University of Illinois Agricultural Extension

Tractor Repair and Maintenance CIRCULAR
425
:
By R. I. SHAWL
UNIVERSITY OF ILLINOIS
COLLEGE OF AGRI­ CULTURE AND AGRICULTURAL EXPERIMENT STATION FROM TRACTOR INSTRUCTION BOOKS
Lubrication is the first and most important con­
sideration in tractor care.
Read your instruction book; study it. Do what it
suggests. Your tractor will do its part if you will do
yours.
Dirt is your worst enemy. Before removing any
part of the tractor, such as inspection plates, plugs, or
covers, be sure to clean thoroly all dirt or foreign
matter away from these points.
No fine piece of machinery should ever be loaded to
full capacity until it has been run light for a reasonable
time.
Tractor Repair and Maintenance By R. 1.
SHAWL
UNIVERSITY OF ILLINOIS COLLEGE OF AGRICULTURE AND AGRICULTURAL EXPERIMENT STATION CIRCULAR 425
PROPER INSTRUCTIONS for the use, care,
and repair of tractors are given in the instruc­
tion book which the manufacturer supplies with
each tractor sold. It is the responsibility of the
purchaser to familiarize himself with this material.
The purpose of this circular is to supplement
the information given in the instruction books on
the repair and maintenance of tractors. A check
list for overhauling the tractor, which should be
helpful in securing a more complete check of the
machine, is given on pages 6 and 7. For index,
see page 48.
U rbana, Illinois
July, 1934
Tractor Repair and Maintenance
By R. I.
SHAWL,
Assistant Chief in Agricultural Engineering
HE KNOWLEDGE and ability to repair and maintain a tractor
and power farming equipment is of utmost importance to the
thousands of tractor owners who are depending upon this equip­
ment to do most of their heavy drawbar and belt work. The fact that
a tractor is heavy and of low speed does not mean that it is crudely
built. The present-day tractor is constructed with just as high quality
of materials, fine workmanship, and careful inspection as are modern
improved automobiles.
A tractor that receives the best of care and is operated a large
number of days each year will do many more hours of work during
its life than a tractor with intermittent operation and poor care. There
are many ways to reduce the necessity of costly repairs. One way is
to use only high-grade oils, greases, and fuels supplied from clean con­
tainers. Checking a tractor for repairs and adjustments each year, or
at other regular intervals, catches all the loose bolts and nuts and the
parts that need adjusting or replacing, a precaution that prevents ser­
ious delays in the field. Every repair and adjustm ent should be taken
care of just as soon as the need is found.
Repair costs on a general-purpose tractor operated under the super­
vision of the Department of Agricultural Engineering at the Illinois
Experiment Station for the past nine and one-half years averaged
$59.37 a year (Table 1). Nearly 6,000 hours of general farm work
were completed. After the first five and one-half years some major
repairs were necessary. The tractor is still good for several years of
work and will not need to be junked until the hour-cost of operation
exceeds that of the newer and better tractors now being manufactured.,
T
Special Tools Needed
Some special tools are needed for overhauling a tractor. See Fig. 1.
The list is not long, nor are the tools very expensive but they are very
necessary. For some jobs it will be necessary either to borrow the
dealer's special tools or have him do the particular job.
Repair Jobs for the Expert Mechanic
Expert mechanics are needed to do some of the repair work on a
tractor. This service is often available from the dealer, but if not, one
3
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4
CIRC ULAR
No. 425
should go to a reliable machine shop or garage. Some of the jobs for
the expert are:
1. Fitting piston pins.
2. Aligning pistons and connecting rods.
3. Refacing valves and valve seats.
4. Scraping in bearings.
5. Checking the governed speed of the engine.
6. Overhauling and repairing the magneto.
7. Soldering fuel tanks.
TABLE 1.-HOURS OF USE, COST OF REPAIRS, AND LABOR ON A NINE AND
ONE-HALF YEAR OLD GENERAL-PURPOSE TRACTOR
Year
19242.. . .... . .. . . . . . . .
1925 ........... .. . . . .
1926 ........ . ........
1927 ........... . . . ...
1928 ......... . ...... .
1929 ............ . .. . .
1930 ...... . ........ . .
1931 ....... . . . ..... . .
1932 ......... . . . .... .
1933 ......... . ...... .
Hours
operated
Cost of
repairs
156.0
467.5
384.0
160 . 7
542.0
875.0
999.0
760.0
730.0
855.0
$ 13.10
22.40
40.00
53.18
53.75
131. 64
114.70
33.68
101. 57
Hours of labor
for repairing
Farm
Expert
20
25
30
34
41
65
76
42
49
3.0
3 .0
5.0
2 .0
16 .0
17 . 5
8.0
8.0
10.0
Hours of
tractor
choresl
14.25 64.75 50.50 9.00 27.79 43.31 36.00 33.00 27.80 35.60 Total ... . ... . ~ . . .. .. .. 5 928 . 0
$564 . 02
382
72 . 5
342.00
ITractor chores consist of greasing, changing oil, filling with water, fuel, and oil,
and cleaning spark plugs.
2Tractor secured in June, 1924.
I
Check List for Periodic Inspection and Repair
A general check list for the inspection and repair of a tractor is
given on pages 6 and 7. Differences in the construction of tractors
make it difficult to include all the parts to be checked and to state the
time that should elapse between periods of inspection and repair.
The parts to be checked and the frequency of checking as suggested
in this list should be compared with the directions in the tractor in­
struction book.
Before a tractor can be properly inspected, it must be cleaned. To
do this, wash it first with water. Then take a paint brush and clean
the tractor with kerosene or gasoline, using a putty knife to scrape off
the thick grease. This operation may take half a day, but it is well
worth while, for with a clean tractor all parts can be easily inspected
and there is little danger of dirt falling into the crank case or bearings
when parts are removed. The importance of preventing dirt from
j
THACTOR REPAIH AND ~I.-\I:\"TE~ .\:\"CE
5
entering the working parts of the tractor cannot be too strongly
emphasized.
A coat of paint can be easily brushed on when the tractor is clean,
which not only protects the tractor from rust, but gives one more
pride and interest in the condition of the machine.
FIG. I.-SPECIAL TOOLS FOH THACTOR REPAIR
(1) Handle with jointed end, (2) ratchet handle, (3) large and small ex­
tensions, (4) adapter for large and small sockets, (5) two types of valve grind­
ers, (6) three types of valve lifters for L-head and valve-in-the-head engines,
(7) thickness gage.
THE TRACTOR ENGINE
The tractor engine, being the source of power for the tractor, needs
frequent care and attention to keep it in first-class condition. Lack of
compression because of bad valve conditions or worn or sticking piston
rings, is one of the chief sources of the lack of power. After a season
of farm work, which may be 300 hours or more, one should check the
compression in each cylinder by cranking the engine slowly and noting
the pull required for each cylinder. If a tractor operates 500 hours or
more a year, it is usually desirable to remove the cylinder head so that
the carbon can be scraped off and the valves inspected.
TRACTOR REPAIR AND MAINTENANCE CHECK LIST Part
When to
check
See
page
What to do
Always consult the instruction book before making adjustments ENGINE
In disassembling the engine, follow order listed below
hours
Cylinder head ..... 700-1,000
Remove carbon and grind valves if necessary ... . .. ..
8
Valve wear .... .. . 700-1,000
Check valve seat, valve face , and stem . ... . . .. . . ..
8
Valve guides .... . . 700-1,000
Wear in valve guides prevents proper seating . .....
9
Valve grinding .... 700-1,000
Reface valve and seat if necessary, and grind ......
9
Valve clearance ... 400
Check valve
after grinding valves . .. . ....
11 Rocker arms ...... 700-1,000
Examine for end play and worn bushings ........ . .
12 Pistons . . . ........ 700-1,000
Remove piston and connecting rod for inspection .. ..
13 Piston rings . ...... 700-1,000
Check ring wea r on piston and in cylinder . ... . ....
13 cl earanc~
Connecting rod . ... 700-1,000
Inspect the bearings a nd take up play . ...... . .. ... 13, 15
1
Cylinders ....... . . 700-1,000
Look for cylinder wear, scoring, and top ridge .... ..
15 Main bearings . . . . 700-1,000
Test crankshaft for looseness in bearings . .... . ....
18 Crankshaft ....... 700-1,000
Test for scoring and out of round ..... . . . . . .......
19 Oil pan . ........ . . 700-1,000
Wash out the oil pan . ... .... . . . .. . . ... . .. ......
19 Oil pump . . .. .... . 700-1,000
Clean and inspect for wear ...... . .... . .. . .......
19 I
Oil screen ......... 400- 800
Clean and inspect for holes-see instruction book . ...
19 60
Clean and inspect filter when oil is drained . . . .......
19 Oil filter .......... 40-
Pressure gage. . ... 700-1,000
Clean and check for pressure .. ..... .. ............ 19,34
Clutch ........... 700-1,000
Look for wear in clutch and throw-out bearing ......
20 Engine support . ... 700-1,000
See that engine is securely fastened .... . . . . .. .. . ..
21 Governor ......... 700-1,000
Inspect for wear and check engine speed . . .........
21 FUEL SYSTEM AND CARBURETOR
Clean all lines and tanks; check for rust, wear, leaks
700-1,000 Inspect needle valve and float chamber cut-off seats ..
22 Float .............
700-1,000 Check for cdndition and fuel level in carburetor bowl
22 Choke ............
300 Must work freely and open up completely .........
24 Carburetor .......
Butterfly valves ...
700-1,000 Wear around shaft will admit air and dust. ........
24 Air cleaner ........
300 Clean the top filter and soak in oil before replacing ...
24 Connections. . . . ..
300 Connections for air cleaner must be tight .... . .....
24 Air breathers ...... .
60 Clean, soak in oil, and replace ....................
25 IGNITION
Inspect ignition system, but do not take system apart
Breaker points .. "1 300 Check points for pitting and proper opening ....... 1 26 Ground brush. . . .. 1,500
Check the ground brush to the armature ..........
27 TRACTOR REPAIR AND MAINTENANCE CHECK LIST (Concluded)
Part
When to
check
What to do
See
page
Impulse starter ....
hours
300
Clean and lubricate according to instructions ..... . 28-29 Distributor. . . ....
300
Wipe carbon and dirt out of distributor cover ......
Dust seal .........
300
Magneto dust seal must be kept in good shape .....
29 Ignition must be timed accurately ..... ..... ..... .
30 Timing ...... . ... . 11,500-2,000
29 Spark plugs . .. ....
200
Clean and check gap at the points ................
30 Spark plug cables ..
700-1,000
Inspect the wires for breaks or rotted condition ....
30 COOLING SYSTEM Radiator care . . ...
300
Flush system twice or more each year .............
31 Radiator cleaning ..
500-1,000
Clean the radiator with washing soda ........ .....
31 Radiator scale .. ... 1,500-3,000
Remove scale when necessary ................... .
31 Hose ............. 1,500
Keep tight and replace if not in good shape . ...... .
32 Radiator curtain ...
700-1,000
Keep in shape for spring and fall use .. ............
32 Thermostat .......
500-1,000
I Keep the cooling system and thermostat clean . . .. .
