Detroit Diesel 4000 Series, Service Manual, Page: 1749 / 2706

SERIES 4000 12/16V SERVICE MANUAL
C 222.05.01 – OPERATION OF ROCKFORD SERIES 270 FAN CLUTCH
AND GENERAL VIEWS
Introduction
The Rockford Fan Drive Clutch is an oil pressure actuated, oil cooled and lubricated, multiplate
clutch designed for infinite fan-to-engine pulley speed ratios assuring prescribed engine coolant
temperatures and minimum engine horsepower losses. Engine oil is supplied to the fan clutch
to provide maximum cooling and lubrication. Some applications may use transmission oil
instead of engine oil.
Engine cooling temperature demands are transmitted to the clutch either by a Rockford fan clutch
thermal sensor located to sense the engine coolant temperature, or by the engine’s electronic
control system. The fan clutch automatically adjusts the fan speed to maintain specified coolant
temperature. It is controlled by the thermal sensor and solenoid valve which cause the fan speed
to be increased or decreased smoothly without shock loads. Oil cooled plates permit clutch
slippage which allows variable fan speeds. See Figure 1045.
Figure 1045 Rockford Series 270 Fan Clutch
The fan clutch shaft acts as a bearing surface for the moving parts. Internal ports and orifices
distribute lubricating/cooling oil, and oil control pressure controls fan speed and modulates the
engagement and disengagement of the fan clutch.
All information subject to change without notice.
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C -1603