TB 9-2320-335-13&P
(TM 9-2320-387-24-1).
Flush cooling system (TM 9-2320-387-24-1).
For surge tank replacement procedures, refer to
TM 9-2320-387-24-1. For radiator support
procedures, refer to para. 3-64.1.
For oil cooler and oil cooler hose replacement
procedures, refer to paras. 3-7.1 and 3-8.1.
Notify DS maintenance to repair radiator
(TM 9-2320-387-24-2).
ENGINE COOLING FAN DESCRIPTION OF OPERATION
When the thermostat detects the coolant is hot, the thermostat opens, and allows the coolant to be
pumped to the radiator where it is routed through a series of fins and tubes. A fan draws in the outside
air to help dissipate the heat before the coolant is recirculated back through the engine.
The fan is driven from the engine crankshaft via the geared fan drive and a viscous drive. The geared
fan drive unit is supported by the front rear crossmember, connects to the harmonic balancer of the
engine and places the viscous drive and fan assembly on the same plane as, and close to, the radiator
for maximum cooling efficiency. A helical gearset is utilized within the geared fan drive to change the
drive angle from the crankshaft to the fan. Gear lube with friction modifier lubricates the internal
components of the geared fan drive using an integral reservoir and pump. Two constant velocity joints
and a torsional driveshaft connect the geared fan drive to the engine crankshaft at the harmonic
balancer.
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