| 摘要 |
PCT No. PCT/SE79/00240 Sec. 371 Date Jul. 24, 1980 Sec. 102(e) Date Jul. 2, 1980 PCT Filed Nov. 21, 1979 PCT Pub. No. WO80/01096 PCT Pub. Date May 29, 1980.A pneumatic operating device, e.g. for controlling valves, includes a cylinder (2) in which a piston (12) is movable. The piston has an axially extending rack part (11) having teeth which engage with teeth on an operating element (10) arranged in the cylinder wall (2b) for rotation transversely of the longitudinal axis of the piston and passing sealingly through said cylinder wall. The piston (12) is provided on the side opposite its rack part with a recess (24) for receiving a part of a spring (26) for the return movement of the piston. The recess (24) extends substantially into the rack part (11) of the piston, preferably through a distance of such length that it extends axially approximately up to or beyond a radial line perpendicular to the piston axis through the center of rotation of the operating element even when the piston is in a position in which the spring is compressed to its maximum. The cylinder of the operating device may have separate end walls (4) which are removably connected to the cylinder by means of screws (7). One of the end walls (4) has arranged therein an opening (15) for connection to an air-supply line. The cylinder wall (2) has an axially extending bore (18) and the end wall (4) a bore (17) which extends at right angles to said bore (21) , said bores together forming an air-supply passage leading to the interior of the cylinder. A substantial part of the peripheral surface of the pistons rack part (11) which abuts and guides against the inner wall of the cylinder (2) is coated with polytetrafluoretylene. |
