When the left pilot valve (joystick) is moved to the left, the cab will swing to the left. When the left pilot valve (joystick) is moved to the right, the cab will swing to the right. When the pilot valve (joystick) is released from either position, the pilot valve (joystick) will return to the HOLD position.
Reference: Refer to the Operation and Maintenance Manual, "Joystick Controls" for more information on the operation of the pilot valve (joysticks).
 | |
| Illustration 1 | g01182909 |
Partial hydraulic schematic (1) Swing motor (2) Main control valve (3) Swing control valve (4) Pilot control valve (Swing and Stick) (5) Oil line forSWING LEFT operation (6) Oil line for SWING RIGHT operation (7) Pilot manifold (8) Swing pump (9) Suction line | |
The swing motor is driven by pressure oil from the swing pump. When the swing joystick is operated, the swing parking brake is released, and the swing motor begins to operate. The swing drive reduces the motor speed in two stages before rotating the upper structure.
Swing Left
When the left pilot valve (joystick) is moved to the left, pilot oil (5) from the pilot valve (joystick) shifts the spool in the swing control valve (3). Oil is routed from the swing pump (8) to main control valve (2) by the pilot manifold (7). The pump receives oil from the tank through hydraulic line (9). From the manifold, the oil flows to the swing motor (1) through the swing control valve. The swing motor rotates the cab to the left through a planetary gear train.
Swing Right
When the left pilot valve (joystick) is moved to the right, pilot oil (6) from the pilot valve (joystick) shifts the spool in the swing control valve (3) in the opposite direction from the SWING LEFT position. Oil is routed from the swing pump (8) to main control valve (2) by the pilot manifold (7). The pump receives oil from the tank through the hydraulic line (9). From the manifold, the oil flows to the swing motor (1) through the swing control valve. The swing motor rotates the cab to the right through a planetary gear train.
Refer to the Systems Operation, "Swing Motor" for more information on the swing motor. Refer to the Systems Operation, "Main Control Valve" for more information on the main control valve and the swing control valve.
Swing Parking Brake
Engaged
 | |
| Illustration 2 | g00880204 |
Parking brake ENGAGED (1) Pinion gear (2) Bearing housing (3) Plate (4) Friction plate (5) Piston (6) Coil spring | |
Friction plates (4) are splined to pinion gear (1). The teeth on the outer circumference of plates (3) engage with the teeth in the inner circumference of housing (2) so that both plates do not rotate.
Friction plate (4), plates (3), and piston (3) are pushed toward the end face of housing (2) by the force of coil spring (6) .
Pinion gear (2) is held by the frictional force between friction plates (4) and plates (3) .
Released
 | |
| Illustration 3 | g00880212 |
Parking brake RELEASED (1) Pinion gear (2) Bearing housing (3) Plate (4) Friction plate (5) Piston (6) Coil spring | |
When the operator swings the cab, the pressure of the pilot oil, that enters the control valve for the swing parking brake, increases. The pilot oil pressure that is increased moves piston (5) to the right against the force of spring (6) .
As a result, the force that is generated by coil spring (6) on the piston no longer holds plate (3) and friction plate (4) together. Therefore, the swing parking brake is released in order to allow the upper structure to swing.