LUBRICATION
The most important thing in the care of a tractor is to oil it; every
moving part should be lubricated, and the greatest care should be taken
to assure a never-failing supply of oil and grease.
Carelessness in lubrication is the principal cause of tractor trouble.
There is nothing complicated or difficult about keeping a tractor
properly oiled; yet more tractors break down from careless lubrication
than from any other cause. Every tractor-maker issues an oiling diagram
and oiling instructions, and there is no excuse for an operator whose
machine does not get the right kind of lubricant in the right quantity
at each place where lubrication is necessary.
The cause of wear is friction; oil reduces friction and so reduces
wear. No matter how smooth and highly polished two pieces of steel may
be, there will be friction between them if they are rubbed together,
and they will wear each other. If they are oiled, the particles of oil
will keep the pieces from touching each other, and there will be no
wear.
Other substances than oil can be used; there are some kinds of
machinery that are lubricated with water, for instance. For general
use, however, oil and grease are the best, and are practically always
used.
The object of a lubricant is to keep two pieces of metal from touching;
it must therefore be able to get between them, and must stay there. If
the pieces are large and heavy, there will be much greater pressure
on the oil than if they are small and light, and the oil must be able
to withstand this pressure and resist being squeezed out. The oil
that would keep the small, light pieces apart might not be able to
stand the pressure of a greater weight, and might be squeezed out from
between two heavy pieces.
Oil has a tendency to cling to whatever it touches, and thick oil
or grease has more of this tendency than a thin, or “runny” oil. If
a thick oil or grease is used on light machinery, such as a sewing
machine, this clinging tendency would make the machine run hard, and
might even prevent its operation.
When oil is heated, it becomes thinner, or more “runny.” Through
this, an oil used in a hot place might get so thin that it would not
lubricate; and on the other hand, an oil that works all right in the
heat of summer might get so thick on a cold winter day as to be useless.
A slow-moving part of a machine uses a thick oil or a grease; a thin
oil must be used for a part that moves at high speed.
Some of the parts of a tractor move slowly and some at high speed; some
are cool and some are hot. Different kinds of lubricants are therefore
required, and it is a grave mistake to use a lubricant that is not
suitable to the work that it is required to do.
The engine is the most difficult part of a tractor to lubricate, and
the part that suffers most if the supply fails or if the wrong kind
of lubricant is used. In the first place, it is so hot that any oil
will burn, being turned to carbon; the best that can be expected of
an oil is that it will resist burning until it has done its work of
lubricating the piston and cylinder.
A tractor engine is more difficult to oil than an automobile or
truck engine for the reason that it works harder and more steadily.
An automobile engine is rarely driven to the limit of its power; it
has frequent opportunities to cool when running down hill. A tractor
engine, on the other hand, works at its full power all day long with
no opportunities to cool off. An oil that gives good satisfaction on
an automobile might ruin a tractor engine through its inability to
withstand the greater heat.
The makers of tractors understand the importance of using proper oils,
and recommend certain brands and grades; these recommendations should
be followed in order to get the best possible results. All makers
specify at least two kinds of lubricants, and most of them three; one
specifies six, which range from a light sewing machine oil to a grease
so thick that it is nearly solid. Whatever the recommendations may be,
they should be followed.
In general, lubricants are classified according to their thickness, and
they range from the light oil used for typewriters and sewing machines
to grease so thick that it may be cut like butter. The thinnest oil
is used for the circuit breaker pivot; this part is usually moved in
one direction by a cam and in the other by a light spring. A thick oil
would gum the bearing to such an extent that the spring might not be
able to move the lever.
