. Finally add the water ~md mix again. Only when every particle of sand and aggregate is covered with a moist layer of cement have you done your work properly. If you are making a path, dig out the ground to the required depth but make your channel a little wider than the finished path. Place boards on edge to the required distance and steady them with wooden pegs driven into the ground. It simplifies matters if the boards are the same height as the path is to be thick. Tip your concrete in and spread it with the shovel. Paths are generally better if slightly rough, and if a board on edge is patted on the surface this will give an ideal finish. In hot weather cover with wet sacks, and in frosty weather protect with dry sacks or straw. But avoid brick or concrete work in frosty weather if you can. Foundations for a greenhouse are made in the same way, but of course they will need to be thicker than paths. For walls, the thickness depends upon the height. If the brickwork is only 2 or 3 ft. such as would be required for the lower part of a greenhouse, 3 in. is ample. For higher walls- say up to 6 or 7 ft.-ma ke the foundation 6 in. thick and 18 in. wide. Let all foundations set for several days before you start laying the bricks. These generally measure 9 in. by 4! in. by 3 in., and the usual plan is to put the first layer so that the length of the brick lies across the foundation if the wall is to be 4~-in. thick. A 9-in. wall often has a 13~-in. base, i.e. one brick lengthwise and the other on end to it. These lower bricks frequently, but not always, are set so that the top is about ground level. If you are constructing a wall which joins to a house, always use a damp-proof course of felt or slate. Bitumen-felt course is obtainable in rolls of suitable widths. Always soak bricks well before laying them as dry bricks quickly absorb the moisture from the cement which then dries too quickly. When building a wall use either the lime mortar or a cement mortar containing 1 part cement to 6 parts sand. Apply a quantity to your foundation and put some on the underside and on 9

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one end of the brick. Set the brick in place, using a line as a guide. A man with a good eye can lay a passably straight and vertical wall without the aid of a plumb line or spirit level, but for really neat work, use either or both of these. Always be sure that no two joins or bonds come one on top of the other, or the wall will be weak. You can amuse yourself for hours planning how to avoid these. To cut bricks, use a bolster. The real bricklayer, of course, is an expert and he nonchalantly uses his trowel. Play safe and use the bolster which is a large flat chisel. Lay the brick on something solid- the ground or some sand- and apply the bolster to the desired spot. Clout it with a hamm er to make indentation, and do the same on the other three sides. Your last blow can be heavy, when the brick will cut quite neatly. As this is not a book on bricklaying I will leave you to get in some practice and puzzle out for yourself the various pattern s of brickwork for walls of different thickness. The simplest is, of course, the stretcher bond wall in which a single row of bricks is laid end to end, the next row beginning with a half brick so that the joins come in the middle of the brick below. Such buildings as garages, coal sheds and the like can be made with concrete or breeze blocks. These measure 18 in. long, 9 in. deep and 3 in. or 4l in. thick. They are naturally much quicker to lay than bricks, and the cost of the building is considerably lower, particularly if breeze blocks are used. Personally I prefer concrete for althou gh they cost a little more they are stronger and they do not have to be "rende red" with a coating of cement to keep the frost out. Observe the same precautions as to joins as with bricks. Many concrete blocks are grooved and tongued at the ends, and if desired a thin cemen t-of pouring consis tency- may be used to fill any gaps. When making a corner, whether of bricks or blocks, interlink one wall with the other. Concrete and breeze blocks may be cut with the bolster as are bricks. If a door is to be fitted, make the frame of stout timber and then erect it in position when you have laid the first layer or two of bricks. If large nails are partly knocked into the wood they will key the timber to the wall very firmly, but make sure that each nail is put where it is embedded in cement. The best plan is to insert the nail when you are ready to lay a row of bricks. One

an

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nail for every three layers is sufficient. Should you be laying bricks across the top of the door frame, remember that cement will not adhere to wood, so get a piece of old wire netting, double it, and cut to the size of the lintel (i.e. the top). Fix this with staples and when the cement is applied it will surround the netting and firmly lock the wood in place. With regard to fence posts, make a wooden box or mould to the required dimensions and pour your mixture into this. These posts need reinforcement, however, and as a rule a couple or three rods of! in. round iron are laid in when part of the mixture has been poured in. A small roll of old wire netting serves the same purpose although it is not so strong. If you are casting gate posts in this way, be sure to insert wooden pegs into the concrete before it sets, for these holes take the hinge bolts. Do not forget to make due allowance for the part of the post that is put into the ground, and remember that these posts require that the hole be dug first-they will not stand hammering in, even if you have shaped the lower end to a point. For fencing posts through which wires will be passed, make the holes before the cement sets. A good plan is to fasten wooden pegs firmly in place in the mould before pouring the concrete. Making Holes in Brickwork Unless a wall is new and the cement not quite dry, it is practically impossible to knock a nail into it. To plug a wall, use a halfinch cold chisel and a hammer and then hammer in a hardwood plug. A better method, however, is to use a special masonry drill of the type made by Rawlplug Ltd. This is something like a twist drill in appearance but the spirals are less acute and the point is of Durium carbide. The tool is used in a carpenter's brace or in a breast drill. An electric drill can be used provided the speed is low. These drills will cut through bricks, tiles, cement, slate, marble and similar materials, leaving a neat hole into which any of the usual plugs can be inserted. When cutting, use as much pressure as possible consistent with the size of the drill. Remove the drill frequently and clear the hole out, otherwise the dust causes overheating and blunting of the drill point. Rawlplug masonry drills can be obtained in a variety of sizes.

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Cutting Earthenware Pipes When laying glazed earthenware drain pipes it is usually necessary to shorten some of them. The best way to do this is to stand the pipe on end and fill it with sand. Mark off with chalk where the pipe is to be severed. Put the edge of a bricklayer's bolster on the mark and tap the shaft end with a hammer, using light blows only. Work round and round the pipe in this way, when it will eventually break off cleanly. Fixing a Stationary Engine to its Foundations Stationary engines should be securely bolted to a firm base of concrete that is for preference a foot or so thick. Knock up a frame of boards about 6 in. larger all round than the engine and whatever it is to drive, then mix 1 part cement, 21 parts of sand and 4 parts aggregate with the appropriate amount of water. Mix this as instructed on page 129, and tip it into your mould, tamping it well down. Before filling to the top insert four billets of wood (smooth and preferably slightly tapered) at the approximate positions of the securing bolts. Fill up the mould and when it has set a little withdraw the billets. While the base is in a soft state, make a small channel so that sump oil can be drained away easily. When the base is quite hard put the securing bolts into the engine base so that the heads are downwards and the nuts near the tops of the threads. Additional anchor is obtained if a few stout washers are dropped down the bolt to rest on the head, thus providing a shoulder. Place the engine in its position and then make a mix of cement and coarse sand or small granite chippings. This mixture should be thin enough to pour. Fill the bolt holes carefully and let it set. Not until then should the nuts be tightened. If the engine is not available and you want to get on with the job you can use either of the following methods. The first is to obtain from the engine manufacturer or supplier a drawing or template showing how far the bolt hole centres are apart. After the wooden billets have been taken out, cut four pieces of fine mesh wire netting, each about three or four inches square. Put a bolt through the middle of each (not forgetting the washers) and lower each bolt into a hole. Add washers under the nuts to give enough thread to pass through the engine baseplate and leave enough for the nut. Carefully space the bolts to

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the correct distances, and then fill the holes with a mix as described above. The netting will support the bolts until the cement is set, when it can be removed. The second method is advisable if you are unable to obtain the exact dimensions of the base-plate. Before pouring in the top four or five inches of concrete into your mould, cut four hardwood blocks, each slightly tapered, and insert them, large end down. Space them to the approximate positions, then fill the mould to the top and let it dry. The engine can then be fastened with coach screws.

CHAPTER 13

Woodworking THE man who lives in the country will always need to know how to make repairs and construct things with wood. Timbers vary considerably in their characteristics, and when possible the wood used for jobs should be chosen on account of its qualitystrength, hardness, resistance to wear, flexibility, durability and so on. For example, ash is excellent for handles, various firs for constructional work, oak for fencing posts. Use elm for making barrows, garden furniture and so on. Larch is good for fences and gates. We very often have to put up with what we can get, but even a soft wood will make a satisfactory job if it is treated to keep out water. Some woods, however, are quite unsuitable for certain jobs because of their brittle nature or because of an overdose of knots. There are today a number of "man-made" woods such as Masonite which are tremendously strong, available in sheets of various thicknesses, reasonable in price, completely free of knots and suitable for many purposes. They can be sawn, planed, drilled and screwed just like any ordinary timber. These woods are obtainable from all builders' merchants, the usual size of sheet being 4 ft. by 8 ft. They may be purchased by the square foot. Woodworking does not require a great number of tools (unless one branches out and starts making furniture) but they should be of good quality and be kept sharp. With the fourteen items given in Chapter 3, pretty well any job on the holding can be done satisfactorily. You probably have most of those on the list and your first task is to put the cutting implements into good condition. A saw consists of a steel blade with hundreds of teeth, all of which should be properly shaped and sharpened. Take a look at your rip saw. The points of the teeth should project equally from the blade. If some are high, some low and a few broken off, then you cannot do good work. If the saw has been used to cut asbestos cement sheet, or you have cut through a nail embedded in a plank, the saw will need special treatment.