32 Fan bearings . ... ..
700-1,000
Check bearings-a wobbly fan may cause breakage ..
33 Fan belt .. , .......
100
Tighten and inspect for wear .....................
33 Fan pulley ....... ,
700-1 ,000
Pulley must be keyed tight on the crankshaft ..... .
33 Water pump ......
100
Check the packing and condition of the shaft ......
33 Antifreeze solution
10
Use the proper antifreeze solution ..... . ... ... , ...
35 FRONT WHEELS, AXLE, AND
STEERING GEAR
I
Wash and repack bearings; replace felt washers .. .
36 700-1 ,000
Tighten bolts holding on skid bands ............. ,
36 700-1,000
See that axle works freely in frame ....... .. ......
37 Front wheels . ... ..
700-1,000
Skid bands .. .. .. .
Front axle ........
Tie rod ..... ......
70D-l,000
Wheels should have
Y2 to %:' inch toe-in at the front ..
37 Axle brace ....... .
700-1,000
Tighten axle and allow free working rear connection . .
37 Steering gear . .....
700-1,000
Take up play if possible and check lubrication . ....
37 !
REAR WHEELS, AXLES, AND
TRANSMISSION Rear wheels . ......
500
Check the lugs and tighten, if loose ... ........ ... .
Rear axles ....... ,
38 700'-1,000
Check axle play and replace felt washers as necessary 36, 38 Transmission ..... . 1,000-2,000
Drain, wash with kerosene, refill with new oil ...... 37-38 Belt pulley . . . . ...
700-1,000
Check bearings for wear .........................
38 Brake ..... , ..... .
700-1,000
Brake is very important; see that it works properly ..
38 CRAWLER TRACKS
Consult the instruction book for special directions on
this type of equipment
8
CIRCULAR
No. 425
In removing the cylinder head, one sometimes has considerable
difficulty in breaking it loose after all the nuts and bolts are removed.
The best way to loosen the head is to turn the engine. crank and let the
compression loosen it; then clean all carbon from the cylinder head
and pistons. It is not good practice to use a cylinder head gasket a
second time unless a new one cannot be obtained. When installing a
new cylinder head gasket, soak it in water for at least ten minutes and
apply some grease to both surfaces before assembling the engine.
Valve wear usually occurs on the valve face and on the stem
where it enters the valve guide. Before removing the valves for in­
spection, number them starting valve No. 1 at the crank end of the
z
,0
'-----­
FIG. 2-CYLINDER HEAD WITH VALVE INSERT SEATS FOR EXHAUST VALVES
(1) Valve inse rt seat, (2) seat in place.
engine. If the valve faces are badly pitted and cannot be reconditioned
by grinding, or if grooves are worn in the valve faces, reface them in
a valve refacing machine.
If the valve seat is in such bad condition that it cannot be restored
by grinding, it can be refaced with reamers. If reaming leaves the seat
too wide, it must be reamed down on top and off at the bottom. The
reaming must usually be done by an expert mechanic and may not be
an entirely satisfactory method of making repairs. A newer and prob­
ably better method of repairing the valve seat is to have a mechanic
from a machine shop or a garage put in new steel alloy valve seat
inserts (Fig. 2). These insert seats do not burn or pit readily, and
therefore give excellent service. The installation is moderate in cost
and can be done at the farm by a garage mechanic. When insert valve
seats have been installed, take care to prevent the motor's overheating
from lack of water or other causes.
Carbon burns on the valve stems just under the valve head and
causes the stem to become rough. The rough stem pushing into the
TRACTOR REPAIR AND MAINTENAKCE
valve guide and abrasives working down into the valve guide cause'
rapid wear, preventing the valve from seating properly. Clean and
polish the valve stems and inspect the valve guides (Fig. 3).
FIG. 3.-POLISHING A VALVE STEM
(1) Block of wood, (2) strip of fine emery cloth.
Valve guides when badly worn do not allow the valve to seat
properly. Worn guides should be driven out with a piece of wood or
soft metal and new ones installed (Fig. 4). One should then take a
valve seat reamer and true up the seat with the valve guides. When
new valve guides are installed, it is usually best to put in new valves.
If the guide is badly worn and is not replaceable, ream the hole larger
and use a valve with an oversized stem. .
Grinding valves is not a difficult job, but requires time and
patience. After the valve has been removed and cleaned, and the face
and seat prepared, as directed under the section on valve wear, it is.
ground to an air-tight fit on the seat by means of a suitable valve­
grinding compound.
There are two commonly used types of valve-grinding compound
on the market:
1. An abrasive mixed with oil to form a sort of paste. This compound,
which is widely used, is put up in small cans containing coarse compound in
one end and fine compound in the other end.
2. A water-mixed compound. This is much finer than the oil-mixed, and
usually grinds faster. PRECAUTION: The water in this compound causes
rapid rusting and sticking of the valve parts. After grinding the valves remove
all of the moisture, dry the parts, and apply a coat of oil. Follow this pre­
caution very carefully. Operate the motor as soon as possible after using the
water-mixed compound.
'
10
CIRCULAR
No.
425
The coarse-grinding compound is designed only for removing the
pits on badly pitted valve seats. After the pits are removed, the valve
is ground with . the fine compound. First coat the valve face with a
thin layer of grinding compound and then place the valve back on its
seat, using a light coil spring over the valve stem to assist in lifting the
~
... l
2
FIG. 4.-CYLINDER HEADS SHOWING VALVE GUIDES
(1) Types of removable one-piece valve guides, (2) split valve guide.
valve while grinding it (Fig. 5). Next turn the valve back and forth
about half way a number of times and allow the spring to lift it Up;
then give it a half turn and grind it some more. Apply very light
pressure and never turn the valve continuously in one direction, for
continuous turning in one direction causes grooves to appear on the
surface. Anyone of the following t061s can be used to turn the valves
while they are being ground: oscillating grinder, small hand drill with
screw driver blade, or a screw driver (Fig. 1). A carpenter's brace is
too heavy and clumsy for this work.
When the compound ceases to grind, wipe it off and apply a new
coat. Continue grinding the valve until a smooth gray band, the width
of the valve seat, which should be from %2 inch to %2 inch, shows all
the way around the valve. This band should have a distinct edge, both
TR ACTOR R E PAIR A
D )'IAI ~T E ' A~CE
top and bottom. When all the pits and grooves are removed, the job
is finished. Clean all grinding compound from the valve and seat, oil
the valve and stem, and assemble the parts.
Valve sticking is nearly always caused by using too heavy
lubricating oil or an inferior grade of lubricating oil or fuel. To
remedy a sticking valve, remove the spark plug and squirt some kero-
FIG. S .-GRINDING VALVES
(1) Light spring to raise valve for turning, (2) board with holes for hold­
ing valves, (3) screw driver type of valve grinder, (4) oscillating type of valve
grinder, (5) cup fo r washing grinding compound from valves, (6) valve lifters.
sene on the valve of an L-head engine, or on the valve stem of a
valve-in-the-head engine after removing the valve cover.
Valve clearance (which is the distance left between the end of
the valve stem and the valve lifter or rocker arm to allow for the
expansion of the heated parts) must be readjusted after the valves are
ground (Fig. 6 ) .
After the engine has been assembled, give the valves a little extra
clearance and run the engine for an hour or so to warm it up thoroly.
This expands the engine parts and cylinder head bolts, so that the head
can be securely tightened down, which is absolutely necessary in a
valve-in-the-head engine before the valves are adjusted. With the
engine warmed up, adjust the valves, using a thickness gage (Fig. 7).
12
CIRCULAR
No. 425
This operation must be carefully done. Crank the engine until the
valve to be adjusted closes; then to be sure that the cam has moved
away from the push rod or valve lifter, give the crank another one­
quarter turn. Loosen the lock nut on the push rod or valve lifter and,
5
6
129t
f;
~
A
2
r;~
B
FIG. 6.-DETAILED VIEW OF VALVE CLEAHANCE ADJUSTMENT
A. Valve-in-the-head engine: (1) valve spring, (2) valve stem, (3) valve
clearance, (4) rocker arm, (5) rocker arm adjusting bolt, (6 and 7) lock nuts,
(8) ball-and-socket joint, (9) push rod, (10) oil hole, (11) removable bronze
bushing, (12) rocker arm shaft.
B. L-head engine: (1) valve spring, (2) valve stem, (3) valve clearance,
(4) stud bolt adjustment, (5) lock nut, (6) valve lifter.
using the thickness gage, adjust the clearance at the end of the valve
stem to the number of thousandths of an inch specified in the instruc­
tion .book. The g"age must bind slightly when pushed under the valve
stem. " Take up all the slack from the push rod and rocker arm when
this measurement is made. This valve clearance runs from .010 to .018
inch" in a valve-in-the-head engine and from .006 to .012 inch in an
L-head engine.
After adjusting the valve clearance, run the engine for a day or
two and then recheck the clearance.
Special wrenches for adjusting the valves are usually supplied with
an L-head engine. Valves that do not have enough clearance fail to
close tightly, leaving a space which allows the hot gases to blow by the
valves, causing burning, warping, and loss of power.
Rocker arms have very little play on the shaft and are held in
place by springs or locks, so that they center over the end of the valve
st~m. Some motors have bushings in the rocker arms that need to be
replaced when worn (Fig. 6).
TRACTOR REPAIR AND MAINTENANCE
13
FIG. 7.-AD]U STING VALVE CLEARANCE
A. Valve-in-the-hcad engine: (1) rocker arm, (2) lock nut and slotted ad­
justing stud, (3) thickness gage, (4) wrench and screw driver for loosening
and turning, (5) spring to keep rocker arms centered over valves.
B. L-head engine: (1) adjusting stud and lock nut, (2) thickness gage,
(3) special wrenches.
Pistons and connecting rods should be removed, cleaned, and
inspected. Remove the piston rings as shown in Fig. 8-A. Oil splash­
ing up against the underside of the hot piston head burns and forms
carbon, which must be scraped off or it will accumulate in sufficient
quantity to break loose and drop into the crank case. Carbon on the
underside of the piston causes the piston to run hotter. Clean the
piston-ring grooves with a screw driver or a piece of broken piston
ring (Fig. 8-B). The piston and the cylinder should be checked for
wear. This is done by inserting a long-bladed feeler gage alongside the
skirt or bottom of the piston when in its natural place in the cylinder.
The clearance should be checked at the side and front of the cylinder.
In new tractors the total clearance between the skirt, or bottom, of the
piston and the cylinder wall will run from .004 to .005 inch. If the
engine has worn so that this clearance exceeds .012 inch, the cylinders
should usually be reconditioned by honing, boring, or grinding, or by
replacing new sleeves, and then installing new pistons.
Piston rings after being removed, as discussed under pistons,
should be cleaned, and checked for side wear in their grooves and for
gap clearance in the cylinder. The top ring will usually show consider­
able wear, especially if a low-grade fuel is used. Put each ring in the
proper cylinder and push the ring about half-way down with the
piston, so that the ring will be placed squarely in the cylinder (Fig.
14
CIRCULAR
No. 425
FIG. 8.-FITTING PISTON RINGS
A. Removing piston rings: (1) with metal strips.
B. Cleaning ring grooves: (1) with broken piston ring.
e. Measuring piston ring clearance in cylinder: (1) replaceable cylinder
sleeve, (2) thickness gage, (3) piston ring pushed down one-third way in
cylinder.
