Abstract: A hydraulic radial piston machine for stepplessly displaceable piston stroke has a plurality of pistons which are formed as roller bodies and abut linearly with their circular spherical regions against a control curve which is formed on a control ring displaceable relative to a cylinder body of the machine, wherein the control curve is formed as a symmetrical spatial curve such that the curve regions which form both the inner dead point for the pistons and the outer dead point for the pistons change in the displacement direction of the control ring.

Abstract: A hydraulic motor is comprised of a rotatable rotor positioned in a stationary housing and provided with a number of radial hollow pistons with cup-shaped cylinders displaceable thereon. The rotor is arranged within the housing by means of a single roller bearing on the driven-side of the rotor; the bearing which is offset radially outwardly from the central axis of the motor absorbs radial and axial forces exerted on the rotor.

Abstract: A hydraulic motor has a stationary housing, a hollow rotor having a plurality of hollow radially extending pistons each provided with two concentric annular walls forming inner and outer chambers communicating with separate fluid-conveying passages, a plurality of cylinders displaceable over the pistons and each having a projection received in the inner chamber of the respective piston, and a central control member having a plurality of fluid-conveying passages cooperating with the fluid-conveying passages of the pistons and displaceable in the axial direction between a plurality of operating positions.

Abstract: A gas cushioned free piston type engine comprises two oppositely arranged combustion cylinders and a pair of pistons reciprocably mounted therein, which are rigidly connected to each other by a common piston rod. The engine includes further a pump cylinder provided in a central part of the engine located between the two combustion cylinders, a pump piston having opposite faces impingeable by fluid, fixed to the piston rod and dividing the pump cylinder into a pair of pump cylinder chambers, a common suction chamber and a common pressure chamber, which, together with inlet valves and outlet valves, are arranged in the central part of the engine.