Conservation of Farm Machinery

New Zealand Journal of Agriculture, Volume 67, Issue 1, 15 July 1943, Page 29

Conservation of Farm Machinery

Care of Rubber Tyres

USE of proper air pressure is the most important . factor in the satisfactory performance and maintenance 'of tractor and implement tyres. Both under-inflation and over-inflation are harmful. UNDER-INFLATION Under-inflation causes a series of diagonal breaks in the sidewall area, usually on the inner sidewall of the furrow wheel tyre caused by repeated buckling of the sidewall. When underinflated, the tyre may slip, on the rim, tearing off the valve stem. Under-inflated implement tyres are exposed to similar injuries, plus the danger of excessive pressure building up and bursting the tyre. OVER-INFLATION Over-inflation reduces traction, causing excessive slippage and resulting in more rapid tread wear. Tractors are shipped from the factory with very high air pressure in the tyres to prevent turning and scuffing during shipment. The air pressure should be reduced to the recommended pressure before tractor is unloaded. Tractor tyres in storage should be kept inflated at recommended operating pressure. In all ploughing operations the inflation in the furrow tyre should be increased by 4 pounds over regular inflation. Implement tyres are often overinflated to a serious degree to take care of excessive overload and fail beyond possible repair. Follow the

implement tyre recommended pressures at all times. TRACTOR TYRE INFLATION. Front All. sizes: 1. 4-ply tyres 28 lb. 2. 6-ply tyres 36 lb. Rear— sizes:' 3. Minimum inflation pressure 12 lb 4. When ploughing, increase pressure in tyre on furrow wheel by 4 lb. 5. When special heavy wheels are used, or heavy loads are carried on the tractor, inflation pressure must be increased: Further information on inflation pressures can be obtained from the tractor or tyre manufacturer. >■ Check Air Pressures every 2 to 3 Weeks. — Use low pressure gauge checked occasionally for accuracy. Always use a valve cap to prevent loss of air. METHODS OF INFLATION. A hand pump is not difficult to use when only a few pounds are needed. A power take-off pump attached to the power take-off, or a spark plug pump which operates by removing spark plug and inserting pump, are both satisfactory. (Do not use spark plug pump with diesel engine.) TRACTION AND EXTRA WEIGHT. Tests .show that traction or pulling power is in direct proportion to the

weight carried. Extra weight is needed only for heavy pulling; not for such work as planting, harrowing, or cultivating, or when heavy equipment is mounted on the tractor.

Added wheel weights increase traction.

Figures represent the pounds pull for each 100 lb. weight on the rear

How to Remove Tyres From Semi-drbp Centre Rims

How to Apply Tyres on Semi-drop Centre Rims.

tyres of tractor, i.e., if each rear wheel carries 1000 lb. (total 2000 lb. on rear axle) then in dry clay average pull would be 55 lb. per 100 lb. or total of 1100 lb. drawbar pull. - Table B shows that it is necessary to have more weight on rear tyres for sand and lucerne than for other conditions. For the best efficiency you should determine the weight to use on driving wheels. Some slippage is normal but should not exceed 16 per cent, for

efficient field operation and 5 per cent, on pavement. From table B note that in sandy soil drawbar pull is increased by an average of 36 lb. for every 100 lb. weight added to rear wheels. Additional drawbar power can be obtained by adding the weight up to the maximum carrying capacity of the tyres. If the weight required for adequate traction exceeds the recommended carrying capacity of . present tyres, oversize tyres should be used. Air, pressures should then be adjusted to take care of additional weight. Addition of weight may be provided by bolting cast iron weights to the wheels. Use of liquid in tyres is less expensive and less difficult to handle with no • objectionable operating effects at tractor speeds up to 25 miles per hour. If very heavy weight is required both water and cast iron can

be used. Your tractor or tyre dealer will suggest methods for applying or removing different weights.

♦Applies to all except 2-ply tyres. Proper Pressure for Mounting Tyres. After mounting the rear tyres inflate to 30 lb. air pressure to force beads firmly on to the rims. The tyre should be inflated to 30 lb. air pres-

