| 摘要 |
A valve may include a valve body, a valve spool, and a valve actuator arrangement. The valve body may comprise a bore and a first and a second passage to the bore. The valve spool may comprise a first end and a second end and be at least partially positioned and slidable within the bore. The valve spool may comprise a first and a second sealing region in sealing contact with the bore. A first chamber may be comprised, at least in part, between the bore and the valve spool at the first end. A second chamber may be comprised, at least in part, between the bore and the valve spool and between the first and the second sealing regions. A third chamber may be comprised, at least in part, between the bore and the valve spool at the second end. A third passage connects the first and the third chambers. The first and the second passages are both open to the second chamber when the valve is at an open position. One and/or both of the first and the second passages are closed to the second chamber when the valve is at a closed position. In certain embodiments, no power is supplied to the valve at the open position and/or the closed position, and momentary loads, applied by solenoids of the valve actuator arrangement, move the valve spool between the open and the closed positions.
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