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| Illustration 1 | g06072116 |
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Hydraulic schematic for STICK OUT (1) Pilot control valve (stick and swing) (2) Stick cylinder (3) Line (stick cylinder rod end) (4) Line (stick cylinder head end) (5) Pilot line (6) Center bypass passage (7) Return passage (8) Main control valve (9) Passage (10) Passage (11) Return line (12) Valve (13) Stick drift reduction valve (14) Pilot line (15) Pilot line (16) Stick I control valve (17) Return passage (18) Check valve (19) Passage (20) Load check valve (21) Center bypass passage (22) Boom II control valve (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 | |
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| Illustration 2 | g03878913 |
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Main control valve (13) Stick drift reduction valve (16) Stick I control valve (27) Stick II control valve | |
When the stick hydraulic circuit is operated independently of other hydraulic circuits, stick I control valve (16) and stick II control valve (27) are operational for both the STICK IN operation and the STICK OUT operation. When stick I control valve (16) and stick II control valve (27) are operated, the oil delivery from idler pump (29) and drive pump (28) is combined. The oil delivery from both pumps flows to stick cylinder (2) to perform a stick operation.
The oil delivery from drive pump (28) flows through parallel feeder passage (24) in main control valve (8) to stick II control valve (27). The oil delivery from idler pump (29) flows through center bypass passage (21) in main control valve (8) to stick I control valve (16).
During a STICK OUT function, the pilot oil flows from pilot control valve (1) through pilot line (5). The pilot oil flow then divides into two flow paths. Part of the pilot oil flows through pilot line (15) to stick I control valve (16) in main control valve (8). The remainder of the pilot oil flows through pilot line (14) to stick II control valve (27) in main control valve (8).
The pilot oil in pilot line (15) shifts the spool of stick I control valve (16). The oil delivery from idler pump (29) that is in center bypass passage (21) flows through load check valve (20), passage (19), stick I control valve (16) and passage (10).
The pilot oil in pilot line (14) shifts the spool of stick II control valve (27). The oil delivery from drive pump (28) that is in center bypass passage (25) flows through load check valve (18) and stick II control valve (27) to passage (9). Oil delivery from drive pump (28) also flows through parallel feeder passage (24), check valve (26) and stick II control valve (27) to passage (9).
The oil delivery from drive pump (28) in passage (9) combines with the oil delivery from idler pump (29) in passage (10). The oil delivery from drive pump (28) and idler pump (29) enters stick drift reduction valve (13). Valve (12) shifts upward and the combined oil delivery flows through line (4) to the head end of stick cylinder (2). This combined pump oil causes the cylinder to retract at an increased rate of speed.
Return oil from the rod end of stick cylinder (2) flows through line (3) and return passage (7) to stick I control valve (16) and stick II control valve (27). The return oil then flows through return passage (17), return passage (23) and return line (11) to the hydraulic tank. The stick moves to the OUT position.
Stick In (Dig Operation with One - Pump Flow)
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| Illustration 3 | g06072119 |
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Hydraulic schematic for STICK IN (dig operation with one-pump flow) (2) Stick cylinder (3) Line (stick cylinder rod end) (4) Line (stick cylinder head end) (16) Stick I control valve (27) Stick II control valve (28) Drive pump (29) Idler pump (30) Pilot pump (31) Stick regeneration valve (32) Spring (33) Spring | |
When the joystick for the stick is moved less than half of the travel distance for STICK IN, the pilot oil pressure that is supplied to stick I control valve (16) and stick II control valve (27) is reduced.
When the stick is moved with one-pump flow, pilot oil causes stick I control valve (16) and stick drift reduction valve (13) to shift. The pilot pressure will not shift 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).
Only one-pump flow is used for operating the STICK IN function. Idler pump (29) is used for one pump flow during a STICK IN function.
The oil delivery from idler pump (29) flows through line (3) to the rod end of stick cylinder (2). Return oil from the head end of stick cylinder (2) flows through line (4), stick drift reduction valve (13) and stick I control valve (16) to the return hydraulic system. The stick moves to the IN position.
Without the oil delivery from drive pump (28), the cylinder rod movement is slow during a STICK IN function. The low speed operation of the stick is performed.
Stick In (Dig Operation with Two - Pump Flow)
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| Illustration 4 | g06072128 |
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Partial schematic for STICK IN (dig operation with two-pump flow) (2) Stick cylinder (3) Line (stick cylinder rod end) (4) Line (stick cylinder head end) (16) Stick I control valve (27) Stick II control valve (28) Drive pump (29) Idler pump (31) Stick regeneration valve (40) Stick unloading valve (44) Passage | |
When the joystick for the stick is moved more than half of the travel distance for STICK IN, the pilot oil pressure that is supplied to stick I control valve (16) and stick II control valve (27) is increased. Drive pump (28) and idler pump (29) are used for two-pump flow during a STICK IN function.
When the stick is moved with two-pump flow, pilot oil causes stick I control valve (16), stick regeneration valve (31) and stick drift reduction valve (13) to shift.
The oil delivery from drive pump (28) and idler pump (29) flows through line (3) to the rod end of stick cylinder (2). A portion of the oil delivery from drive pump (28) and idler pump (29) also flows through stick regeneration valve (31) to passage (44). Oil delivery pressure in passage (44) causes stick unloading valve (40) to shift.
Return oil from the head end of stick cylinder (2) flows through line (4), stick drift reduction valve (13) and stick I control valve (16) to the return hydraulic system. The orifice in stick I control valve (16) causes the return oil pressure in line (4) to increase. A portion of the return oil flow from line (4) flows through stick regeneration valve (31) to stick unloading valve (40) and to the return hydraulic system. The stick moves to the IN position.