[Illustration: FIG. 73.—“MOGUL” OILING DIAGRAM]
----+----------------------+----------------------------+-----------
KEY | DESCRIPTION | QUANTITY |LUBRICATION
----+----------------------+----------------------------+-----------
ONCE EVERY HOUR
----+----------------------+----------------------------+-----------
L | Rear axle bearing | Two complete turns | Cup Grease
----+----------------------+----------------------------+-----------
ONCE EVERY TWO HOURS
----+----------------------+----------------------------+-----------
A | Differential hub | One complete turn | Cup Grease
B | Rear wheel hub | One complete turn | Cup Grease
C | Differential pinion | One complete turn | Cup Grease
H | Front wheel hub | Two complete turns | Cup Grease
T | Governor and cam | Two complete turns | Cup Grease
| shaft bearing | |
----+----------------------+----------------------------+-----------
TWICE EVERY DAY
----+----------------------+----------------------------+-----------
E | Governor | Oil | Cylinder
| | | oil
F | Outboard bearing | Two complete turns when | Cup Grease
| grease cups | plowing |
G | Transmission | One pint | See note
| | | below
|{ Magneto trip | Grease every 5 hours | Cup Grease
N |{ Magneto roller and | Oil every 5 hours | Oil
|{ slide | |
J | Steering worm | Keep covered | Cup Grease
W | Steering hub grease | One complete turn | Cup Grease
| cups | |
V | Steering worm shaft | Oil every 5 hours |
R | Lubricator eccentric | Oil every 5 hours (keep |
| | wool in pocket) |
P | Cam roller slide | Oil every 5 hours |
K | Valve levers | Fill with oil every 5 hours|
| | (keep wool in pockets) |
----+----------------------+----------------------------+-----------
ONCE EVERY DAY TRACTOR IS IN USE
----+----------------------+----------------------------+-----------
U | Steering sector shaft| One complete turn | Cup Grease
----+----------------------+----------------------------+-----------
D | MECHANICAL LUBRICATOR
| Fill with a good grade of heavy gas engine cylinder oil.
| Turn the crank on the mechanical oiler 40 to 50 times when
| starting the engine.
| IMPORTANT
| In cool or cold weather the oil in lubricator tank must be
| warmed as it will not flow readily unless of the right
| temperature.
----+---------------------------------------------------------------
G | TRANSMISSION
| In warm weather, use heavy oil such as “600” transmission
| or Polarine transmission oil; in cold weather, use a good
| light oil.
S | GOVERNOR
| Cylinder oil in governor should cover shoe.
M | MAGNETO
| Oil magneto bearings once a week with sewing machine or
| cream separator oil.
----+---------------------------------------------------------------
The oil used in an engine is thicker, and has a high _burning point_
and high _viscosity_; that is, it should be able to resist burning, and
should not get so thin when it is heated that it will be squeezed out
of the bearings. The same kind of oil that is used in the engine can be
used in many other parts of the tractor.
Grease is usually used for the gears of the transmission and drive.
There is very great pressure between the teeth of two meshing gears,
and only thick oil and grease have sufficient viscosity to resist being
squeezed out.
The thickest grease is used on the tracks of caterpillar-type tractors.
Before operating a tractor, the lubrication chart supplied by the
manufacturer should be studied with great care, and all of its
requirements should be observed. This chart is usually in the form of
a diagram accompanied by a table, as shown in Figure 73, which is the
lubrication chart of one of the International Harvester tractors. This
figure illustrates the constant attention that is demanded by this most
important part of tractor operation.
[Illustration: FIG. 74.—“ILLINOIS” OILING DIAGRAM]
The table calls for four lubricants, these being sewing machine oil,
which is very thin and liquid; gas engine cylinder oil; transmission
oil, which is as thick as molasses; and cup grease, which is like
butter.
The engine is oiled automatically, the only requirements being to keep
the oil tank filled, and to be sure that the oiler is working. The
other parts of the tractor are oiled or greased by hand.
Figure 74 is the oiling chart of the Illinois tractor.
There are three systems used for engine lubrication: _splash_, _force
feed_, and by a mechanical oiler. In the splash system, a pool of oil
is maintained in the crank case, of such a depth that the ends of the
connecting rods just dip into it. They strike it with sufficient force
to splash it to all parts of the crank case, the oil that strikes the
pistons being carried up into the cylinders and lubricating the walls.
The end of the connecting rod is often fitted with a dipper, as shown
in Figure 75, to strike into the oil, as well as an oil catcher,
shown in the same drawing, which is a little trough that catches the
splashing oil and guides it to the connecting rod bearing.
[Illustration: FIG. 75.—END OF “TWIN CITY” CONNECTING ROD]
To oil the wrist pin bearing there is an oil groove around the piston
that collects oil from the cylinder walls; a hole connects this groove
with the hollow wrist pin, from which other oil holes lead to the
bearing. This is shown in Figure 76.
[Illustration: FIG. 76.—WRIST PIN LUBRICATION]
In the force feed system a pump driven by the engine forces oil through
pipes and channels to all of the bearing surfaces. Oil collects in a
pocket in the crank case, called the _sump_, and is drawn from it by
the pump. The sump is usually provided with a wire mesh strainer that
separates out any dirt.