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First of all file down the points of the teeth until they are all the same height. To do this, place the file lengthwise along the saw blade-but be careful of your fingers. Use a flat file, and continue the work until there is a small shiny flat on the end of each tooth. The next step is called "shaping". With a triangular file, work across the blade in each "V" until every tooth is brought to a sharp point. After shaping the teeth must be "set", which means that all alternate teeth are bent slightly to one side of the blade and the others made to point to the other side. The degree of set need be quite small, for its purpose is to provide clearance for the blade as it slides through the cut. Setting is best done with a special saw set which ensures equal bending. These tools are adjustable and can be used for almost any kind of saw. Another method is to use a set consisting of a flat strip of steel with slots cut along its edges, the slots being of different depths and widths. These have to be used carefully as it is necessary to bend all the teeth the same amount. Only the upper half of each tooth should be bent or there is danger of tooth breakage. As to the degree of set, this should really depend upon the condition and the kind of wood to be sawn, but see that there is sufficient clearance for the blade to run freely in the saw cut. A point to bear in mind is that the teeth must be bent in the same direction as that in which they were originally set. The final operation is sharpening. The angle of the cutting edge of saw teeth varies a fair amount. A rip saw, for instance, has the cutting edge sloping back more than a general purpose saw in which the edge is only a few degrees from the verticalabout 15 degrees. This gives a finer cut. For most farm purposes, however, the tip saw teeth will do, especially if the wood is green. To sharpen the teeth, use an 8-in. or lO-in. triangular file. Put the saw in the vice so that the blade is gripped a little below the teeth, the handle of the saw being on your left. Put the file into a gulley in which the tooth on the left points away from you. Point the tip of the file a little towards the saw tip. Hold the file level and make a forward cut, following the line of the file. Put a little more pressure on the left-hand side of the file as you make the cut. Always lift the file clear of the work on the back stroke. Repeat until the tooth on the left of the gulley

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has a sharp cutting edge. Now move the file into the next but one gulley and repeat all along the blade. When one side is done, turn the saw round and do the other side. It will probably be necessary to go over the saw again, and possibly even a third time, but it is worth while to make a good job. Sharpening a Chisel To sharpen a chisel that is nicked, or which has seen much service it is necessary to grind it, preferably on a grinding wheel. Hold the blade bevelled side downwards and against the wheel, which should be turning towards you. Grind the blade to a bevel of from 25 to 30 degrees (this actually gives a bevelled edge that is a little more than twice the thickness of the blade itself). Touch the blade lightly against the wheel and frequently dip the tool in water to cool it. Move the blade from side to side of the grinding wheel face but make sure that the cutting edge is kept square with the blade sides. Check with a try-square. Continue grinding until the dull edge is removed and all the nicks have been ground out. The next step is to whet the blade on an oilstone. Put a few drops of thin oil on the stone, lay the bevelled edge on the stone and very slightly raise the handle. The blade should be held so that the cutting edge is at an oblique angle to the edge of the stone. Carry on whetting until a slight burr or wire edge is formed. To remove the wire edge, turn the blade over and lay itflat on the stone. A few strokes only are needed, but if the wire edge is turned to the bevelled side, whet that side again. Repeat until the wire edge has gone, at which stage the tool will be sharp. A keener edge may be obtained by finishing on a leather strop. Grinding can be done on a fiat carborundum stone but this takes longer than with a wheel. Remember to hold the blade at the correct angle throughout each stroke to prevent the bevel from becoming slightly convex. Planes Plane irons are treated in the same way as chisels, but before using the oilstone, round off the corners of the cutting edge slightly on the grindstone to prevent scoring the wood when planing.

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Good work can never be done with a plane in which the blade g iron, too, i~ wrongly set. The position of the cap or backin well as the as plished accom affects the ease with which work is on the flat put be , course of quality of the job. The cap iron must, be downbevel blade cutting side of the cutting blade, and the parallel be should iron cap wards in the frame. The edge of the of an th sixteen a work, ry to the cutting edge and, for all ordina the across cutting for plane the inch from it. But when setting found is t amoun actual The grain, reduce this distance a little. by trial and error, for if the blade tends to tear rather than cut, reduce the distance still more. Be careful not to let the blade edge come into contact with the cap iron, or it will be blunted. When replacing the blade in the stock make sure that it projects an equal amoun t all along its edge. A distance of a sixteenth of an inch is generally about right, but this might have to be reduced or increased. Apply pressure on the forward end of the plane at the start of the cut, and on the rear of the plane at the end of the cut. In this way a level surface will be made. Do not thrust jerkily or hard- a plane in good condition will run smoothly. See that the wood is firmly held and, when you can, plane with the grain and not against it. Set the plane iron to make a light cut, otherwise there is a chance of tearing out lumps and clogging the plane. End grain should be planed with the plane edge oblique to the wood. This makes a better cut. It will help to make a neater job if (a) a small block of wood is clamped to the far edge of the wood being planed or (b) the far edge is chamfered a little. Both these methods will prevent splitting. A third way is to plane partly from one edge and partly from the other. Remember to lay the plane on its side when you pick up another tool. Wooden plane stocks often suffer from neglect, and it is a good plan to apply linseed oil liberally until no more can be absorbed. This will not only preserve the wood and prevent it from splitting throug h dryness, but it reduces wear on the face. Planning a Job

Success in carpentry depends upon three things: good tools, skill in using them, and sound planning. The absence of any of

138 MA INT BNA NCB OF HO RTI CUL TUR AL ~QU1PMBNT these three makes for unsatisfactory wor tools sharp and ready. The next thin k. So far we have our g is to plan the work. A trained carpenter will instantly visu alise the job put before him. His experience tells him tha t this or tha t design will give the best results. The design decides the types of join t required and so on. The beginner mu st take mo re time ove r planning. He must ask himself exactly wha t is required of the construction. Is it to be permanent or temporary? Wh at wor k has it to do? Wh at material is available? Is it necessary to eco nomise in timber1- Are any special bracings needed to tak e exc eptional strains? Are any additional supports needed becaus e the covering material is in small pieces? The list could be exte nded considerably. It might well be desirable to make a few drawings, not only of the complete job , but of variou s parts. Possibly a shed will have to be sectional for easy dismantl ing and re-erection. Perhaps it will have to be mounted on whe els, in which case the best position for these mu st be thought out. Maybe there is an existing doo r which could be utilised, thu s necessitating a careful planning of the doo r frame. Tak e plen ty of time over the design of a large or imp orta nt job for so ofte n one can discover some new or better way of accomplishing one's aim. By doing this, a useful piece of timber can be saved. By doing tha t, a possible future extension can be added easily. Getting down to details, ask yoursel f if the proposed construction is the strongest or mo st suitable. Wh at strains are likely to be placed upo n this or tha t part? By the time you have settled upo n the design you will hav e unconsciously formulated a pla n of act ion -yo u will kno w the starting poi nt and wil l have decided on the necessary timber and oth er materials. You will, in fact, have don e some very useful work for it is work which has already saved you conside rable lab our and possibly material. Making a Sawing Stool Sawing timber means the expenditur e of labour, but cutting it the wrong size add s insult to injury. A sound rule is to measure twice and cut once; it is a rule tha t can save a lot of money. It is not possible to make a good job of sawing unless the wood is held firmly and at the right height. A carpenter therefore uses .a

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sawing stool, so let us begin by making one. You will need four pieces of 3 in. by 2 in., each 2 ft. long; one piece of 4 in. by 2 in. 3ft. long, and a couple of odd pieces described later. Splay the legs as shown in Fig. 47. The most difficult part is cutting the ends of the legs to fit round the top of the stool. The best way to do this is to draw a full-sized plan of the stool end on a piece of brown paper, when the depth and angle of the cut can be measured. It will then be an easy matter to make pencil marks on the timber to allow a close fit to the top bar.