D. Filing piston ring ends to secure proper clearance in cylinder: (1) vise,
(2) piston ring held lightly in vise, (3) sharp flat file.
E. Fitting piston ring to piston ring groove: (1) new piston ring, (2) rol­
ling ring around groove.
F. Dressing down width of piston ring: (1) board, (2) fine emery cloth,
(3) piston ring.
8-C). Measure the gap or end clearance with a thickness gage. Adjust
the ring gap clearance by filing (Fig. 8-D) as follows:
1. In small bore engines allow at least .007 inch for the ring gap clearance.
2. For the top piston ring gap, allow .003 inch clearance for each inch of
cylinder diameter. In some engines all of the rings are fitted with .003 inch
clearance.
3. For the next ring gap, allow .0025 to .003 inch for each inch of cylinder
diameter.
4. The bottom ring and the oil ring can be fitted with .002 inch for each
inch of cylinder diameter if a closer fit than that given in number 3 is desired,
provided that the total gap is not less than .007 inch.
If standard-sized piston rings are too small, rings with oversized
diameters starting with .005 inch oversize and larger can be used. If a
TRACTOR REPAIR AND MAINTENANCE
15
cylinder takes more than a .015 inch oversized ring, it is usually in need
of reconditioning. If oil pumping cannot be stopped with new piston
rings, the cylinders usually must be reconditioned.
If the gap exceeds the limits given above, install new rings pro­
vided that not more than .008 to .010 inch wear has taken place in the
cylinders. If the wear exceeds this limit, it is probably best to recondi­
tion the cylinders or put in new sleeves. Rings with straight cut or
diagonally cut joints are most commonly used, and make it easier to
measure the clearance than where step joints are used. In fitting new
piston rings, observe carefully the following procedure:
1. Fit the ring to the piston groove as shown in Fig. 8-E. If the ring is too
tight, dress it down in width until it moves freely in the groove. The ring can
be dressed by rubbing it on a sheet of fine emery paper placed on a smooth
surface (Fig. 8-F).
2. Check the ring in the cylinder for proper gap clearance, as previously
described (Fig. 8-C). Do this part of the work very carefully.
3. Assemble the rings on the pistons, using the three metal strips, as shown
in Fig. 8-A. When the rings are fitted with different gap clearances, put the
ring with the most clearance in the top groove.
Cylinders become worn from improper lubrication, abrasives in
the crank case, and dirt coming in thru the carburetor. Eliminate all of
these causes as far as possible. Piston rings rubbing the cylinder walls
cause wear, and on engines that have been used a long time there is
likely to be a ridge left at the top of the cylinder just above the top
piston ring. Remove this ridge with a suitable reamer when new rings
are installed to prevent their being broken by striking it. In engines
equipped with replaceable cylinder sleeves, cylinder wear can be easily
repaired by putting in a new assembly of sleeves, pistons, rings, pins,
and bushings (Fig. 9). In other types of engines the cylinders must be
bored, ground, or honed. Some machine shops are equipped to bore or
hone the cylinders at the farm, but the cylinder block must be taken
to the shop to be ground. The method of reconditioning the cylinder
will depend largely upon the conditions under which the work is to be
done and their effect upon the cost.
Connecting rods may have bearing surfaces at both the top and
the bottom (Fig. 10). Wear in the bronze bushing at the top of the
connecting rod can be detected by a tapping sound while the motor is
running or by looseness when the piston and rod assembly are removed
and inspected. This looseness can be taken care of by putting in a new
piston pin and bushing or an oversized piston pin. Usually the first
method is employed. This replacement, which is difficult to make on
the farm because of the accuracy of workmanship required, should
usually be done in a machine shop. The cost is small compared with
16
CIRCULAR
No. 425
the satisfactory service resulting from such work. When the piston pin
and bushing or bushings are assembled, the piston must be aligned cor­
rectly with the connecting rod or it will bind in the cylinder and cause
excessive wear. Aligning must be done in a machine shop. Be sure
that the part which holds the piston pin in place is securely fastened.
~
FIG. 9.-SET OF REPLACEABLE CYLINDER SLEEVES OR LINER S WITH
PISTONS FITTED TO SLEEVES
(1) Sleeve, (2) piston complete, (3) piston pin, (4) piston pin bushing,
(5) rubber gasket for sealing bottom of sleeve to prevent water leakage into
crank case.
Connecting rod bearings require very little adjusting if the operator
has been careful to use good oil and to keep dirt from getting into the
crank case, unless the crankshaft gets out of round. When fitting con­
necting rod bearings, keep in mind that in some of these bearings the
shims are the only means of holding the bearings in place and pre­
venting them from turning. These shims should be inspected for wear
at the place where the bearing fits up against them, and replaced if
wear is noticeable. It is customary to use two heavy shims on each
side of the bearing with thin shims placed between them (Fig. 10-10).
If the bearing edges that fit against the shims are worn off and do not
fit up tightly, the edges may be built up with solder and then dressed
down even with the bearing cap edge.
17
TRACTOR REPAIR AND MAINTENANCE
If there is sufficient play in the bearings to require taking up (Fig.
ll-A), proceed as follows:
1. Mark all bearing halves beginning with the front cylinder and proceeding
to the back on the side next to the camshaft, if this has not been done by the
manufacturer. This precaution will prevent putting bearings on wrong.
2. Remove enough shims of equal thickness from each side of the bearing
to be adjusted to take up most of the play. Tighten the nuts firmly with a
socket wrench and check the bearing for tightness. When the bearing gets to
the place where the removal of the thinnest shim, approximately .002 inch,
makes the drag too hard or the fit too tight, then replacing this thin shim should
give the proper fit. Bearings that are thoroly worn in do not need to be tight­
ened so much that they bind.
7
FIG. 10.-COMPLETE PISTON A D CONNECTING ROD ASSEMBLIES
(1) Piston pin, (2) lock washer for bolt, (3) bolt for securing piston pin
in end of connecting rod, (4) connecting rod bearing fastened to connecting rod
halves, (5) bearing surface for piston pin, (6) piston pin held securely at this
point to prevent turning, (7) piston pin held unmovable in piston, (8) bearing
surface for piston pin, (9) shims, (10) arrangement of shims with a heavy
shim on both sides of thin ones to keep bearing from turning, (11) removable
connecting rod bearing, (12) bearing cap.
3. When one bearing has been adjusted, loosen it and adjust the next.
When all the bearings have been checked, tighten them all and see that the
crankshaft turns freely.
4. Be sure that new cotter keys are inserted to keep the nuts from working
off the bolts. Never loosen a nut to line up the holes so that a cotter key can
be inserted-tighten it tighter or file off the nut. Do not tighten the nuts
enough to strip the threads.
5. Allow a imall amount of sidewise play of the connecting rod on the
crankshaft to prevent the sides of the rod from binding. This play may vary
from .004 to .012 inch according to the engine.
When a bearing in the engine burns out, do not install a new bear­
ing and run the engine until the cause for the bearing failure is located
and corrected. An obstruction in the pressure oil pipe leading to a
18
CIRCULAR
No. 425
bearing usually causes the bearing to burn out. Since babbitt from the
bearing is likely to enter the oil lines, it is very important that all of
these passages be cleaned and inspected. A tire pump can be used to
force air thru the pipes and passageways.
N ever allow an ,engine to be run with a bearing knock. A loose con­
necting rod bearing will soon pound the crankshaft out of round, so
that the bearing cannot be kept adjusted.
FIG. n.-TESTING CONNECTING ROD AND CRANKSHAFT FOR LOOSE BEARINGS
A. Method of testing connecting rod bearing for looseness: (1) connect­
ing rod bearing, (2) bar for prying, (3) block of wood.
B. Testing crankshaft for vertical play by moving shaft up and down with
jack.
Main bearings should be checked for end-play and up-and-down
play each 700 to 1,000 hours of use. Altho these bearings seldom give
trouble, they gradually wear chiefly because of poor lubricating oil,
thin oil, and the accumulation of dirt and grit in the crank case.
Play in the main bearings on some engines can be checked by re­
moving the crank-case inspection plates and prying up and down on
the crankshaft (Fig. 11-B). This same method can be used for testing
connecting rod bearings if one holds the connecting rod down with the
hand from the top while prying up from underneath. If the hand
holes are not present, remove the oil pan and use a jack to work the
crankshaft up and down (Fig. 11-B). A bar can be used to pry the
crankshaft endwise to check the end-play, which may vary from .004
to .008 inch.
Usually anyone of the main bearings may be adjusted for wear
without removing the engine. Be sure the bearings are marked on the
side next to the camshaft so that they can be replaced correctly. Re­
move the bearing cap, take out a thin shim on either side, and tighten
TRACTOR REPAIR AND MAINTENANCE
19
the bearing again. Follow the method discussed under connecting rods
with this exception: when one bearing is adjusted it is tightened up
before the next one is loosened. If the engine has been removed and
is turned upside down, then adjust the bearings as described under
connecting rods.
If there is felt packing around the front and rear main bearings
to prevent oil leakage, it must be carefully handled and replaced. It
is often best to put in new packing.
If there is too much end-play, it is usually, due to the thrust flange
on the main bearing or to bearings wearing off. A new bearing may
need to be installed. It may be advisable to secure expert advice on
this problem. Some bearings are installed without scraping, but if
scraping is necessary have it done by a competent mechanic. Be sure
that the nuts holding the main bearings are securely. fastened.
Crankshafts sometimes are pounded out of round at the crank­
pin bearings by the action of the connecting rods. When the crank­
throw bearing is so much out of round that the connecting rods cannot
be kept tight, it is necessary to have the crankshaft machined round or
exchanged for a reconditioned shaft. Some tractor companies ex­
change crankshafts and supply new bearings at a very low cost.
Oil pans collect quantities of dirt, grit, and sludge, and need to
be removed and washed every 700 to 1,000 hours. The inside of the
engine should be washed with gasoline. When replacing the pan, be
sure the gasket is in good condition or considerable loss of oil from
leaks may result.
Oil pumps are usually of the gear type and require little care.
Inspect the pump when the oil pan is off, however, so as to prevent
excessive wear and possible breakage (Fig. ,12).
Oil screens should be cleaned after each 700 to 1,000 hours of
use, or more often if they are easily removed. Watch to see that
all corners of the oil screen are soldered or sealed, and that there
are no holes to let larger particles of material into the oil pump to
be circulated thru the motor. These large particles often stop up
some of the oil holes and ,cause bearings to burn out.
Oil filters, which take out much of the foreign material that is
being circulated with the oil, need cleaning each time the oil is changed
(Fig, 13). Wash the filter and inspect it for holes or tears before it is
replaced. Oil filters are desirable additions to all tractors.
Oil pressure gages sometimes become worn or broken and do
not register the correct pressure. Before condemning the oil when the
pressure is low, try another gage that registers correctly. If the gage is
20
CIRCULAR
No.
