| 摘要 |
PCT No. PCT/US80/01704 Sec. 371 Date Dec. 19, 1980 Sec. 102(e) Date Dec. 19, 1980 PCT Filed Dec. 19, 1980 PCT Pub. No. WO82/02230 PCT Pub. Date Jul. 8, 1982.A mechanism (80) is provided to controllably lower an actuator (28) upon the loss of a source (62) of pilot fluid in a fluid system requiring a float condition of operation. A resolver (80) is located in a vent line of a make-up valve and is connected to a second load supporting end (32) of the actuator (28) and is controllably vented to a tank (38) by moving a pilot control valve (48) to a fourth position (D). This eliminates the need to provide complicated systems having pilot operated check valves which are more difficult to control.
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