| 摘要 |
PCT No. PCT/JP93/01577 Sec. 371 Date Apr. 13, 1995 Sec. 102(e) Date Apr. 13, 1995 PCT Filed Oct. 29, 1993 PCT Pub. No. WO94/10447 PCT Pub. Date May 11, 1994There is provided a displacement control system for a variable displacement hydraulic pump which has a displacement control piston assembly (6) having a large diameter chamber (7) for operating a displacement control member (5) of the variable displacement hydraulic pump selectively in a direction of smaller displacement and in a direction of larger displacement, first control valve (8) and second control valve (9) for selectively communicating the large diameter chamber of the displacement control piston assembly with a pump discharge line and a tank, the first control valve being placed at a supply position by the pump discharge pressure, and at a drain position by a spring associated with the displacement control piston assembly via a feedback lever, and the second control valve being placed at a first position by the pump discharge pressure for communicating the pump port and the large diameter chamber and at a second position by a load pressure for communicating the pump port and the large diameter chamber and at a second position by a load pressure for communicating the large diameter chamber to the first control valve, the flow path area is varied at the intermediate position of a fluid passage from the large diameter chamber to the pump discharge passage or to a tank. With the construction set forth above, supply speed and drain speed of the pump discharge pressure to and from the large diameter chamber of the displacement control piston assembly is varied by variation of cross-sectional flow area at the intermediate position of the fluid passage. By this, response characteristics in displacement control of the variable displacement hydraulic valve can be adjusted to improve operability of a work implement.
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