425
all right, low pressure may be due to thin oil or to wear in the bear­
ings, which allows the oil to escape too rapidly. Some engines have an
adjustment for increasing the oil pressure but it is often better to
remedy the trouble than to change the adjustment. Consult the instruc­
tion book or your dealer about changing this adjustment.
a
FIG. 12.-GEAR PUMPS FOR CIRCULATING CRANK-CASE OIL
(1) Pump housing, (2) pump driving gear, (3) oil pumping gears, (4) ad­
justment for regulating oil pressure, (5) oil screen.
FIG. 13.-CLEANING CRANK-CASE OIL PURIFIER
(1) Oil purifier base, (2) cover, (3) filter unit, (4) brush for cleaning,
(5) removing dirt accumulated on filter.
Clutch wear tak~s place very slowly unless the clutch is abused
by the operator's slipping the clutch to slow down the tractor
speed or allowing the foot or hand to rest on the clutch pedal or
handle. A new clutch may require some adjusting until it is worn in
TRACTOR REPAIR AND MAI NTENA N CE
' Zt
smoothly. Most clutches are of the single disc dry-plate type and oil
must be prevented from getting on the plates. If oil gets on the clutch
plates, it can be partially removed by washing the plates with gasoline~
The clutch should be adjusted so that it will not slip when the trac­
tor is pulling its full load. Consult the instruction book for details on'
the adjustment of the clutch.
When the clutch is released, considerable pressure must be applied'
to the clutch throw-out bearing or clutch yoke to overcome the spring:
3
FIG.
14.-SPEED
COUNTERS
(1) Direct reading speed counter, (2) accumulative speed counter reading
to 100, (3) accumulative speed counter reading to 10,000.
pressure. This bearing must be greased as instructed or it will wear
rapidly. Usually some clearance is left between the lever or pedal that
disengages the clutch, and the throw-out bearing. Check this carefully.
If tightening will not prevent the clutch from slipping, new friction
plates or new springs may be needed, or the slipping may be due to an
overloaded tractor.
Engine supports sometimes work loose and need to be tight­
ened. Engines having the front supported at one point are subject to­
wear at this point, which allows the engine ' to move, often destroying
the water hose connections between the radiator and the engine. If
wear exists at this point and no adjustment is provided, build up the
support by welding or brazing and dress it down to fit.
Governor adjustment is very important on a tractor engine_
Using a reliable speed counter (Fig. 14) test the engine speed at the
end of the crankshaft, the belt pulley, or the breaker point end of 'the
22
CIRC ULA R
No, 425
magneto armature. Check for the governed speed of the engine at "no
load," which will be somewhat faster than the working speed. If a
speed counter is not available, have the dealer check the engine speed.
Do not run the engine faster than the manufacturer's listed idling
speed.
Wear in the governor parts may cause slow engine response to the
action of the governor.
FUEL SYSTEM AND CARBURETOR
Fuel systems become clogged from dirt and rust and require a
thoro cleaning at least once a year. Remove all the fuel lines and blow
thru them. Remove the fuel tank, clean it out, and inspect it for wear
and rusted places. The felt padding between the support and the bot­
tom of the tank often wears thru allowing the tank to rub. Felt pack­
ing from a horse shoulder pad, leather, or rubber will make a satis­
factory rest for the ta'nk. If the gas tank needs to be soldered, take it
to a repair shop. Do not try to make the repair yourself-it is ex­
tremely dangerous unless one is experienced in such work. Be sure to
clean all the fuel screens and, after assembling the system, test all con­
nections for leaks.
Carburetors rriay be the source of considerable engine trouble.
The same carburetor is used for gasoline, kerosene, and distillate or
"£tiel oil, but it requires adjusting according to the body or viscosity of
the fuel. The heavier fuels, such as distillate, 'require a slightly larger
opening of the needle valve (Fig. 15). Old carburetors may show con­
:siderable wear and need careful checking.
The needle valve in some carburetors may have a ring worn around
it where it has been screwed down on the seat. This wear prevents the
proper adjustment of the carburetor. If the point of the needle valve
is not in very bad condition, it can be repointed. Sometimes both the
needle valve and its seat can be replaced.
The float chamber cut-off shuts the fuel off from the carburetor
when the bowl fills to the proper level. Any leakage from the bowl is
usually due to something under this valve, or the valve may be so badly
,worn that it will not seat properly. Tapping the carburetor bowl sharp­
ly may dislodge the dirt. If the cut-off valve and seat are worn, re­
'place both of these parts. Repair replacements for these parts are
l:1sually carried by the implement dealer.
The purpose of the float is to maintain the proper fuel level in
,t he carburetor. In old carburetors, the float may be worn at its hinge
23
TRACTOR REPAIR AND MAINTENANCE
_~~==-i*-2
1
B
FIG. lS.-TYPES OF CARBURETORS
A. Needle valve type of carburetor without adjustable idling device: (1) air
intake, (2) choke valve, (3) needle valve, (4) throttle valve, (5) mlxmg
chamber, (6) secondary air valve, (7) float valve cut-off, (8) removable float
valve seat, (9) fuel inlet, (10) spray nozzle, (11) needle valve seat, (12) drain
cock, (13) low speed tube, (14) float chamber, (15) bowl, (16) drain pipe,
(17) float.
B. Automatic type of carburetor with adjustable idling device: (1) air in­
take, (2) carburetor choke, (3) outlet to engine, (4) butterfly throttle, (5) air
passage supplying compensating jet, (6) idling needle valve, (7) float valve
cut-off and seat, (8) fuel screen, (9) float, (10) constant flow opening supply­
ing gas, (11) main jet feeder, (12) compensating well, (13) idling tube ox jet.
(14) compensating jet, (15) main fuel jet, (16) venturi tube.
~4
CIRCULAR
No. 425
and where it rubs against the cut-off. If the cut-off holds properly,
bending the float arm so as to lower the float will lower the fuel level.
The proper fuel level' is often listed in the instruction book, or may be
obtained from the company. When metal floats are used, holes may
occur which must be soldered, care being taken to remove all excess
solder which, if left, would increase the weight of the float. When cork
floats are used, the shellac coating may become cracked, allowing the
float to soak up fuel and thus become heavy. Secure a new float if
possible; otherwise clean off the shellac, dry the float thoroly, and then
apply two coats of high grade shellac.
The choke should work freely, and one should be careful to see
that it opens up completely in order to prevent excessive fuel
consumption.
Butterfly valve is the name applied to the throttle valve and the
choke valve of the carburetor. The shafts that hold these valves ex­
tend thru the side of the carburetor for the purpose of attaching the
controls; they must fit the holes snugly or air and dirt will enter the
engine. The air may cause hard engine starting and uneven running,
..and the dirt will cause wear.
Air cleaner neglect soon results in a worn-out motor. Servicing
the cleaner is one of the most important jobs in the daily care of the
tractor. The dust entering a tractor working under very dusty condi­
tions without an efficient air cleaner may cut out the cylinder walls,
pistons, and other rubbing parts of the motor to such an extent that in
ten to fifteel'l. day new parts will have to be supplied.
Follow the manufacturer's directions exactl')l in caring for the air
cleaner. Each 300 hours, or more often under extreme dust conditions,
remove the entire air cleaner in types where the filter is not removable,
wash it inside, dip the filter part in oil, and assemble the cleaner (Fig.
16-B). Daily care of the cleaner is absolutely necessary. On cleaners
having oil in the cup at the bottom it is very necessary to use oil of
the proper body in the cup (Fig. 16-A). The usual recommendations
.are as follows:
1. For temperatures 40° F. or more, use oil drained from the crank case.
2. For temperatures 40° to 10° F. above zero, use four parts of drained
'Crank-case oil and one part of kerosene.
3. For 10° F. above zero or colder, use equal parts of drained crank-case oil
and kerosene.
Connections to the air cleaner must be inspected frequently for
air leaks. Always maintain air-tight connections at the joints, and re­
place these parts when necessary.
TRACTOR REPAIR AND .~VIAl -TENA 1\ CE
25
Air breathers are provided on some tractors for the purpose
of ventilating the crank case and the transmission (Fig. 16-C). If
these are of the filter type, follow the instructions given for their care.
If instructions are not available, wash the filter and dip it in oil each
60 hours.
FIG.
16.-TYPEI!.
OF
AIR
CLEANERS AND
AIR
BREATHERS
A. Oil type air cleaner: (1) oil sump, (2) oil level, (3) air inlet, (4) fine
wire filter, (5) air outlet.
B. Washing filter of air cleaner: (1) oil cup, (2) oil level, (3) main
body of cleaner containing wire filter, (4) washing filter with kerosene or
gasoline.
.
C. Types of crank-case air breathers: (1) breather with removable filter
unit, (2) section of a breather filled with fiber filter, (3) breather filled with
fine wire filter, (4) small breather cap filled with fiber, (5) breather covered
with several thicknesses of fine wire, (6) breather filled with steel wool.
THE IGNITION SYSTEM
The ignition system of a tractor usually consists of a high-tension
magneto equipped with an impulse starter (Fig. 17). This magneto is
a complicated piece of equipment and, in general, any extensive repair­
ing should be done by an expert. The instruction book gives complete
directions for taking care of the magneto-follow it closely. Since
magnetos require very little oil, over-oiling may destroy the windings
26
CIRCULAR
No. 425
,
inside the magneto. When the magneto is removed for the purpose of
taking it to a repair man, the directions in the instruction book for its
retiming must be followed exactly. There are, however, a few places
on the magneto which the operator must take care of, and the follow­
4
FIG.
17.-P ARTS
OF A HIGH TENSION MAGNETO
(1) Breaker cover with ground for stopping engine, (2) breaker (inter­
rupter) assembly, (3) screw for attaching assembly, (4) distributor disc,
(5) distributor cap, (6) distributor brushes, (7) collector brush for high ten­
sion current.
ing suggestions may be helpful in securing better service from the
magneto. Before opening any part of a magneto make certain that all
the dirt and dust is removed.
Breaker points, when separated, stop the flow of low-voltage
current which has been generated by the magneto and is flowing thru
the magneto circuit. The heat at the time of the separation of the
breaker points causes the points to corrode and burn, eventually mak­
ing poor contact (Fig. 18-A).
Breaker points are made of two types of material-platinum and
tungsten steel-both of which resist corroding and burning to a high
degree. Platinum points, now seldom used, are soft enough to allow
filing; but tungsten steel points, most commonly used, are extremely
hard and can be dressed only by using a carborundum strip or an oil
stone.
Inspect the breaker point on a new magneto each 50 to 100 hours
of use until the tractor has run 300 hours, after which inspection at
intervals of 300 hours will be sufficient. This can be done by removing
the breaker cover and pushing the points apart. Any scale or corrosion
can usually be scraped off, but if the points are pitted they must be
TRACTOR REPAIR AND MAINTENANCE
27
dressed until all signs of the pits are removed. After the points have
been properly dressed, check the distance between them when they are
separated by the cam. This distance must be maintained at .012 to .015
inch at all times. When an automatic impulse starter is used on a mag­
neto, it is difficult to stop the engine so that the breaker points are
FIG.
18.-TYPES
OF MAGNETO BREAKER POINTS AND THEIR ADJUSTMENT
A. Types of breaker or contact points: (1) insulated breaker point as­
sembly, (2) movable breaker point assembly, (3) breaker points, (4) breaker
spring for holding points together.
