Characteristics and Operation of the HMMWV's Lubrication System.

Introduction to the High Mobility Multi- Purpose Wheeled Vehicle HMMVV
Page Navigation
16

because of the heavy loads that are placed on them. There are many other

less critical engine parts such as the camshaft, valve stems, rocker arms,

and timing chains that also need a constant supply of oil.

(2) Oil as a Coolant.

Engine oil circulated throughout the engine

also serves to remove heat from the friction points.

The oil circulates

through the engine and drains to the sump. The heat picked up by the oil

while it is circulated is removed by an airflow around the outside of the

sump. In some instances where the sump is not exposed to a flow of air, it

is necessary to add an oil cooling unit that transfers the heat from the oil

to the engine cooling system through an oil cooler mounted in front of the

radiator. The HMMWV has this type of cooler.

b. Characteristics and Operation of the HMMWV's Lubrication System.

The lubricating system in the HMMWV engine is a pressure feed type. Normal

operating pressure for the system is 20 to 50 psi; at idle, the operating

pressure may drop down to 15 psi.

The engine crankcase (minus the oil

filter) contains 7 quarts, 8 quarts with the filter.

There are three different weights of oil that are used in the HMMWV engine,

depending under what temperature the vehicle is expected to operate. If the

temperature is above 40 F, then heavy duty engine oil (OE/HDO 30) is used;

if the temperature ranges between 40 F to -15 F, then OE/HDO 10 oil is

used; if the temperature falls between -15 F to -65 F, an arctic type

engine oil (OEA) must be used.

The engine lubrication system is composed of an oil pan reservoir, oil

filter, gear-driven oil pump, and an oil cooler. The pump is mounted on the

rear main bearing cap. Oil is picked up by a tube and is pumped to the oil

cooler. The oil cooler is mounted in front of the radiator. The oil then

flows from the oil cooler to the oil filter, located on the left side of the

engine. The oil filter is of the cartridge-type and all oil going to the

engine must first pass through it.

This type of filter is also called a

full flow filter.