Stick Out
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| Illustration 1 | g00890401 |
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Hydraulic schematic for STICK OUT (1) Stick cylinder (2) Line (oil flow from stick cylinder head end) (3) Line (oil flow to stick cylinder rod end) (4) Valve (5) Stick drift reduction valve (6) Main control valve (7) Line (8) Passage (9) Return passage (10) Return passage (11) Return passage (12) Center bypass passage (13) Stick II control valve (14) Center bypass passage (15) Load check valve (16) Check valve (17) Passage (18) Center bypass passage (19) Check valve (20) Boom II control valve (21) Stick I control valve (22) Parallel feeder passage (23) Return line (24) Pilot line (25) Pilot line (26) Pilot line (27) Pilot control valve (stick and swing) (28) Left pump (29) Right pump (30) Pilot pump |
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| Illustration 2 | g00695552 |
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Main control valve (13) Stick II control valve (21) Stick I control valve |
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| Illustration 3 | g00695556 |
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Main control valve (bottom view) (5) Stick drift reduction valve |
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When the stick hydraulic circuit is operated independently of other hydraulic circuits, stick I control valve (21) and stick II control valve (13) are operational for both the STICK IN operation and the STICK OUT operation. When the stick I control valve and the stick II control valve are operated, the oil delivery from right pump (29) and left pump (28 ) is combined. The oil delivery from both pumps flows to stick cylinder (1) in order to perform a stick operation.
The oil delivery from right pump (29) flows through parallel feeder passage (22) in main control valve (6) to stick II control valve (13). The oil delivery from left pump (28) flows through center bypass passage (18) in main control valve (6) to stick II control valve (21) .
When the joystick for the stick is moved to the STICK OUT position, the pilot oil flows from pilot control valve (27) through pilot line (26). The pilot oil flow then divides into two flow paths. Part of the pilot oil flows through pilot line (24) to stick I control valve (21) in main control valve (6). The remainder of the pilot oil flows through pilot line (25) to stick II control valve (13) in the main control valve.
The pilot oil in pilot line (24) shifts the spool of stick I control valve (21). The oil delivery from left pump (28) that is in center bypass passage (18) flows through load check valve (15), passage (17) and passage (8). The oil delivery from the left pump then enters stick drift reduction valve (5). Valve (4) shifts to the left and the oil delivery flows through line (3) to the rod end of stick cylinder (1) .
The pilot oil in pilot line (25) shifts the spool of stick II control valve (13). The oil delivery from right pump (29) in center bypass passage (12) cannot flow through the stick II control valve to center bypass passage (14) and return passage (11). Part of the oil delivery from the right pump now flows through check valve (16) and the stick II control valve to line (7). The remainder of the oil delivery from the right pump flows through parallel feeder passage (22), check valve (19) and the stick II control valve to line (7). All of the oil delivery from the right pump in line (7) flows to stick drift reduction valve (5) and combines with the oil delivery from the left pump. The combined pump oil flows to the rod end of stick cylinder (1). This combined pump oil causes the cylinder to retract at an increased rate of speed.
Return oil from the head end of the stick cylinder flows through line (2) and return passage (9) to stick I control valve (21). The return oil then flows through return passage (10) and return line (23) to the hydraulic tank.
Stick In
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| Illustration 4 | g00890405 |
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Hydraulic schematic for STICK IN (fast with 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 reduction valve (6) Main control valve (9) Passage (10) Return passage (11) Return passage (12) Center bypass passage (13) Stick II control valve (15) Load check valve (16) Check valve (18) Center bypass passage (19) Check valve (21) Stick I control valve (22) Parallel feeder passage (23) Return line (27) Pilot control valve (stick and swing) (28) Left pump (29) Right pump (30) Pilot pump (31) Stick regeneration valve (32) Stick unloading valve (33) Pilot line (34) Pilot line (35) Pilot line (36) Pilot line (37) Passage (38) Pilot line (39) Pilot line (40) Pressure reducing valve for boom priority (41) Pilot line (42) Line (43) Passage (44) Passage (45) Passage (46) Passage (47) Passage (48) Check valve |
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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.
