Patent ID: 7736139

Claim:
A motor driven by pressure medium supplied from an external pressure source, the motor comprising a motor easing with a working chamber having a cylindrical inner wall and a main axis, a stator part which forms an axial supply pipe for supply of pressure medium to the working chamber through a port opening in the stator part, a rotor part which is rotatably mounted on the stator part, the rotor part's axis of rotation being arranged eccentrically relative to the working chamber's main axis, the rotor part being provided with an inlet port such that the port opening in the stator part interacts with the inlet port in the rotor part for supply of pressure medium to a pressure chamber in the working chamber, a hinge part which is mounted to the rotor part and which provides a sealing-forming abutment against the working chamber's inner wall, the hinge part being provided with a port opening which communicates with the inlet port in the rotor part, the hinge part being further provided with a piston which is formed by a curved plate part, the piston being pivotably mounted on the hinge part in one end, and arranged with a sealing-forming abutment against the working chamber's inner wall at the other end, the piston dividing the working chamber into the pressure chamber and a discharge chamber when the motor is operating, a constantly open discharge opening to discharge, the discharge opening being arranged in the wall of the motor casing from the working chamber's discharge chamber.