B. Adjusting breaker points for gap clearance: (1) insulated adjustable
breaker, (2) magneto wrench with breaker gap gage, (3) thickness gage,
(4) breaker cover, (5) safety spark gap screw.
held wide open. If this difficulty is encountered, turn the engine until
the impulse starter trips, and then back the engine up until the points
open. The engine can usually be turned backwards by squeezing the
fan belt together and turning the fan backwards. Sometimes the im­
pulse starter pawls can be held out of working position, and the engine
turned until the breaker points are wide open. For checking the gap
between the points use the gage attached to the magneto wrench (Fig.
18-B). If the magneto wrench becomes lost use a thickness gage to set
the points. Make sure that the spring operating the movable breaker
point works freely and exerts sufficient pressure to hold the points
together firmly.
The ground brush on a magneto extends from the side or
bottom of the magneto frame to the armature frame and helps to make
28
CIRCULAR
No. 425
a better contact between the frame and the armature (Fig. 19). This
brush should be removed and inspected each 1,500 hours to see that it
has not become glazed, which would prevent it from making good con­
tact. If the brush is glazed, dres; it with fine emery cloth. A new
brush may need to be installed after a time.
2.
FIG. 19.-MAGNETO GROUND BRUSH
(1) Ground brush, (2) impulse starter, (3) safety spark gap screw.
FIG. 20.-MM';NETO IMPUL SE STARTERS
(1) Impulse starter, (2) starter pawls or fingers, (3) impulse covers,
(4) breaker point ground for stopping engine.
TRACTOR REPAIR AND MAINTENANCE
29
Impulse starters provide a method of increasing the speed of
the magneto when the engine is being cranked (Fig. 20). This mech­
anism works as follows: A spring from the drive shaft of the engine
drives the magneto. Just before the engine cylinder is ready to fire,
the magneto armature is stopped and the spring is wound up until the
engine piston reaches the end of the compression stroke. Then the
spring is released and flips the magneto armature around thru the place
FIG.
21.-WIPING
CARBON FROM DISTRIBUTOR DISC
(1) Distributor disc, (2) distributor housing, (3) high tension pick-up
brush, (4) high tension delivery brush, (5) spark plug wire pick-up brush,
(6) impulse starter.
where the spark is produced. When the engine starts, the pawl which
stops the armature is thrown out of position by centrifugal force and
remains in this position as long as the engine runs.
If the impulse starter collects enough dirt to cause it to stick, it can
be cleaned with kerosene or light oil, as indicated in the jnst.ruction
book.
Distributor caps and discs on magnetos where carbon brushes
are used collect carbon, which sometimes short circuits the high ten­
sion spark. Once or twice a season remove the cap and using a rag
moistened with gasoline wipe off the distributor disc where the brushes
rub (Fig. 21). Be sure the brushes all work freely and make good
contact with the distributor disc.
Dust seals are provided at all places on the magneto where dust
can damage the working parts. These seals are usually made of felt
30
CIRCULAR
No.
425
and should be carefully inspected before the particular part is replaced
on the magneto.
Magneto timing is thoroly discussed by most instruction books.
If the instruction book is lost, the manufacturer will gladly supply a
new one.
Spark plugs work under extreme heat conditions in the cylinder
and consequently they will deteriorate in time. It is best to use the
type of spark plug recommended by the tractor manufacturer, for it
has been selected only after rigid testing. The shape and design of the
plug playa very important part in reducing its operating temperature.
The points of the spark plug gradually burn away, because of the
intense heat in the cylinder, and the distance or clearance between them
FIG.
22.-ADJUSTING
SPARK
PLUG
(1) Measuring the gap, which should be
GAP
CLEARANCE
to .025 inch, with magneto
wrench gage, (2) bending outside wire for proper gap clearance.
.020
is widened to such an extent that poor operation results. Examine the
plugs each 200 hours and check the point gap with the gage ~ttached
to the magneto wrench (Fig. 22). Keep the distance of separation
between .020 and .025 inch. Always bend the outside wire when ad­
justing the points. Too wide a gap will cause the engine to miss fire at
high speeds, and too narrow a gap will cause poor idling of the engine.
Clean the spark plugs when they are removed for inspection. The
two-piece plugs are easy t.o clean, but they must be securely tightened
when assembled. If the plug looks faulty, put in a new porcelain or
supply a new plug. A faulty plug produces a weak spark.
Spark plug cables gradually become oil-soaked and deteriorate.
In this condition they are likely to allow the high-tension spark to
short circuit on its way to the plug. A short circuit causes a weak
spark or a total failure of the spark. Replace the cables if there is
any doubt about their condition.
TRACTOR REPAIR AND MAINTENANCE
31
THE COOLING SYSTEM
The cooling system of a tractor requires considerable attention on
the part of the operator if he is to secure the proper fuel economy and
power from the tractor. The cooling system is designed to maintain
the engine temperature at from 180 to 190 0 F. under the hottest
operating conditions. When the engine IS operated in cool or cold
weather, some means must be provided to keep the engine hot. An
engine running too cool, especially when low-grade fuels are used, re­
sults in excessive fuel consumption and dilution of the crank-case oil.
Radiator care is essential to the proper heat control of the
tractor. Use rain water to fill the radiator, because it is free from lime
and other minerals which form a coating or scale inside the cooling
system and eventually cause the engine to overheat. Prevent all
foreign material from collecting on the front of the radiator and keep
the radiator overflow pipe open.
The cooling system should be drained and flushed with clean water
after each 300 hours of use, in order that accumulated dirt may be
removed. CAUTION-never pour cold water into a hot engine, or
extremely hot water into a very cold engine, because the sudden con­
traction or expansion caused by the water may result in the cracking of
the cylinder head or engine block. If it is impossible to let a hot engine
cool before adding water, let the engine run and add the water very
slowly.
Radiator scale can be removed by the use of chemicals which
loosen and dissolve it. If directions are not found in the instruction
book for removing lime and scale, proceed as follows:
1. It is usually recommended that the radiator be cleaned once a year by
using a solution of strong washing soda. Determine the amount of water the
radiator will hold, and fill it half full with rain water. Take the remaining half
of the water, heat to boiling, and add all the washing soda it will dissolve.
Pour this saturated washing-soda solution into the radiator while the solution
is hot and run the engine for 10 to 20 hours at regular farm work, after which
completely drain the radiator, flush with clean water, and refill as usual. This
yearly treatment helps to prevent the scale from forming in the radiator and
cooling system.
2. If the soda treatment will not remove the scale, a solution of hydro­
chloric (commercial muriatic) acid may be used. CAUTION: This acid in
solution is a solvent of the metals of which the radiator is made, and it is ex­
tremely important that the directions be followed exactly.
. The short-time method of removing the radiator scale is accom­
plished by using a strong hydrochloric acid solution which consists of
equal parts of water and acid. After draining the cooling system and
washing it out with clean water, fill the radiator with the strong acid
32
CIRC U LAR
No. 425
solution. Let this solution stand in the radiator, without running the
engine, as long as the solution continues to foam. ( The foaming is
due to the acid attacking and dissolving the scale). Then drain the
radiator and flush with clean water. Repeat the acid treatment again,
just as described above, and let it stand as long as foaming continues.
When the foaming stops, the scale is all dissolved and the radiator
must be drained immediately. Fill the radiator with clean water and
add two or three handful~ of washing soda, the purpose of which is
to neutralize any acid which may be left in the cooling system. Run
the engine for about ten minutes, then drain the cooling system, and
refill with clean water. This process, which does not take a great
while, must be watched carefully, for the acid will attack the radiator
metal after the scale is removed. Do not forget the final soda neutral­
izing treatment.
The long-time method .of removing radiator scale is as follows:
make a weak acid solution consisting of one part of hydrochloric acid
and seven parts of rain water. Drain the radiator and cooling system
of the tractor and fill with this solution. Allow this solution to stand
in the radiator for 36 hours without running the tractor. Then drain
and refill the radiator with clean water and add two or three handfuls
of washing soda. Run the engine for five or ten minutes, drain the
radiator, and fill it with clean water. The soda treatment neutralizes
any acid that may be left in the system.
Some tractor companies recommend special compounds of their
own for cleaning radiators. In addition to these one can purchase a
number of reliable radiator cleaning compounds on the market. Some
household sink drain cleaners are also recommended by the manufac­
turers for cleaning cooling systems.
Radiator hose becomes old and rotten and needs replacing oc­
casionally. Always check the hose and hose connections and keep them
in good condition, especially when antifreeze solutions are being used.
If the hose clamps do not hold, a piece of wire can be wrapped around
the hose and twisted tightly, in addition to the regular clamp. Apply
shellac to the hose joints to give the proper seal.
Radiator curtains are provided on some tractors for the purpose
of maintaining the proper engine temperature in cool weather (Fig.
23). Keep the curtain in good repair and use it as instructed by the:
manufacturer. If a curtain is not provided, it is an easy matter to
make one for the radiator.
Thermostat temperature control of the cooling sy stem is pro­
vided on some tractors. The thermostat is placed in the water outlet
TRACTOR REPAIR AND MAINTENANCE
33
from the top of the engine to the top of the radiator. It is operated by
heat and prevents the circulation of water thru the radiator until the
water is thoroly warmed. Inspect the thermostat to make sure that it
does not become coated with lime or other foreign material in the
cooling water and fail to operate properly. Cleaning the radiator, as
has been recommended, should keep this part working properly.
In order to tell the exact radiator temperature, even if a thermo­
stat is used, one should equip the engine with a water temperature
FIG. 23.-RADIATOR CURTAIN FOR CONTROLLING ENGINE WATER TEMPERATURE
thermometer. Some tractors include this thermometer as regular
equipment (Fig. 24-A).
Fan bearings operating at high speeds often show considerable
wear. A loose, wobbly fan causes considerable vibration, which may
result in the fan or its support breaking and seriously damaging the
radiator. Replace the bearings and shaft if necessary (Fig. 24-B).
Fan pulleys are fastened to the crankshaft by a key or bolt.
Inspect the pulley to see that it is held tightly in place.
Fan belts should be checked after each 100 hours of use and
tIghtened as necessary. A loose fan belt allows the fan to slip,
which causes the engine to overheat.
Water pump care is very important in the proper operation of
the tractor engine (Fig. 24·- C). Many water pumps require a special
water-pump grease which is rather hard and will not melt and mix
with the hot water of the cooling system. If ordinary cup grease is
used for lubricating these pumps, it will melt and mix with the cooling
water and cause considerable radiator clogging. Inspect the pump
34
CIRCULAR
FIG .
ing
(6)
(2)
for
24.-P ARTS
No. 425
OF COOLING SYSTEM AND OIL GAGE
A. Gages for determining: (1) cooling water temperature, (2) oil pressure.
B. Parts of a radiator cooling fan: (1) fan blades, (2) fan hub contain­
bearings, (3) fan shaft, (4) felt washer oil seal, (5) metal washers,
shoulder washer, (7) tapered roller bearings.
C. Polishing pump shaft and replacing packing and nut: (1) pump shaft,
bronze collar, (3) packing nut, (4) strip of fine emery cloth, (5) wrench
tightening packing nut.
