The present invention relates to a method of manufacturing a drum of an axial piston machine by machining a cylindrical round metal, with the machining comprising a forging and with at least one structural element of the drum being produced or prefabricated by the forging.

A hydraulic pump assembly comprises a rotatable piston drum (20) with at least one centrifugal lever (23) pivotally attached thereto for radial movements between radial flanges (20) under the action of centrifugal force at rotation of the piston drum. The centrifugal lever (23) is arranged to control the position of a valve member, preferably a ball (22), at the opening end of a bore (21) in the piston drum (20). There is a defined friction surface (28; 32) between the lever (23) and one of the radial flanges (20), and there are spring means (29-31; 25, 33) for resiliently biasing the lever against said one of the flanges.

A hydraulic motor includes a motor mechanism that rotates by hydraulic liquid that is supplied/discharged from a hydraulic liquid pressure source through one of a first motor passage and a second motor passage. The hydraulic motor comprises a casing that defines a casing chamber which accommodates the motor mechanism, and a flushing passage that is in communication with the casing chamber and extracts a portion of the hydraulic liquid from a low pressure side among the first motor passage and the second motor passage and leads it to the casing chamber.

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.

Systems and methods for a variable displacement hydraulic motor. The hydraulic motor, in one example, includes a swash plate with a tilt angle, multiple piston assemblies configured to rotate about a drive shaft. In the motor, each of the piston assemblies includes an inner piston slideably coupled to an outer piston that mates with a cylinder in a cylinder block and a retainer device configured to inhibit axial movement of the outer piston in a first position and permit axial movement of the outer piston in a second position.

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.

Methods and systems for a variable balancing piston motor are described. In one example, a hydraulic displacement motor includes a valve plate coupled to at least one piston of a cylinder block, the valve plate comprising a plurality of grooves fluidly coupled to a passage comprising a valve.

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 hydrostatic axial piston machine has a housing. In the housing of the hydrostatic axial piston machine, an actuating pressure cylinder is formed at an angle to the drive shaft. A control valve is inserted into the actuating pressure cylinder in a cartridge type of design. In order to enable maximum movement of an actuating piston in the direction toward the control valve, the cartridge is of shortened design. To this end, an actuating pressure port, which is arranged between a high-pressure port and a low-pressure port, and an actuating pressure passage are arranged completely inside the cartridge.

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.