Patent ID: 8708123

Claim:
A hydraulic pump assembly in a system for distributing torque between at least one of front and rear axles of an all wheel drive vehicle or between left and right wheels of a two or four wheel drive vehicle, the system comprising at least one limited slip coupling having a disc package and a piston acting thereon, the piston being actuated by the hydraulic pump assembly, wherein the hydraulic pump assembly comprises an electric motor, a hydraulic pump driven thereby, and a centrifugal regulator also driven thereby, the centrifugal regulator controlling a pressure overflow valve, connected to the oil outlet of the hydraulic pump, wherein the hydraulic pump assembly comprises an axial piston pump having a piston drum rotatable in a pump housing and containing a number of reciprocable axial pistons, at least one centrifugal lever pivotally attached to the piston drum, and a valve member connected to the centrifugal lever and being arranged for cooperation with a mouth of an oil outlet bore in the piston drum to form the pressure overflow valve.