SAFETY RESET AND CONVERTER HOLD VALVE GROUP 8S3330 - Caterpillar

The STICK IN operation contains a regeneration circuit. When the joystick for the stick is moved to the STICK IN position, stick regeneration valve (31) and stick unloading valve (32) are operational in the stick hydraulic circuit. The return oil from the rod end of stick cylinder (1) is supplied to the head end of the stick cylinder. The regeneration circuit makes more effective use of the return oil from the stick cylinder. This allows the oil delivery from the right pump and the left pump to perform other implement functions during a STICK IN operation.When the joystick for the stick is moved to the STICK IN position, pilot oil from pilot control valve (27) flows through pilot line (33). The pilot oil flow then divides into several flow paths. Part of the pilot oil flows through pilot line (34), pilot line (35) and pilot line (36) to stick I control valve (21). The pilot oil in pilot line (36) also flows through passage (37) in stick drift reduction valve (5). Part of the pilot oil flows through pilot line (38) to stick regeneration valve (31). The remainder of the pilot oil flows through pilot line (39), the pressure reducing valve for boom priority (40) and pilot line (41) to stick II control valve (13) .Since the pilot oil pressure has caused the spool in stick I control valve (21) to shift downward, the oil delivery from the left pump flows through center bypass passage (18), load check valve (15), stick I control valve (21) and passage (9) to line (2) .The pilot oil pressure in pilot line (41) has caused the spool in stick II control valve (13) to shift downward. Part of the oil delivery from the right pump that is in center bypass passage (12) flows through check valve (16) and stick II control valve (13) to line (42). The remainder of the oil delivery from the right pump flows through parallel feeder passage (22), check valve (19) and stick II control valve (13) to line (42). All of the oil delivery from the right pump in line (42) flows to line (2) and combines with the oil delivery from the left pump. The combined pump oil flows to the head end of stick cylinder (1) .The return oil from the rod end of the stick cylinder flows through line (3) to stick drift reduction valve (5). Valve (4) in the stick drift reduction valve shifts to the left and the return oil enters passage (43). Part of the return oil in passage (43) flows through stick I control valve (21), return passage (10) and return line (23) to the hydraulic tank. The remainder of the return oil flows through the regeneration circuit to the head end of the stick cylinders.
Illustration 5 g01158577
Hydraulic schematic for STICK IN (slow without regeneration) (1) Stick cylinder (2) Line (oil flow to stick cylinder head end) (3) Line (oil flow from stick cylinder rod end) (4) Valve (5) Stick drift