The Sauer PV axial piston variable displacement pumps, Series 20, are of swash plate construction with variable flow capability suitable for hydrostatic transmissions with closed circuit. The flow rate of sauer PV22 hydraulic piston pump is proportional to the pumps driven speed displacement, which, in turn, is determined by the swash plate angle. The latter is infinitely adjustable between zero and maximum displacement. Flow direction of sauer PV22 hydraulic piston pump is reserved by titling the swash plate to the opposite side of the neutral or zero displacement position. These units and parts are fit, form and function replacements for Sauer-Sundstrand series 20 components