SPACER 4I5006 - Caterpillar

Service Brakes Released with Parking Brake Released - Engine on
Illustration 1 g06227775
Engine running with service brakes and parking brake released
(1) Fan, brake, and hoist / ejector pump
(2) Cutoff spool
(3) Flow compensator spool
(4) Brake signal revolver
(5) Brake priority valve
(6) Signal resolver
(7) Brake charge control valve
(8) Service brake check valve
(9) Brake pressure sensors
(10) Parking brake accumulator check valve
(11) Park brake control valve
(12) Parking brake pressure sensor
(13) Inverse resolver
(14) Parking brake accumulator
(15) Rear brake accumulator
(16) Front brake accumulator
(17) Front brake and retarding valve group
(18) Center, rear brake, and retarding valve group
(19) Front axle brake group left and right
(20) Rear axle spool
(21) Front axle spool
(22) Parking brake actuator
(23) Center brake group left and right
(24) Rear brake group left and right
(25) Main hydraulic oil tank
(26) Actuator bias spring
(D) TBPR
(J) TPI
(K) Brake control valveNote: Callouts not mentioned in explanations of systems operation are shown for reference purposes only.In this illustration, the parking brake and service brake are released and the engine is on. The transmission ECM energizes park brake control valve solenoid (11) when the transmission control is moved from the park position. With the solenoid energized , the park brake control valve sends oil from parking brake accumulator (14) to pressurize parking brake actuator (22). As the actuator is pressurized, the actuator piston moves the actuator rod outward, releasing the parking brake.When parking brake pressure sensor (12) detects the pressure in the parking brake system, the transmission ECM shares that data with the instrument cluster and the parking brake indicator lamp will be turned "OFF".If the parking brake pressure sensor (12) detects the pressure in the parking brake system has fallen below the specified operating pressure, the transmission ECM will de-energize the brake charge control valve solenoid (7). When de-energizeD, the brake charge control valve sends brake hydraulic system pressure into the signal resolver network, causing fan, brake, and hoist pump (1) to upstroke. When the pump upstrokes, the increase in pump flow and the resulting increase in system pressure will recharge the parking brake and parking brake accumulator (14).Service Brakes Engaged with Parking Brake Released - Engine on
Illustration 2 g06227773
Engine running with service brakes engaged and parking brake released
(1) Fan, brake, and hoist / ejector pump
(2) Cutoff spool
(3) Flow compensator spool
(4) Brake signal revolver
(5) Brake priority valve
(6) Signal resolver
(7) Brake charge control valve
(8) Service brake check valve
(9) Brake pressure sensors
(10) Parking brake accumulator check valve
(11) Park brake control valve
(12) Parking brake pressure sensor
(13) Inverse resolver
(14) Parking brake accumulator
(15) Rear brake accumulator
(16) Front brake accumulator
(17) Front automatic retarder control valve
(18) Center and rear automatic retarder control valve
(19) Front axle brake group left and right
(20) Rear axle spool
(21) Front axle spool
(22) Parking brake actuator
(23) Center brake group left and right
(24) Rear brake group left and right
(25) Main hydraulic oil tank
(26) Actuator bias spring
(D) TBPR
(J) TPI
(K) Brake control valveNote: Callouts not mentioned in explanations of systems operation are shown for reference purposes only.When the operator depresses the brake pedal, rear axle spool (20) and front axle spool (21) in the brake control valve move down The front