PLATE AS 8I0986 - Caterpillar

Swing Hydraulic System
The swing hydraulic system uses only one control valve spool in the main control valve that supplies high-pressure oil to the swing motor. A solenoid controlled swing priority valve is integrated into the main control valve and is used to ensure that the swing hydraulic system has idler pump oil priority before the stick hydraulic system. This Swing Priority Strategy is used to aid in machine productivity. A swing relief loss strategy is also used to reduce the load on the engine by initially DESTROKING the idler pump at the start of swing movement.The swing motor is a fixed displacement, bidirectional piston type hydraulic motor. The swing motor has a pinion gear attached to the output shaft. The pinion gear engages with the internal gear teeth of the large swing gear (swing bearing). The swing gear is held stationary to the undercarriage structure. When the swing motor rotates, the upper structure rotates above the undercarriage structure.Swing joystick movement causes the swing pilot control valve to send pilot oil to the swing control valve spool. The swing control valve spool shifts and sends high-pressure pump supply oil from the idler pump to the swing motor. The movement of the swing control valve spool controls the oil flow rate and the direction of oil flow to the swing motor.Other components of the swing system include:
Swing priority solenoid
Swing control valve
Swing motor
Anti-reaction valves
Swing parking brake and swing parking brake solenoid
Swing driveNote: Refer to the appropriate sections in this manual for more information.