ENGINE GP-CORE 4850355 - Caterpillar

Illustration 1 g02732718
(1) Hydraulic Tank
(2) Machine ECM
(3) Monitor
(4) Parking brake Switch
(5) Brake Control Valve
(6) Brake Line to Front Axle
(7) Brake Accumulators
(8) Parking brake Valve
(9) Parking brake Pressure Sensor
(10) Brake Accumulator Manifold
(11) Brake Line to Rear Axle
(12) Brake Charge Pressure Sensor
(13) Fan/Brake Pump
(14) Engine
Illustration 2 g06092958
(1) Hydraulic Tank
(2) Machine ECM
(3) Monitor
(4) Parking Brake Switch
(5) Brake Control Valve
(6) Brake Line to Front Axle
(7) Brake Accumulators
(8) Parking Brake Valve
(9) Parking brake Pressure Sensor
(10) Brake Accumulator Manifold
(11) Brake Line to Rear Axle
(12) Brake Charge Pressure Sensor
(13) Fan/Brake Pump
(14) Engine
(15) Parking Brake
(16) CAN Data Link
(17) Parking Brake Valve
(18) Brake Charging Valve
(19) Inverse Shuttle Valve
(20) Relief Valve
(21) Check Valve
(22) Orifice
(23) Priority Valve
(24) Screen
(25) Flow Control ValveThe braking and hydraulic fan system contains fixed displacement hydraulic pump (13). The braking system has priority over the hydraulic fan system.When the engine is started, hydraulic oil is drawn from tank (1) by brake and fan drive pump (13). Relief valve (20) is closed. Hydraulic oil flows from pump (13) to priority valve (23). Then, the hydraulic oil flows through priority valve (23) to the right side of the priority valve through valve (25). Oil also flows to the left side of the priority valve. The hydraulic oil and the spring pressure counter the pressure of the pilot oil that flows to the left side of the priority valve. The priority valve is held to the left as the accumulators charge.The priority valve directs hydraulic oil to screen (24). The oil flows through orifice (22) to check valve (21). As the hydraulic oil pressure increases, the check valve opens. The hydraulic oil flows through the brake inverse shuttle valve (19). The shuttle valves direct hydraulic oil to the accumulator with the lowest pressure first. As the hydraulic oil pressure to the first accumulator increases, the shuttle valve moves. Both accumulators charge at equal pressures. Hydraulic oil also flows to relief valve (20) through the flow control valve (25).As the accumulators charge, hydraulic oil pressure increases to relief valve (20). When the hydraulic oil pressure overcomes the spring pressure on the relief valve, the relief valve moves down. The hydraulic oil to the right side of the priority valve drains to the inlet side of the brake and fan drive pump (13). Then, the oil pressure on the left side of the priority valve moves the priority valve to the right. Most of the flow of hydraulic oil is directed to the fan drive system. A small amount of hydraulic oil flows to the right side of the priority valve and to the relief valve. Because the relief valve is open, the oil flows to the inlet side of the pump.The flow of hydraulic oil from brake accumulators (7) is blocked at brake control valve (5). When brake pedal is pressed, the brake control valve routes hydraulic oil to rear service brakes (11) and to front service brakes (6). The service brakes are engaged. Pressure feedback is sensed by each spool in the brake control valve. The operator should be able