Patent ID: 6071086
Filing Date: 2000-06-06
Classification: F04B

Abstract:
A radial piston hydrostatic machine having a first fluid displacement stage and a second fluid displacement stage and comprising a housing defining an internal chamber; a rotatable cylinder-barrel located within said internal chamber and provided with a series of cylinders each containing a piston, the reciprocaticng action of the pistons within said cylinders acting as said second fluid displacement stage; an annular track-ring surrounding said cylinder-barrel and having an track-surface, said track-ring having an solid interior and where said track-surface is uniform in form across its width over the entire circumferential length on which said pistons are operatively connected to, said track-surface defining the outer perimeter of said first displacement stage and said cylinder-barrel defining the inner perimeter of said first displacement stage, said track-ring dividing said internal chamber into a main chamber and a sub-chamber and where the volume space radially outwards of said track-ring is said main chamber and the volume space radially inwards of said track-surface is said sub-chamber; said cylinder-barrel containing said pistons act in unison as a rotating-group of said machine and where fluid distribution by way of first and second ducts provided in said housing and arranged to open axially adjacent said rotating-group and generally radially inwards of said track-surface for communication with said sub-chamber, and where said rotating-group operating within said sub-chamber acts as said first fluid displacement stage for transferring fluid between said first and second ducts to the said second fluid displacement stage.