| |
| Illustration 1 | g02420477 |
|
Hydraulic schematic for GRAPPLE CLOSE (1) Grapple cylinders (2) Line (3) Line (4) Pilot line (5) Main control valve (6) Return passage (7) Parallel feeder passage (8) Load check valve (9) Center bypass passage (10) Grapple control valve OPEN/CLOSE (11) Pilot line (12) Proportional reducing valves (grapple control) (13) Negative flow control line (14) Pilot line (15) Control valve (grapple rotate) (16) Pilot line (17) Line (18) Grapple rotate motor (19) Line (20) Crossover relief valve (rotate counterclockwise) (21) Spool (22) Dump valve (23) Main relief valve (24) Crossover relief valve (rotate clockwise) (25) Spring (26) Passage (27) Passage (28) Return line (29) Passage (30) Supply line (31) Pilot line (32) Spring (33) Proportional reducing valves (negative flow control) (34) Negative flow control line (35) Pilot line (36) Auxiliary pump (37) Drive pump (38) Idler pump (39) Pilot pump (40) Hydraulic tank (41) Line (42) Pilot oil manifold | |
| |
| Illustration 2 | g02420678 |
|
Main control valve (10) Grapple control valve OPEN/CLOSE | |
| |
| Illustration 3 | g02423662 |
|
Located in pump compartment (12) Proportional reducing valves (grapple control) | |
The oil delivery for the open/close operation is supplied by drive pump (37) only.
The oil delivery from drive pump (37) flows through line (41) and center bypass passage (9) in main control valve (5) to grapple control valve (10).
When the hydraulic activation control lever is in the UNLOCKED position, the oil delivery from pilot pump (39) flows through pilot oil manifold (42) and pilot line (35) to proportional reducing valves (grapple control) (12). When the switch for the grapple is activated to the GRAPPLE CLOSE position, pilot oil flows through proportional reducing valves (12) and pilot line (4) to grapple control valve (10). The pilot oil pressure shifts the spool in the grapple control valve to the left. The pilot oil on the other end of the spool in the grapple control valve flows through pilot line (11) and proportional reducing valves (12) to hydraulic tank (40).
Since the spool in the grapple control valve is fully shifted, center bypass passage (9) is blocked. None of the oil delivery from the drive pump flows to the negative flow control orifice and no negative flow control pressure is created in center bypass passage (9). Proportional reducing valve (33) is energized when proportional reducing valve (12) is activated. Pilot oil line (14) supplies pilot oil pressure to proportional reducing valves (33). The machine ECM controls proportional reducing valves (33) in order to control the negative flow control pressure to the idler pump and the drive pump. The output flow rate of the pumps is adjusted. Oil flows through parallel feeder passage (7), load check valve (8), grapple control valve (10) and line (3) to the head end of grapple cylinders (1).
Reference: For more information concerning the negative flow control operation, refer to Systems Operation, "Negative Flow Control System".
The return oil from grapple cylinders (1) flows through line (2), the passage in grapple control valve (10), and return passage (6) to hydraulic tank (40).
The GRAPPLE OPEN operation is similar to the GRAPPLE CLOSE operation.
In the event the switch for the grapple cylinders is moved to the GRAPPLE OPEN position, pilot oil flow from proportional reducing valve (12). Oil flow from proportional reducing valve (12) flows through pilot line (11) to grapple control valve (10). The spool in grapple control valve (10) shifts to the right. The oil delivery from the drive pump now flows through line (2) to the grapple cylinders.
When the switch for the grapple cylinders is in the OFF position, the grapple control valve is maintained in the NEUTRAL position. The oil flow to the grapple cylinders is blocked.
| |
| Illustration 4 | g02420681 |
|
(15) Control valve (grapple rotate)
(40) Hydraulic tank (43) Swing motor | |
The oil delivery for the grapple rotate circuit is supplied by auxiliary pump (36).
The oil delivery from auxiliary pump (36) flows through line (30) to grapple control valve (15). When spool (21) is in the NEUTRAL position, oil flows through dump valve (22) at a lower pressure to hydraulic tank (40). The dumping of the oil pressure that is created by auxiliary pump (36) prevents excessive heat and damage to the grapple rotate circuit. When spool (21) is moved from the NEUTRAL position, system pressure flows through passage (29) which creates pressure on dump valve (22) which will close the spool of the dump valve. Pressure will raise in the grapple rotate circuit until the pressure reaches the setting of relief valve (23). Relief valve (23) maintains the pressure of the grapple rotate circuit when the rotate control valve is operated.
When the switch for the grapple is activated to the GRAPPLE ROTATE COUNTERCLOCKWISE position, a solenoid valve in proportional reducing valves (12) shifts. A solenoid valve in proportional reducing valves (12) shifts, allowing pilot oil to flow through pilot line (31). Spool (21) in grapple control valve (15) shifts against spring (25).
When the spool in the grapple control valve is shifted in the COUNTERCLOCKWISE position, the oil delivery from the auxiliary pump flows through spool (21), passage (26), and line (17) to grapple rotate motor (18). The grapple will rotate counterclockwise.
The return oil from grapple rotate motor (18) flows through line (19), passage (27), spool (21), and return line (28) to hydraulic tank (40).
The GRAPPLE ROTATE CLOCKWISE operation is similar to the GRAPPLE ROTATE COUNTERCLOCKWISE operation.
When the switch for the grapple is activated to the GRAPPLE ROTATE CLOCKWISE position, a solenoid valve in proportional reducing valves (12) shifts allowing pilot oil to flow through pilot line (16). Spool (21) in grapple control valve (15) shifts against spring (32). The oil delivery from the auxiliary pump now flows through spool (21), passage (27), and line (19) to the grapple rotate motor.
When the switch for the grapple rotate is in the OFF position, springs (25) and (32) maintain spool (21) in the NEUTRAL position. The oil flow from the grapple rotate motor is returned to the hydraulic tank.
Crossover Relief Valve(Grapple Rotate)
The crossover relief valves prevent cavitation in the grapple rotate motor. The crossover relief valves also prevent a shock load when the grapple rotate motor stops.
When the spool in the control valve shifts to the NEUTRAL position, oil flow to the grapple rotate motor is blocked. Pressure will increase in line (19) from the inertia that is created by the rotating grapple. This will cause the spool in relief valve (24) to shift against the spring. The passage in the relief valve will open. Return oil will flow through the check valve in relief valve (20) to line (17) as makeup oil to grapple rotate motor (18). Grapple rotate motor (18) will continue to rotate until the pressure in line (19) is unable to overcome the force of the spring in relief valve (24). The grapple rotate motor will stop rotating.