PLATE 8F4243 - Caterpillar

When the joystick for the stick is moved less than half of the travel distance for STICK IN, low pilot oil pressure is supplied to stick I control valve (16) and stick II control valve (27).When the stick is moved at a low speed, stick I control valve (16) opens. The pilot pressure will not shift stick II control valve (27) or stick regeneration valve (31). The force of spring (33) in stick I control valve (16) is less than the force of spring (32) in stick II control valve (27). Because of the low pilot oil pressure, stick I control valve (16) will open and stick II control valve (27) will remain closed.The oil delivery from idler pump (29) now flows to the rod end of stick cylinder (2). Without the oil delivery from drive pump (28), the cylinder rod movement slows down when the stick is moved to the STICK IN function. The low speed operation of the stick is performed.Stick In (Fast)
Illustration 4 g02409736
Hydraulic schematic for STICK IN (fast with regeneration)
(1) Pilot control valve (stick and swing)
(2) Stick cylinder
(3) Line (oil flow to stick cylinder head end)
(4) Line (oil flow from stick cylinder rod end)
(7) Passage
(8) Main control valve
(11) Return line
(12) Valve
(13) Stick drift reduction valve
(16) Stick I control valve
(17) Return passage
(18) Check valve
(20) Load check valve
(21) Center bypass passage
(23) Return passage
(24) Parallel feeder passage
(25) Center bypass passage
(26) Check valve
(27) Stick II control valve
(28) Drive pump
(29) Idler pump
(30) Pilot pump
(31) Stick regeneration valve
(34) Pilot line
(36) Pilot line
(38) Pilot line
(39) Passage
(40) Stick unloading valve
(41) Passage
(42) Passage
(43) Passage
(44) Passage
(45) Check valve
(46) Passage
(47) Pilot line The STICK IN operation contains a regeneration circuit. During a STICK IN function, stick regeneration valve (31) and stick unloading valve (40) are operational in the stick hydraulic circuit. The return oil from the head end of stick cylinder (2) is supplied to the rod 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 idler pump and the drive pump to perform other implement functions during a STICK IN function.When the joystick for the stick is moved to the STICK IN position, pilot oil from pilot control valve (1) flows through pilot line (36). The pilot oil flow then divides into several flow paths. Part of the pilot oil flows through pilot line (38) to stick I control valve (16) and part flows to pilot line (34). The pilot oil in pilot line (34) also flows through passage (46) in stick drift reduction valve (13). Part of the pilot oil in pilot line (34) flows through pilot line (47) to stick regeneration valve (31).Since the pilot oil pressure has caused the spool in stick I control valve (16) to shift to the right, the oil delivery from the idler pump flows through center bypass passage (21), load check valve (20), stick I control valve (16) and passage (7) to line (4).The pilot oil pressure does not