sure every time the tyre bead is pushed away from the rim seat at any point. Then completely deflate to allow tube to take its natural position. Re-inflate to recommended pressure. . If this procedure is not followed, the tyre will slip and shear off the valve stem. Effect of Air Pressure on Traction.— Tyres should not be operated below minimum air pressures shown in the table. For more traction, use additional weight. Under-inflation makes little difference in traction and ruins tyres. With oversize tyres continue to use recommended inflation and increase traction by the use of additional weight. FOR BELT WORK. When a rubber-tyred tractor is operated on belt work, static electricity may be developed, and if not grounded, may be dangerous. Ground the machine by having a chain, wire, or rod connect the metal framework to the ground. On tractors with wide front wheels there is danger of the belt cutting the front tyre. This can be prevented. • 1. If the left front wheel is raised on a block, the top of the right wheel will be tilted outward away from the belt. 2. A hole may be dug in the ground to lower the right front wheel below the belt. ' 3. Stakes or iron rods may be used to prevent belt from swaying. 4. A piece of sheet iron can be bent to fit over the tyre as a shield. Avoid Tyre Damage Some types of service, as, for example, in disc or mouldboard ploughing where the right tyre runs in the furrow and is distorted by the tilt of the tractor, the sidewall is subjected to severe folding pressure when the tyre is not properly inflated. The tilt of the tractor causes sidewall thrust which, combined with heavy pull of the plough, causes . the inner sidewall of the tyre to buckle. This continuous folding or buckling causes cord

separation and a series of breaks which cause failure of the tube by chafing. Increase pressure in the tyre on the furrow wheel by 4 lb. and adjust the

plough hitch laterally so that tyre does not crowd the furrow wall in order , . . „ n ~,, to plough full Wldth cut

How to Remove Tyres From Drop Centre Rims.

How to Apply Tyres on Drop Centre Rims.

Bruise or Impact Breaks are caused by hitting some object. Cords rupture easily if drawn tight by excessive pressure. Force is greater if impact is at high speed. The use of extra ply tyres, adjustment of pressures to recommendations, and greater care in driving will decrease the impact break hazard. . Weather Checking.— Tyres inflated to excessively high pressure and tyresexposed to sunlight, draughts, or electrical discharges develop small checks. Painting of tyres with common paints, varnishes, or lacquers may also cause this condition. Unless these checks develop into flexing or radial cracks

the condition is not serious. Adjustment of air pressure and protection from the elements will prevent , this condition. Even a good coating of mud on tyres is helpful. Tread and Sidewall — Rubber cuts more easily when wet. Cuts should be repaired as soon as possible to stop localised flexing and fabric decay. Attend to repairs at once, major damage can often be avoided by care and attention at the right time. Tread Wear and Cutting Due to Spinning. Tractor tyres with insufficient weights or excessive inflation will wear tread bars rough, or will snag and cut the bars when subjected

to severe service on abrasive surfaces. Sudden engagement of the clutch causes this type of wear. Addition of wheel weights, adjustment of air pressure to meet recommendations, decreasing draft load and proper operation will remedy this condition. Fast Wear due to Wiping on Hard Road Surfaces. On hard roads with low air pressure there is an undesirable distortion of the tyre during which the tread bars shift while going under and coming out from under the load. On hard surface this wipes off the rubber of the tread bars or lugs. This wear takes place on the back of

the lugs in contrast to wear on the front of the lugs caused by slipping. If tyres are to operate on roadways or other hard surface for any length of time, and draft load is not ■ great, increase the air pressure to maximum recommendation. . Sidewall Wear—Scuffing Front Tyres. —This condition is encountered mainly on front tyres. On wide front type tractors it is generally caused in ploughing by riding the front right or furrow tyre against the side of the, unploughed land. On dual front cultivating type tractors in irrigated areas, or in heavy soil sections where planting is upon beds, the dual front tyres scuff against the sides of the beds. Front tyres operating in ruts soon wear off the thin sidewall against the sides of the ruts. (Note illustration.) . A much larger proportion of the tread volume is in the shoulder or upper sidewall region of the multior triple-rib front tractor tyre and this tyre is recommended wherever sidewall scuffing of front tyres is encountered.

' Proper setting of ploughs so that they will cut full width without riding against the furrow wall will correct this condition on wide front tractors. Damaged Rubber Valves. — When valves are tom off , tubes, it indicates a slippage of the tyre bead on the rim or an improper centring of the valve in the hole of the rim. Slippage may be caused by (1) low air pressure, (2). improper seating of the bead on the rim, (3) use of soap solution on bead or rim when mounting tyre. When this occurs demount tyres and clean rims and wheels carefully. Mount tyre and inflate to 30 lb., then deflate completely, allowing tube to take natural position, then re-inflate to recommended air pressure. Chains. — tyres are available for wet grass and slippery ice conditions. For severe muddy, ground conditions, lug-type chains are used. Flexing of the tyre and creeping action of the chain will break the mud loose as the wheel rotates, giving traction equal to spade lug wheels. ■

