TM 5-3805-291-23-1
THEORY OF OPERATION - CONTINUED
0003 00
BRAKE AND HYDRAULIC FAN SYSTEM - CONTINUED
(1)
Operation at Brake Cut-In Pressure. When brake system pressure is below cut-in pressure, brake sys-
tem receives a higher priority than fan system. Priority valve is closed and pump flow to fan motor is
blocked.
427-C1765
(2)
Operation with Fan Speed Solenoid De-Energized.
(a) Fan system has priority when brake system pressure is at cut-out pressure. Fan speed solenoid controls
pump load sensing pressure when brake system is fully charged. Fan speed solenoid is a proportional
solenoid. As current to fan speed solenoid increases, output pressure decreases. When fan speed sole-
noid is de-energized, output pressure to load sensing port is at maximum. Pump will be fully stroked
and send maximum flow to fan motor. Thus, fan motor is turning at maximum speed.
0003 00-88