Patent ID: 7143684

Claim:
A hydraulic actuator comprising a housing having an interior, a rod extending within said housing and comprising an extension within the interior; a piston mounted on the extension and reciprocal within said interior, said piston dividing said interior into a piston chamber and a rod chamber, said piston comprising a passage having an opening and adapted for hydraulic fluid flow between said piston chamber and said rod chamber; and a disc valve assembly comprising a washer mounted to said extension overlying the opening and spaced apart therefrom; a valve pack mounted to the extension between said washer and the piston, said valve pack comprising at least one disc valve having a flexible portion remote from the extension and having an unflexed position; and a spacer arrangement disposed between said at least one disc valve and said washer to space said flexible portion of said at least one disc valve apart from the washer, said spacer comprising a first support point supporting the valve pack relative to said washer and at least one second support point spaced apart from the flexible portion of the disc valve in said unflexed position; wherein said valve pack is adapted to flex between a valve closed position wherein the opening is closed to prevent hydraulic fluid flow from the rod chamber to the piston chamber and an open position wherein the flexible portion engages the washer to open said valve assembly to allow hydraulic fluid flow from the piston chamber to the rod chamber, and further wherein the second support point engages the disc valve pack in the open position to reduce stress attributable to said flexing at said first support point; wherein the spacer arrangement comprises a first element adjacent the disc valve pack and including the first support point, and second element adjacent the washer and comprising the second support point.