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 77 of 346
TM 9-2350-261-20-1
THEORY OF OPERATION — Continued
0003 00
Transfer Gearcase
The transfer gearcase transfers power from the engine to the transmission. The transfer gearcase is a compact unit that
transfers power from the engine flywheel to transmission torque converter. An engine disconnect allows the engine to run
without transferring power to the transmission. A power takeoff drives the differential oil pump and a ramp pump. Another
power takeoff drives the cooling fan, and a third drives the generator.
Transmission
The transmission is a three speed, constant mesh, planetary gear train with hydraulic torque converter and lockup clutch. It
automatically selects the proper gear based on road and load conditions. The transmission delivers power from the transfer
gearcase to the differential.
Exhaust System
Major exhaust system parts are the exhaust manifolds and muffler. The exhaust manifolds carry the exhaust gases to the
muffler. The muffler cuts down engine noise and allows exhaust to escape outside the carrier.
Cooling System
The cooling system cools the engine and transmission. It consists of a fan, fan drive belts, radiator, coolant pump, auxiliary
tank, transmission oil cooler, and thermostats. The cooling system contains approximately 14 gallons of liquid coolant. The
liquid coolant is pumped by the coolant pump from the radiator and circulated through the engine and thermostat and back to
the radiator where it loses heat to the atmosphere. This process keeps the engine, transmission, and differential temperature
inasafeoperatingrange.
As coolant flows through the engine, it absorbs heat from the engine and transmission. The heated coolant then flows to the
radiator to remove coolant heat. The coolant fan pulls outside air in and through the radiator to remove heat. The fan is
powered by the transfer gearcase.
The radiator auxiliary tank acts as an overflow tank to keep the cooling system from overpressurizing. It also removes
air from the engine coolant.
Engine Air System
The engine air system allows air to enter the engine. The air cleaner filters air through a reusable filter element before delivery
to the engine. An air filter indicator shows when the element is clogged and needs cleaning or replacing. After being filtered,
the air moves through the air horn and into the engine cylinders.
Differential Components
The differential consists of three major assemblies, the right angle gearbox, steering unit with brake shoes, and two output
shafts.
Power flow is from the transmission to the right angle gearbox to the steering unit.
When driving straight forward, the steering unit delivers equal power to both output shafts. Pressure on either right or left
steering lever slows or stops the right or left brake drum, inside the center steering unit, and reduces the speed of the right or
left output shaft. By slowing down on one side you increase the speed of the other and the carrier will turn in the direction
of the applied brake.
Equal pressure on both steering levers applies both brakes and slows or stops the carrier.
The differential overheat switch is connected to a warning light in the driver’s compartment. When warning light comes on it
means oil temperature is too high.
0003 00-2
Back to Top
