The invention relates to improved bearing and lubrication between cylinder blocks (3) and valve segments (2) of hydraulic axial piston units (1) and their rotating kits. In the valve segments first and a second kidney-shaped ports (11, 21) are formed rotationally symmetric with regard to a rotational axis of the cylinder block for providing a suction and a discharge port for charging and discharging hydraulic fluid to and from cylinder bores (8) in the cylinder block. At the radial outer edges of the kidney-shaped ports a plurality of concave formed hydrostatic bearing notches (50) are provided on a sliding surface (7) facing the cylinder block and intersecting with one of the kidney-shaped ports. Alternatively the bearing notches can be located on a bottom surface (9) of the cylinder block extending outwards from outer edges of openings (35) for charging and discharging hydraulic fluid to and from the cylinder bores.