A variable displacement pump-motor includes a pump-motor having a plurality of cylinders and pistons, and further including a main shaft rotatable relative to the system body. A hydro mechanical control system includes a plurality of main stage valves in communication with the plurality of cylinders. Each of the main stage valves is configured to open and close a cylinder of the plurality of cylinders to one or more of high or low pressure fluid sources. A pilot spool valve is in selective communication with each of the main stage valves. The pilot spool rotates with the main shaft. The pilot spool includes coding configured to operate each of the main stage valves to open and close the respective cylinders to the one or more high and low pressure fluid sources according to a translational position of the pilot spool and rotation of the pilot spool by the main shaft.

A hydraulic machine comprising: an outer casing comprising a first front plate and a second front plate, a shaft rotatable about a main axis, a first rotor comprising a first rotor body rotatable with said shaft around said main axis, and a plurality of first pistons with respective spherical ring heads fixed to said first rotor body, a second rotor comprising a second rotor body and a plurality of second pistons with respective spherical ring heads, wherein the second rotor is rotatable about a secondary axis, inclined with respect to said main axis, a plurality of sleeves that are separate and independent from each other, each having a cylinder open at opposite ends and engaged on opposite sides by a first piston and by a second piston.

The devices comprises a distributor (16) that presents distribution ducts opening out into a radial distribution face (16A), and a distributor-counterpart engaged in each other in such a manner that two main enclosures (18, 20) are provided between their opposite axially-extending faces. The device comprises a cylinder-capacity selector comprising two slides (24, 26) arranged after the other in a bore (22) of the element engaged in the other, to which are connected the main enclosures (18, 20) and at least some of the distribution ducts (30, 31). The slides are able to adopt at least three distinct configurations establishing different connections between the main ducts (18, 20) and the distribution ducts via the main enclosures, in order to be able to obtain at least three distinct operating cylinder capacities.

The disclosure relates to a hydrostatic axial piston machine having a housing, having a drive shaft, to which a flange disc is fastened in a rotationally fixed manner, and having a swash plate, to which a rotor disc, driven by the drive shaft or the flange disc, is rotatably mounted, and having a plurality of displacement units arranged distributed between the flange disc and the rotor disc and around the axis of the drive shaft, each displacement unit comprising a cylinder sleeve and a piston which extends into the cylinder sleeve and has a ball head and a spherical joint head which extends into the cylinder sleeve, wherein during operation, the piston plunges more or less far into the cylinder sleeve.

A hydraulic rotating machine adapted to be actuated and rotated by supply and discharge of a working fluid includes a cylinder block to which a shaft is coupled, the cylinder block being configured to be rotate together with the shaft; a cylinder formed to have an opening portion on one end side of the cylinder block, a recessed portion being formed on an inner circumference of the cylinder; and a bush inserted from the opening portion of the cylinder and provided on the inside of the cylinder, the bush having a projection portion filled into the recessed portion by plastic deformation. The recessed portion is formed in such a manner that width along an axial direction of the cylinder becomes smaller toward the depth direction.

An axial hydraulic pump-motor, in which a cylinder block having a plurality of cylinder bores on a valve plate having a high-pressure side port and a low-pressure side port for controlling an amount of reciprocation of a piston in each of the cylinder bores, the hydraulic pump-motor includes: a residual pressure release port provided on the valve plate and communicating until the cylinder bore on a top dead center side communicates with the low-pressure side port; a residual pressure acquisition portion obtaining a value of a residual pressure in the cylinder bore on the top dead center side; and a directional switching valve switching a flow path between the residual pressure release port and an hydraulic oil tank and a flow path between the residual pressure release port and the low-pressure side port.

Disclosed is a hydraulic machine (2) comprising:a bearing support member (8),a cylinder block (16),a brake piston (20) that is movably mounted with respect to the bearing support member between a braking position in which the piston is shape-matchingly engaged with the cylinder block in such a way as to prevent the cylinder block from rotating with respect to the piston and a brake-release position in which the piston lets the cylinder block rotate freely with respect to the piston, andat least one bearing (14) supported by the bearing support member (8), the piston and the bearing being on the same side of the cylinder block with reference to the direction of a main axis (X-X) of the machine, a perimeter (59) of the piston (20), oriented in the opposite direction to the axis, being configured so as to prevent the piston from rotating with respect to the bearing support member.