| 摘要 |
The invention is concerned with an improvement in a valve system comprising a fluid operated main control valve and adjustable servo valve means for controlling the main valve, the main valve including a main valve spool reciprocal therewithin and a first and a second main valve chamber, one adjacent each end of the main valve spool. The improvement of the invention comprises an adjusting means operating via fluid displacement. Briefly, the improvement comprises means for moving the main valve spool responsive to a first fluid being flowed in to a first main valve chamber at a first end of the spool and at the same time being flowed out of a second main valve chamber at a second end of the spool. Also part of the improvement are servo valve means operating on pressure from a pressurized pilot fluid source for controlling the first fluid flow to and from the first and second main valve chambers. Further a part of the improvement of the invention is means for adjusting the servo valve means to control the movement of the main valve spool to a selected position.
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