Patent ID: 7686607

Claim:
An actuator, comprising: a hydraulic force translator with a first piston unit and a second piston unit that move relative to each other, wherein: the first piston unit has an effective area that is larger than the second piston unit, the first piston unit and the second piston unit enclose a pressure chamber together with a spacer, and the spacer can be fixed relative to a stationary chassis by a hydraulically operated clamping device that applies an axial force; a first pressure reservoir and a second pressure reservoir adapted to be connected via a valve arrangement to a chamber of the force translator, the first pressure reservoir having a higher pressure than the second pressure reservoir, wherein the chamber of the force translator is: operatively connected to the second piston unit, enlarged during an out-movement of the second piston unit, connected to the second pressure reservoir via the valve arrangement, and, connected via the valve arrangement to the first pressure reservoir so as to charge the first pressure reservoir when reducing the chamber in size; and a directional control valve that connects the first pressure reservoir to the clamping device.