The stick drift reduction valve is placed in the stick circuit between the main control valve and the stick cylinder. When the joystick for the stick is in the NEUTRAL position, the stick drift reduction valve stops oil leakage from the rod end of the stick cylinder. Stopping oil leakage prevents stick drift.
| |
| Illustration 1 | g06616708 |
|
Main control valve (1) Stick drift reduction valve (2) Stick drift reduction valve spool | |
| |
| Illustration 2 | g06356021 |
|
Stick drift reduction valve (1) Stick drift reduction valve (2) Stick drift reduction valve spool (3) Passage to head end of stick cylinder (5) Stick cylinder (9) Passage (11) Spring (13) Passage to rod end of stick cylinder (14) Passage (17) Stick 1 control valve | |
| |
| Illustration 3 | g06357113 |
|
Stick drift reduction valve (STICK OUT) (1) Stick drift reduction valve (2) Stick drift reduction valve spool (3) Passage to head end of stick cylinder (4) Passage (stick cylinder retract solenoid) (5) Stick cylinder (6) Passage from stick 1 control valve (7) Drain passage (8) Passage to stick cylinder extend solenoid for drift reduction spool shift (9) Passage (10) Passage (11) Spring (12) Spring chamber (13) Passage to rod end of stick cylinder (14) Passage (15) Passage from stick 2 control valve (16) Passage (stick cylinder extend solenoid) (17) Stick 1 control valve | |
When the joystick is moved to the STICK OUT position, pilot oil from the pilot manifold is not sent through passage (8) to stick drift reduction valve spool (2). The stick drift reduction valve spool does not shift.
The oil flow from the stick 2 control valve in passage (15) and stick 1 control valve in passage (6) combines in the main control valve at the stick drift reduction valve passage (14). As the oil pressure in passage (14) increases, drift reduction valve (1) shifts against the force of spring (11). The oil in spring chamber (12) flows through passages (10) and (9) to passage (14). The oil in passage (14) now flows to the rod end of the stick cylinder through passage (13).
| |
| Illustration 4 | g06356060 |
|
Stick drift reduction valve (STICK IN) (1) Stick drift reduction valve (2) Stick drift reduction valve spool (3) Passage to head end of stick cylinder (4) Passage from stick cylinder retract solenoid (5) Stick cylinder (6) Passage from stick 1 control valve (7) Drain passage (8) Passage from stick cylinder extend solenoid for drift reduction spool shift (9) Passage (10) Passage (11) Spring (12) Spring chamber (13) Passage to rod end of stick cylinder (14) Passage (15) Passage from stick 2 control valve (16) Passage from stick cylinder extend solenoid for stick control valve (17) Stick 1 control valve | |
When the joystick is moved to the STICK IN position, pilot oil from the pilot manifold is sent through passage (8) to stick drift reduction valve spool (2). The stick drift reduction valve spool shifts. The oil in spring chamber (12) flows through passage (10), drift reduction valve spool (2), and drain line (7) to the hydraulic tank.
The return oil from the stick cylinder rod end enters passage (13). Since the pressure in spring chamber (12) is low, the oil in passage (13) shifts drift reduction valve (1) against the force of spring (11). The oil from the rod end of the stick cylinders then flows through passage (14), and passage (6) to stick 1 control valve (17).