, Protection of Tyres.— Although the tread and sidewall rubber. of tractor and implement tyres is compounded to resist action of sunlight, it is advisable to keep tractor under cover and jacked ,up when not in use over a long period of time. When put back in service inflate tyres to correct pressure. Do not allow tyres to come in contact with grease or oil, as both destroy rubber. After using tractor for spraying, wash off any chemicals that may have dropped on the tyres. Tyre — lnspect tyres occasionally for possible injuries. Sidewall or Tread Rubber Cut through Exposing Fabric. Wash out cut with benzine and fill with tread cut repair gum to prevent moisture and dirt from working into the fabric and damaging it. Puncture. tyre is punctured by a large nail a rubber repair plug should be inserted from the inside. Cuts. — from running over something sharp or breaks in the cord body by hitting obstructions can be repaired temporarily. Clean fabric inside of

the tyre. Coat with cold patching cement. and allow to, dry thoroughly, then install a cemented cold patch large enough, to cover. 3 in. to 4 in. surface in all. directions around injury. Fill in outside, with tread cut repair gum to prevent. dirt and moisture working into the tyre.. This is temporary. As soon as convenient remove the tyre and have it vulcanised permanently. i

Truck Tyres Special Points for Extending Truck Tyre Mileage:— , • If possible, change over to wide-base rims.Tyres give better service on rims larger than the generally recognised as “standard” sizes. For greater mileage change over to rims one size wider than normal,. (Also — rims damage tyre beads. Clean rims with wire brush. Do not use oil or grease.)

Take extra care in hot weather. — An increase in temperature from 75 deg. to 85 deg. will result, in 13 per cent., less tread wear. Slower driving and more frequent stop-overs will counteract this heating action. Match duals properly.— no case should tyres differing more : than -J in. in diameter be placed on the: same dual assembly., . Watch for axle —A sagging axle forces the inside tyre of a dual as-

sembly to carry more than its share of the load, resulting in fast, irregular tyre wear on the inside shoulder of the inside dual. HOW TO MAKE TYRES LAST LONGER. Tyre saving rules that apply to both car and truck tyres. Drive' at slower — Your tyres will run with less slippage, thus reducing tyre-wearing friction (e.g.—By reducing speed from 50 to 35 m.p.h. tyre life is increased 33 per cent.) Check tyre pressures regularly.— Too little pressure pulls the cords loose. It also causes irregular tread wear; too much pressure wears out the centre of the bulged tread and leads to broken.cords. . Be sure to check air pressures with an accurate hand gauge. Check brakes and wheel alignment. —Unequally adjusted brakes cause one tyre to grip more than the others and wearing it out more rapidly. A wheel only J in. out of alignment drags a tyre sideways 87 feet in every mile, grinding off the tread and causing irregular wear. Rotate tyres.— equalise wear on passenger tyres, change wheel position of your tyres every 2000 or 3000 miles as follows: Spare to right rear, right rear to left front, left front to left rear, left rear to right front, right front to spare. Keep caps on valve . stems.—Valve caps keep out dirt and prevent slow leaks. Have tyres retreaded in time. — Smooth tyres with sound bodies may have new treads applied and so give many more miles of economical service. Truck tyres should be removed for retreading with a minimum of l-Bth of an inch of original tread remaining on the centres. Car tyres should be retreaded before the tread design becomes bald. These . rules, of course, apply only to those eligible for retreading services. Have your tyres examined for cuts and bruises. Small cuts collect abrasive dirt, small' stones, and tyre-killing dampness, causing ply separation and eventual complete tyre failure. . Bumping into curbs or hitting stones may cause inside fabric breaks without outward sign. Do not overload tyres.— Overloading causes fast wear because the load per square inch of contact area is increased; 10 per cent, overloading decreases tyre life 18 per cent; 20 per cent, overloading decreases it 30 per cent. Have tyres mounted by a tyre expert. Mounting tyres improperly may cause premature failure . . . the tube can be chafed, pinched, creased, or the valve can be pinched out. You can practise many of the suggestions in this article yourself but others must be performed by competent tyre specialists. Rememberit is your duty to save rubber yet keep your car and truck on the road as long as possible.

1501b. weights on Rear Wheels Pounds Drawbar Pull On ploughed Ground On Sod None .. 1600 3000 1. Weights per wheel 1725 3200 2. Weights per wheel . 1850 3400 3. Weights per wheel 1975 3600

TABLE A-Relation of extra weight to extra traction

Drawbar Pull per 1001b. Weight on Rear Wheels. (501b. on each wheel). High Low Average Concrete Road .75 .57 .66 Dry Clay .62 .49 .55 Sandy Loam .58 .48 .50 Dry Sand .42 .29 .36 Lucerne .41 .31 .36

TABLE B—Relation of surface to drawbar pull.

Tyre Size All Rim Diam 4 ply 6 ply 8 ply 10 ply 3.50 40 4.00 36 48 5.00, 5.50 32 44 6.00, 6.50, 7.00 28 40 56 7.50, 8.25 24 36 48 9.00 20 32 44 56 11.25 28 36 44 12.75 24 32

IMPLEMENT TYRE INFLATION DATA.