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| Illustration 1 | g02160286 |
Hydraulic schematic for SWING RIGHT (1) Passage (swing pump supply oil) (2) Motor rotary group (left) (3) Swing parking brake (4) Left swing motor (5) Passage (parking brake release pressure) (6) Solenoid valve (swing parking brake) (7) Line (parking brake release pressure) (8) Passage (swing pump supply oil) (9) Right swing motor (10) Swing parking brake (11) Motor rotary group (right) (12) Passage (return oil) (13) Case drain line (14) Passage (return oil) (15) Relief valve (crossover) (anti-reaction valve) (16) Line (return oil) (17) Line (swing pump supply oil) (18) Line (parking brake release pressure) (19) Line (return oil) (20) Passage (return oil) (21) Passage (swing pump supply oil) (22) Swing control valve (23) Main control valve (24) Back pressure valve (25) Proportional valve for swing left (26) Back pressure valve (27) Passage (swing pump supply oil) (28) Bypass valve (29) Line (swing pump supply oil) (30) Pilot pump (31) Swing pump (32) Line (pilot oil supply) (33) Hydraulic tank (34) Pilot manifold (35) Line (return oil) (36) Line (return pilot oil) (37) Line (pilot oil supply to proportional valve) (38) Proportional valve for swing right | |
Introduction
Swing pump (31) supplies oil to right swing motor (9) and left swing motor (4). The two swing motors are identical in operation. The swing motors have the following differences in construction:
- Only the left swing motor is equipped with anti-reaction valve (15) .
- Only the left swing motor is equipped with solenoid valve for the swing parking brake (6) .
- Only the right swing motor is equipped with swing control valve (22) .
Swing control valve (22) is mounted on the top of the right swing motor. The swing control valve operates both swing motors. During a swing operation, swing parking brakes (10) and (3) release in order for the swing motors to operate. Each swing motor is mounted to a swing drive. The swing drives are identical in construction and operation. The swing drives reduce the motor speed to the second stage in order to rotate the upper structure.
SWING RIGHT Operation
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| Illustration 2 | g02160309 |
Swing motor compartment (4) Left swing motor (6) Solenoid valve (swing parking brake) (9) Right swing motor (13) Drain line (22) Swing control valve | |
The oil delivery from pilot pump (30) flows through line (32), pilot manifold (34), and line (37) to the proportional valve for swing right (38) and the proportional valve for swing left (25) at swing control valve (22). When the swing joystick is in the NEUTRAL position, full pilot pressure at each end of the spool in swing control valve (22) maintains the spool in the center position. The oil delivery from the pilot pump also flows through line (18) to solenoid valve (6) for the swing parking brake.
When the swing joystick is moved in order to perform a SWING RIGHT operation, the swing joystick sends an electrical signal input to the machine ECM.
The machine ECM sends an electrical signal to solenoid valve (6) for the swing parking brake at left swing motor (4). When the solenoid valve for the swing parking brake is energized, pilot oil in line (18) flows through solenoid valve (6) and passage (5) to the swing parking brake (3). The pilot oil also flows through line (7) to swing parking brake (10) at right swing motor (9). This pilot oil pressure releases the swing parking brake. The swing parking brakes are released before swing pump supply oil flows to the swing motors.
The machine ECM also sends an electrical signal to the proportional valve for swing right (38). When the proportional valve is energized, a return passage to the hydraulic tank in the valve begins to open. Pilot system oil pressure that acts on the right end of the spool in swing control valve (22) begins to decrease.
Pilot system oil pressure that acts on the left end of the spool in swing control valve (22) moves the spool toward proportional valve (38). When the spool in the swing control valve shifts, swing pump supply oil from swing pump (31) flows through line (29) and passage (27) to swing control valve (22) .
Swing pump supply oil then flows through passage (21) and passage (8) to motor rotary group (11) in right swing motor (9). The swing pump supply oil in passage (21) also flows through passages (17) and (1) to motor rotary group (2) of left swing motor (4). The motor rotary groups rotate and the upper structure rotates in a clockwise direction. Return oil from the motor rotary group for the right swing motor passes through passage (12). Return oil from the motor rotary group for the left swing motor passes through passage (14) and line (16). The return oil from the left swing motor combines with the return oil from the right swing motor. The return oil then flows through passage (20) and swing control valve (22). The return oil then flows through back pressure valve (26) and return line (35) to hydraulic tank (33) .
When the swing joystick is moved to the NEUTRAL position, the machine ECM de-energizes the proportional valve for swing right (38). When the proportional valve is de-energized, spring force shifts the proportional valve. Pilot system oil pressure that acts on the right end of the spool in swing control valve (22) increases. The spool in the swing control valve moves to the left. Since full pilot pressure is now acting on both ends of the spool in the swing control valve, the spool returns to the center position.
Passages (20) and (21) at swing control valve (22) close. Since no swing pump supply oil flows to the swing motors, the SWING RIGHT operation begins to stop.
The machine ECM de-energizes solenoid valve (6) in approximately 6.5 seconds after the machine ECM de-energizes proportional valve (38). When the solenoid valve for the swing parking brake is de-energized, pilot oil in line (18) does not flow through the solenoid valve to swing parking brakes (10) and (3). The oil in passages (7) and (5) flows to drain line (13). Both swing parking brakes begin to engage by spring force. This time delay ensures that the swing parking brake does not engage completely until the rotation of the swing motor stops.
When the travel controls are operated, the machine ECM does not energize the solenoid valve for the swing parking brake. Swing parking brake (10) and swing parking brake (3) do not release.
SWING LEFT Operation
The machine operates in the same manner for the SWING LEFT operation as the SWING RIGHT operation. Swing pump supply oil to the rotary groups of the swing motors causes the upper structure to rotate in a counterclockwise direction.