TM-9-2350-261-20-1 Unit Maintenance Manual Volume 1 M113A2 M577A2 M1064 M1068 M1059 M901A1 Download
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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 in a safe operating range. 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