[Illustration: FIG. 77.—FORCE FEED OILING SYSTEM OF “GRAY” ENGINE]
From the oil pump the oil is forced to the bearings by pipes and by
holes drilled in the crank shaft and other parts, as shown in Figure 77.
[Illustration: FIG. 78.—OIL PUMP]
An oil pump is illustrated in Figure 78. It consists of a plunger
driven by the engine, working in a cylinder provided with two ball
check valves, one for inlet and the other for outlet. On an upward
stroke of the plunger the cylinder fills with oil, which is forced to
the engine bearings by the following inward stroke.
[Illustration: FIG. 79.—“E.B.” OIL PUMP]
Figure 79 shows a similar pump with a strainer over the intake, the
outlet being through the holes L in the pipe H. In the pump illustrated
in Figure 80 the plunger is hollow, and fills with oil during an
inward stroke; the oil is forced out to a passage around the plunger,
and passes to the bearings by the holes H.
[Illustration: FIG. 80.—OIL PUMP WITH HOLLOW PLUNGER]
Figure 81 shows two methods of preventing oil from leaking out around
the plunger. In the first of these, a channel is formed in the upper
part of the pump cylinder, leading to the crank case; any oil that
leaks past the plunger flows to the crank case by this drain pipe and
is not wasted. In the second method a packing of soft material, such
as cotton or asbestos, is placed around the plunger, and is pressed
against it by a _gland_, which is like a thick washer. A _packing nut_
screws against the gland, and thus squeezes the packing against the
plunger.
[Illustration: FIG. 81.—METHODS OF PREVENTING OIL LEAKS]
[Illustration: FIG. 82.—“TITAN” LUBRICATOR]
A _mechanical lubricator_, or _oiler_, consists of several small oil
pumps placed in an oil tank, each pump feeding one special bearing,
and all driven by the engine. Figure 82 is a top view of a 2-cylinder
horizontal engine oiled by a six-feed oiler. The bearings that it
oils are the two ends of the crank shaft, the two ends of the cam
shaft, and the two cylinders; the gears and other bearings are oiled
by splash. An oiler is adjustable, so that it will feed any desired
quantity of oil.
[Illustration: FIG. 83.—“I.H.C.” METHOD OF OILING CRANK PINS]
Figure 83 shows a side view and an end view of the crank shaft of a
2-cylinder horizontal engine. To each end of the crank is attached a
ring, B, formed into a channel; oil splashing into this ring is thrown
into the channel by centrifugal force, and flows by holes, A, to the
crank pin bearings.
The oil forced to the cylinders from the oiler, Figure 82, reaches the
wrist pin by grooves and holes, A, Figure 83.
A 6-feed oiler is also shown in Figure 84.
[Illustration: FIG. 84.—“HART-PARR” OILING SYSTEM]
[Illustration: FIG. 85.—OIL CUP]
[Illustration]
[Illustration]
[Illustration: FIG. 86.—PROPER USE OF A GREASE CUP]
Figure 85 is an _oil cup_, which is used to feed an individual bearing.
It is a glass cup holding oil with an opening at the bottom into which
fits a needle valve. When the engine is at rest, the needle valve
handle at the top is turned down, which allows a spring to close the
needle valve; on starting the engine the needle valve is raised, and
the oil flows out by gravity. The dripping oil may be seen through a
sight glass at the bottom.
In the force feed and oiler systems the oil feeds only when the engine
is running, but with an oil cup the oil feeds all of the time that the
needle valve is raised. Care must therefore be taken to turn on the oil
cup when starting the engine, and to turn it off when the engine is
stopped.
Change speed gears and differentials are usually enclosed in oil-tight
housings that contain a supply of oil or grease. The only attention
that is required is to see that they have the necessary amount, and
that the lubricant is of the right kind.
[Illustration: FIG. 87.—“TITAN” 10-20 OILING DIAGRAM]
[Illustration: FIG. 88.—“INTERNATIONAL” OILING DIAGRAM]
The bearings of wheels and of many other parts of a tractor are
lubricated with grease fed by _grease cups_; a grease cup has a cover
that, when screwed down, forces the grease out of a hole in the bottom
of the cup. In using a grease cup it is not sufficient simply to give
the cover a turn or two; the cover should be screwed down enough to
force an ample supply of grease to the bearing. This is illustrated in
Figure 86.
Figures 87 and 88 are oiling diagrams. They show the many points at
which a tractor must be lubricated, and it should be remembered that
the failure to maintain a plentiful supply of lubricant at any one of
these points will mean the wear and breakdown of that particular part.