TRACTOR REPAIR AND MAINTENANCE
35
packing each year and replace it if the packing nut is screwed nearly
up. A leaking water pump causes the driving shaft to rust and cor­
rode, and a rough shaft makes it impossible to keep the packing tight
and prevent leaking. Unscrew the packing nuts and polish the shaft
with fine emery cloth if it is accessible; otherwise the shaft may need
to be removed for repairing.
Antifreeze solutions for cold weather operation of tractors are
as necessary as they are for automobiles. The temperature of the
solution in the tractor motor cooling system should run from 180 to
190 0 F.; therefore, alcohol, which evaporates at 160 0 F., will not prove
satisfactory as an antifreeze solution unless the motor temperature is
kept below the evaporation point of alcohol. Tractors using the
thermo-syphon system of water circulation (no pump being used, the
water circulating only upon becoming hot) will run too hot under full
load to use alcohol. Manufacturers of tractors with thermo-syphon
cooling systems often recommend using just water, with a caution to
adjust the radiator cover to keep the temperature above freezing. The
water must be drained as soon as the tractor is stopped. Distilled
glycerine, Ethylene Glycol (Prestone) and other antifreeze mixtures
of this nature are recommended by some manufacturers for their trac­
tors. The chief objection to many of these solutions is the high cost
per gallon, altho once put in the radiator they can be saved and used
over again the next year. Heat does not evaporate these solutions, but
extreme care must be taken to prevent leaks. It is a good plan to keep
an open can under the end of the radiator overflow pipe when ex­
pensive solutions are used so that if any of the cooling solution over­
flows it may be saved.
Honey is sometimes recommended as an antifreeze solution, but
it is not satisfactory because it burns and chars, leaving a residue
which clogs up the radiator.
Kerosene, distillate, fuel oils, and furnace oils have been used by
some operators as antifreeze solutions. Kerosene is too volatile and
there is some danger from the fumes catching on fire. The heavier
fuels listed above are sometimes used, if they flow at low enough tem­
peratures, but since they may cause the engine to overheat one must
use caution when opening the radiator on account of explosive gases
which may be formed.
Most tractor instruction books give tables or recommendations for
antifreeze solutions. It is important not to use a solution of calcium
chlorid or other alkaline solutions, as such solutions are injurious to the
metal parts.
36
CIRCUL A R
No.
425
WHEELS, STEERING GEAR, AND TRANSMISSION
Front Wheels and Steering Gear
Front wheels work under very dusty conditions and are subject
to considerable wear. Remove the wheels and bearings each 700 to
1,000 hours of use and wash them carefully. The felt washer on the
side of the wheel next to the frame must be in good condition to keep
the dirt out of the bearings (Fig. 25-A). Since these washers stretch
with use, it is desirable to put in new felt washers each year. Replace
the bearings and wheel and tighten the lock nut until the wheel turns
FIG. 25.-FRON T AND REAR AXLE PARTS
A. Front axle parts: (1) axle or spindle, (2) spindle nut, (3) shoulder
washer, (4) front tapered roller bearing, (5) rear tapered roller bearing,
(6) felt washer grease seal.
B. Rear axle bearing adjustment and tractor brake: (1) axle bearing,
(2) shims for adjusting bearing, (3) rear axle, (4) brake band and lining,
(5) brake pulley, (6) brake adj ustment.
hard; then back the nut off slowly until the wheel turns freely and has
a very slight amount of end-play. Be sure to place the cotter key in
the nut at the end of the axle. When lubricating the front wheels,
force enough grease in so that some of it comes out at the inside of
the wheel; this insures a sufficient supply of grease and pushes out any
dirt that tends to enter the bearing.
Skid bands aid greatly in turning, and they need replacing when
badly worn. Proper skid bands will help steer the tractor out of dead
TRACTOR REPAIR AND MAINTENANCE
37
furrows and help to prevent accidents caused by skidding of the
front end of the tractor.
Front axles do not need much attention, but it is desirable to
make sure that the pin holding the axle to the engine or frame is
securely fastened and properly lubricated.
The tie rod must be firmly fastened to each wheel spindle arm
and all play removed. Adjust the tie rod so that the wheels are one­
half to three-fourths of an inch closer at the front than at the back.
This is called "toe-in"; it keeps the wheels working freely on their
axles and makes steering easier.
The axle brace, when present, is a V -shaped rod extending from
either side of the axle to the bottom of the crank case or tractor frame.
The connection at the axle must be kept tight and the ball-and-socket
joint or other connection at the rear kept properly adjusted and
lubricated ..
Steering gears are usually enclosed and operate in a bath of oil.
This oil must be checked and changed occasionally in some types of
construction. If there is considerable play in the steering wheel, take
it up by means of the adjustment, if one is provided, and check the
play in the drag link ball-and-socket joints.
Transmission, Rear Wheels, Pulley and Brake
The transmission seldom gives trouble, if kept properly lubricated,
unless some defective parts have been installed. Each gear, shaft, and
bearing in the transmission is tested separately, but sometimes they
contain flaws which cannot be detected. Defective parts are usually re­
placed by the manufacturer. If very extensive repairs are to be made
on the transmission, it is advisable to secure the help of the dealer.
The transmission must be checked whenever the oil is changed
to see that there are no loose shafts or bearings. If any worn parts are
found, consult the dealer immediately about their replacement.
Since it is extremely important to keep dust out of the transmis­
sion, the gaskets and dust seals must be carefully inspected. Most
transmissions have a breather provided to relieve the inside pressure
caused by heat expanding the air and lubricant. If this breather is
equipped with an air cleaner, see that it is properly serviced.
Transmission lubricants or oils gradually become contaminated
by dust and metal particles from the inside of the transmission. These
abrasives, which are held in suspension by the thick body of the trans­
mission oil, circulate with the oil and cause serious wear if the oil is
38
CIRCULAR
No. 425
not changed. The length of time the oil should be used in the trans­
mission is a somewhat disputed question among tractor users. In gen­
eral, it is good practice to change the transmission oil after the tractor
has been used from 400 to 700 hours to get rid of the abrasives that
collect in the transmission, and after that each 1,000 to 2,000 hours of
use. Manufacturers usually recommend changing the oil each year,
but since a transmission case holds from 5 to 15 gallons of oil it is
difficult to get the operators to assume the expense of changing oil
each year. If the tractor is operated in very cold weather, the trans­
mission oil must be thinned down with a light, low cold-test oil, such
as an SAE lOW. Then the tractor must be drained and filled with a
heavier oil before it is used in warm weather. See the section on the
discussion of oils (page 42).
Rear wheels require little attention except to see that all the
lugs are fastened tightly, that the rivets in the spokes are holding
properly, and that the bolts fastening the wheel to the axle are always
tight.
Rear axles are supported on bearings which gradually wear and
allow the transmission lubricant to work out. The play should be
taken up if an adjustment is provided, and a new oil seal should be
installed (Fig. 25-B). If adjustments are not provided for taking up
the axle bearing play, new parts should be installed eventually.
The belt pulley is usually self-lubricated if it runs with the
engine, but if it can be thrown out of gear there is usually a place pro­
vided for lubrication when the pulley is being used. The driving gears
for the pulley should mesh properly. Shims are often provided for
making this adjustment.
The brake on a tractor is very important (Fig. 25-B). There is
great danger to the operator and equipment in backing up to machinery
on slanting or, sometimes, level ground if the tractor cannot be stopped
from rolling. The brakes on general-purpose tractors are necessary
for short turning. Many of these brakes are of the internal expanding
type consisting of two shoes which are forced apart by a cam. After
the brakes have become worn, the play can be taken up by either plac­
ing shims back of the plates against which the cam works, or by
supplying a new cam. To test the brakes, jack up one wheel and try
turning it with the brake set. Remove the jack and repeat the same
process with the other wheel. Brake linings must be replaced if worn.
Tractors equipped with rubber tires should not be operated at all with­
out good brakes.
TRACTOR REPAIR AND MAINTENANCE
39
LUBRICATING OILS AND LUBRICATION OF THE TRACTOR! One tractor manufacturer states at the beginning of the instruction
book that ((lubrication is the first and most important consideration in
the life of the tractor." All manufacturers insist upon the use of high­
grade oils in their tractors, because they know that these oils will hold
their body and lubricating qualities longer under heat and pressure
than low-grade oils. Tractors require the same high-quality oils as are
used in automobiles.
Quality in crank-case oils is difficult to determine, and even
laboratory tests do not reveal just what will happen to an oil when
used in the crank case of an engine. The best assurance of securing
oil of a high grade or high quality is to purchase the better grades of
oil manufactured by dependable oil companies who have established a
national reputation for quality products and whose success depends
upon maintaining this quality. Along with quality it is essential to
secure the proper body or viscosity of oil recommended for the engine.
High-quality oirs are stable and well refined. They have all the
impurities removed that it is possible to take out, have good color, low
carbon content, low cold test, and stand up under heat and pressure.
Low-grade oils are made to meet competition and are seldom eco­
nomical altho they may be lower in price. They are usually unstable,
which means that they thin out under heat, cause corrosion of valves
and piston rings, and give off carbon, sulfur, gum, and tarry sub­
stances, which foul the motor parts and fail to provide a protective oil
film between moving parts. They may also contain quantities of wax,
which causes the oil to become stiff in cold weather.
Do oils wear out? is a question that is so often asked. Oils of high
quality, being very stable and well refined, do not wear out. They
become contaminated, however, with dirt, carbon, and metal particles
lRequests for testing oils are received from many tractor owners each year.
These tests, which are made in the applied chemical testing laboratory of the
University of Illinois, cover the physical and chemical properties of the oil, but
do not give information about the service the oil will give in a tractor or auto­
mobile.
The charge made for testing a sample of oil is five dollars, and one quart
of oil is required for the test. All communications about testing oils should be
directed to the Department of Chemistry, 105 Chemistry Building, University of
Illinois, Urbana.
If the person requesting the test has not had sufficient training to interpret
the meaning of the tests, they will be of little benefit to him. The importance of
selecting good oils has been emphasized and it is strongly recommended that
oils be purchased for quality rather than low cost.
40
CIRCULAR
No. 425
from the engine, and become diluted with the fuel working past the
piston. Oil in this condition must be changed in order to get rid of
the impurities. Oil of poor quality actually wears out, because much of
it undergoes a chemical reaction which changes it into forms not suit­
able for lubrication.
FIG. 26.-S AYBOLT UNIVERSAL VISCOSIMETER FOR DETERMINING
VISCOSITY OR BODY OF OIL
(1) Outside shell,
heater for water bath,
from oil tube, (6) stop
tube"for cooling water
(2) oil tube surrounded by a water bath, (3) electric
(4) thermometer, (5) beaker (60 cc.) for receiving oil
watch, (7) filling cup and strainer, (8) water circulating
bath, (9) agitator handle for water bath.
Re-refined oils are now being sold rather extensively and at a
lower price than new oils, and many tractor operators are wondering
whether these oils are safe to use. When a sample of re-refined oil is
compared with a new oil of the same kind, the laboratory test usually
runs practically the same for both oils, with the exception that the re­
refined oil may have a little less carbon. Laboratory studies of re­
refined oils carried on by the U. S. Bureau of Standards have not in­
cluded service tests, so that information on the relative performance
of new and re-refined oils is not available from this source. There are
a number of oil refining machines in use, however, and many tractor
and automobile operators report that re-refined oil gives satisfactory
service.
