Patent ID: 7472547

Claim:
A hydraulic differential with a variable displacement hydraulic unit of the axial piston type, a fixed displacement hydraulic unit of the axial piston type, a stationary housing for mounting the hydraulic units, an input shaft for coupling to a variable speed power source and an output shaft for coupling to a constant speed load, wherein the input and output shafts extend out of a single end of the stationary housing, comprising: a wobbler and a port plate for the variable displacement hydraulic unit coupled to the stationary housing; an axial block and piston set for the variable displacement hydraulic unit, a port plate for the fixed displacement hydraulic unit and a wobbler for the fixed displacement hydraulic unit coupled to the input shaft; and an axial block and piston set for the fixed displacement hydraulic unit coupled to the output shaft; wherein the variable displacement hydraulic unit port plate and the fixed displacement hydraulic unit port plate couple together through a circumferential interface to minimise hydraulic thrust forces developed by the hydraulic units.