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.
Stick Out
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| Illustration 1 | g02712601 |
Stick drift reduction valve STICK OUT (1) Stick drift reduction valve (2) Drain port (3) Passage (4) Port (5) Valve (6) Passage (7) Spring (8) Spring chamber (9) Spool (10) Drain passage (11) Port (12) Port (13) Passage (14) Port | |
When the joystick is moved to perform a STICK OUT operation, pilot oil is not sent from the pilot control valve to port (12) of stick drift reduction valve (1). Spool (9) does not shift.
The oil flow from the stick I and stick II control valves combines in the main control valve. The combined oil flow enters port (4) of the stick drift reduction valve. The combined oil flow flows into passage (3). As the oil pressure in passage (3) increases, valve (5) shifts against the force of spring (7). The oil in spring chamber (8) flows through passages (13) and (6) to port (14). The oil delivery in passage (3) now flows through port (14) to the rod end of the stick cylinders.
Stick In
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| Illustration 2 | g02714923 |
Stick drift reduction valve (STICK IN) (1) Stick drift reduction valve (2) Drain port (3) Passage (4) Port (5) Valve (6) Passage (7) Spring (8) Spring chamber (9) Spool (10) Drain passage (11) Port (12) Port (13) Passage (14) Port (15) Spring chamber (16) Plug | |
When the joystick is moved to perform a STICK IN operation, pilot oil is sent from the pilot control valve to port (12) of stick drift reduction valve (1). Spool (9) shifts until the spool contacts plug (16). The oil in spring chamber (8) flows through passage (13), the orifice in spool (9), and spring chamber (15). From spring chamber (15) the oil then returns to drain line (10) and to the hydraulic tank.
The return oil from the stick cylinder rod end enters port (14). Since the pressure in spring chamber (8) is low, the oil in port (14) shifts valve (5) against the force of spring (7). The oil from the rod end of the stick cylinders flows through port (14), passage (3) and port (4) to the stick I control valve.