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Q. How are ball or roller bearings lubricated?

A. The method of installation and the duties they are to perform are the factors governing the lubrication of anti-friction bearings. They are generally lubricated with high grade mineral oils

and greases.

Q. What grade of oil is most suited for heavy loads and low speed?

A. A heavy bodied lubricant of the semi-fluid type is best adapted for use in bearings subject to heavy loads and revolving at low speed. Greases having about the consistency of vaseline or petroleum jelly are generally applied for this purpose.

Q. What grade of lubricant is best suited for light loads at high speeds?

A. If an anti-friction bearing is housed in an oil retaining, dust excluding housing, it is good practice to use a medium grade machine oil and run the bearings in a constant bath of lubricant. Heavier greases produce an item of friction, which while negligible in low speed bearings may be high enough to be objectionable in high speed forms.

Q. Why are animal or vegetable oils undesirable?

A. Ball or roller bearings should not be lubricated with oils of organic derivation because these are not stable enough. They oxidize or become rancid on exposure to the air and are apt to gum up in the bearing. Animal oils are also apt to contain fatty acids.

Q. Why are acidulous oils injurious?

A. Oils containing acid should never be used with ball or roller bearings because the acid will etch or discolor the highly polished surfaces of the anti-friction members and the races. This etching and rust deposits will interfere with smooth operation and tend to produce rapid depreciation of the bearings.

Q. Give somre general precautions to be observed in installing anti-friction bearings.

A. Anti-friction bearings should always be installed in mountings that can be effectively closed to prevent escape of oil or entrance of dirt, grit and water. Ball bearings should never be driven in place with a steel drift or hammer because the races are hard steel and are apt to be cracked unless they are forced in place either with a steady pressure from a press or by blows applied through the medium of a block of hard wood or piece of Babbit metal interposed between the hammer and the bearings. The blow should always be directed or the pressure exerted against the race that is being forced in place.

LESSON TWENTY-SIX

HOW TO START AND CONTROL AUTOMOBILE POWER

PLANT

Q. Before starting automobile engines, what precautions are necessary?

A. The motorist should make sure that there is plenty of gasoline in the tank and that it is turned on so it will flow to the carburetor. The radiator should also be filled with clean water and the oiler must also receive attention. The gear shift lever is placed in the neutral notch and the emergency brake hand lever is locked in such a way that the brakes are engaged. The spark lever on the steering wheel is set at a retard position and the throttle or gas lever is slightly advanced. The switch for the ignition system is then placed in its active position.

Q. Why must radiator be filled ?

A. It is imperative that there be enough water in the cooling system or the engine will soon become overheated.

Q. Why must oil supply be inspected?

A. If an automobile engine is run for any length of time without lubricant it will be seriously damaged, so before attempt is made to start the engine for a day's service it is well to see that there is an adequate supply of lubricant in the oiling system.

Q. Why must gasoline be turned on at the tank?

A. At the tank end of the pipe line conveying gasoline to the carburetor will be found a shut off valve as indicated at Fig. 246. If this valve is closed no fuel will reach the carburetor so it is important to open it up or see if it is opened before attempting to start the engine.

Q. Why must switch be closed?

A. The switch must be closed or placed in operative position so the current can flow to the spark plugs depended on to ignite the fuel in the cylinders.

Q. If both battery and magneto ignition are provided, which is preferable to start on, and why?

A. The switch lever should be placed on the battery side of the switch as indicated at Fig. 247-A because it is easier to start an engine with a battery spark than it is from the average magneto.

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Fig. 246 – Typical Fuel System Showing Shut-off Valve at Tank.

With a battery the current is always available whereas it must be generated by revolving the magneto armature if attempt is made to start on the magneto. Some forms of magneto, notably those of the true high tension type, generate current enough to ignite the gas even if the armature is turned slowly. Magnetos of the transformer coil type do not generate current enough at low speeds provided by hand cranking to furnish positive ignition. Most car manufacturers, therefore, advise starting on the battery.

Q. Where should speed change gear lever be, and why?

A. The gear shifting lever should be in neutral position, as shown at Fig. 247-B, because if it is in one of the speed positions so that a pair of gears are meshed it will not be possible to turn the engine without moving the car. If the engine is a type that is easily started it may pick up its explosions quick enough so the car will move as soon as the engine starts.

Q. Why should spark lever be retarded?

A. The spark lever should be placed in the retard position, as shown at Fig. 247-C, because an advanced or early spark will pro

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Fig. 247.-Position of Switch, Gear Shift and Motor Control Levers

on Overland Car Before Starting Engine.

duce a back kick or preignition in the cylinder that will tend to reverse the crankshaft rotation and bring the starting crank forcibly in contact with the operator's arm or wrist.

Q. How should throttle control lever be placed?

A. The throttle control lever should be partially advanced in order that a supply of gas be drawn into the motor cylinder as the engine is cranked over by hand. The position of the throttle lever relative to that of the spark control on the Overland car is outlined at Fig. 247-C.

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