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.

A flow divider assembly for use with a hydraulic pump provides flow to separate drive motors for use in a vehicle or other application. A pair of flow divider motors may be mounted on a block and have a common axis of rotation. The ratio between the two may be controlled by adjustment of the angles of the respective thrust bearings of the flow divider motors. A valve may connect the outlet of one of the flow divider motors or the outlet of the other flow divider motor. passage to the second outlet passage. Additional bypass valves may be provided to permit direct connection between the hydraulic pump and the separate drive motors.

A hydraulic unit includes a driving mechanism whose displacement volume is adjustable to two operational states by means of a position-able adjustment element. The adjustment element can be positioned by a servo piston of a servo unit into a first, initial position and a second, operative position. A first front face and a second front face of the servo piston, which are opposing each other, can be pressurized individually with pressurized hydraulic fluid in order to position the servo piston at either end position of a servo cylinder of the servo unit. The servo piston is of a stepped design thereby forming a ring-shaped damping surface opposing the first front face. In the servo cylinder a ring-shaped shoulder surface is formed opposing the damping surface such that a damping volume is formed in the servo cylinder by the damping surface, the shoulder surface and the servo cylinder.

The present invention addresses the problem of providing a swash-plate hydraulic motor or a swash-plate hydraulic pump having a structure in which the swash plate can be stably held without mounting a shoe to the swash plate-side end of a tilt control piston. An example of the embodiment of the present invention is a swash-plate hydraulic motor (1). A spherical section (8b) is integrally formed on the swash plate-side end surface of a tilt piston (8), and a groove (10) into which the spherical section (8b) is fitted in a slidable manner is formed in the support surface (7b) (second support surface (7b2)) of the swash plate (7). The groove (10) is a part of the second support surface (7b2) and has a shape having a predetermined width and having a longitudinal direction which is oriented perpendicularly to the direction which connects two pivots (11).

A hydrostatic axial piston machine includes a double-acting actuating cylinder configured to adjust the piston displacement. The actuating cylinder has two actuating chambers that are connected to two spatially separated cartridge valves. The two cartridge valves are inserted obliquely into a wall section of the axial piston machine. The wall section on the one hand forms a wall of the housing of the axial piston machine and on the other hand forms a wall of the actuating cylinder.

A sliding shoe for supporting a piston of a hydrostatic axial piston machine against a swash plate includes a sliding face that defines a central concentric pressure pocket that is flat in order to stabilize the sliding shoe. The pressure pocket has radial supply grooves in order to ensure an optimal supply of pressure medium to the pressure pocket from a central mouth opening. The radial supply grooves extend through the pressure pocket and as far as a circumferential groove which surrounds the pressure pocket.

A hydraulic unit includes a driving mechanism whose displacement volume is adjustable to two operational states by means of a position-able adjustment element. The adjustment element can be positioned by a servo piston of a servo unit into a first, initial position and a second, operative position. A first front face and a second front face of the servo piston, which are opposing each other, can be pressurized individually with pressurized hydraulic fluid in order to position the servo piston at either end position of a servo cylinder of the servo unit. The servo piston is of a stepped design thereby forming a ring-shaped damping surface opposing the first front face. In the servo cylinder a ring-shaped shoulder surface is formed opposing the damping surface such that a damping volume is formed in the servo cylinder by the damping surface, the shoulder surface and the servo cylinder.

A piston motor includes a bush in the form of a curved plate held in sliding contact with a back surface of a tiltable swash plate, a supply/discharge passage formed on the casing including a swash plate port formed on the swash plate and open on the back surface of the swash plate and a bush port penetrating through the bush and provided from a piston to the swash plate, and an elastic ring interposed between the casing and the bush and surrounding an opening end of the bush port.

A hydrostatic axial piston machine (1) utilizing a bent-axis construction has a driveshaft (4) with a drive flange (3) rotatable around an axis of rotation (R.sub.t) inside a housing (2). A cylinder barrel (7) has pistons (10) fastened in an articulated manner to the drive flange (3). The drive flange (3) is supported on a housing-side slide face (101) by an axial bearing (100) in the form of a hydrostatically relieved sliding bearing (102) having a plurality of slippers (105). Each of the slippers (105) is mounted in an articulated manner in the drive flange (3) so that when the drive flange (3) rotates, a compensating force (F.sub.FR) acts on the slipper (105) which is in the opposite direction to the centrifugal force (F.sub.F) acting on the slipper (105). The point of application (AP) of the compensating force (F.sub.FR) on the slipper (105) is selected so that there is no tipping moment on the slipper (105) or to compensate for some or all of any tipping moment that does occur.

A method for operating an axial piston machine of swashplate design, in which a swashplate is settable by means of an adjustment device, and in which a controlled variable of the axial piston machine is regulated by predetermining a manipulated variable. Under the assumption of a constant intended value of the controlled variable, a future profile of the controlled variable is ascertained using a model of the axial piston machine in which respective current values of at least one operating variable of the axial piston machine, which comprises the controlled variable, and a current value of the manipulated variable are taken into account. A value to be set for the manipulated variable is ascertained and set taking into account the future profile of the controlled variable.