Stick In (Fast with Regeneration - Work Tool Suspended)
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| Illustration 5 | g06072157 |
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Hydraulic schematic for STICK IN (fast with regeneration) (1) Pilot control valve (stick and swing) (2) Stick cylinder (3) Line (stick cylinder rod end) (4) Line (stick cylinder head 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. When the work tool is suspended above the ground during a STICK IN function, stick regeneration valve (31) is operational in the stick hydraulic circuit. The return oil from the head end of stick cylinder (2) is supplied to the rod end of stick cylinder (2). The regeneration circuit makes more effective use of the return oil from stick cylinder (2). This action allows the oil delivery from idler pump (29) and drive pump (28) to perform other implement functions during a STICK IN function.
When the joystick for the stick is moved to the STICK IN function, 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 (34) and pilot line (38) to stick I control valve (16). The pilot oil in pilot line (34) also flows through passage (46) in stick drift reduction valve (13). Part of the pilot oil 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 idler pump (29) flows through center bypass passage (21), load check valve (20), stick I control valve (16) and passage (7) to line (3).
Part of the oil delivery from drive pump (28) that is in center bypass passage (25) flows through check valve (18) and stick II control valve (27) to passage (7). The remainder of the oil delivery from drive pump (28) flows through parallel feeder passage (24), check valve (26) and stick II control valve (27) to passage (7). All of the oil delivery from drive pump (28) combines in passage (7) with the oil delivery from idler pump (29) and flows to line (3). The combined pump oil flows to the rod end of stick cylinder (2).
The return oil from the head end of stick cylinder (2) flows through line (4) to stick drift reduction valve (13). Valve (12) in stick drift reduction valve (13) shifts UP and the return oil enters passage (42). Part of the return oil in passage (42) flows through stick I control valve (16), return passage (17) and return line (11) to the hydraulic tank. The remainder of the return oil flows through the regeneration circuit to the head end of stick cylinder (2).
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| Illustration 6 | g02234136 |
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STICK IN (fast with regeneration) (7) Passage (8) Main control valve (31) Stick regeneration valve (40) Stick unloading valve (42) Passage (45) Check valve (49) Port (51) Spring | |
The stick hydraulic circuit contains a regeneration circuit. The regeneration circuit allows the return oil from the rod end of stick cylinder (2) to be supplied to the head end of stick cylinder (2) during a fast STICK IN operation.
Note: The regeneration circuit is only enabled when the following two conditions are met. The stick is moved from the OUT position to being perpendicular to the ground and the work tool is suspended above the ground.
During a fast STICK IN function, pilot oil flow from pilot control valve (1) flows through pilot line (47) and into port (49) . Stick regeneration valve (31) shifts to the right. The return oil from the rod end of stick cylinder (2) flows through passage (42) and through the throttling slots on valve (31) to check valve (45). Check valve (45) opens and the return oil flows through passage (7). The return oil from the rod end of stick cylinder (2) in passage (7) combines with the oil delivery from idler pump (29) and drive pump (28). This combined oil flow now flows into the head end of stick cylinder (2).
Note: Oil pressure acting on the left end of stick regeneration valve (31) is not high enough to overcome the force of spring (51), therefore stick unloading valve (40) does not shift.
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| Illustration 7 | g02234137 |
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STICK IN (slow without regeneration) (7) Passage (8) Main control valve (31) Stick regeneration valve (39) Return passage (40) Stick unloading valve (41) Passage (42) Passage (44) Passage (45) Check valve (49) Port (50) Passage (51) Spring | |
During a slow STICK IN function, a limited amount of pilot oil flow from pilot control valve (1) flows through pilot line (47) and into port (49). Stick regeneration valve (31) shifts slightly to the right. A small amount of return oil from the rod end of stick cylinder (2) flows through passage (42) and through the throttling slots on valve (31) to check valve (45). Spring pressure closes check valve (45). The return oil from the rod end of stick cylinder (2) in passage (42) flows through passage (50) and returns to tank through passage (39).
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| Illustration 8 | g02280334 |
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STICK IN (with resistance) without regeneration (7) Passage (8) Main control valve (31) Stick regeneration valve (39) Return passage (40) Stick unloading valve (41) Passage (42) Passage (44) Passage (45) Check valve (49) Port (50) Passage (51) Spring | |
Stick unloading valve (40) works with stick regeneration valve (31) to relieve return oil in the rod end of stick cylinder (2).
During a STICK IN function, pilot oil flow from pilot control valve (1) flows through pilot line (47) to port (49). Stick regeneration valve (31) shifts to the right. The return oil from the rod end of stick cylinder (2) flows through passage (42) and through the throttling slots on valve (31) to check valve (45). Check valve (45) closes and the return oil flows through passage (39) to the hydraulic tank.
The high-pressure oil flows through passage (7) and passage (41). The high-pressure oil now acts on the end of stick unloading valve (40). When the force of the high-pressure oil becomes greater than the force of spring (51), stick unloading valve (40) shifts to the right. The return oil from the rod end of stick cylinder (2) in passage (42) flows past the throttling slots on stick regeneration valve (31), through passage (50), to stick unloading valve (40) and to return passage (39). From passage (39) the return oil flows into the return circuit and to the hydraulic tank. The return oil from the rod end of stick cylinder (2) is quickly unloaded. Now, the regeneration circuit for the stick cylinder is inoperable.