| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To simply and surely control a servo actuator 32 irrelevant to the lowering of an internal pressure of a feed passage 44. <P>SOLUTION: High pressure fluid to be guided to a mode changeover valve 50 is taken out in an interval between the mode changeover valve 50 and the servo actuator 32 by a selection valve 60 capable of roughly stopping a counterflow, so that even if the fluid pressure in the feed passage 44 lowers, the high pressure fluid is sealed in first and second pilot passages 63 and 64, at least, for a prescribed time. As a result, the high pressure fluid sealed in the pilot passages 63 and 64 continuously act on a spool 52 of the mode changeover valve 50 so as to continuously retain a prescribed position. <P>COPYRIGHT: (C)2004,JPO</p> |
