| 摘要 |
A controlled piston ( 20, 62, 102 ) having a first end ( 24, 64, 104 ) mounted in a controlled piston sleeve ( 22 ) and a spool ( 16 ) movably mounted in a spool sleeve ( 18 ), a first fluid passage ( 40, 66, 108 ) from the spool ( 16 ) to the controlled piston first end ( 24, 64, 104 ), the position of the spool ( 16 ) affecting a position of the controlled piston ( 20, 62, 102 ), an FFV ( 42, 68, 110 ) in an FFV sleeve ( 44, 70, 112 ) in the first fluid passage ( 40, 66, 108 ) having a first end section ( 46, 74, 116 ), a second end section ( 48, 78, 120 ) and a central section ( 50, 82, 126 ) having a third diameter less than the diameters of the first and second sections, the FFV ( 42, 68, 110 ) being shiftable between a first position blocking the first fluid passage ( 40, 66, 108 ) and a second position allowing fluid flow past the central section ( 50, 82, 126 ) to the controlled piston ( 20, 62, 102 ), and a second fluid passage ( 56, 88, 134 ) from the spool ( 16 ) to the FFV first end section ( 46, 74, 116 ). Shifting the spool ( 16 ) to a failsafe position shifts the FFV ( 42, 68, 110 ) to the first position to fix the controlled piston ( 20, 62, 102 ) in place.
|