~-1'-6~

;-----5-0"-----~

I

FIG. 47

Use a tenon saw to make the cut, and either pare the waste with a chisel or cut it out with the saw. The legs can be screwed or bolted to the top. A coach bolt will be satisfactory if a washer is put under the nut which is then pulled up tight. If screws are used affix two in each join. The legs are made steadier by screwing on a piece of! or 1 in. thick plank as shown. If squared-up timber is in short supply, the legs can be made of wood cut from saplings, but the fitting will be more difficult. When using a sawing stool, put one knee on the timber to steady it, and saw at an angle of 60 degrees. Keep the forearm and the saw in a straight line as this enables the maximum power to be used. Avoid bending the wrist, and use a fairly light pressure on the downstroke. The eye should be in line with the blade to ensure a straight cut. When cutting across a long plank, two sawing stools are needed, and generally when cutting across the grain the angle of the saw is increased to 45 degrees. Use steady strokes, utilising the full length of the blade.

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Joints Makin g joints is an import ant part of carpentry, indeed it is impossible to make things withou t them. The most commonly used joints are shown in Fig. 48. The butt joint is the simplest but of course not suitable for all work. The abuttin g end should be cut squarely, and the best way of doing this is to mark all round the wood, using a try-square. Guesswork is not satisfactory, even for the practised worker. Butt joints may be nailed, screwed or glued, but when this form of joint is used to make a panel, use glue. In the chapte r on bricks and concrete, reference was made to a box for measuring out the materials. The instructions were somewhat vague, so let us do the job properly. The box is to be 12 in. by 12 in. and 6 in. deep; it must be very strong for the weight of half a cubic foot of sand is considerable. We need hard, close-grained wood, say elm. As to thickness, it ought not to be much under one inch. Nothin g elabor ate is required, so the corners will be butt-jointed. Bearing in mind what we have learned about planni ng we discover that the two sides of the box must be 12 in. long and the two ends 14 in. to allow for the butt. The bottom should be pieces of similar material, but they have to cover an area of 14 in. by 14 in., so either the wood for this must be seven inches wide or we must use three strips. Cut the two side pieces carefully so as to have square ends. Elm is not a good wood for nailing along the grain, so drill and use screws, putting three in eachjo in. After markin g the positions, drill holes large enough to take the shank of the screw, countersink them and then make pilot holes for the screw threads. Use 2-in. "1O's". When the sides and ends have been firmly screwed together, fit the bottom in the same way, but to give added strength, either bind the ends and bottom with hoop iron or use wire and staples. Handle s may be fitted if required, but make sure they are strong and well secured. Lap joints are formed by one piece of wood extending over another, with a section of each removed, see Fig. 48 (b). Laps are used for corners, to form a tee, a cross, or to join two pieces together endways. It will be appreciated that some wood is planed smooth and others are left rough-sawn, this being a matter for the carpen ter to decide. In erecting a shed, for example,

WO OD WO RK IN G

141

j

j

j

j

j

j

j FIG .

48

j

j

j

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MA INT ENA NCE OF HO RTI CUL TUR AL EQU IPM ENT

rough-sawn timber would be quite satisfactory, but for cold frames and so on, planed wood is des irable. Fig. 49 shows a lap join t separated, and from this diagram you will be able to make the necessa ry cuts. After sawing to the required depth, which is of course hal f through the wood, chisel 9ut the wMte carefully, taking a littl e out at a time. Use a mallet on the chisel and do not hit har d for you are working with the grain. Too heavy a blow might cut farther than is needed, thus weakening the wood. Lap joints can be nailed, screwed or glued.

~

C 7 _/- -

----------=FIG .

49

Take care in marking out or you r ove r-all measurements will be reduced. Similarly, do not par e awa y more tha n hal f the dep th or the two pieces will not be flush. If you are making a middle lap join t, thus forming a tee, remember tha t the strength of the join t depends upon its close fit. Saw a shade inside you r markin g line to allow for the set of the saw, for a cut is always wider tha n the blade. When removing the waste from the wood with a double saw cut, work from one side to the middle, the chisel bein g held at an angle, then turn the wood rou nd and again wor k to the middle. Finish off by taking thin parings with the chis el held level. On a cross lap joint, bot h pieces would be treated in this way. A rab bet join t is simple enough to make, and the illustration on page 141 (c) plus you r knowledge of a lap join t will ensure success. This join t can also be nailed, screwed or glued. Mortise and tenon joints are more difficult to make, but they provide one of the best methods of joining wood. For tha t reason, mortise and tenon constructio n is used for farm gates.

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The mortise is the rectangular hole cut through one member and the tenon is the projection from the other member. This type of joint can be open, see Fig. 48 (d), or "through", see Fig. 48 (e). Careful marking out is necessary and chiseling should not be hurried. To cut the mortise, mark it out carefully and bore a series of holes through. Squaring up is done with the chisel. Use an auger bit the same width as the mortise, and bore the outer end holes first. Be sure that the drill is vertical. What has been learned about making the lap joint will be of value when cutting the tenon, but be very careful when removing the last of the parings for it is easy to take off too much. The tenon should fit snugly, be reasonably tight, but not so much so that it strains the sides of the mortise. Sometimes tenons are purposely made a little slack, a wedge being driven in to tighten them. In the long run the extra time speni in making a job a sound one is worth while. It is always annoying to have to patch up a bad job a few months later. No doubt this advice will fall on some deaf ears-and I must confess that I occasionally lapse myself-so, as the old stand-by is the nail (or the screw for the more conscientious) here is some useful information.

NaBs. There are dozens of different nails, but the round wire or common nail is the handiest. Common nails are of a fairly large diameter and have a roughened head. Box nails are similar but thinner and, as their name implies, are used in making boxes and crates. English square-cut nails no doubt have their uses, but I sometimes wonder if anyone but an expert can knock one in without bending it. I know I can't. When driving nails it is as well to use wrist action alone for light driving, but wrist and elbow for heavier hammering. Some people seldom drive in a nail without splitting the wood, but if this is likely to happen-and you know by instinct-use a bradawl first, setting the sharp edge across the grain. Once the wood splits, the nail will not hold. A blunt pointed nail reduces the likelihood of splitting. The use of too many nails weakens a joint. Avoid putting one

144 MAINTENANCE OF HOR.TICULTUR.AL EQUIPMENT nail next to another along the same line of grain or a split will almost certainly result. Do not put nails too close to the .end or edge of a piece of wood-if this cannot be avoided, drill a hole slightly smaller than the diameter of the nail, using a twist drill for the purpose. When nailing a butt joint and you have to put the nails along the grain of the wood, slant them so that the points are closer together than the heads, as this gives a better hold.

Screws Screws have more holding power than nails. They take longer to' fix, but they can generally be removed without damaging the wood, and one can never be sure when it will be necessary to dismantle a structure. The most commonly used screw is the flatheaded which is best fitted into a countersunk hole so that the top is flush with the wood surface. With regard to length, have all the threaded portion screwed into the main timber, leaving the smooth shank to pass through the piece attached. Bore a hole just large enough to take the shank. There should also be a hole for the thread. In hardwoods this pilot hole, as it is called, needs to be a little larger than in softwoods. Lubricate a wood screw before driving it in. I generally use oil, but some people believe that this expands the fibres and makes the screw harder to remove, although I have not experienced this trouble myself. The recmrimended lubricant is soap or wax. Removing screws sometimes ·pr~ents a problem, but the application of paraffin oil, given time to soak in, often does the trick. Another trick is to grip the head with pincers (not pliers) by laying the jaws on their sides so that one jaw comes each side of the screw slot. If the pincers are then firmly gripped, the jaws will bite into the head and provide an excellent hold. It might be necessary to cut away a little of the wood before doing this. If the screw head is so badly rusted that the slot is not deep enough to retain the driver, don't try more than once or you will damage the slot beyond repair. Cut a deeper slot, using two blades in a hacksaw. You will probably find this difficult in some cases. The edge of a thin, flat file can also be used. An Eclipse handle will be found very helpful for some of these jobs. This is an aluminium handle made to take a broken hacksaw

