CYLINDER AS 2368670 - Caterpillar

Illustration 1 g01333593
(1) Pilot line (2) Grapple cylinders (3) Control valve (grapple cylinders) (4) Center bypass passage (5) Line (6) Line (7) Pilot control valve (grapple control) (8) Load check valve (9) Line (10) Pilot line (11) Return passage (12) Parallel feeder passage (13) Main control valve (right) (14) Negative flow control line (15) Pilot line (16) Proportional reducing valve (negative flow control) (17) Pilot line (18) Pilot oil manifold (19) Auxiliary pump (20) Idler pump (21) Drive pump (22) Pilot pump (23) Negative flow control line (24) Control valve (grapple rotate) (25) Pilot line (26) Line (27) Grapple rotate motor (28) Line (29) Crossover relief valve (rotate counterclockwise) (30) Crossover relief valve (rotate clockwise) (31) Dump valve (32) Spool (33) Spring (34) Passage (35) Main relief valve (36) Passage (37) Passage (38) Return line (39) Supply line (40) Pilot line (41) Spring (42) Hydraulic tankGrapple Open/Close Operation
The oil delivery for the open/close operation is supplied by drive pump (21) only.The oil delivery from drive pump (21) flows through line (9) and center bypass passage (4) in main control valve (13) to grapple control valve (3) .When the hydraulic activation control lever is in the UNLOCKED position, the oil delivery from pilot pump (22) flows through pilot oil manifold (18) and pilot line (15) to pilot control valve (7) . When the switch for the grapple is activated to the GRAPPLE OPEN position, pilot oil flows through pilot control valve (7) and pilot line (10) to grapple control valve (3) . The pilot oil pressure shifts the spool in the grapple control valve upward. The pilot oil on the other end of the spool in the grapple control valve flows through pilot line (1) and pilot control valve (7) to hydraulic tank (42) .Since the spool in the grapple control valve is fully shifted, center bypass passage (4) 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 (4) . Proportional reducing valve (16) is energized when pilot control valve (7) is activated. Pilot oil line (17) supplies pilot oil pressure to proportional reducing valve (16) . The machine ECM controls proportional reducing valve (16) 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 (12) , load check valve (8) , grapple control valve (3) and line (6) to the rod end of grapple cylinders (2) .ReferenceFor more information concerning the negative flow control operation, refer to Systems Operation, "Negative Flow Control System".The return oil from grapple cylinders (2) flows through line (5) , the passage in grapple control valve (3) , and return passage (11) to hydraulic tank (42) .The GRAPPLE CLOSE operation is similar to the GRAPPLE OPEN operation.When the switch for the grapple cylinders is moved to the GRAPPLE CLOSE position, pilot oil