Patent ID: 7635255
Filing Date: 2009-12-22
Classification: B60K,F04B

Abstract:
1. In a hydraulic machine having a plurality of pistons reciprocally mounted in respective cylinders formed in a cylinder block fixed in a housing and positioned circumferentially at a first radial distance about the rotational axis of a drive element, each said piston having a body portion and a head end connected to said body portion, each respective cylinder having a valve end and an open head portion, a split swash-plate driven by said drive element and having a variably-inclined rotor that rotates and nutates and a wobbler that only nutates, and said pistons also having a stroke varying in accordance with the inclination of said swash-plate up to a predetermined maximum, the improvement comprising: a flat face located on said wobbler; said head end of each said piston being spherical, being connected to said body portion by a narrowed neck portion, and extending at all times beyond said head end of said respective cylinder; said body portion of each piston having an elongated axial cylindrical length such that the piston is supported within said respective cylinder to assure minimal lateral displacement of said head end of said piston when said shoe is in relative sliding contact with said flat face at all times during said stroke; a respective sliding shoe pivotally and directly affixed to said spherical head end of each said respective piston without any intermediate dog-bone; each said respective sliding shoe being maintained in direct sliding contact with said flat face of said wobbler during all relative rotary motions between said piston and said flat face; and a hold-down assembly for biasing each said sliding shoe toward said flat face of said wobbler, said hold-down assembly comprising: said washers being operationally in sliding contact with said hold-down element for movement relative thereto in response to the changing relative positions of said sliding shoes when said flat face of said rotor is inclined relative to said rotational axis of the drive element.