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blade, and its big advantage is that the blade is held firmly. A screwdriver bit in a carpenter's brace gives excellent turning power owing to the leverage, but see that the bit fits snugly in the slot, and press hard on the brace when turning. If you find that the screw turns but refuses to come out, as it will do if the rust is severe, turn it several times to loosen it and then use pincers to grip the head edge, then turn and pull. As a last resort, use a shell bit in a brace and drill round the screw, removing a circular plug with the screw in its middle. The hole can then be filled with a hardwood dowel. Never hammer a wood screw in. This is a sign of shoddy workmanship. Anyway, you might one day have to get that screw out and you will find the head damaged. You might think I have given too much space to the subject of screws, but, believe me, this information will save you a lot of trouble. It is often necessary to glue a joint, and for this I advise Casco. It is obtainable in powder form and cold water is used for mixing. I have yet to find a better adhesive; it is extremely tough, very durable and waterproof. The glue has scores of uses including the repair of gun stocks, ladders, gates, etc. A thick mixture sets very quickly and is helpful when the job cannot be clamped for very long. Making an Extension Ladder The chief thing to bear in mind when making a ladder is safety. All timber used must be sound, straight-grained and free of knots. It is advisable to tell the wood merchant the purpose for which the timber is to be used, for his experience is invaluable. Here are the dimensions of a small extending ladder which has been in use for over twenty years. Lower half: Sides 6 ft. long, 21 in. wide and 1k in. thick. These are, of course, the finished dimensio!l:s. The eight rungs are of hardwood, rectangular in section, measuring It in. by ~ in. Length 141 in. Upper half: Sides as above. Seven rungs of the same sectional size but 11 tin. long. This ladder extends to 10 ft. 8 in. Longer ladders should have thicker sides, and should be wider. Before cutting the rungs it is as well to buy the necessary iron fittings in case these are slightly wider or narrower than your 10

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MAINTENANCE OF HORTICULTURAL EQUIPMENT

planned dimensions. You can make the fittings yourself, however, as described later. Cut and plane the four side pieces, then mark the position of the rung holes. In a small ladder such as the above, the rungs are spaced with their centres 91 in. apart, and the centre of the lowest rung is 3 in. from the bottom of the side pieces. The rungs are set on edge so that the user stands on the narrow side. Slightly taper the end of each rung and then cut the holes as described earlier in this chapter. The holes should go right through so that the rung ends are flush with the outside of the

FIG. 50

uprights. They can be secured by wedges, by nails, or by gluing, but be sure that each rung fits tightly yet does not split the wood. If desired, the ladder sides may be prevented from spreading apart by the insertion of a long bolt under one or two of the rungs, although this will not be necessary if the joints have been made correctly. The top section is, of course, narrower than the other, being constructed to slide inside the uprights of the lower portion. Fittings are made out of I-in. thick iron, and a blacksmith will do the bending for a shilling or two. Two brackets are needed for supporting the top portion on the rungs of the bottom half. Use one coach bolt near the bend, and one stout screw. Fig. 50 shows the dimensions of these brackets and how they are fixed. Two more brackets are needed (see Fig. 51). These should be

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bent at right angles as shown. Each of these brackets is placed inside the uprights of the bottom portion, just below the top rung. The tee head fits the edge of the side piece at the back. Put coach bolts throug h the holes "A" to clamp the bracket firmly to the side pieces. When both brackets are fitted, insert an iron rod (not less than i in. diameter) throug h the two holes "B" and rivet the ends over securely. This fitting must be very carefully made, for your safety depends upon it.

A

(0

FIG. 51

The top portion slides under this iron bar and is suppor ted by the clips which rest on the rungs of the lower portion of the ladder. Round rungs are commonly used in the building trade, but the amateu r will find it easier and more convenient to obtain supplies of the type described. Making Gates The requirements of a good gate are that it should be an effective barrier against livestock and that it should be rigid, durable and properly hung. Thus, reasonably strong timbers are needed, except, of course, if the gate merely has to keep out

148 MAINT ENANC E OF HORTI CULTU RAL EQUIP MENT

chickens. Rigidity is probably the next most important feature, for sagging gates deteriorate rapidly, partly because of loose joints, but chiefly because they are strained every time they are opened. As we shall see in the next chapter, the triangle is the strqngest of constructions, and this should form the basis of gate design (see Fig. 52). In practice the most essential parts of any gate-

FIG. 52

from a constructional point of view at any rate-a re the three parts shown in the sketch. The remainder of the frame bears down upon the strut "C" which, if properly fixed, will carry the load without any distortion of the framework. This principle is naturally subject to considerable variation; for instance, the oblique strut can be mortised or half-jointed to the vertical and horizontal bars, or in its simplest form it may be laid on and nailed. The essential thing, however, is that this strut should bear upon the upright and not upon the lower bar of the gate. It is not necessary for this strut to be of the same thickness as the other parts of the frame -its value lies in its position. Once this principle has been understood, the actual manufacture of the gate is simply a question of sound jointing. The best gates are mortised; but very satisfactory gates have half-lap joints, while many a useful one is simply nailed or screwed. With regard to timber, oak and larch are extremely durable,

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but there is no reason why other woods should not be used provided they are treated with a preservative occasionally. In this connection, note that it is worth while treating each piece of timber when it has been cut and shaped, for this retards rotting at the joins. The whole gate is then given its proper coating after it has been hung. The life of many gates is curtailed because the posts to which they-are hinged are insecure or not strong enough to bear the weight. A farm gate post needs to be 3 ft. 6 in. in the groundi.e. very nearly half its total length. Every other post should be 2 ft. in the ground with stones rammed well down around it. The post should be thoroUghly soaked in creosote or other preservative before insertion, and care should be taken that the preservative be carried up to a distance of at least a foot above ground level. It is better still if the whole post can. be thoroughly impregnated. Strong hinges are important, and their fitting should be a matter of careful consideration. It may be, for example, that you want a gate to swing to and shut itself. This can be achieved by setting the bottom hinge out farther than the top. Such a gate would swing to whichever way it was opened. Another method, applicable to a gate which opens only one way, is to set one of the hinges out of vertical sideways with the other.

Preserving Wood Preserve posts and other outside woodwork against weather effects by using creosote or tar. Both are cheap and easy to obtain and the protection given is more or less permanent. Creosote is poisonous to wood-destroying insects and prevents fungi from growing on timber. Posts should first be sharpened and then stood in a drum containing creosote. The liquid should be at least 2 ft. deep so that all the lower portion of the stake to just above ground level is thoroughly saturated. Leave for several days if possible to allow good penetr~tion. A brush can be used, of course, but at least two or three coats should be given. Creosote cannot be painted over and it should not be used inside the house owing to the penetrating smell and danger of food taint. A little tar mixed with the creosote gives a darker and more lasting colour. Another material used with a similar object is copper sulphate

150 MAINT ENANC E OF HORTI CULTU RAL EQUIP MENT

crystals dissolved in water (1 lb. of crystals to 10 gallons of water). Immerse the stake ends for at least twenty-four hours. This substance does not actually waterproof the wood but it does check rot. For compost bins apply a liberal coating of old engine oil every time you make a fresh heap.

CHAP TER 14

Roofs and Buildings outbuildings are indispensable on holdings, for at times they house a considerable proportion of the farmer's capital. Cover is needed for machinery and implements, for stocks of cattle food and produce. Water pumps and lighting plant should be under a weather- and frost-proof cover, while on a smallholding a sound and dry packing shed is essential. Very few of us are able to start with new buildin gs-usu ally one has to rescue old ones from collapse. All the same many that are decrepit or rickety can be saved by careful bracing. There is nothing stronger than a rigid triangle, and whenever possible this form should be adopted. A simple illustration of the principle is found in a roof where collar beams are inserted. These are lengths of timber joining two opposite rafters, just like the horizontal bar in the capital letter A. Squares and rectangles are frequently weak and an entire wall of tiinber construction will sometimes bend or become distorted for the lack of a single diagonal bracing strip. Even a box-like construction such as a timber shed or barn can be pushed out of shape by a heavy gale, whereas the intelligent use of a few planks will enable the structure to withstand a hurricane. If you examine the roof timbers of a well built house you will find that the rafters -those lengths of wood reaching from the wall tops or eaves to the ridge of the roof-a re joined together with what is called a purlin. This is a piece of timber which runs the length of the roof about half-way up the rafters, serving to keep them correctly spaced. Usually there are a number of struts leading from the purlins down to the ceiling joists, and these, it will be noted, add more triangles to the construction. A study of this type of roof will repay you when you come to erect sheds and buildings yourself. The weakest part of a roof is the ridge, and the fitting of collar beams prevents movement. Usually a lean-to shed roof, i.e. a shed built up to an existing wall, will not need a middle support if the roof span is under 8 ft. in depth, nor will a ridge type of roof need collar beams if

GOOD

151

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MAINT ENANC E OF HORTI CULTU RAL EQUIP MENT

the building is not more than 10 ft. wide. It might be desirable, however, to use a triangular wooden plate at each ridge join, especially if one has not built a roof before and the timbers have not been cut dead accurate. The plates should be 1 in. thick and about 8 in. wide (see Fig. 53). Screw them to the rafters. On buildings more than 10 ft. wide, use a collar beam at every three or four pairs of rafters. Extra plates can of course be added if thought desirable. A roof with a frame that is not completely rigid cannot be made really waterproof, for a high wind will disturb any joint

FIG. 53

which has movement. Thus the first essential is to have a firm foundation for whatever material is being used for the roof covering. As far as this book is concerned we shall deal with three types only, these being corrugated iron, asbestos cement sheets and roofing felt. Little need be said about corrugated iron for its qualities are surely known to all. It is not a heavy material and it does not require much support, for horizontal timbers placed about 4 ft. apart are ample. The spacing, however, depends upon the length of the sheets used. If these are not more than 6 ft. and the building is a small one, it is possible to dispense with a middle support bar, but put one in if you can spare the wood. Corrugated iron sheets are usually 2 ft. 6 in. wide and have 3 in. corrugations, so that when one sheet overlaps the next, the effective width of each is 2 ft. 3 in. Remember this when you order. Lengths vary from 3 ft. in rises of 6 in. up to 10 ft. If your walls are of brick or concrete blocks, be sure to secure the timber roofing frame firmly. Timbers which are laid on the wall top should be bolted down to the brickwork if possible.

