no other attention than to see that the proper grade of oil is supplied through the breather pipe when the oil indicator on the left side of the crankcase indicates that oil is needed. The amount of oil necessary to make the indicator register at the word "full" is seven quarts, which is enough for from four to five hundred miles of ordinary running. The oil is circulated by a plunger

Fig. 216.-Overland Constant Level Oiling System.

pump located on the center rib of the cylinder block. The pump is operated by the camshaft.

The lubricant is drawn from the oil base through a fine mesh screen, and forced direct to the three main bearings from which it overflows to the oil pan. Six wells in the oil pan directly underneath the connecting rods are supplied with oil constantly, and a constant level is maintained at any motor speed and under all conditions of road travel. The lower end of each connecting rod is supplied with an oil dip which scoops oil directly to the connecting bearings, and splashes the lubricant on the piston walls au

wrist pin bearings. The overflow from the front main bearing flows to the front timing gear. From there it is carried by gravity to all gears on the transverse shaft. It is very important that the oil strainer be kept clean so that the circulation of the oil be insured. For this reason the removal of the oil strainer has been made easy. By loosening the four stud nuts on the bottom of the crankcase the cylinder screen may be withdrawn and cleaned by dipping it in a pail of gasoline.

In replacing the screen it is well to shellac the gasket between the strainer flange and crankcase to make sure that the lubricant is properly retained. A drain plug is also provided in the bottom of the crankcase for draining the lubricant. This should be done once every thousand miles. The crankcase should then be washed out with kerosene into the breather pipe. After the kerosene has been removed replace the plug and refill the system by using the old lubricant, being careful to strain it through a fine grade of muslin, and add fresh lubricant to make up the proper amount.

The proper working of the system is indicated by a pressure gauge located upon the instrument board of the cowl dash of the car in plain view of the driver. It is not necessary that this gauge indicate a given amount of pressure in pounds; it will be sufficient to notice the slightest detection of pressure by the needle moving to the right when the motor is accelerated. For motor lubrication use a light cylinder oil, free from carbon and having a flash-point of not lower than 425, and a fire-point of not less than 475 degrees Fahrenheit.

Another forced feed system in which no reliance is placed on splash feed due to the connecting rods dipping the lubricant is shown at Fig. 217. This is used on some Pierce-Arrow six-cylinder motors, and includes a novel feature of having the oil supplied drawn from the oil container at the bottom of the crankcase to an oil reservoir carried above the cylinders. While the oil is supplied to the reservoir by the pump it flows to the bearing points indicated by gravity through oil supply tubes of large size. Both the oil reservoir and the bottom of the crankcase are inclined twenty-five degrees, this inclination being given to the oil reser voir when running up or down a grade, each lead will get an

equal supply of oil. There are eight of these leads at the bottom of the oil reservoir, one leading to the timing gear compartment of the crankcase, the others to the main bearings of the crankshaft. The connecting rods are lubricated through suitable drilled passageways in the crankshaft. As is true of other systems of this nature, the interior of the engine base is filled with an oil mist all the time that the engine is in operation, this serving to

Fig. 217.-Oiling System Used on Many Early Pierce-Arrow Motors.

lubricate the piston, cylinder walls, and valve operating mechanism.

The simple pressure feed system used on the National ear is shown at Fig. 218. In this the bottom of the crankcase serves as a main reservoir for the lubricant. It is drawn from this by a geared oil pump driven by bevel gearing from the camshaft, the discharge from the pump being piped to an indicator gauge on the dash. The return from this indicator is directed to a conduit running the length of the crankcase which supplies the oil to the

compartments into which the connecting rods dip to splash the lubricant about the crankcase interior. Attention is directed to the oil wells or pockets above the main bearings which catch part of the oil distributed by the connecting rods and which feed it to the main crankshaft bearings.

Another example of the system in which the oil is forced to the main bearings and from these members to the crankshaft interior which is used on the Marmon motor, is shown at Fig. 219. This operates in the same manner as the Pierce-Arrow system out

lined at Fig. 217, except that all of the lubricant is carried in oil reservoirs attached to the bottom of the crankcase. On some engines, especially of the Knight slide valve form, it is desirable. to increase the oil supply as the engine speed increases. This may be easily done, as shown at Fig. 220, by providing swinging oil troughs operated by linkage which is interlocked with the carburetor throttle actuating lever. A top view of the system showing the six oil troughs is given at A. At B the various positions. of the trough for high throttle, intermediate throttle, and low throttle are clearly indicated by dotted lines. A side sectional view at C shows the supply pipes used to fill the troughs, and

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also shows the rod employed to tilt the trough. With these members in the position indicated the connecting rod will take out more oil on account of the higher level. This position is used only on the highest motor speeds. On the intermediate speeds not as much oil is required as when the engine is running fast, therefore the troughs are tilted to a point where the oil level will be reduced. This system has the advantage of preventing smoking

due to burning too much oil, as in those systems where immovable troughs are employed the level of oil in these members must be kept high enough to supply positive lubricity at high motor speeds. Obviously, this amount of lubricant may be too much for lower engine speeds and the surplus lubricant will be discharged through the exhaust in the form of smoke.

The pressure feed system used on the Cadillac eight-cylinder V motor is shown at Fig. 221. In this it will be observed that the oil is supplied to the three main bearings of the four-throw crankshaft by pipes leading from a manifold running along the oil reser