Hydraulic pump or motor

Claim 2

A hydraulic energy translating device comprising: housing means, valve means in said housing means having inlet and discharge ports, a cylinder block rotatable relative to said valve means and having axial cylinders serially communicable with the inlet and discharge ports, pistons slidable in said cylinders, said pistons having bearing slippers pivotally mounted on the ends thereof, an inclined cam plate at one end of the cylinder block for reciprocating said pistons in the cylinder block including a relatively rough supporting surface, and a thin flat thrust plate of resiliently flexible spring steel material loosely mounted on said supporting surface having a bearing slipper engaging surface on the side of the thin plate facing away from said rough supporting surface, said bearing slipper engaging surface being substantially smoother than said rough supporting surface, said thrust plate being sufficiently thin to resiliently deform against said rough supporting surface under normal hydraulic pressure of the device without undue stress in the thrust plate.

Claim 3

A hydraulic pump or motor unit, comprising: a housing, a valve member in said housing having an inlet port and an outlet port, a cylinder block having one end slidably engaging said valve member and having a plurality of axially disposed parallel cylinders that serially communicate with the inlet port and the outlet port as the cylinder block rotates, pistons slidable in said cylinders, bearing slippers pivotally mounted on the ends of the pistons and having bearing surfaces, an inclined cam plate at one end of the cylinder block for reciprocating said pistons in the cylinders including a relatively rough cast unmachined supporting surface having a finish substantially rougher than 16 RMS, and a flat deformable thrust ring of resilient spring steel material loosely positioned on said supporting surface and being sufficiently thin and resilient to resiliently conform to the irregularities in the supporting surface under normal load conditions without undue stress in the thrust ring and with return to an initial condition when not under load, said thrust ring having a bearing surface slidably engaging the slipper bearing surfaces and having a surface finish of 16 RMS or less.

Claim 4

A hydraulic pump or motor unit, comprising: a housing, a valve member in said housing having an inlet port and an outlet port, a cylinder block having one end slidably engaging said valve member and having a plurality of axially disposed parallel cylinders that serially communicate with the inlet port and the outlet port as the cylinder block rotates, pistons slidable in said cylinders, bearing slippers pivotally mounted on the ends of the pistons and having bearing surfaces, an inclined cam plate at one end of the cylinder block for reciprocating said pistons in the cylinders including a relatively rough cast unmachined supporting surface having a finish substantially rougher than 16 RMS, and a flat deformable thrust ring of resilient spring steel material loosely positioned on said supporting surface and being sufficiently thin and resilient to resiliently conform to the irregularities in the supporting surface under normal load conditions without undue stress in the thrust ring and with return to an initial condition when not under load, said thrust ring having a bearing surface slidably engaging the slipper bearing surfaces and having a surface finish of 16 RMS or less.