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Another effective method, and one that is cheaper, is to drive some stout nails into the wood, leaving about half their length unburied. The timber is then laid in position along the wall top (nails downwards) and cement packed in. This grips the nails very firmly and also keeps out draughts and rain. The iron sheets should overlap the roof ends for an inch or two as this helps to protect the woodwork, but do not have a big overlap or the metal will bend up and possibly work loose in a gale. Fasten the sheets to the timber with special galvanised nails which have a large domed washer at the head, and drive throug h the ridges and not the valleys. Asbestos cement sheets are used today more than galvanised iron, although iron can be used again and again and will not break. Owing to the brittle nature of asbestos sheets they must be handled very carefully, especially when it is necessary to cut a sheet measuring 8 ft. by 4 ft. Do not attemp t to carry a sheet of this size without assistance, and even then, hold the sheet by its sides and not by the ends, particularly when laying it down. There are three methods of cutting this material. One is to saw it-a comm on procedure but one that is hard on the saw which cannot afterwards be used to cut timber without being resharpened. The second method is to lay the sheet on a firm and level surface and, using a straight-edge, scratch with a screwdriver or other such implement. A fair amoun t of pressure is needed for this and unless the sheet is on a level surface it is almost sure to break. When the score is deep, say an eighth of an inch, the sheet is then slid over the suppor t until the score lies along the edge. Careful pressure on the overhaJlging portion usuall y-but not alway s-resu lts in a clean break. It is as well to practise on odd pieces until the knack is found. The safest method of all is to use the tool illustrated in Fig. 54. It is operated by hand and it nibbles its way along leaving a clean cut edge that is chamfered (or weathered) on the underside. This tool costs 19s. 6d., but as asbestos is lOs. or so per sheet it might be well worth while investing in this cutter. There is anothe r model designed to cut corrugated. sheets of the same material, which it will neatly sever either straight across or obliquely. Asbestos sheeting is usually fastened. with flat-headed galvanised nails, and although drilling is not necessary as a rule, I

154 MAINT ENANC B OF HORTI CULTU RAL BQUIP MBNT advise it when nailing near to the edge of the materi al. If the buildin g is only a tempory- one it is better to use screws, otherwise the sheets are bound to be broken when the nails are removed . Use round- headed ename lled screws and put a galvanised washer under the head. Roofing Felt Roofin g felt if put on proper ly Win last for many years. It is essential that when this materi al is used the roof be first boarde d in to provid e a firm suppor t, for more roofing is destroy ed by bad fixing than by bad weather. The rafters should be spaced about 2 ft. apart and the boards nailed on. Wider spacin g frequentl y means that the timber will twist and warp. Use boards of uniform thickness if possible but if not, pack up the thin ones so that the upper sides are level. Drive the nails well in so that no heads stand proud of the boardi ng. With regard to the roofing felt itself, it pays to buy the best quality, for after all the cost of the felt is small compa red with that of the labour of fixing it. Felt is not strong enough to withsta nd rough treatm ent, so when spread ing out the roll to measu re off the length require d, see that the ground is free from stones and the like, and do not walk on the materi al. Use a straight-edge and a lino knife or a pair of large, sharp scissors. Measu re up carefully and make allowance for turning the materi al over the edge of the boards . WIiether the felt should be applied in horizontal or vertical strips is a matter of person al preference, but if you run it horizo ntally, start laying it at the eaves of the building. Let the felt overlap so as to come 1 in. below the bottom edge of the boardi ng, and secure with nails spaced at 2 in. intervals. Use galvanised nails with large, llathea ds and select the length accord ing to the thickness of the boardi ng. For a 1 in. board use i in. nails. Lap each subseq uent sheet 3 in. over that below it and nail throug h the centre of each overlap , keepin g of course to the 2 in. nail spacing throug hout. Watch that you do not drive any of the nails into a join between two boards . If your shed is a longish one and the horizo ntal strip is put on in two pieces, the overlap must be 12 in. to preven t water creeping in. Work up the roof to the ridge, then do the other side. Cap the ridge with a 12 in. strip bent along the middle so that half the

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width comes each side. To make the roof gale-proof, obtain some batten and screw it, using 3 ft. spacing, down the roof from the ridge to the eaves. Finish off by nailing the felt to the edges of the boards . If you have a felted roof that is torn, but not badly enough to warran t replacement, patchin g is quite satisfactory, but be sure to have a good overlap , say 12 in. all round. A little tar used under the patch keeps water from seeping in, especially at the top.

Sealing In a lean-to shed it is import ant to make a good seal between the vertical wall and the top of the roof. Corrug ated iron can be effectively joined by first applying cement, then coating it when dry with a bitumi nous prepar ation such as Rito. This is applied with a small trowel or putty knife. The bitume n should be carried over the edges of the cement and make a close join with the brickwork. If plain asbestos cement sheeting is used for the roof, the bitume n alone makes a good seal so long as the asbestos fits reasonably close to the wall. If it does not, use cement to close the gap. Corrug ated asbestos will need cement as well as the bitume n. When the lean-to roof is of felt, rake out the mortar from a joint above the top of the shed roof, then cut a strip of felt wide enough to tuck into the joint, come down the wall and extend six inches down the roof. This strip is then bent to shape, tucked closely into the groove between the bricks, and nailed to the roof at the usual 2 in. intervals. As far as glasshouses are concerned, mainte nance of the roof should never be neglected,. for apart from the danger to oneself or staff from broken glass, the collapse of a roof might mean a very heavy financial loss. On commercial holdings where there are large areas of these houses, arrang ements can be made for the manuf acturer to carry out a regular inspection. Nevertheless, the owner should at all times watch for signs of decay and leakage. Painting Timbe r framing can be preserved in several ways, such as by the applica tion of creosote or one of the proprie tary wood

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MA INT ENA NCE OF HO RTI CU LTU RA L EQU IPM ENT

preservers. Usually, however, woo dwo rk is painted. Pai nt is not per man ent nor is it an ine rt substance. It consists of oils, pigments and oth er materials which are app lied in liquid form. In course of time the composition dries out completely, when it loses its protective qualities and mu st be rene wed.- When we say a pain t is "dr y" we generally refer merely to the surface. The cos t of the material is small com par ed with tha t of the lab our required to app ly it correctl y, so cheap pai nts are not economical. But even the best quality pai nts can not give lasting pro tect ion unless they are used pro perly, and the secret of goo d wor k is careful preparation. Rub down with glasspaper all rou gh and uneven surfaces, but if the pai nt is bad ly crac ked or blis tered it is wiser to remove it completely. The re are two ways of doi ng this, one with a blowlamp and scraper, and the oth er with pai nt stripper. This, however, is rath er expensive so kee p tha t for glasshouse wor k where the blowlamp is not suitable . Clean out gutters and scrape all iron wor k with a wire brush. Rub rusty spots over with emery clot h or, bet ter still, app ly a rus t remover, such as Jenolite. Unless all rus t is removed it will spre ad und er the pai nt and lift it. Carefully bru sh off all dus t from bot h woo d and metal before applying pain t. There is surely little need to give instructions as to applying the pai nt, for if the pre par ato ry wor k has been well done, painting is a simple mat ter. All the same, use a well load ed bru sh to ensure a goo d film, but do not app ly so thic k a coa t tha t it runs. Once again I stress the desirability of using the bes t pain ts and the best brushes. A goo n bru sh is rath er expensive, but it will last for years if properly cleaned and stored. Never let pai nt dry on a brush. If you have to stop for dinner, put the bru sh into a jar of water, but at the end of the day, was h the implement in turp s substitute. Do not let a bru sh stan d on its bristles for any length of time for they will curl per manently. Ma ny painters dril l a small hole thro ugh the handle, the n if a piece of wire is pushed thro ugh the hole the bru sh can be supported, with the bristles in the cleaning fluid. When a painting job is done, wash the bru sh in turp s substitute, then in war m water and soap. Finally rinse it in clean water, sha ke it out , let it dry , and the n store on a shelf or han g up.

