A hydrostatic piston machine unit, which is in particular designed as a hydrostatic axial piston machine unit, comprises at least two driving mechanisms that can be driven synchronously and have displacement pistons which each perform a reciprocating motion in operation and are provided for delivery into a common pressure line. The hydrostatic piston machine unit has a jointly assigned precompression volume for the at least two driving mechanisms.

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°.

A hydrostatic piston machine unit, which is in particular designed as a hydrostatic axial piston machine unit, comprises at least two driving mechanisms that can be driven synchronously and have displacement pistons which each perform a reciprocating motion in operation and are provided for delivery into a common pressure line. The hydrostatic piston machine unit has a jointly assigned precompression volume for the at least two driving mechanisms.

A method for manufacturing an at least sectionally spherical-cap-shaped recess on a drive shaft for a hydrostatic axial piston machine includes whirling of the recess and heat treatment of the recess to form a wear layer. A drive shaft for a hydrostatic axial piston machine includes at least one recess manufactured according to the method. A hydrostatic axial piston machine includes a drive shaft with at least one recess manufactured according to the method.

A hydraulic unit includes a housing, a pump located in the housing, and a motor located in the housing and operably connected to the pump such that the motor is driven in response to fluid pressure delivered to the motor from the pump. An output shaft is operably connected to and driven by the motor and includes a body having a first end and a second opposite end, and a first flange and a substantially identical second flange integrally formed with the body of the shaft adjacent the second end. A relief is formed about a circumference of the body. A plurality of first splines are integrally formed with an exterior of the body between the second portion and the third portion, and a plurality of second splines are integrally formed with an interior surface of the body adjacent the second end.

A method for manufacturing an at least sectionally spherical-cap-shaped recess on a drive shaft for a hydrostatic axial piston machine includes whirling of the recess and heat treatment of the recess to form a wear layer. A drive shaft for a hydrostatic axial piston machine includes at least one recess manufactured according to the method. A hydrostatic axial piston machine includes a drive shaft with at least one recess manufactured according to the method.

A fixed shaft of a hydraulic unit is provided including a body having a first end and a second opposite end. A first flange and a substantially identical second flange are integrally formed with the body of the shaft adjacent the second end. The second end of the body has an outer diameter of 0.9900.005 inches (2.5150127 cm). The first and second flange each have an axial length parallel to a longitudinal axis of the body of about 0.0850.010 inches (0.2160.0254 cm). The first and second flange having an outer diameter of 1.359 inches (3.452 cm). The first flange and the second flange are separated by from one another by a distance of about 0.3162 inches (0.8031 cm). The portion of the body between the first flange and the second flange has an outer diameter of about 1.2013 inches (3.051 cm).