TM-9-2350-261-20-1
CARRIER, M113A2, M577A2, M1064, M1068, M1059 AND M901A1
TECHNICAL MANUAL; UNIT MAINTENANCE MANUAL - VOLUME 1 OF 4
TM-9-2350-261-20-1 - Page 76 of 346
TM 9-2350-261-20-1
THEORY OF OPERATION
0003 00
SCOPE
This work package describes how major systems and components of the carrier operate. An understanding of how each part
functions in a system and how components relate to each other will help solve possible maintenance problems with the carrier.
Study this information and its illustrations closely. It will help you to know the major systems and components and their parts.
POWER PLANT
The power plant consists of the diesel engine, transfer gearcase, transmission, and differential. The fuel, exhaust, cooling,
starter, generator, and engine air systems are support systems for the power plant.
Diesel Engine
The diesel engine is the primary source of power for the carrier. The engine converts air and diesel fuel into energy and
delivers this power to the transfer gearcase.
Starter
The engine is equipped with a heavy duty starter. The starter, with built-in solenoid, is used to crank the engine for starting.
Generator
The generator is part of the carrier electrical system. It is driven by the transfer gearcase. The generator charges the batteries
in the carrier when the engine is running. A regulator mounted in the driver’s compartment keeps the voltage at correct levels.
Generator Field Switch
The generator field switch is mounted on the secondary fuel filter. When starting the engine, the generator field switch is open
and the generator is not energized to allow the engine to start with less drag. When the secondary fuel filter is pressurized
with fuel, the generator field switch closes and signals the regulator to energize the generator and start charging the batteries.
Oil System
The differential oil cooling system keeps the oil clean and within proper operating temperature range. The components of
the system and their functions are:
The differential oil cooler unit is mounted on the engine. By circulating the hot oil through this unit, heat is given off to the
surrounding engine coolant. Engine coolant is in turn cooled by the engine cooling system.
Oil cleanliness is maintained by circulating engine oil through the engine oil filter, and differential oil through the differential
oil filter. Transmission oil is cleaned by the transmission oil filter, which is an integral part of the transmission.
Differential oil pump is mounted on the transfer gearcase. It pumps oil from the bottom of the differential housing and to the
differential oil filter. Oil flows through the filter, cooler, and back to the top of the differential.
Fuel System
Diesel fuel is stored in the fuel tank located inside the carrier. Fuel is gravity-fed to the primary fuel filter. The engine-driven
fuel pump draws fuel from the primary fuel filter and pumps fuel through the secondary fuel filter to the engine injectors.
The injectors force fuel into combustion cylinders where it is mixed with air and changed into energy. The excess fuel
is returned to the fuel tank.
External fuel tanks are mounted on the rear of the carrier and hold about 95 gallons of diesel fuel. Shutoff cocks are located
inside of carrier at each connection. Turn fuel on and off for maintenance (M981 and M1064 only).
000300-1
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