FAN DRIVE GROUP 4N3141 - Caterpillar

Grapple Open/Close Operation
Illustration 1 g01902115
Grapple OPEN with reduction of pilot oil (1) Grapple cylinders (2) Line (3) Line (4) Main control valve (right body) (5) Control valve (grapple cylinders) (6) Center bypass passage (7) Parallel feeder passage (8) Load check valve (9) Return passage (10) Pilot oil manifold (11) Line (12) Drive pump (13) Idler pump (14) Pilot pump (15) Pilot line (16) Negative flow control line (17) Proportional reducing valve (negative flow control) (18) Negative flow control line (19) Pilot control valve (grapple and boom) (20) Pilot line (21) Pilot line (22) Pilot line (23) Reducing valve (24) Hydraulic tank (25) Pilot line (43) Implement pressure switch (44) Pressure switch for GRAPPLE OPENThe oil delivery for the open/close operation is supplied by drive pump (12) only.The oil delivery from drive pump (12) flows through line (11) and center bypass passage (6) in main control valve (4) to grapple control valve (5) .When the hydraulic activation control lever is in the UNLOCKED position, the oil delivery from pilot pump (14) flows through pilot oil manifold (10) and pilot line (20) to pilot control valve (19) . When the right joystick for the grapple is shifted to the GRAPPLE OPEN position, pilot oil flows through pilot control valve (19) , pilot line (21) , reducing valve (23) , and pilot line (25) to grapple control valve (5) . The pilot oil pressure shifts the spool in the grapple control valve downward. The pilot oil on the other end of the spool in the grapple control valve flows through pilot line (22) and pilot control valve (19) to hydraulic tank (24) .Note: When implement pressure switch (43) and the pressure switch for GRAPPLE OPEN (44) is activated, reducing valve (23) reduces the pilot oil flow to grapple control valve (5) in order to slow the speed of grapple open. This function is shown in Illustration 1.The return oil from grapple cylinders (1) flows through line (2) , the passage in grapple control valve (5) , and return passage (9) to hydraulic tank (24) .The GRAPPLE CLOSE operation is similar to the GRAPPLE OPEN operation.When the right joystick for the grapple cylinders is shifted to the GRAPPLE CLOSE position, pilot oil flow from pilot control valve (19) flows through pilot line (22) to grapple control valve (5) . The spool in grapple control valve (5) shifts upward. The oil delivery from the drive pump now flows through line (2) to the grapple cylinders.When the right joystick for the grapple cylinders is in the NEUTRAL position, the grapple control valve is maintained in the NEUTRAL position. The oil flow to the grapple cylinders is blocked.Grapple Rotate
Illustration 2 g01262974
(26) Line (27) Grapple rotate motor (28) Pilot line (29) Solenoid valves (30) Solenoid valve (31) Solenoid valve (32) Makeup valves (33) Control valve (34) Valve (35) Valve (36) Control valve (37) Line (38) Auxiliary pump (39) Hydraulic tank (40) Pilot line (41) Pilot pump (42) Drive pumpThe grapple rotate circuit allows the implement to be rotated.