41
TRACTOR REPAIR AND i\IAINTENA ' CE
The body or viscosity of an oil is very important In selecting
the proper grade of oil for the crank case. The apparatus for de­
termining oil viscosity is called a Saybolt Viscosimeter (Fig. 26).1
There has been a great deal of confusion in the past about oils, largely
because of the manner of designating the bodies of the oils, such as
light, medium, medium heavy, heavy, and so forth, which gave little
information about the comparative bodies of various brands of oil. To
overcome this misunderstanding and to provide a standard system of
TABLE 2.-CRANK-CASE LUBRICATING OIL VISCOSITY NUMBERS:
SAE RECOMMENDED PRACTICE
The SAE viscosity numbers constitute a classification of crank-case lubricating
oi Is in terms of viscosity only. Other factors of oil quality or character are not
considered.
Viscosity ranges, Saybolt Universal, secondsSAE viscosity No.
10................... .
20 ......... . ......... .
30 . .... . .............. '
40................... .
50................. . . .
60 ................. . . .
70 . ... . .............. .
At 130° Fahrenheit
Minimum
Maximum
90
Less than 120
Less than 185
Less than 255
120
185
255
At 210 0 Fahrenheit
Minimum
75
105
125
Maximum
Less
Less
Less
Less
than
than
than
than
75
105
125
150
For prediluted oils, SAE viscosity numbers by which the oils are classified shall
be determined by the viscosity of the undiluted oils. Wherever the SAE viscosity
numbers are used on prediluted oils, the container labels should show in some suitable
manner that the SAE number applies to the undiluted oil.
comparing the body or viscosity of all oils, the Society of Automotive
Engineers developed what is called the SAE oil numbers. These num­
bers, starting with 10 and running in intervals of 10's up to 70, have a
definite viscosity or body range for each number so that the t~actor or
engine manufacturer can specify for the crank case, the correct SAE
oil number, which will apply to all brands of oil. The oil companies
stamp these numbers on the containers of their various grades of oil so
that the buyer knows just what body of oil he is purchasing. The SAE
standards for the grades of crank-case oil are shown in Table 2.
Most of the late-model tractors use SAE 30 or 40 oil in the sum­
mer, and 20 or 30 oil in the winter.
lThe viscosity or body of an oil is given as the number of seconds it takes
60 cc. of it to run thru a standard opening at a given temperature. The tem­
peratures used are 100, 130, and 210 0 F., the last two temperatures being the
ones used in the SAE oil recommendations.
42
CmCULAR
No. 425
Hard starting in cold weather has been largely overcome during
the past year (1933) by the introduction of two new light oils which
flow at very low temperatures. These two oils, listed as SAE lOW
and 20W, are light in body and are so completely dewaxed, or treated
to prevent the wax from congealing, that they do not solidify at low
temperatures. These oils insure easy starting in cold weather, but the
oil consumption of the engine runs somewhat higher. The automobile
manufacturers recommend the use of these oils as follows:
Temperatures ranging from 40° F. to 0° F., use SAE 20W.
Temperatures ranging from 0° F. to minus 15° F ., use SAE lOW.
Temperatures below minus 15° F., use lOW plus 10 percent kerosene.
Many tractor manufacturers are recommending the use of 20W for
ordinary cold weather operation and lOW for extremely cold weather.
The SAE standards for lOW and 20W oils are based on the viscosity
or body of the oil at 0° F., and do not refer to quality in any way.
The standards are as follows:
SAE Oil lOW .... . .......... . ....... .
SAE Oil 20W .... .... ... ............ .
Seconds viscosity at 0° F.
Minimum
Maximum
5,000
10,000 10,000
40,000 The SAE lOW and 20W oils should not be confused with the reg­
ular SAE 10 and 20 oils because these latter grades often have a much
higher viscosity at zero, which means harder engine starting and
delayed oil circulation.
During 1933 a number of engine tests were run using the new light
oils, and it was found that these oils circulate more freely and pene­
trate to parts of the engines that heavy oils cannot reach. Bearings
do not "seize" or burn out because the oil is too thin, but rather be­
cause the oil is too heavy to penetrate to all parts of the motor. Auto­
mobiles and tractors are being designed with much smaller bearing and
piston clearances which require the use of lighter-bodied oils.
Transmission oils or lubricants work under entirely different
conditions from crank-case oils. The method of refining these oils is
therefore somewhat different. At one time the heavy black oil known
as 600W was recommended for all transmissions and rear axles. Many
changes in transmissions and their lubrication requirements have oc­
curred, however, and a number of types of transmission lubricants
have been developed which are especially suited to the present types
of gears, bearings, and gear-tooth pressures.
Most of the tractor transmission lubricants now in use are fluid.
Since these lubricants are not required to stand up under extreme
TRACTOR REPAIR AND .MAI~TEK _,\~KE
43
gear-tooth pressure/ standard transmission lubricants of the proper
body are very satisfactory.
Transmission and rear axle lubricants of high quality are made
from properly refined mineral oils (petroleum oils) and should not
contain grit, sediment, acid, alkali , soap, resin, excessive moisture, or
any substance not derived from petroleum. In order to secure trans­
mission lubricants having a high quality and meeting the above require­
ments, one should purchase them from reliable companies.
Standards for the regular grades of transmission lubricants have
been set up by the Society of Automotive Engineers and are shown
in Table 3.
TABLE 3.- TRANSMISSION AND REAR-AxLE LUBRICANT VISCOSITY NUMBERS:
SAE RECOMMENDED PRACTICE
(The SAE viscosity numbers for transmission and rear-axle lubricants constitute
a classification in terms of viscosity and of consistency at low temperatures only. Other
factors of quality or characters are not considered.)
SAE viscosity No.
Viscosity range, equivalent
of Saybolt Furol,l
seconds at 100 0 F.
Minimum
Consistency.
Must not channel
in service at-
Maximum
80 ....... . . ....... ... . . . ......
-10 0 F. .. .
Less than 80
90 ....... . ...... _.............
Less than 150
zero 80
110 .... . ........ ............ ...
150
Less than 300
+10 0 F. 160 .......... . ... . . . . . .........
Less than 600
300
+35 0 F. 250 .... . ..... . .......... .. .....
600
............
. ..... lSaybolt Universal values are approximately ten times Saybolt Furol values as
listed above. for the same oil at the same temperature.
SAE 160 transmission lubricant is usually recommended for use in
tractors for summer temperatures above 35 F. and SAE 90 for tem­
peratures from freezing down to zero. The SAE 80 and 250 are not
usually recommended except for extreme cold or heat.
Tractor manufacturers often recommend that the summer trans­
mission lubricant must pour at temperatures as low as zero. This re0
ISome trucks and automobiles require more specialized lubricants for the
transmission and rear axles. Trucks with their increasing loads, greater speed,
and special types of gears develop pressures running into thousands of pounds
per square inch of gear-tooth contact. Standard transmission lubricants cannot
withstand these pressures, and consequently allow the gear teeth to make metal­
to-metal contact, which causes rapid wear and gear failure. In order that gears
working under the above conditions may be lubricated, special lubricants called
"extreme pressure," or "EP," lubricants have been developed during the past
three years and can be purchased on the market.
44
CIRCULAR
No. 425
quirement is desirable because it allows the tractor to be used in zero
weather without the necessity of thinning down the transmission oil.
Greases for lubricating purposes are mixtures of petroleum
lubricating oils and soaps. The soap tends to harden and its chief
function is to give body or stiffness to the grease so that it will remain
in a bearing. Usually the more petroleum oil there is in the grease the
better the lubricant. A high percentage of petroleum oil makes a soft
grease.
Quality in greases is important and requires the use of the purest
mineral oils, animal and vegetable fats, and alkalies. The type of alkali
used in the grease determines to a large extent the general character
of the product. The alkalies most commonly used are calcium or lime,
soda, aluminum stearate, and lead aleate. The lead-base greases are
objectionable because the lead either settles out or causes excessive
wear in anti friction bearings.
U sed tractor and automobile crank-case oils do not make good
lubricants for farm machinery, chiefly because they are too thin to
stay in the bearings. The lubricant drained from the transmission
makes a better machinery oil, but it should be allowed to stand long
enough for the dirt and abrasives to settle.
TRACTOR FUELS
Several types of fuels are available for use in a tractor. The choice
of a fuel depends upon the design of the tractor and the atmospheric
temperature in which it works.
Some tractors burn only gasoline, while others are equipped to burn
both gasoline and kerosene. Farmers are beginning to use more of the
low-grade fuels in their kerosene-burning engines in order to reduce
tractor operating costs. The economy in burning low-grade fuels de­
pends upon the design of the tractor engine and the skill of the opera­
tor. It is generally understood that engines burning low-grade fuels
will require more repairs and servicing than those burning gasoline.
An engine burning gasoline usually develops greater power
than that developed by the same engine when equipped to burn kero­
sene or other low-grade fuels, the reason being that gasoline can be
more completely vaporized and burned in the engine under all condi­
tions, which is not true with low-grade fuels. The extra power derived
from burning gasoline, however, is not likely to offset the economy of
using low-grade fuels, even tho the upkeep cost of the tractor is some­
what greater when low-grade fuels are used.
TRACTOR REPAIR AND :MAINTE ANCE
4S
Burning low-grade fuels is accomplished most successfully
under the following engine conditions:
1. The temperature of the cooling water must be kept just below the boiling
point.
2. The intake manifold must be kept hot enough to vaporize the fuel as it
enters the engine.
3. The crank case should be ventilated on types of engines which carry the
oil supply in the crank case.
4. The engine must operate smoothly on the fuel.
Success in burning low-grade fuels depends largely upon the ability
of the operator to maintain the proper engine temperatures (Fig. 27).
FIG. 27.-ENGINE MANIFOLD CONSTRUCTION FOR BURNING
GASOLINE OR LOW-GRADE FUELS
A. Hand-operated manifold heat regulator: (1) exhaust manifold, (2) in­
take manifold, (3) lever for changing heat set for burning gasoline, (4) position
of lever for burning low-grade fuels, (5) crank-case breather, (6) air cleaner.
B. Lever-operated manifold heat regulator: (1) heating chamber for fuel,
(2) exhaust manifold, (3) hot manifold position for burning low-grade fuels,
(4) cold manifold position for burning gasoline.
Since it is difficult to maintain proper engine temperature in cool or
cold weather, low-grade fuels do not, as a rule, operate as successfully
under these conditions. The oil in the crank case must be carefully
watched for dilution and changed when necessary.
K in ds of low-grade fu els being used in tractors at the present
time are: distillate, tractor distillate, fuel oil No.1, and furnace oil
No.1. These fuels resemble each other rather closely and are not
much different in price. Some of these fuels have about the same
quality as kerosene and work equally well. The quality of distillate
or other low-grade fuels is lowered by the percentage of sulfur pres­
ent, which, if excessive, makes these fuels undesirable. In North
Dakota College of Agriculture Extension Circular 94, "Distillate as a
Tractor Fuel," it is stated that the sulfur content of this fuel should
not exceed .138 percent. Sulfur from the fuel works down into the
engine crank case and, in the presence of water, forms a weak sulfuric
46
CiRCU LAR
No. 425
acid which rapidly eats or corrodes the bright metal parts of the engine
and causes wear and improper fitting of parts. Frequent starting, stop­
ping, and idling of engines in cold weather increases acid formation.