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| Illustration 5 | g00890410 |
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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 reduction valve (6) Main control valve (9) Passage (10) Return passage (11) Return passage (12) Center bypass passage (13) Stick II control valve (15) Load check valve (16) Check valve (18) Center bypass passage (19) Check valve (21) Stick I control valve (22) Parallel feeder passage (23) Return line (27) Pilot control valve (stick and swing) (28) Left pump (29) Right pump (30) Pilot pump (31) Stick regeneration valve (32) Stick unloading valve (33) Pilot line (34) Pilot line (35) Pilot line (36) Pilot line (37) Passage (38) Pilot line (39) Pilot line (40) Pressure reducing valve for boom priority (41) Pilot line (42) Line (43) Passage (44) Passage (45) Passage (46) Passage (47) Passage (48) Check valve |
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When the stick is slowly moved in, the pilot pressure does not shift stick II control valve (13) and the pilot pressure does not shift stick regeneration valve (31) .
Stick Regeneration Valve
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| Illustration 6 | g00747505 |
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Stick regeneration valve (6) Main control valve (9) Passage (31) Stick regeneration valve (38) Pilot line (43) Passage (48) Check valve |
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The stick hydraulic circuit contains a regeneration circuit. This regeneration circuit allows the return oil from the rod end of the stick cylinder to be supplied to the head end of the stick cylinder during the STICK IN operation.
When the joystick for the stick is moved to the STICK IN position, pilot oil flow from the pilot control valve (stick and swing) flows through pilot line (38). Stick regeneration valve (31) shifts downward. The return oil from the rod end of the stick cylinder flows through passage (43) and through the throttling slots on valve (31) to check valve (48). Check valve (48) opens and the return oil flows through passage (9). The return oil from the rod end of the stick cylinder in passage (9) combines with the oil delivery from the right pump and the left pump. This combined oil flow now flows into the head end of the stick cylinder.
Stick Unloading Valve
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| Illustration 7 | g00747506 |
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Stick unloading valve (6) Main control valve (9) Passage (31) Stick regeneration valve (32) Stick unloading valve (38) Pilot line (43) Passage (44) Passage (46) Passage (47) Passage (49) Passage (50) Spring |
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Stick unloading valve (32) works in conjunction with stick regeneration valve (31) in order to relieve high pressure in the head end of the stick cylinder during a STICK IN operation.
When the joystick for the stick is moved to the STICK IN position, pilot oil flow from the pilot control valve (stick and swing) flows through pilot line (38). Stick regeneration valve (31) shifts downward. The return oil from the rod end of the stick cylinder flows through passage (43) and through the throttling slots on valve (31) to check valve (48). Check valve (48) opens and the return oil flows through passage (9). The return oil from the rod end of the stick cylinder in passage (9) combines with the oil delivery from the right pump and the left pump. This combined oil flow now flows into the head end of the stick cylinder.
Because of the volume of oil that is forced into the head end of the stick cylinder during the regeneration cycle of the STICK IN operation, the pressure of the oil in the head end of the stick cylinder increases. The high pressure oil flows through passage (9) and passage (44). The high pressure oil now acts on the end of stick unloading valve (32). When the force of the high pressure oil becomes greater than the force of spring (50), the stick unloading valve shifts downward. The return oil from the rod end of the stick cylinder in passage (43) flows past the throttling slots on stick regeneration valve (31), through passage (49), through stick unloading valve (32) and passage (47) and into the return circuit to the hydraulic tank. The return oil from the rod end of the stick cylinder is quickly unloaded. At this time, the regeneration circuit for the stick cylinder is inoperable.
When the oil pressure at the head end of the stick cylinder decreases, the oil pressure that acts on the end of stick unloading valve (32) also decreases. The force of spring (50) shifts the stick unloading valve upward. The return oil from the rod end of the stick cylinder is supplied to the head end of the stick cylinder. The regeneration circuit is again operable.