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picked up by the rapidly reciprocating piston and reduce friction between the piston and piston rings and cylinder wall.
The diagram at Fig. 119 outlines clearly all parts of a simple constant level splash system having a sight feed on the dash. The direction of oil flow can be easily determined by the arrows. The lubricant is drawn from the sump or container at the bottom of the crank case through a screen attached to the intake pipe of a gear driven oil pump. The pump discharge goes to the sight feed
on the dash and a pipe from the lower portion of this indicator returns the lubricant to spreader members which divert the liquid into the oil troughs under the connecting rods. With this method of lubrication the oil is kept in constant circulation and as the level is always maintained at the proper height in the oil troughs, there is no possibility of the engine becoming under or over lubricated and a constant supply of oil is insured under all operating conditions.
Q. Can oil be circulated without pumps ?
circulate the oil around a power plant interior, as in some the design is such that the flywheel itself serves as an oil distributing member. A typical system of this nature is shown at Fig. 120. The power plant crankcase is inclined toward the rear end so that a pocket is formed in which the oil can collect to a certain height that will insure its being picked up by the periphery of the rapidly moving flywheel rim. The oil thrown from the flywheel is collected by a main oil pipe to an oil feed regulator controlled by the accelerator or throttle lever. From this point a portion of the oil is diverted to an oil duct which joins the four cylinders, while the
Fig. 120.—Oil Supply System of Hupmobile Motor Depends on Fly
wheel to Circulate Lubricant.
remainder flows into the main oil duct cored out in the crankcase to the three main bearings. Oil passages are drilled from the main bearings to the crank throws and these are thoroughly filled with oil which after lubricating the connecting rod caps is thrown about the interior of the engine by centrifugal force and insures that all interior parts not supplied directly by the oil ducts will receive lubricant. Oil thrown by the flywheel is also diverted to the trans
mission gears and universal joint, from which it is returned by a pipe joining the universal joint casing with the flywheel pocket at the rear of the crankcase.
Q. What types of punips are used to circulate oil?
A. Two forms of pumps are used to circulate oil, the gear form which is shown at Figs. 119 and 121 and the plunger pump clearly outlined at Fig. 122. The gear pump consists of a pair of spur gears, having large teeth, meshing together in a closely fitted metal
Fig. 121.—Method of Lubrication by Supplying Oil to Main Bearings
by Pressure Supplied by Gear Pump. case. One of the gears serves as the driving member and is turned by any suitable mechanical connection with the engine crankshaft or camshaft. The plunger pump is usually cam operated, as indicated at Fig. 122, because it works with a reciprocating motion instead of a rotary movement. Both forms outlined are positive though the plunger form is capable of exerting more pressure on the oil than either the spur gear or eccentric forms also widely used.
Q. Why should oil supplied to engines be carefully regulated?
A. It is imperative to insure efficient engine action that the oil be supplied in measured quantities that will be just right for the
conditions under which the power plant is operated. If the lubricating oil is introduced in excessive quantities a considerable portion will be forced into the combustion chamber, where it will be burned by the excessive heat present at that point and produce carbon deposit in the interior of the cylinder head. When an engine is supplied with too much oil the surplus will escape at all pos
sible bearing points and the wasted lubricant performs no useful service. If the oil is not supplied in sufficiently large quantities the bearings will heat because of the friction between their parts and some of the engine power will be lost. If the oil supply is interrupted through accidents, the part may heat up sufficiently so