Patent ID: 6418717
Filing Date: 2002-07-16
Classification: B60T,F16D

Abstract:
A hydraulic cylinder comprising a piston with a main seal in sealed sliding contact within a small diameter portion of a bore in a housing to define a working chamber ahead of the piston for the discharge of pressurized fluid from the bore via a outlet when the piston is undertaking a working stroke, an inlet into a larger diameter portion of the bore from an associated reservoir, a sleeve in the larger diameter portion of the bore, the sleeve including axially extending grooves which allow fluid flow between the reservoir inlet and working chamber, said flow between the reservoir inlet and working chamber being closed by the main piston seal during a working stroke of the cylinder, flow through the grooves between the reservoir inlet and working chamber being open for recuperation of fluid from the reservoir to the working chamber when the piston is in a fully retracted condition with its main seal within the sleeve, the piston also carrying a secondary seal which is in sealed sliding contact with the larger diameter portion of the bore to seal the bore against all egress of fluid.