IDLER GP-FRONT 2979234 - Caterpillar

Swing Hydraulic System
When the swing joystick is moved in order to perform a SWING operation, the swing joystick sends an electrical signal input to the machine ECM.The machine ECM sends an electrical signal to solenoid valve for the swing parking brake on the left swing motor. When the solenoid valve for the swing parking brake is energized, pilot oil in line flows through the solenoid valve. Pilot oil then flows through a passage to the swing parking brake. The pilot oil also flows through line to swing parking brake at right swing motor. This pilot oil pressure releases the swing parking brake. The swing parking brakes are released before supply oil flows to the swing motors.The swing hydraulic system uses two proportional reducing valves to control one valve spool. The valve spool is located in the center section of the main control valve that supplies high-pressure oil to the swing motor.The oil delivery for the swing hydraulic circuit is supplied by the rear pump only. When the swing joystick is moved from the NEUTRAL position, swing brake solenoid is activated by the machine ECM. Swing parking brake is then released. Motor rotary group starts to rotate. The swing motor is mounted on top of the swing drive. The swing drive is installed on the upper structure. The swing drive reduces the motor speed by two stages. The swing drive rotates the upper structure.The swing motors are a fixed displacement, bidirectional piston type hydraulic motor. The swing motors have 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 motors rotate, the upper structure rotates above the undercarriage structure.Other components of the swing system include:
Swing proportional solenoids
Swing control valve
Swing motors
Anti-reaction valves
Swing parking brakes and swing parking brake solenoid
Swing drivesNote: Refer to the appropriate sections in this manual for more information.