| 摘要 |
<p>A pressure-fluid-operated power unit producing a rotating motion for positioning valves or similar actuators into a desired position. The power unit comprises an annular cylinder space (1) and at least two pairs of pistons arranged to move in said cylinder space (1) respect to each other, first pistons of the piston pairs being arranged to rotate around the shaft of the cylinder space (1) and second pistons being immovably arranged with respect to at least one end flange (12) of the cylinder space (1) or to a casing (2) of the cylinder space, and pressure fluid conduits for leading pressure fluid into and out of the spaces between the pistons.</p> |
