Abstract: A fluid-operated actuator comprising a chamber part (1) with at least one chamber (12, 13), a carrier (3) which is rotatably mounted in the chamber part (1), and a plunger piston (2) in the form of a circular arc. The plunger piston can be moved along the circular arc and thereby rotate about the carrier's axis of rotation (50) since it extends in the chamber and is arranged to connect with the carrier (3). According to the invention the plunger piston (2) via a sealing device (32, 33, 42-45) is passed sealingly through an opening (14, 15) in the chamber (12, 13), there being a clearance between the surface of that section of the plunger piston which is located in the chamber and the chamber walls. Furthermore that section of the plunger piston which is located outside the chamber (12, 13) is supported along its radially outer surface by a support part (4) which is attached to the chamber part (1).

Abstract: A spring operated valve actuator with variable return force includes a compact spring mechanism with a short but very powerful closing characteristic. The energy provided by the spring mechanism is applied during the entire movement of the valve, with varying forces localized according to particular needs. The spring mechanism and a movable piston member are mechanically and drivingly interconnected by a variable reduction mechanism.

Abstract: A self-coupling flange for coupling and at the same time both axially and radially locking two components especially is suited for coupling of an actuator to a valve. The flange includes an upper member to be fixed to or incorporated into one component and a lower part member to be fixed to another component. An annular piston having a locking ring is movable into an inner axial opening in the lower member to move the two members from an offset position to an aligned position with respective sloping contact faces in abutment.