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Glazing The ability to make a good job of glazing is useful. To replace a broken pane of glass, put on some stout gloves and pull away the bigger pieces. Then chip out the old putty from the frame, using an old chisel or knife. Remove any nails found and clean the woodw ork withou t injuring it. Brush on some undercoating paint, for putty will not adhere to bare wood. Carefully measure the frame and cut the glass an eighth of an inch less in width and depth than the frame. Lay the glass that is to be cut on a level table or bench which has been covered with several thicknesses of unfolded newspaper, a piece of seamless sacking or an old blanket. In case the sheet of glass is not square, check this with your carpenter's try-square. Use a straight-edge and make your cut in a single but firm stroke. Never have two goes at the same line. If for some reason the cutter fails to make a proper scratch it is safer to turn the glass over and make a fresh cut on the reverse side. Having trimme d up a square edge carefully rule off the required amoun t makin g due allowance for the distance between the straight-edge and the actual cutting wheel or diamond. If the cutter has done its work properly the glass such as is used for windows can generally be broken over the .edge of the table by applying a quick pressU1e of the hand. If difficulty is encountered, lightly tap the underside of the glass, following along the line of the scratch. A little practice on some odd scraps of glass will soon show if it is the cutter or yourself that is at fault. Next work up some putty in the hands, kneading it until it is pliable, then press a thin layer into the rebate. The glass is then gently pressed into place so that some of the putty is forced out at the back. Take care to put the glass in so that it does not actually touch the wood, or there is a likelihood of its breaking if the window is slammed. Insert a few lino brads or small tintacks to hold the glass in and, with a light hamm er sliding on the glass, knock the tacks in until they are firm. The front putty can now be applied. Soften this and press it in with the fingers. The finishing bevel is made with a putty knife.· If there are any fine strips of putty left on the glass after knifing, remove them with a brush or the bevel might become spoiled. Finally, paint over the putty so that the paint spreads slightly on to the glass, for in this way a water-tight seal is made.

158

MAINT ENANC E OF HORTI CULTU RAL EQUIP MENT

One can, of course, affix glass by using Seelastik, Secomastic or similar preparations. These materials never set hard as does putty, and they allow for a certain amoun t of movement of the woodwork due to temper ature changes. Both prepar ations named may be painted over if desired, but only after the surface has dried out for a day or two. The material is most useful for sealing all sorts of joints, but if the gap is wide, stuff it first with tow as this type of putty is somewhat expensive unless bought in large quantities.

CHAP TER 15

Some useful odd jobs chapte r contain s inform ation about a numbe r of odd jobs on the holdin g-jobs difficult to fit in elsewhere. Nevertheless you will, 1 think, find them useful.

THIS

SharpeDiDg Shears and Scissors Garde n shears can be sharpe ned quite well with a coarse carbor undum stone. Grip one of the blades in a vice and rub the stone backw ards and forwar ds along the blade, keeping the stone flat on the original cutting edge. Any wire edge formed can be removed by laying the stone fiat agains t the inner face of the blade but rub lightly. Blades which are nicked should be ground on a grinding wheel. Adjust ment of the blades is made by tightening the nut, which should always have a spring washer under it. If the nut is too slack the blades will not cut, and if too tight the work will be hard. Remov e all rust from the inner faces of the blades and put a spot of oil on the bolt. Should the nut consta ntly work loose, try using anothe r spring washer, for these lose their tension after a time, but if no washer is available, leave the old one on and add an extra nut. If the lower nut is held while the upper one is tightened, neither will work loose. Never burr the bolt end over. Scissors may be sharpe ned in the same way, but after using the carbor undum stone, finish off by whetting on an oilstone or hone. Some scissors are very hard and these should be ground . Make sure that the origina l angle of grindin g is mainta ined, and move the blade slowly across the wheel face. Use only a moder ate pressu re and frequently dip the blade in water to cool it. Whet the back of the blade lightly on an oilstone to remov e the wire edge. Cheap scissors used for garden work can sometimes be sharpe ned with a file. Cracke d Petrol Pipes Sometimes a petrol pipe cracks or is chafed throug h. If the damag e is small it can be soldered, but if this is not practic able 159

160 MAINT ENANC E OF HORTI CULTU RAL EQUIP MENT or the pipe is long and suffers a good deal of vibration, it is best to reinforce it. Clean the pipe thoroughly and then tin it. Next get a length of copper wire, clean it well and wrap it closely round the pipe, carrying it for a quarter to half an inch beyond the ends of the damage. Apply flux and solder the wire coil to the pipe. Make sure that the solder flows evenly and smoothly over the whole wrapping. A large iron will probably be needed. Oil Lamps and Heater s To get the best results from oil lamps, they must be clean and so must the fuel. Despite careful handling, impurities generally find their way into paraffin oil and this eventually gets into the lamp container and on to the wick. It is therefore well worth while to use a funnel which has a fine gauze strainer. Damp wicks cause trouble, so dry a new wick in a warm oven before fitting it. Take this opportunity to clean out the bowl of the lamp. Tight wicks put a big strain upon the raising mechanism, and if the wick you have is too thick, stretch it well to get a start in the burner, then hold it taut and run the burner up and down (using the wick turner) until the cogs operate freely. Burners must be kept free of carbon; they can be scraped or rubbed over with emery cloth. Wick type heaters and lamps often smoke because a strand of cotton protrudes beyond the wick top. Turn the wick up until it is level with the top of the burner and then trim level with a safety razor blade. Lay the blade flat and scrape carefully. This will at all events remove the carbon and, if you are lucky, trim the wick dead level. Anoth er way to level a wick is to let the lamp burn dry until the wick smoulders, then, if it is carefully rubbed (in one direction only) with a piece of newspaper, all projecting strands will come off. Press the wick lightly to obtain a level top. If the wick carrier wears so that the wick does not lift, replace the carrier. Pressure Lamps Pressure lamps, stoves and blowlamps operate on almost exactly the same principle, and the following information on the overhaul of a TiIIey lamp will enable you to maintain the other types in good working order.

SOME USEFUL ODD lOBS

161

The general principle is that the fuel is forced up a tube by air pressure. From this tube the liquid passes into a heated pipe where it is vaporised. On emerging from a small nozzle, the gas mixes with air and is burned. To overhaul a lamp, begin with the pump. Unscrew this from the container and take out the pump plunger which has at its lower end a leather washer just like that on a bicycle pump. If the leather is hard, knead into it a little petroleum jelly or thin machine oil, but should the leather be brittle and cracked, fit a new one. The leather is usually secured by a small nut under which is a metal washer. Tighten the nut firmly, and when replacing the plunger do not buckle the leather or the pump will not operate efficiently. At the bottom of the pump tube is a small valve under a cover. Remove this cover and take out the valve. It is of brass, shaped like a mushroom, and it has a tiny rubber washer set in the head. Sometimes these washers break or become worn or cut, in which case fit a new one. Packets containing a complete set of washers for these lamps can be obtained from all ironmongers, but in case of emergency a satisfactory-if temporary-repair can be made by turning the washer over and refitting it. Replace the valve, the spring, and then the cap. It should be noted that on these lamps it is not necessary to use any spanners (except perhaps for tightening the nut holding the pump washer in place). At the top of the pump is a knurled ring used to provide a grip when refitting the pump. Inside this cap is another washer. A new @ne should be fitted if the old one is damaged. A faulty washer here means loss of air pressure. Next remove.the burner and mantle together, lifting them off the vaporiser tube. Unscrew the vaporiser, this is the long tube terminating just above the control knob. The control knob unit should now be unscrewed. At the lower end of it is a small cap and a fine gauze filter. Unscrew the cap and then wash the filter in clean paraffin. A choked filter will not allow the lamp to burn properly, and a broken filter will allow impurities to clog the nipple, so if the gauze is damaged, fit a new filter. When the filter is removed another mushroom valve and a spring will be seen. Inspect the washer on this valve (it is just like that on the bottom of the pump) and renew it if damaged. Put the spring back on to the valve stem before replacing the filter. II

