| 摘要 |
PCT No. PCT/JP95/01547 Sec. 371 Date Feb. 4, 1997 Sec. 102(e) Date Feb. 4, 1997 PCT Filed Aug. 3, 1995 PCT Pub. No. WO96/04481 PCT Pub. Date Feb. 15, 1996A directional control valve unit includes a first actuator port connected to a raising side chamber of a working machine cylinder. In addition, a second actuator port is connected to a lowering side chamber of the working machine cylinder. A regeneration passage makes the second actuator port communicate with a regeneration port through a check valve. A main spool is adapted to supply a pressure oil to the second actuator port and to make the first actuator port communicate with a tank port and the regeneration port by moving the main spool in one direction. The directional control valve unit also includes a switching device for switching the maximum moving distance of the main spool in the one direction in a plurality of stages.
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