Variable-displacement axial piston pump

In a variable-displacement hydraulic pump having a pump housing and having contained within the pump housing a rotationally-driven pump barrel, multiple, variable stroke, fluid-pumping pistons contained within the rotationally-driven pump barrel, and an angularly-positioned piston thrust plate that co-operates with the fluid-pumping pistons, in combination:

• a position sensor housing removably secured to the pump housing;
• an electromagnetic position sensor assembly partially contained within said position sensor housing, partially contained within the pump housing;
• an electromagnetic rotational speed sensor assembly partially contained within said position sensor housing, partially contained within the pump housing, and positioned to sense surface discontinuities in the rotationally-driven pump barrel;
• a hydraulic fluid pressure sensor assembly partially contained within said position sensor housing;
• and
• multiple resilient fluid pressure seals engaging only static surfaces of each said sensor assemblies,
• said electromagnetic position sensor assembly, said electromagnetic rotational speed sensor assembly, and said hydraulic fluid pressure sensor assembly each having a respective static resilient pressure seal that is compressed sufficiently to preclude the leakage of pressurized hydraulic fluid to regions positioned between said position sensor housing and the pump housing.