WHEEL GP-FINAL DRIVE & BRAKE 2V4347 - Caterpillar

Brake Operation at Cut Out Pressure
Illustration 4 g06058996
(1) Brake pressure sensor
(2) Brake accumulator port (Rear brakes)
(3) Rod
(4) Inverse shuttle valve
(5) Brake accumulator port (Front brakes)
(6) Main relief valve
(7) Cut in / cut out valve
(8) Orifice
(9) Screen
(10) Tank return port
(11) Brake / fan discharge pressure tap
(12) Pump supply port
(13) Load sensing port
(14) Shuttle valve
(15) Supply port for fan motor
(16) Priority valve
(17) Fan speed solenoid
(18) Check valveWhen brake system pressure reaches the cut out pressure, cut in / cut out valve (7) opens. Cut in / cut out valve (7) drains the spring side to tank return port (17). System pressure overcomes the spring pressure on cut in / cut out valve (7). Cut in / cut out valve (7) shifts to the right. When cut in / cut out valve (7) shifts to the right, pressurized oil from the right side of shuttle valve (14) and the spring side of priority valve (16) is metered to tank return port (10). System pressure overcomes the spring pressure on priority valve (16). Priority valve (16) opens and the priority valve allows pump flow to the fan system. At the same time, shuttle valve (14) shifts to the right. This allows the pump to sense the pressure requirements of the fan system. Check valve (18) closes and the check valve maintains brake system pressure.Operation of the Hydraulic Fan System
Operation at the Brake Cut In Pressure
Illustration 5 g06059012
(1) Brake pressure sensor
(2) Brake accumulator port (Rear brakes)
(3) Rod
(4) Inverse shuttle valve
(5) Brake accumulator port (Front brakes)
(6) Main relief valve
(7) Cut in / cut out valve
(8) Orifice
(9) Screen
(10) Tank return port
(11) Brake / fan discharge pressure tap
(12) Pump supply port
(13) Load sensing port
(14) Shuttle valve
(15) Supply port for fan motor
(16) Priority valve
(17) Fan speed solenoid
(18) Check valveWhen the brake system pressure is below cut in pressure, the brake system receives a higher priority than the fan system. Priority valve (16) is closed. Pump flow to the fan motor is blocked when the priority valve is closed.Operation with the Fan Speed Solenoid De-Energized
Illustration 6 g06059024
(1) Brake pressure sensor
(2) Brake accumulator port (Rear brakes)
(3) Rod
(4) Inverse shuttle valve
(5) Brake accumulator port (Front brakes)
(6) Main relief valve
(7) Cut in / cut out valve
(8) Orifice
(9) Screen
(10) Tank return port
(11) Brake / fan discharge pressure tap
(12) Pump supply port
(13) Load sensing port
(14) Shuttle valve
(15) Supply port for fan motor
(16) Priority valve
(17) Fan speed solenoid
(18) Check valveThe fan system has priority when the brake system pressure is at the cut out pressure. Fan speed solenoid (17) controls the load sensing pressure for the pump when the brake system is fully charged. Fan speed solenoid (17) is a proportional solenoid. As current to the fan speed solenoid increases, the output pressure decreases. When fan speed solenoid (17) is de-energized, the output pressure to the load sensing port is maximum. The pump will be fully stroked and the pump will send maximum flow to the fan motor. Thus, the fan motor is turning at maximum speed.Pump flow enters the control manifold through port (13). Oil flow