In a drive device using a hydraulic pump controlled by a rotatable swash plate, the swash plate includes a pocket and a trunnion engaged to the pocket and rotatable about an axis of rotation offset from the swash plate axis of rotation. An interface is formed on a first end of the trunnion, and a first arcuate side of the interface engages a flat portion of the first side of the pocket as the trunnion is rotated in a first direction, and a second arcuate side of the interface engages a flat portion of the second side of the pocket as the trunnion is rotated in the opposite direction. The swash plate may also include at least one protrusion on a top surface extending in a direction perpendicular to swash plate axis of rotation to engage the housing and limit axial movement of the swash plate.

To provide a sliding member which has hardness that is suitable for the circumstance, to which heavy load is applied, and which is excellent in abrasion resistance property. The sliding member contains a sliding layer for slidably supporting a body to be slid, shot blasting being performed on a surface of the sliding layer, and a sliding surface formed on a surface of the sliding layer, the sliding surface having an uneven configuration with arithmetic mean roughness (Ra) of 1.0 m through 2.5 m, 10-point average roughness (Rz) of 5.0 m through 10.0 m, and surface hardness (Hv) of 220 through 250.

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 rolling bearing includes rollers clamped between an inner raceway and an outer bearing shell. The outer bearing shell bears with its outer circumferential surface against an outer component which can be a housing of an axial piston machine. The inner raceway is either formed directly on an inner component, or it is formed on an inner bearing shell, which bears against the inner component. In order to permit tilting of the inner component, wherein the rollers remain in predetermined contact with the two raceways, at least one beveled contact region or a region reduced in another way is provided on the outer circumferential surface of the outer bearing shell.

A variable-displacement engine comprises an engine block, cylinders and power shaft. Pistons and connecting rods mounted in the cylinders drive a wobble plate having a rotating ring portion and non-rotating ring portion connected to allow relative rotation therebetween while constraining the portions to remain parallel. The wobble plate defines an inclination plane, pivot axis and wobble plate angle . A piston control mechanism (PCM) includes a control yoke rotating with the power shaft and extending to an axially and radially fixed anchor line, a control shaft mounted on the yoke at the control line and a control arm extending from the rotating ring portion and defining a control slot captured over the control shaft. A lift mechanism changes the axial position of the pivot axis, in turn changing, via the PCM, the wobble plate angle . This changes the piston displacement of the engine while maintaining a predetermined compression ratio.

Hydraulic axial piston unit (1) of the swashplate construction type having a drive shaft (2) adapted to drive or be driven by a cylinder block (4). The cylinder block comprises a plurality of cylinder bores (6), in which several pistons (8) are moveable in general along the rotational axis (10) of the drive shaft (2) and relative to the cylinder bores (6). First ends of the pistons (8) protrude outside of the cylinder bores (6) and are slidable fixed by means of slippers (14) to a swashplate (16). The slippers (14) are hold down in a sliding manner on a sliding surface (18) of the swashplate (16) by means of a slipper hold down ring (20) arranged parallel to the sliding surface (18). The slipper hold down ring (20) is in a sliding contact with its radial inner surface (22) with a matching surface (26) on a guide ball (24) rotationally fixed on the drive shaft (2) and axially moveable in direction of the rotational axis (10) relative to the cylinder block (4) against resilient forces of springs (28) characterized in that a mounting ring (30) is attached to the cylinder block (4) in order to limit the axial movement of the guide ball (24) towards the cylinder block (4).

A bent-axis hydrostatic axial piston machine (1) has a drive shaft (4) with a drive flange (3) rotatable around an axis of rotation (R.sub.t) and a cylinder drum (7) rotatable around an axis of rotation (R.sub.z). The cylinder drum (7) has a plurality of piston bores (8) concentric to the axis of rotation (R.sub.z) of the cylinder drum (7) and having longitudinally displaceable pistons (10) fastened in an articulated manner to the drive flange (3). Between the drive shaft (4) and the cylinder drum (7) there is a drive joint (30) (constant velocity joint) for rotationally synchronous rotation of the cylinder drum (7) and the drive shaft (4). The drive joint (30) and the cylinder drum (7) include a longitudinal bore (11) concentric to the axis of rotation (R.sub.z) of the cylinder drum, through which bore (11) the drive shaft (4) extends such that in the vicinity of the drive shaft (4) there is a torque transfer to a cylinder-drum-side end of the axial piston machine (1).

A variable-displacement engine comprises an engine block, power shaft and rotating cylinder block. Pistons and connecting rods mounted in the cylinder block connect to a wobble plate having a rotating ring portion and non-rotating ring portion connected to allow relative rotation therebetween while constraining the portions to remain parallel. The wobble plate defines an inclination plane, pivot axis and wobble plate angle . A piston control mechanism includes axial lift, control lever supported by the lift and by an anchor bearing, and links connecting the control lever to the wobble plate. Axial movement of the lift changes the axial position of the control lever pivot and changes the control lever angle, in turn changing, via the connecting links, the wobble plate angle and the axial position of the wobble plate pivot axis. This changes the piston displacement of the engine while maintaining substantially constant compression ratio.

A spring return apparatus for elastically prestressing sliding pads against a sliding bearing face of an axial piston machine. The sliding pads are positioned on working pistons mounted axially movably in cylinders of a cylinder barrel that drives a drive shaft including a spring plate and a supporting plate. The spring plate includes a ring region surrounding a central opening, and levers extending radially from the ring region. The levers are arranged spaced apart or distributed uniformly in the circumferential direction, and are elastically flexible and/or elastically pivotable in the axial direction. Every two adjacent levers delimit a receiving region for receiving a tapered section of a working piston or a sliding pad. The supporting plate has a circular ring-shaped supporting region configured to support radially outer end sections of the levers if the supporting plate is arranged concentrically with respect to and axially adjacently to the spring plate.

An outer circumferential surface of a trunnion shaft includes a sliding contact region that has a circular arc shape as viewed along a slanting axis line and is substantially brought into contact with an inner circumferential surface of the bearing portion in a rotatably sliding manner, and at least one suction groove that forms a pocket portion between the suction groove and the inner surface of the bearing portion. The pocket portion is opened to an inner space of housing on at least one side in an axis line direction of the trunnion shaft.