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| Illustration 1 | g02161998 |
Left swing motor (rear view) (1) Block (3) Anti-reaction valve (4) Anti-reaction valve | |
At the stop of a swing operation, it is difficult to stop the upper structure and implements smoothly at the desired position. This is due to the mass (weight and size) of the upper structure. The outlet port of the swing motor is blocked. This causes an oscillation or a rocking motion in the swing motor. Anti-reaction valves (3) and (4) provide a more exact swing movement. The anti-reaction valves also prevent shock load at the stop of the swing operation. Anti-reaction valves (3) and (4) are located in block (1). Block (1) is mounted on the rear of the left swing motor.
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| Illustration 2 | g00646776 |
Anti-reaction valve (swing operation) (1) Block (2) Swing pump (3) Anti-reaction valve (4) Anti-reaction valve (5) Motor rotary group (6) Internal passage (7) Port (return oil) (8) Passage (return oil) (9) Internal passage (10) Passage (supply oil) (11) Port (supply oil) (12) Internal passage (13) Spring (14) Valve seat (15) Passage (16) Plunger (17) Passage (18) Spring (19) Piston chamber (20) Passage (21) Spring chamber (22) Spring (23) Valve seat (24) Plunger (25) Spring (26) Piston (27) Passage (28) Spring chamber (29) Piston (30) Swing control valve | |
When the swing joystick is in the NEUTRAL position, no oil from the swing pump is supplied to motor rotary group (6). Plungers (24) and (16) in the anti-reaction valves are shifted downward by the force of springs (25) and (18). Valve seats (23) and (14) are shifted downward against the plungers by springs (22) and (13) .
When the swing joystick is activated, the oil delivery from swing pump (2) flows through swing control valve (30), port (11), passage (10) and passage (12) to motor rotary group (5). From the motor rotary group, the oil flows through passage (6), passage (8) and port (7). The motor rotary group rotates.
Pressure oil from the swing pump at port (11) also flows to anti-reaction valves (3) and (4). At anti-reaction valve (3), swing pump pressure and the force of spring (22) shifts valve seat (23) downward against plunger (24). Plunger (24) shifts downward against piston (26). Swing pump pressure at anti-reaction valve (4) flows through passage (9) into spring chamber (28). Plunger (16) shifts upward against the force of spring (18). Valve seat (14) is moved upward against the force of spring (13) by plunger (16).
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| Illustration 3 | g00646780 |
Anti-reaction valve (swing stop) (1) Block (2) Swing pump (3) Anti-reaction valve (4) Anti-reaction valve (5) Motor rotary group (6) Internal passage (7) Port (return oil) (8) Passage (return oil) (9) Internal passage (10) Passage (supply oil) (11) Port (supply oil) (12) Internal passage (13) Spring (14) Valve seat (15) Passage (16) Plunger (17) Passage (18) Spring (19) Piston chamber (20) Passage (21) Spring chamber (22) Spring (23) Valve seat (24) Plunger (25) Spring (26) Piston (27) Passage (30) Swing control valve (31) Orifice (32) Valve chamber (33) Passage (34) Ball (35) Orifice (36) Ball (37) Valve chamber | |
When the swing joystick is returned to the NEUTRAL position, no oil flows from passage (10) to motor rotary group (5). The motor rotary group continues to rotate because of the mass (weight and size) of the machine. The oil pressure in passage (8) increases and the oil pressure in passage (10) decreases. The high-pressure oil in passage (8) enters anti-reaction valve (4). The oil flows through passages (15) and (17) to piston chamber (19). The pressure oil in piston chamber (19) forces plunger (16) upward against the force of spring (18). Valve seat (14) is shifted upward against the force of spring (13) .
A portion of the high-pressure oil in passage (8) flows through passage (27) and the oil enters anti-reaction valve (3). The oil then flows through passage (20) to spring chamber (21). Plunger (24) and valve seat (23) shift upward against the force of springs (25) and (22) .
When the swing motor attempts to stop and the inertia of the upper structure decreases, the oil pressure in passage (8) gradually decreases. Oil pressure in piston chamber (19) decreases. The force of spring (18) causes plunger (16) to shift downward at a rapid rate. Valve seat (14) shifts downward by the force of spring (13). Since orifice (31) restricts the flow of oil from valve chamber (32), valve seat (14) shifts slowly. The contact between plunger (16) and valve seat (14) is no longer maintained. The oil pressure in passage (15) forces ball (34) against the top end of plunger (16). Oil in passage (8) now flows through passages (33) and (9) to passage (10) .
During the separation of plunger (16) and valve seat (14) in anti-reaction valve (4), anti-reaction valve (3) activates also. In anti-reaction valve (3), the pressure of the oil that flows from spring chamber (21) to passage (8) decreases. The force of spring (25) causes plunger (24) to shift downward. The force of spring (22) causes valve seat (23) to shift downward. Since orifice (35) restricts the flow of oil from valve chamber (37), valve seat (23) shifts slowly. The contact between plunger (24) and valve seat (23) is no longer maintained. The oil pressure in passage (20) forces ball (36) against the top end of plunger (24). Oil cannot flow from passage (8) through passage (27) to passage (10) .
Since passages (8) and (10) are connected by anti-reaction valve (4), a more exact swing movement is possible. The shock load at the stop of the swing operation is minimized. A slight shock load may occur due to the gear backlash of the swing drive.
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| Illustration 4 | g00786243 |
Anti-reaction valve (reverse rotation) (2) Swing pump (3) Anti-reaction valve (4) Anti-reaction valve (5) Motor rotary group (8) Passage (return oil) (9) Internal passage (10) Passage (supply oil) (14) Valve seat (16) Plunger (20) Passage (23) Valve seat (24) Plunger (27) Passage (30) Swing control valve (33) Passage (34) Ball (36) Ball | |
When motor rotary group (5) rotates in the reverse direction, oil pressure in passage (10) increases and oil pressure in passage (8) decreases. Anti-reaction valves (3) and (4) function in order to stop the swing movement of the upper structure with a slight reversed motion.
In anti-reaction valve (3), plunger (24) and valve seat (23) separate from each other. Ball (36) is forced against plunger (24) by the pressure oil in passage (10). Oil can now flow from passage (10) through passages (20) and (27) to passage (8) .
In anti-reaction valve (4), plunger (16) and valve seat (14) separate from each other. Ball (34) is forced against plunger (16) by the pressure oil in passage (33). Oil cannot flow from passage (10) through passage (9) to passage (8) .
The oil pressure in passage (10) decreases and the rotation of motor rotary group (5) is prevented. The swing movement is gradually stopped.