| 摘要 |
1. Hydraulic control valve comprising a principal valve (11) having a sliding valve member and being able to ensure the stopping of a jack (5) which it controls, at a predetermined position in a precise manner, in spite, on the one hand of the presence of a dead travel between the start of the control of the jack in one direction and in the other, and on the other hand of the irregularity of leakages in the closed position, characterized in that it includes, in combination with the principal valve (11), a mechanical or electrical detector (18) of the position of the valve member (10) and an auxiliary distribution system (20) controlled by said detector (18), this auxiliary system sending selectively to the controlled jack (5) a very weak flow of oil or other hydraulic liquid relative to that which it receives in the fully open position of the principal valve (11), so as to bring it to a predetermined position, or neutral position, situated within the aforesaid dead travel.
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