The present invention relates to a hydraulic device (10) with radial pistons, comprising: a shaft (12) arranged along an axis (1); a cover (13) forming a casing element, the cover and the shaft being free to rotate with respect to one another; a distribution assembly comprising: a multi-lobe cam (14); a cylinder block (15); a distributor (16) configured to exert a thrust force (P) against the cylinder block (15) along the axis (11) of the shaft; an assembly (22) of mechanical bearings comprising at least one mechanical bearing (22a) mounted in radial contact between the cover (13) and shaft (12), said assembly being configured to take up the thrust force (P) exerted by the distributor (16); and a radial contact ball bearing mounted in radial contact between the cover (13) and the shaft (12).

A hydrostatic axial piston pump of swashplate construction, which is also configured to be operated as a motor, has a stationary control plate against which a rotating cylinder drum is tensioned. During operation, a tilting tendency of the cylinder drum arises in the direction of that quadrant of the control plate which is operatively connected to the first part of the displacement stroke of the pistons. The control plate has a supporting device configured for the cylinder drum. The supporting device is arranged adjacent to an outer edge of the control plate in the first quadrant thereof. The supporting device is configured to be formed by a hydrostatically relieved additional field.

The device comprises a casing portion that has an open axial end and that has two main holes, respectively for fluid feed and for fluid discharge. Said holes open out in an inside axial face of the casing portion, respectively via a first main orifice and via a second main orifice that are disposed in succession in the direction going away from the open axial end. The inside axial face has first, second, and third sealing inside bearing surface arrangements, respectively situated between the open axial end and the first main orifice, between the two main orifices, and beyond the second main orifice. At least two of the three arrangements are staggered inside arrangements, each of which comprises two axial bearing surfaces that are staggered relative to each other, and that are separated by a shoulder facing towards the open axial end.

A method for controlling torque equilibrium of a hydraulic motor, the method includes: setting a torque equilibrium reference position in a control system, setting a reference direction in the control system, determining one or more high-pressure torque producing cylinders towards the torque equilibrium reference position in a reference direction in the control system, and opening a high-pressure valve on each of one or more high-pressure torque producing cylinders to produce a torque towards the torque equilibrium reference position in the reference direction on the drive shaft of the motor.

A hydraulic pump/motor includes: a cylinder block rotating about a rotation axis; a piston in a cylinder bore; and a valve plate facing a cylinder port. The valve plate includes: a high pressure port through which oil discharged from the cylinder port flows; a low pressure port through which the oil to be sucked into the cylinder port flows; a region disposed between the high and low pressure ports in a circumferential direction of the rotation axis and including a top dead center position facing the cylinder port of the cylinder bore in which the piston moved to a top dead center is disposed; and a residual pressure release port between the top dead center position and the low pressure port in the region. The residual pressure release port includes first and second ports disposed at positions different from each other in the radial direction of the rotation axis.

A valve plate of a hydraulic motor includes first and second pressure ports, and first and second oil grooves, the first and second pressure ports being alternately communicated with a cylinder bore in a cylinder block by bidirectional relative rotation in a state of being in contact with an end face of the cylinder block. Further, pad oil grooves communicating with the first oil groove and opened toward the end face of the cylinder block are provided in outer peripheral portions of the first and second pressure ports in a pad region, and the plurality of pad oil grooves is provided such that a proportion of an opening area to the end face of the cylinder block is larger at two end portions close to the second oil grooves than at a central portion separated from the second oil grooves in a circumferential direction of relative rotation.

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.

An axial reciprocation device having a main piston and an anchor piston coupled to one another via a swivel joint interconnecting 20 a pair of connecting rods, the main piston positioned in a main cylinder bore and the anchor piston positioned in an anchor piston bore of a housing, such that the main piston is configured for axial reciprocation in the main cylinder bore; wherein variable positioning of the anchor piston along the anchor piston bore results in variable displacement of the main piston of hydraulic fluid with respect to an inlet/outlet port of the housing.

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.

A selection system, comprising: a sheath defining an internal housing extending in a longitudinal direction; a link rod disposed in said internal housing, and extending in the longitudinal direction; and a selection slide mounted to slide in the internal housing, about the link rod; the link rod being held stationary relative to the sheath against movement in translation in the longitudinal direction by stop means; the system being characterized in that the stop means comprise: a base that is a body of revolution and includes a conical portion; and a shell comprising two shell portions each including a conical portion configured to come to bear in plane manner against the conical portion of the base.