Abstract: A hydraulic fluid pressure energy translating device comprising an axial multi-piston pump including an axially and laterally constrained barrel and a floatingly disposed port plate responsive to hydrostatic forces within the pump. The port plate includes hydrostatic pressure balancing means which tend to balance hydrostatic forces acting on the port plate during operation of the pump to maintain an optimum bearing clearance between the port plate and barrel, thereby controlling fluid leakage and maintaining adequate lubrication and support at this interface.