A housing having a first housing end and a second housing end, a substantially cylindrical work chamber formed in the housing, a piston which is arranged in the work chamber so as to be displaceable and which divides the work chamber into a first work space near the first housing end and a second work space near the second housing end, a piston rod which is arranged at one side of the piston and which projects through the first work space and is guided out of the work chamber in a sealed manner at the first housing end through a guiding and sealing device, and a valve chamber which is formed in the housing parallel to the work chamber and in which a first valve assembly and a second valve assembly are arranged. The work chamber is always completely filled with a liquid medium and the valve chamber is at least partially filled with a liquid medium.