| 摘要 |
A fluid-operated actuator for rotatable valve stems and the like includes a double ended piston reciprocally carried in a sealed housing. The housing has a pair of sleeves threaded into a central body. The sleeves support opposite end regions of the piston and provide adjustable stops to limit the piston stroke. A stem is journaled for rotation in the body. The stem and piston are interconnected by a lever slidably received in the stem and pivotally coupled to the piston. The lever rotates the stem in response to reciprocation of the piston. The sliding connection between the lever and the stem provides a thrust connection between the lever and the stem and permits the lever-arm through which torque forces are applied to the stem to increase as the piston nears opposite ends of its stroke. An adapter bushing is removably connected to one end region of the stem. The bushing is interchangeable with other bushings having standard-sized central apertures and is removable for through-machining of its central aperture to facilitate connection of the actuator to any shape of valve stem. Assembling the actuator is facilitated by providing the piston with a slot which will nest the lever, whereby the piston and lever are insertable as an assembly into the housing.
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