| 摘要 |
A valve actuator is disclosed that can be selectively driven by hydraulic or electrical power, or both, in the alternative. A driving motor engages a drive which, through a clutching mechanism ultimately engages the actuator shaft. The actuator shaft has a spiral groove which is ultimately engaged by cammed spheresmoved into the groove, thus making the drive system which is retained longitudinally, drive the shaft upon rotation of the drive system. Upon release of energy to the driver, be it electrical, hydraulic, or pneumatic, the clutching system disengages so that the balls come out of contact from the spiral groove allowing a return spring to snap the valve shut by longitudinal movement of the actuator shaft.
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