CLIP 1S1025 - Caterpillar

Illustration 1 g01004041
Service brakes disengaged. Parking brake disengagedWhen the pedal in the cab is not operated, the service brakes are disengaged.Oil flows from piston pump (18) through check and pressure reducing valve (6). The oil is blocked by the spools of brake control valve (12). Oil flows into accumulators (5) and (13) .Oil also flows through brake control valve (14) into accumulator (8). Oil flow though the brake control valve depends on the position of the parking brake control. Refer to Systems Operation, Testing and Adjusting, "Parking Brake System" for further information.Accumulators (5) and (13) charge until the required system pressure is achieved. When the required system pressure is achieved, the pump control valve, which is part of piston pump (18), moves and the piston pump destrokes. The piston pump continues to produce enough flow in order to overcome losses within the system. The check valves within check and pressure reducing valve (6) maintain pressure in the accumulators.
Illustration 2 g01004042
Service brakes engaged. Parking brake disengagedWhen the pedal in the cab is pressed, the service brakes are engaged.Oil flows through brake control valve (12) to service brakes (1) and (17) for the front axle and service brakes (10) and (19) for the center axle.Pressure in the lines to the service brakes activates pressure switches (4) and (11). Pressure switch (4) causes the brake lights to illuminate and pressure switch (11) changes the downshift point of the transmission in order to maintain engine speed.Pressure drops in the line from piston pump (18) which causes the pump control valve, which is part of the piston pump, to move and the piston pump upstrokes until the required system pressure is achieved and accumulators (5) and (13) are fully charged.If the engine or the piston pump fail, accumulators (5) and (13) supply the oil flow that is required to engage the service brakes.Component Locations
Illustration 3 g01004045
Typical exampleService brakes (1), (10), (17), and (19) are located on each wheel of the front and center axles.
Illustration 4 g01004046
Pressure switches (4) and (11) are located on the brake control valve on the front of the cab.
Illustration 5 g01004049
Accumulators (5) and (13) are located behind a panel on the right side of the cab.
Illustration 6 g01004051
Check and pressure reducing valve (6) is located beneath the cab. Pressure switch (7) is installed in the check and pressure reducing valve.
Illustration 7 g01004054
Brake control valve (12) is located on the front of the cab.
Illustration 8 g01004056
Piston pump (18) is located on the left side of the engine.