162

MAINTENANCE OF HORTICULTURAL EQUIPMENT

The small control knob is fastened to a thin spindle which passes through a knurled cover called a gland. IT this cover is loose the lamp will not burn steadily for the control gradually closes. Tighten the gland a little, but not so much that the knob is difficult to turn. Before replacing the control knob unit inspect the washer which seals the joint between the unit itself and the tube into which it screws. Renew this washer if it is damaged or worn. The vaporiser tube should not be interfered with, nor should the thin wire inside it be removed. Vaporisers should be renewed after 500 hours of use (say once every three months of normal winter lighting) for they become choked with carbon. Inquisitive people like myself have taken out the thin wire and cleaned the carbon off it, but on the whole I doubt if by doing so any good is achieved. Check the condition of the washer. As to the burner, this should be dismantled and cleaned. Take off the mantle-you will of course break it, so have a new one handy. Unscrew the domed cap on the top of the burner and with a small brush clean the tube and the ring of holes on the underside of the burner. Clean the outside too, then fit a new mantle after the burner has been replaced. Unless you make a practice of straining the oil as you fill the container, the time will come when the tube which runs from the bottom of the control knob unit down into the paraffin becomes partially blocked by impurities. It should be possible to pour oil down this tube, so if you find it blocked, insert a piece of wire down it, and when it is free, wash the container out carefully. Blowlamps Fig. 55 is a drawing of a Monitor blowlamp, and it shows the tube inside the container. The information given above will enable you to keep your blowlamp working efficiently. Pressure stoves used for cooking are much the same in principle, but of course the burner is different. Always make sure that the vaporiser has been heated sufficiently or the fuel will emerge from the nipple in the form of liquid instead of vapour. If the flame of a cooker stove or a paraffin blowlamp appears lopsided or uneven, clear the nipple

163

SOME USEFU L ODD JOBS

Nrpump Vaporiser Nipple ---Igniting wick

Nozzle Spirit cup

8rass bDdy

Intake ",be

FIG. 55

with the pricker. Incidentally, never use petrol in any appliance

de.signed for paraffin.

Petrol blowla mps are designed differently from those which run on paraffin oil, for the petrol lamp has no pump. The fuel rises to the burner up a wick. These lamps are contro lled by a screw shut-of f valve which also carries a fine wire that cleans the nipple every time the lamp is shut off. Flame Guns Mainte nance of flame guns is much the same as for pressure lamps, stoves and blowlamps, the essentials for satisfactory service being cleanliness of the fuel and air-tightness of the variou s washers. In the McAll an gun there are three leather washers to inspect. One is under the filler cap, one is in the contro l valve, and the third behind the jet. All these washer s tend to dry out

164

MAINT ENANC E OF HORTI CULTU RAL EQUIP MENT

when the gun is stored, and they should be replace d by new ones if defective. It is often possible to recond ition dry washers by kneading a little petrole um jelly into them. Pressure is retaine d in the tank by a Schrad er valve of the type used in pneum atic tyres. The top cap should be replaced after pumpi ng, as dust may cause the valve to leak. There is a gland in the contro l valve, and leakage at this point may be stoppe d by tiglitening the gland nut. If no fuel emerges from the jet when the air pressu re is correc t and the contro l valve is opened , shut the valve and remov e the jet for cleaning. Water in the fuel or in the tank will put the lamp out, and if the gun has been standin g unused for long period s, it is possible that some conden sation will have taken place. If water is suspected, drain the fuel tank and flush it out once or twice with clean paraffin, then refill.

on Drum as Engine Cover A useful co"er for an engine can be made from a 5 or 10 gallon oil drum, obtain able from a garage for a few pence. A straigh t cut is made along the drum from end to end (the seam acts as a guide). Half the top and half the bottom are then removed, and the sides opened out as shown in Fig. 56.

FIG. 56

Repairing Galvanised Tanks Small holes in galvanised tanks can be effectively sealed in the following manne r. Drill the hole so that it is large enough to take

SOME USEFUL ODD JOBS

165

a small bolt, then obtain or make two stout metal washers, each with a hole the same diameter as the bolt. Next cut two washers of some flexible material such as rubber or leather. Slip a metal washer on the bolt, follow it with the rubber and insert the bolt through the hole in the tank. Add the second rubber washer, then the metal one and screw on the nut tightly. It is possible to repair large holes by making a plate and drilling bolt holes at 1 in. spacing all round the edge and bolting this to the tank. The sealing washer can be of rubber or any of the proprietary gasket materials such as Hallite. Galvanised iron can be soldered, but the ordinary fluxes are not satisfactory. Get a tin of Frysol A39 Soldering Fluid, Black Band Grade. This flux is suitable for all general work, the green band being recommended for copper and brass work and the yellow band for tinplate and delicate work. Fitting a New Handle to a Spade or Fork Remove the head of the old rivets by grinding, filing, hacksawing, or with a cold chisel, then punch them out. Fit the pieces of the broken handle together and measure their length, for a new handle that is longer or shorter will be awkward to use. The amount of taper needed varies a little, but usually if a i in. circle is inscribed on the end as shown in Fig. 57 this will be a sufficient guide. Make sure that the circle is placed exactly as shown. Hold the shaft in a vice and with a rasp or the Surform tool described in Chapter 3, pare away the wood from a point about four inches from the end, tapering it down to the inscribed circle. Try the handle occasionally for fit in the split sides of the old spade, and continue paring until the wood fits snugly and well down towards the solid neck. The straps should not be forced apart. When the handle has been made to fit properly, tap it in lightly with a mallet and then drill the holes for the new rivets. This is best done by gripping the straps in a vice and making a small hole right through the wood. Start near to the neck of the spade and be careful how you direct the drill or it will come up against metal. H the hole has not been drilled quite squarely, turn the spade round and drill from the other side. This pilot hole will act as a guide for the final drill, which is generally 1 in. in diameter. The

166

MAINTBNANCB OF HORTICULTURAL EQUIPMENT

HANDLE

-.~------------------- ~~5'---------------------:-------------------::--:;--:=--~-------~----~---I I

•• I

I

FIG. 57

rivets can be made from a piece of 1 in. round mild steel rod, or from coach bolts. H bolts are used the square under the head will have to -be filed off. H rod is used it will be necessarv t
SOME USEFUL ODD JOBS

167

mallet, then hammer in the wedge. Cut the excess wood close to the head. If a metal wedge is used, cut the surplus wood offbefore driving it in. Sharpening Auger and Centre Bits Special files are obtainable for sharpening auger bits, although the work can be done with a small triangular file. An auger has two ears or nibs which scribe the hole and enable the flutes to feed irito the wood. Between each nib and the shank or tool centre is a cutting edge. File the inside of the leading edge of each nib to bring it to a sharp edge. Never file the outside of the nibs. Sharpen the cutting edges with light strokes, keeping to the original bevel, and remove approximately the same amount of material from each one. A centre bit has a square, tapered point, a single cutting edge and a scriber, and all these should be kept sharp with a small, smooth file. The edge of a thin oilstone can be used to put a razor-like finish to the cutting edge of both types of drill.

Oilstones Two kinds of oilstone are used in workshops-natural stone, and those made of "artificial" abrasives, of which carborundum is an example. One big advantage of artificial stones is that they are more uniform in their texture. A further advantage is that they can be made with one side coarser than the other, thus rough grinding and finishing are done on the same stone. Grinding stones should never be used dry, or the particles of metal and the abrasive will clog the surface and reduce the cutting efficiency. With grinding wheels, the rapid speed of rotation flings off loose particles, leaving the stone sharp. Flat oilstones should be lubricated with a mixture of medium oil and paraffin, and sufficient applied to float off the loose material. Dirty stones can be cleaned in paraffin oil. When sharpening tools narrower than the stone face, move the tool over the whole area to promote even wear. Truing up a Grindstone Grindstones-the old fashioned sandstone type-sometimes become water-soaked and develop a soft spot, causing the wheel to get out of round and awkward to use. To dress the wheel

168

MAINTENANCE OF HORTICULTURAL EQUIPMENT

and bring it back to truth, revolve the wheel so that its edge comes towards you, and make a series of grooves with the end of an old file. COntinue until the "flat" is just lightly scored, then chip away the ridges with a cold chisel. When it is as smooth as the chisel will make it, finish off with a sharp flint, ~e wheel being turned fairly fast. If your wheel is mounted in a water trough, keep this dry except when grinding.

169

1 ect way corr The to hold a hacksaw. Not e the angle and the grip

FIG .

FIG .

2

The Surform plan e

9 Ban jo cou plin g showing hollow bolt and filter gauze

FIG .

M.H .E.- ll*

170

FIG. 10 Carbur ettor on Mk. 10 ViIliers engine. Govern or adjustm ents are referred to on page 67. A and B are the adjustin g nuts

FIG. 12 Two modern types of sparkin g plug

171

FIG. 13 Contact breaker of Wico flywheel magneto

FIG. 14 Contact breaker of Villiers flywheel magneto

172

FIG. 15 Air filter element, J.A.P. Model 2A engine

FIG. 17 Amal carburettor as fitted to Howard Gem Rotary Hoe

173

FIG. 19

Throttle slide of Villiers Mk. 25C carburettor. On the left is an end view of the slide showing jet adjustment screw

FIG. 20

Villiers two-stroke engine with cylinder removed

FIG. 21 Removing rings from piston

174

22 Villiers Mk. to engine. C is valve cover, and A is the top of the governor rod. Inlet pipe securing nuts are marked B FIG.

