A hydrostatic axial piston machine (1) has a cylinder barrel (7) with a plurality of piston bores having pistons (10) fastened in an articulated manner to a drive flange (3). For articulated fastening of the pistons (10) to the drive flange (3), ball joints (20) are provided that are formed by a spherical cap-shaped receptacle socket (3a) in an end surface (3b) of the drive flange (3) and a ball head (10a) that is operatively connected with the piston (10). The receptacle sockets (3a) are each in the form of hemispheres that extend to the ball equator, and on one end surface (3b) of the drive flange (3), in the vicinity of the receptacle sockets (3a), there is a retaining web (30) that extends beyond the ball equator of the hemisphere to grip the ball head (10a) at an angle of greater than 180°.

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 swash plate compressor in which a lubricating film is not formed on a sliding contact surface of the swash plate and the piston owing to the use of the semispherical shoe. The semispherical shoe (4) is subjected to sliding contact with the swash plate of the swash plate compressor and the piston thereof. A base material (5) consists of a metallic member having a resin layer (6b) formed on a surface of a planar part (4b) that is subjected to sliding contact with the swash plate. A resin layer (6a) is formed on a surface of a spherical part (4a) to be subjected to sliding contact with the piston. The resin layer (6a) and the resin layer (6b) are integral with each other. At least one portion of the base material (5) is exposed.

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).

An axial piston machine is shown comprising a cylinder drum rotatable around an axis of rotation and having at least a cylinder, a piston arranged in said cylinder, a swash plate arranged in front of said cylinder drum, said piston being provided with a slipper (11) resting against said swash plate and having a pressure area (17) on a side facing said swash plate, wherein a cylinder axis of said cylinder is arranged on a circle line (27) around said axis of rotation (16). Such a machine should be made compact. To this end said pressure area (17) deviates from a circular form.

An axial piston machine includes a retraction plate, first apertures of which are each penetrated by an associated sliding shoe. A joint section of the sliding shoe deviates from a circular cylindrical shape such that it has a largest diameter which is spaced apart from the web section, wherein the joint section has a reduced diameter between the largest diameter and the web section compared to the largest diameter. In a reference state, the joint section contacts an inner circumferential surface of the associated first aperture such that a minimum distance is obtained between the web section and the spherical outer surface section, and the inner circumferential surface of the first aperture is adapted to the non-circular cylindrical joint section of the sliding shoe such that the inner circumferential surface and the joint section contact each other in the reference state away from the largest diameter of the joint section.

It is an object of the present invention to provide a semispherical shoe which can be prevented from being subjected to seizure even in a dry lubrication state in which there is no lubricating oil at the start time of an operation of a swash plate compressor, is excellent in its sliding contact property and load resistance, does not deteriorate in its lubricating property due to generated frictional heat, does not subject a resin layer to peeling from a base material, and ensures sufficient durability. It is another object of the present invention to provide a swash plate compressor in which a lubricating film is not formed on a sliding contact surface of the swash plate and that of a piston owing to the use of the semispherical shoe. A semispherical shoe (4) is subjected to sliding contact with the swash plate of the swash plate compressor and the piston thereof. Abase material (5) consists of a metallic member. A resin layer (6b) is formed on a surface of a planar part (4b) to be subjected to sliding contact with the swash plate. A resin layer (6a) is formed on a surface of a spherical part (4a) to be subjected to sliding contact with the piston. The resin layer (6a) and the resin layer (6b) are integral with each other. At least one portion of the base material (5) is not covered with the resin layer (6) and is exposed.

A hydraulic piston motor/pump is disclosed herein. The hydraulic piston motor/pump includes a first rotor including a first cylinder, a second rotor opposing the first rotor and including a second cylinder that opposes the first cylinder, a first swashplate including a first angled face adjacent the first rotor, a second swashplate adjacent the second rotor and opposing the first swashplate, a first shoe cage including a first piston opening, a second shoe cage including a second piston opening, a piston configured to travel into and out of the first cylinder and the second cylinder, a piston shoe configured to engage the piston, the first shoe cage, and the second shoe cage, and a shaft engaging the first shoe cage and the second shoe cage and configured to rotate in response to a rotation of the first shoe cage and the second shoe cage.

A hydraulic piston motor/pump includes a first rotor including a first cylinder, a second rotor opposing the first rotor and including a second cylinder that opposes the first cylinder, a first swashplate including a first angled face adjacent the first rotor, a second swashplate adjacent the second rotor and opposing the first swashplate. The hydraulic piston motor/pump further includes a first shoe cage including a first piston opening, a second shoe cage including a second piston opening, a piston configured to travel into and out of the first cylinder and the second cylinder, a piston shoe configured to engage the piston, the first shoe cage, and the second shoe cage, and a shaft engaging the first shoe cage and the second shoe cage. The shaft configured to rotate in response to a rotation of the first shoe cage and the second shoe cage.