COIL AS 2457465 - Caterpillar

Service and Parking Brake System
S/N: SBR591-UP
Illustration 1 g01430991
Hydraulic schematic for the braking system (1) Steering cylinder (2) Steering cylinder (3) Steering cylinder crossover relief valve (4) Steering cylinder crossover relief valve (5) STIC steering pilot valve (6) Brake release cylinder (7) Pressure tap for the brake release system (8) Front wheel brakes (9) Pressure tap for the front service brake circuit (10) Secondary steering diverter valve (11) Secondary steering pump (12) Steering control valve (13) Steering release diverter valve (14) Check valve (15) Brake release sequence valve (16) Parking brake control valve (17) Rear brake accumulator (18) Front brake accumulator (19) Steering system pressure tap (20) Spool (21) Implement and steering solenoid valve (22) Service brake pedal (23) Service brake and transmission neutralizer pedal (24) Residual brake oil pressure switch for the rear brakes (25) Shuttle valve (26) Hydraulic oil cooler (27) Line from implement lift circuit (28) Selector and pressure control valve (29) Parking brake solenoid valve (30) Service brake oil pressure switch (31) Check valve (32) Pressure tap for the parking brake (33) Secondary steering flow switch (34) Primary steering flow switch (35) Check valve (36) Dual pilot check valve (37) Automatic lubrication system connection port (38) Parking brake oil pressure switch (39) Service brake control valve (40) Residual brake oil pressure switch for the front brakes (41) Brake accumulator oil pressure switch - brake application (42) Check valve (43) Steering neutralizer valve for a left turn (44) Steering neutralizer valve for a right turn (45) Check valve (46) Pressure tap for the pilot circuit (47) Pressure tap for the rear service brake circuit (48) Rear wheel brakes (49) Breaker relief valve (50) Pilot oil pressure reducing valve (51) Portable hydraulic pump quick connect coupler (52) Pressure tap for the brake accumulator charging circuit (53) Brake accumulator oil pressure switch - alert indicator (54) Pilot and braking pump (55) Steering pump (56) Hydraulic tank (57) Hydraulic filters (58) Portable hydraulic pump quick connect coupler (59) Brake accumulator charging valveWheel brakes (8) and (48) are divided into two sections. The service brake section is an oil pressure applied and spring released brake. The parking brake section is an oil pressure disengaged and spring engaged brake. The service brake can be used when the parking brake is disengaged.The service brakes are controlled by two brake pedals in the operator station. The left and right brake pedal assemblies are connected by a mechanical linkage. The left pedal is service brake and transmission neutralizer pedal (23). The right pedal is service brake pedal (22) .When service brake pedal (22) is depressed, only the service brakes are applied. When service brake and transmission neutralizer pedal (23) is depressed, the service brakes are applied and the transmission is neutralized. This allows the full engine power to be used in the hydraulic system. When service brake and transmission neutralizer pedal (23) is released, the transmission engages and the service brakes are released.With the engine running, oil flows from hydraulic tank (56) to pilot and