An articulated coupling is provided for a piston sealing device for a piston which includes a fixed skirt and a sliding skirt interconnected by a mechanical inter-skirt connection for axially compressing a continuous extensible segment under the action of a sliding skirt spring, the coupling replacing, on the one hand, the fixed skirt by a ball-joint skirt and providing, on the other hand, a troncospherical piston end which cooperates with a skirt troncospherical bearing surface provided on the ball joint skirt while an articulation unit interposed between the inter-skirt mechanical connection and the piston and/or between the connection and the sliding skirt.

A hydraulic piston machine is described comprising a piston (1) having a hollow (2) secured by a wall (3) and an insert (4) arranged in the hollow. Such a machine should have a high efficiency at low costs. To this end the insert (4) comprises a section (29) which extends out of the hollow (2).

A hydrostatic axial piston machine includes a housing, a connection plate closing the housing, working connections formed on the connection plate, a drive shaft, a swashplate, a cylinder drum coupled to the shaft in the direction of rotation, bores formed in the drum and each including a piston, a control plate against which the drum bears, a retraction plate for removing a piston from the bores, and a retraction ball arranged in front of the first end face of the drum which surrounds a drum neck of the drum and the shaft and by which the retraction plate is loaded in the direction of the swashplate. A pressure chamber is defined by seals between the retraction ball, the drum, and the shaft, and is configured to be acted upon by a pressure above a housing pressure. The retraction ball is sealed against the drum neck and against the shaft.

A piston shoe as a sliding component includes a base section, which is made of steel, and a sliding section having a sliding surface, which is made of copper alloy and joined to the base section. The base section and the sliding section are joined, with a base section joint region being formed in the base section, the base section joint region including a base section joint surface that is a surface joined to the sliding section and having smaller grains than other regions in the base section.

The cooling and lubricating system is provided for a piston sealing device for a piston, which includes a fixed skirt and a sliding skirt joined together by an interskirt mechanical connection to axially compress a continuous extensible segment under the action of a sliding skirt spring. The system adds to the device a sliding skirt thrust ring so as to insert between the fixed skirt and the continuous extensible segment a flow valve traversed by the interskirt mechanical connection. The valve is held at rest away from the fixed skirt by a valve return spring on the one hand, and including a flow calibration orifice on the other hand.

The hydraulic piston forms a hydraulic chamber with a cylinder and has a cylindrical body which receives a seal and whose external cylindrical surface is housed with little clearance in the cylinder in such a manner as to leave an interstitial space, the cylindrical body being run through by a cooling and lubrication pipe which can be opened or closed by a cooling and lubrication valve which is moved by translation by a valve-actuator in such a manner that fluid can pass via a flow calibration opening from the hydraulic chamber to the interstitial space when the pressure existing in the hydraulic chamber is low and cannot pass when the pressure in the chamber is high.

A piston pump/motor includes a cylinder block rotated with a shaft; a piston slidably inserted into a cylinder that is formed on the cylinder block; a shoe rotatably connected to a tip end portion of the piston, the shoe being in sliding contact with the tip end portion; and a swash plate with which the shoe is in sliding contact. The shoe has a piston slide portion in sliding contact with the piston and a swash-plate slide portion in sliding contact with the swash plate; a shoe body portion on which the piston slide portion and the swash-plate slide portion are mounted; and a first lock portion and a second lock portion provided across the shoe body portion, and the piston slide portion and the swash-plate slide portion, respectively, the first lock portion and the second lock portion regulating relative rotation between the shoe body portion, and the piston slide portion and the swash-plate slide portion.

A hydrostatic positive-displacement machine, in particular a hydrostatic axial piston machine, having a cylinder drum with at least one cylinder, in which a longitudinally displaceable piston is received, which is supported directly or indirectly by a support portion on an inclined plane of the positive-displacement machine. An outer circumferential surface portion of the piston is in bearing contact with an inner circumferential surface portion of the cylinder.

The hydraulic piston (1) constitutes a hydraulic chamber (5) with a cylinder (4) and has a cylindrical body (6) connectedfrom the side of the chamber (5)by a link-stop valve (3) to a cooling and lubricating gasket valve (2) which is passed right through by a flow calibration opening (27), the valve (2) being able to move in longitudinal translation over a short stroke with respect to the body (6) or to be held at a distance from the body (6) by the valve link-stop (3), a valve return spring (30) tending to move the valve (2) away from the cylindrical body (6).

A drive assembly includes a drive motor at least in part contained in a housing and having a rotor rotating an output shaft. A selector mechanism, at least in part contained in the housing, is movable into one of a plurality of orientations corresponding to one of a plurality of drive motor settings. An actuator, at least in part contained in the housing, is arranged to move the selector mechanism into one of the plurality of orientations. The actuator has first and second pistons each disposed in a piston chamber of the housing for movement by hydraulic pressure. The second piston is arranged in contact with the first piston and configured to aggregate and transfer forces from hydraulic movement of the first piston and the second piston to move the selector mechanism.