COUPLING 1W5534 - Caterpillar

Illustration 1 g00905015
The braking and hydraulic fan system contains a fixed displacement hydraulic pump (8). The braking system has priority over the hydraulic fan system.When the engine is started, hydraulic oil is drawn from tank (9) by the braking and hydraulic fan pump (8). The flow of hydraulic oil into the hydraulic fan system is blocked by the flow control valve (25) for the brakes until the accumulators are fully charged. Hydraulic oil does flow from braking and hydraulic fan pump (8) through filter (31) to orifice (7) and through check valve (6). The oil then flows through shuttle valve (4) to the accumulators (16) in order to charge the accumulators. Shuttle valve (4) will direct flow to the accumulator with the lowest pressure. This allows both of the accumulators to charge to equal pressures.Flow control valve (25) for the brakes is controlled by brake charging solenoid valve (15). Brake charging solenoid valve (15) is controlled by the machine ECM. The brake charging solenoid valve controls the pressure drop across orifice (26). The control of the brake charging solenoid valve is based on the pressure that is detected by brake charging pressure sensor (5). When the pressure in the accumulators rises above the cutout pressure, brake charging pressure sensor (5) will detect the rise in pressure. The machine ECM will then send a signal to the brake charging solenoid valve (15) in order to shift the brake charging solenoid valve more open. When the brake charging solenoid valve shifts more open, the pilot oil that acts on flow control valve (25) for the brakes is vented to the tank. The pressure drop across orifice (26) will increase.