Therefore oil should never be left in the crank case long in cold
weather regardless of the fuel used, unless the engine is thoroly
warmed up every few days and operated in this condition for several
hours.
When purchasing low-grade fuels one should make quality the
first consideration. Because of the lack of standard specifications for
low-grade fuels, the' best assurance of securing quality is to buy from
dependable oil companies with favorable reputations for products of
high quality and preferably those that refine their own fuels or those
that buy from companies refining their own fuels.
The saving in fuel costs made by using low-grade fuels is re­
ported in North Dakota Extension Circular 94 as follows: "Distillate
fuel costing 9 cents per gallon will save approximately 15 to 20 cents
per hour in the fuel cost of the average 3-4 plow-size tractor compared
. to kerosene costing 15 cents per gallon." The saving in fuel cost is
the only reason for using low-grade fuels.
OPERATION AND STORAGE OF THE TRACTOR
Breaking in New and Repaired Tractors
A tractor, like an automobile, is a piece of fine machinery and as
such requires some time for the parts to loosen up and adjust them­
selves. During the first fifty hours at least, a tractor should be run at
half load or less, for it is this period of operation that largely deter­
mines the future reliability of the machine.
Adhere strictly to the directions given in the instruction book for
breaking in a new tractor. Starting a new tractor according to the
manufacturer's directions in the instruction book will greatly increase
its life and service. One company recommends using an SAE 10 oil in
all its tractors for the first 100 hours and then changing to SAE 30.
Breaking in a tractor after it has been overhauled should be done
as carefully as if the tractor were new. Use a light oil (SAE 20 or 30)
and run the tractor with a light load the first day at least. Idling the
tractor for three or four hours before using it in the field is strongly
recommended.
Cold Weather Operating Suggestions
Satisfactory operation of tractors in cold weather requires con­
siderable attention from the operator. The following suggestions,
47
TRACTOR REPAIR AND MAINTENANCE
which have been covered in your instruction book or
are listed for your convenience:
111
this circular,
1. Change the crank-case oil to a lighter grade.
2. Each day loosen the oil drain plug in the bottom of the oil pan enough
to allow water accumulated in the crank case to drain out.
3. Use a higher-grade fuel.
4. Keep the fuel tank full if the tractor stands idle, in order to prevent
moisture from condensing in the tank.
S. For hard starting, prime the motor with a solution of half gasoline and
half ether.
6. Use a diluted oil in the oil cup of the air cleaner.
7. Keep the engine warm by using a radiator cover or installing a shutter.
8. Drain the radiator and engine when the tractor is stopped if an anti­
freeze solution is not used.
9. Use a transmission oil that will not stiffen and channel.
How to Store the Tractor
If a tractor is to be stored for any length of time, careful attention
should be given to the following suggestions:
1. Store the tractor in a dry place and run it up on boards.
2. Clean the tractor thoroly with gasoline or kerosene and a stiff brush.
3. If the crank-case oil is thin, drain, refill, and run the engine for a few
minutes to distribute the new oil thru the engine.
4. Drain the radiator and engine block and leave the drains open.
S. When the engine has cooled, remove the spark plugs, put one-half pint of
crank-case oil in each cylinder, and turn the engine by hand a few times to
distribute the oil, after which replace the plugs.
6. Drain the fuel from the tanks and carburetor and leave the drains open.
7. Put fresh lubricant in all bearings.
8. Stop up the end of the exhaust pipe with a rag to keep moisture from
entering the valves and cylinders.
48
CIRCULAR
No. 425 INDEX
PAGE
Air breathers .. . .................. . ..... .. 25 Air cleaner . . . ... .. ........ . ... ...... ... 24-25 Antifreeze solutions. . . . . . . . . . . . . . . . . . . . . .. 35 Axles, front and rear ..... . .............. 36-38 Axle brace . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 37 Bearings, clutch throw-out ... .............. 21 connecting rod ............ . .. ... . . ... 16-17 crankshaft. ......... . . . ........ . ..... 18- 19 fan .... . ....... .. .... .. ...... . .... . ... 33 main .. ......... . ... .. . . ..... . ....... 18-19 piston pin . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 15
rear axle . . . . . . . . . . . .
. . . . . . . . . . . . .. 38 Belt pulley. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 38 Brake . . . . . . . . . . . .
. . . .... . . 36, 38
Breaker points, types. .
. .. 26-28 Butterfly valve . .
. .......... 24 Carburetor. . . . . . . . . . . .. . . . ........ . .. . .. 22 check list for . . . . . . . . . . . . . . . . . . . .
6
types of . . . . . . . . . . . . . . .. . . . . . ... . .... 23 Check list for tractor. . . . . . . . . . . . .. . .. . ... 4- 7 Choke ...... ..... .
. .. 24 Clutch . . . .. . ...... .... ... .. ........
20 Compression, loss of . . . . . . . . . . . . . . . . . . . . .. 5 Connecting rods ..................... 13, 15- 17 Cooling system ......................... 31-36 check list for . . . . . . . . . . . . . . . . . . . . . . . . .
7
parts of . . . . . . . . . . . . . ................ 34 Crank-case oils, see Oils Crankshaft . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 19 Crawler tracks . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Cut-off valve ..... . ....................... 22 Cylinder head. . . . . . . . . . . . . . . . . . . . . . . . . . .. 8 Cylinder head gasket. . . . . . . . . . . . . . . . . . . . .. 8 Cylinders ..... . ....... . ...... . ......... 15- 16 Cylinder sleeves . . . . . . . . . . . . . . . . . . . . . . . . .. 16 Distributor cap . . . . . . . . . . . . . . . . . . . . . . . . . .. 29 Distributor disc ... . .............. . ... . ... 29 Dust seals ... . ...... ... ................ 29- 30 Engine, check-list for. . . . . . . . . . . . . . . .
hard starting, reasons for .
Engine supports .. ...
... ........
6
42 21 Fan, parts of . . . . . . . . . . . . . . . . . . .
. . . . 33-34 Float. .............. ... . . ... . ............ 22 Fuels for tractor ........................ 44-46 Gasoline, use of in tractor.... ............ 44-45 Governor, adjustment of. ................ 21-22 Greases for lubricating . .. . ................ 44 Ground brush for magneto . . . . ........... 27-28 Hose and connections. . . . . . . . . . . . . . . . . . . .. 32 Ignition system. ........................ 25-31 check list for . .. . ............... ... .. " . 6- 7 See also Magneto Impulse starter for magneto.. . . .......... 28-29 Lubrication ............................ 39-42 Lubrication system, engine. ......... . ..... . 19 Magneto .............. . . . ....... .... .. 25-30 Manifold heating . . . . . . . . . . . . . . . .
45 Needle valve and seat . . . . . . . . . . . . . . . . . . . .. 22 PAGE
Oil filters ................ . .. .... . ..... . 19-20 Oil pans . .... . ............... . .... ... . . .. 19 Oil pressure gages. .... .. ...... ....... 19-20,34 Oil pumps .. . ............ . ... . ......... 19-20 Oil screens . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 19 Oil seals .... .. .. ................... .. .. 36-37 Oils, lubricating ................ . ....... 39-44 Oils, crank-case, body or viscosity of. . . . . . .. 41 purifier for .. , ............ .. ... . ..... . .. 20 quality of. ........................... 39-40 la boratory tests of ........ . . . ... .. . . .. 39- 40 re-refined ...... ... . . ................... 40 SAE oil numbers . . . . . . . . . . . . . . . . . . . . . .. 41 Oils, transmission and rear-axle ........... 42-44 extreme press ure.. . . . . . . . . . . . . . . . . . . . . .. 43 SAE oil numbers. . . . . . . . . . . . . . . . . . . . . .. 43 Oils, used . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 44 Piston pin bearing ..................... .. . 15 Pi st on rings, cleaning and fitting of ...... . 13-15 Pistons ... .......... ... ...... . .. . ...... 13- 17 Press ure gage . ... ...... . .. .. ........... 19,34 Pump shaft . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 34 R adiat or, care a nd cleaning of. . ............ 31 Radi a tor curtain. ....................... 32- 33 Radiator hose. . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 Radiat or scale, removal with chemicals . .. . 31- 32 R epairs, check list for ..................... 4-7 cost of . .. . ........... . ....... . ........ 3-4 Rocker arms .. . ..... . .. . ............... 12-13 Skid bands.. ........... . .... " ......... 36-37 Spark plug cables .. .. ..................... 30 Spark plugs . . .......... .. ........ .. .. . . .. 30 Speed counters . .. .. .. ............. . .... 21-22 Steering gear. ............ ... ............. 37 Temperature, engine, control with thermo­
stat . .. .. . .. ..... ..... ....... .. .... 32-33 with radiator cover ............. . ..... 33,47 Tie rod .... . ...... . ... .. .. . . .. ........... 37 Timing of magnet o . . ................ . .... 30 Tools, special, for tractor repai r ......... . .. 3-5 Tractor, cleaning of . ..... . ........ . ....... 4-5 Tractor, operation of when new . . . . . . . . . . .. 46 operation of in cold weather.. .. . ....... 46-47 Tractor, storage of. ... ... ...... . . ......... 47 Tractor, general-purpose, labor records on . . .. 4 hours operated. . . . . . . . . . . . . . . . . . . . . . . . . 4 Transmission ........................... 37-38 Transmission lubricants, see Oils, transmission Valve insert seats.. . . . . . . . . . . . . . . . . . . . . . .. 8 Valve grinding compounds ........ . ....... 9-10 Valve guides ............... . ...... .... .. 9-10 Valve stem, polishing of. . . . . . . . . . . . . . . . . .. 9 Valves, cause of sticking ................... 11 clearance adj ustment . .... .... ......... 11-13 grinding of. ... . ......... . ............ . 9-11 inspection of. . . . . . . . . . . . . . . . . . . . . . . . . .. 5 reconditioning of. . . . . . . . . . . . . . . . . . . . . .. 8 wear of ........ '" .. . . . . . . .. . . . . ....... 8 Viscosimeter . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 40 Water pump, care of. ...... . ........ . ... 33-35 Wheels, check list for . . . . . . . . . . . . . . . . . . . .. 7 front ......................... . .... . . 36-37 rear ......................... .. ...... 36,38 FROM TRACTOR INSTRUCTION BOOKS
Whether the owner derives the maximum service
from his tractor depends largely on the care exercised
in its operation and maintenance.
The life and efficient working of the engine depends
on proper lubrication; neglect in this particular may
cause serious trouble, excessive wear, and complete
breakdown.
A reasonably good understanding of the principles
of operation is necessary to care intelligently for any
piece of machinery.
Delay in making needed repairs, large or small, often
proves costly.
Printed in furtherance of the Agricultural Extension Act approved
by Congress May 8, 1914. H. 'vV. MUMFORD, Director. Agricultural
Extension Service. University of Illinois.
10M-8-34-5974
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