23 Villiers Mk. to engine showing valve chamber FIG.

175

FIG.

24

Villiers flywheel magneto armature plate showing coil, core, and contact breaker

FIG. 25 Governor linkage on J.A.P. Model 2A engine

176

26 Governor adjustment. l.A.P. engine FIG.

FIG. 27 Wico type A magneto showing impulse starter trip lever at A

28 Contact breaker of Wico type A magneto FIG.

177

31 Replacing dog clutch segments on a Trusty FIG.

FIG.

33

Belt tension adjustment on the Howard Bantam

34 Clutch adjustment on the B.M.B. Hoemate FIG.

178

N

FIG.

35

Drake & Fletcher Model L.O. pump

Fuel Pipe to Injector

Vent Plug Fuel Pump Delivery Union

FIG.

36

The Lister Diesel

179

FIG. 37 Lister Diesel engine installed. Note position of the cooling tank

180

FIG. 42 Commo n type of fuse holder

FIG. 43

Parts of a pump gland

FIG. 54

Tool for cutting asbestos sheet

INDEX A

Adjusting carburettors: Amal,57 Villiers, Indll',trial engine, 58 on Mk. 25C engine, 59 Zenith, 12T, 56 Air cleaners, 53 Amal carbun:ttor. I}pe 22,'53, 57 Asbestos sheets, cUlling. i 53 Auger bits, !>harpening. 167 B

Battery care, 110 Belt clutches, 72 Belt repair, 11 a Belt tension, 73 Belts, 72, J 17 Blowlamps, 162 B.M.B. Hocmate clutch adjustment" 81 Boiler maintenance, 124 ' Brazing, 33 Brickwork, 127 Broken bolts, 89 Building repairs, 151 Buying second-hand machine, 21

C Carburettors: adjustments to, 55 Amal,57 choked jet, 58 principles, 44 ViIliers, 58 Zenith 12T, 56 Care of batteries, 110 generators, 109 Carrying capacity of electric wires, 102 Cement mortar, 127 Centre bits, sharpening, 167 Centrifugal clutches, 78 relining, 78 Chains, 73 adjusting, 74 aligning, 75 maintenance, 73 repair,75 tension, 74 Choked fuel supply, 46 jet, 58 Choosing a machine, 18 Cle"uing a , -Jrtact breaker, 49 sparking plug, 51 fuel system, 46 Concrete, 128 Condensers, 64

Contact breakers: adjusting gap. 50 cleaning, 4'i Vilhers.50 Wico • .fY CIlItche~,

78 c.:ntritug,11. 78 relining, 78 Trusty dog clutch, 78 Cracked petrol pipe. 15\1 Cuttcr bal"'>. sharpening, 85 Culling a,be,tos sheet. 153 bricks, 130 earthenware pipes, 132 thr~ad'i, 37 D

Deep bore wells. I! 3 Decarbonising, 60 Demonstrations. 20 Diesel engines, <)4 Differential gears, 76 lock,77 Difficult starting, 50 Disc harrows, sharpening, 83 Dog clutches, 78 Drill sharpening, 30 Drilling metals, 30 Dusting machines, 93 Dynamo maintenance, 109 E

Economics of motor cultivation, 11 Electrical terms, 100 Electricity, <)9 Engine governors, 46 Extending ladder, how to make, 145 F

Fault finding, 50 Files, 27 Filters, air, 53 petrol,46 Fitting new handle to axe, 166 fork, 165 Fixing electric light cables, 104 Four-stroke engines, 41 Four-wheeled tractors, 16 Fuel system, cleaning, 46

G Galvanised iron tanks, repairing, 164 Gates, 147 181

182

MAINTENANCE OF HORTICULTURAL EQUIPMENT

Gear-boxes, 19 Gem carburettor adjustment, 57 Generator maintenance, 109 Glands, 115 Glass cutting, 157 Glazing, 157 Gluing, 145 Grass cutters, 83 Grinding wheels, 38 Grindstone, truing, 167 H

Hacksaw, how to use, 27 Hard soldering, 33 Hire purchase, 14 Hot and cold sparking plugs, 54 How an engine works, 41 Hub ratchets, 77 Hydrometer test for batteries, III Hydrometers, 111 I

Ignition principles, 47 testing, 50 Implement maintenance, 83 Impulse coupling, 69 Installing a diesel engine, 96 stationary engine, 132 J J.A.P. engines: carburettor adjustment, 56 governor adjustment, 67 overhauling Model 2A, 66 removing flywheel, 65 servicing information, 68 Joints, woodworking, 140 K

Knapsack sprayers,91 L

Lacing a leather belt, 118 Lawn mowers, 84 sharpening, 84 Lighting plants-Lister, 101 -Lucas Freelite, 99 -Yardley Wavis, 100 Lime mortar, 127 Lister diesel engine, 94 bleeding fuel system, 95 Loose nuts, 36 Low voltage lighting, 99 wiring, 101 Lucas Freelite lighting plant, 99

Lubricants for drills, 30 Lubrication, 52 M

Magnetos, 42, 47, 51, 69 timing Villiers, 65 Wico Type A, 69 Making a sawing stool, 138 an extending ladder, 145 gates, 147 holes in brickwork, 131 Mowers, 84 maintenance, 84 N

Nails, 143 Nozzles, 91

o Oil-bath air cleaners, 54 Oil burners, 124 Oil drum as engine cover, 164 Oil lamp maintenance, 160 Oils, 52 Oilstones, 167 Operating costs, 13 Overhauling a J.A.P. Model 2A engine, 66 P

Packing glands, 115 Paint brushes, 156 Painting, 155 Petrol engines, 41 filters, 46 Pipe fittings, 121 Pipe work, 120 Planes, sharpening, 136 Surform,28 Preparing wood for painting, 156 Preserving wood, 149 Pressure lamp maintenance, 160 Principles of carburation, 44 mechanics, 39 R

Re-forming threads on bolts, 36 Relining a clutch, 78 Removing broken bolts, 89 Villiers flywheel, 64 Repairing cracked petrol pipes, 159 galvanised tanks, 164 leaky petrol tank, 32 rubber tyres, 82 Riveting, 34

183-

INDEX Roofing felt, 154 Roofs, 151 asbestos sheets, 153 bracing, 152 corrugated iron, 152 re-covering with felt, 154 Rotary hoes, 87 scythes, sharpening, 84 Rotor maintenance, 87 Rust prevention, 88 S Sawing angle-iron, 27 stool, how to make, 138 Saws, sharpening, 135 Screws, 144 Sealing roofs, 155 Second-hand machines, buying, 21 Shallow wells, 114 Sharpening auger bits, 167 centre bits, 167 chisels, 136 cultivators, 83 cutter bar knives, 85 disc harrows, 83 drills, 30 lawn mowers, 84 plane irons, 136 rotary scythes, 84 saws, 135 scissors, 159 shears, 159 twist drills, 30 Single-wheeled cultivators, 15 Soldering, 31 Sparking plugs: adjusting gap, 52 cleaning, 51 function, 49 hot and cold, 54 testing, 51 Specific gravity, 111 Sprayers, 90 Starting-up troubles, 50 Straightening bent hoe blades, 87 Surform plane, 28 T Taps and dies, 37 Thread cutting, 37 Three-wheelers, 16 Timing a magneto, 65, 69 Tools for workshop, 25 Track machines, 16 Transmission, 72 maintenance, 77

Trusty dog clutch, 78 Tube repairing, 81 Tuning an Amal carburettor, 57 Villiers carburettor, 58 Zenith carburettor (l2T), 56 Twist drills, 30 Two-stroke engines, 43 Two-strokes, difficult starting, 52 Two-wheeled cultivators, 15 Tyres, 81

v Valve grinding, 63 Valves, 42 Villiers engines: carburettor adju~tment, 58 contact breaker, 50 governor adjustment, 67 removing flywheel, 64 replacing condenser, 64 servicing information, 70 timing the magneto, 65 W

Water pumps, 113 anti-frost measures, 116 belt drive, 117 cup leathers, 115 frozen,ll7 glands, 115 Water supplies, 113 Wheel bearings, 88 Wico flywheel magneto: contact breaker, 49 replacing condenser, 65 type A magneto, 69 contact breaker, 70 impulse coupling, 69 replacing, 69 Wind-driven lighting plant, 99 Wiring house for electric light, lOt Wood preservatives, 149 Woodworking, 134 joints, 140 tools, 25 Workshop equipment, 25 Workshops, 24

Y Yardley-Wavis lighting plant, 100 Z

Zenith carburettor Model 12T, 56

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