CYLINDER GP 1153523 - Caterpillar

Illustration 1 g00942574
The parking brake control valve is located on the left side of the rear frame.
Illustration 2 g00942573
Parking brake control valve (1) Parking brake solenoid valve (2) Port to parking brakes (3) Port to hydraulic tank (4) Pressure tap for parking brake system (5) Parking brake oil pressure switch (6) Port to brake release sequence valve (if equipped) (7) Port from parking brake oil pressure reducing valve (8) PlugThe parking brake control valve has two parking brake solenoid valves (1) controlled by a parking brake switch in the operator station. The optional remote control system when fitted also controls the operation of solenoids (1).
Illustration 3 g00942575
Schematic for the parking brake control valve (1) Parking brake solenoid valves (2) Port to parking brakes (3) Port to hydraulic tank (4) Pressure tap for parking brake system (5) Parking brake oil pressure switch (6) Port to brake release sequence valve (if equipped) (7) Port from parking brake oil pressure reducing valve (8) Plug (9) Valve spoolsWhen the engine is running and the parking brake switch is in the ON position, no power is supplied to solenoids (1). Oil pressure from the parking brake oil pressure reducing valve at port (7) is stopped by valve spools (9). The parking brakes are engaged by the force of the parking brake springs. Oil from the parking brakes is free to return to the hydraulic tank through port (6), valve spools (9) and hydraulic tank port (3) .When the parking brake switch is moved to the OFF position, power is supplied to solenoids (1). Solenoids (1) energize and move valve spools (9). Oil pressure from the parking brake oil pressure reducing valve at port (7) flows through valve spools (9) and port (2) to the parking brakes. Oil pressure disengages the parking brakes and allows the machine to move.Machines equipped with the optional brake release system contain the brake release sequence valve which is connected to port (6). When the parking brake is disengaged, oil pressure is directed through port (6) to the brake release sequence valve.