STICK AS 9R8501 - Caterpillar

Illustration 1 g00903714
Swing Pump (1) Swing pump (2) Head of swing pump (3) Charge pump (4) Regulator valve for swing pump (5) Actuator piston (6) Pressure cutoff valve (7) Charge relief valve (8) Crossover relief and makeup valve (9) Pressure tap for swing left circuit (10) Pressure tap for circuit for swing right (11) Tap for upstroke pressure
Illustration 2 g00955191
Cross Section of Swing Pump (3) Charge pump (4) Swing pump regulator (5) Actuator piston (6) Cutoff valve (12) Line to swing pilot valve (13) Line to swing motor (14) Line to swing motor (15) Barrel (16) Swashplate (17) Input shaftSwing pump (1) is a variable displacement piston pump with a swashplate. The pump is driven from the output on the main pump drive.The swing system is a closed loop system and pump (1) is designed to upstroke in either direction. In a closed loop system, the swing direction is changed by upstroking the pump in the opposite direction. Swing pump (1) and the swing hydraulic circuit are separate from the main hydraulic pump and the circuit.Charge pump (3) is a gerotor type pump that is incorporated in the manifold with charging relief valve (7), crossover relief valve (8) and cutoff valve (6). The oil from charge pump (3) passes an external oil filter before entering the low pressure side of swing pump (1) .The pump zero position can be adjusted through mechanical adjustment screws. Swing brake torque can be adjusted at swing pump regulator (4) by replacing the brake spools.Components
Swing pump (1) is a swashplate type pump that is used for hydrostatic drives. The pump is driven from the main pump drive output. Pump regulator (4) and charge pump (3) are mounted on the pump housing.The angle of swashplate (16) is changed by actuator piston (5). By directing control oil to either side of actuator piston (5), swashplate (16) is tilted in the corresponding direction.When swing pump regulator (4) is in the NEUTRAL position, swashplate (16) is at a zero degree angle and the pump flow is zero. Actuator piston (5) is used to upstroke the pump in either direction from the zero degree angle. When swashplate (16) is passing the zero degree angle, the flow changes the swing direction smoothly.Charge pump (3) is a gear type pump that is connected to the swing pump housing through a connecting plate. The charge pump is used to keep the swing circuit pressurized with oil. The charge oil is also used to help cool the swing pump.