CHAPTER 1: INTRODUCTION
TM 9-2350-256-20
1-24 APU-Continued
c. LUBRICATION
A gear-type pump draws oil from the crankcase and
delivers it through a replaceable oil filter to the engine.
Normal oil pressure should be 25 psi (172 kPa) or
higher under normal operating conditions. A
crankcase oil drain valve with operating handle is
provided to drain the lubricating oil without removing
the unit from the vehicle.
d. GOVERNOR
Constant speed is set to maintain engine speed at 2000
100 rpm. The governor uses a ball-and-cup
mechanism on the camshaft gear as the sensing device.
A yoke resting on the cup connects to an arm-and-
spring mechanism controlling the throttle lever. Any
change in engine speed is transmitted from the cup to
the yoke and to the throttle. The speed may be
adjusted by changing the spring tension.
e. FUEL SYSTEM
The fuel system consists basically of a primary and
secondary fuel filter, fuel transfer pump, injection
pump, and injection nozzle. The transfer pump,
operating off the camshaft, draws fuel from the supply
tank and delivers it through the two filters to the
injection pump. The injection pump meters and
delivers the fuel at high pressure to the nozzle.
1-25 M8A3 GPFU
The GPFU installation in the M88A1 vehicle is made up of two separate M8A3 systems. One M8A3 GPFU serves the
personnel on the left side of the vehicle and is operated by the driver. The other M8A3 GPFU serves the commander,
mechanic, and rigger with the control switch located at the mechanic's station. Electrical power for operation of the
purifier units is obtained by tapping into convenient dome light power leads.
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