SEAL-O-RING 2822935 - Caterpillar

Illustration 1 g00819784
Brake System Schematic (1) Service brake valve (2) Supply line from brake accumulator to service brake valve (3) Brake accumulator (4) Pressure switch for low brake pressure indicator (5) Return line from service brake valve to tank (6) Supply line from main pump (7) Load sensing line from accumulator charging valve to metering pump (steering) (8) Return line to tank (9) Supply line from accumulator charging valve to brake accumulator (10) Accumulator charging valve (11) Supply from accumulator charging valve to trailer brake valve (12) Return line from trailer brakes to tank (13) Trailer brake valve (14) Supply line to trailer brakes (15) Pilot line for trailer brake valve (16) Parking brake pedal (17) Parking brake switch (18) Service brake pedal (19) Parking brake cable (20) Brake pedal sensor (potentiometer) (21) Parking brake lever assembly (22) Brake discs (23) Supply line to brake discs (24) Pressure switch for stop lightsThe machine is equipped with a power assisted hydraulic braking system which activates oil immersed multiple brake discs (22). The brake discs are located on each side of the differential in the front axle only.Oil to the braking system is supplied from the main hydraulic system. Oil from the main hydraulic pump flows through line (6) to accumulator charging valve (10). Oil from the accumulator charging valve flows to brake accumulator (3) through line (9). The accumulator stores hydraulic energy for actuating the brakes. Pressure that is stored in accumulator (3) can also be used for a limited number of effective applications of the brakes if the engine or the main pump become inoperable. If the machine is equipped with trailer brakes, oil also flows to trailer brake valve (13) through line (11) in order to apply the brakes on the trailer. The accumulator charging valve maintains the pressure in the accumulator within a preset range while the engine is running. When the pressure in the accumulator reaches 16000 kPa (2321 psi) the braking system is fully charged.The operation of the main hydraulic pump is described in Steering System, RENR5157.When the system is fully charged, oil at 16000 kPa (2321 psi) is present in lines (9) and (2) .Brake pedal (18) is connected to a mechanical linkage in order to operate service brake valve (1). When the brake pedal is pressed, oil pressure is transmitted from line (2) through brake valve (1) to line (23) in order to apply the brake discs in the front axle. When the machine is equipped with a braking system for a trailer, pilot oil is also transmitted through line (15) in order to open the spool in trailer brake valve (13). Pressurized oil in line (11) then flows through valve (13) into line (14) in order to apply the brakes on the trailer.When brake pedal (18) is applied, the movement of the pedal is measured by sensor (20). The measurement is transmitted to the hydrostatic transmission electronic control module. The control module signals the hydrostatic pump to destroke, and the transmission is