Rack and pinion power steering gear mechanism

Claim 1

A power rack and pinion assembly for a vehicle steering linkage comprising a power cylinder, a power piston rod positioned within said power cylinder, a piston carried on said piston rod and defining on either side thereof opposed pressure chambers in said power cylinder, an inner sleeve concentrically disposed within said power cylinder, an outer sleeve surrounding said power cylinder and defining therebetween an annular pressure passage, a steering gear housing supporting one end of said power cylinder and one end of said inner sleeve, an annular bushing supported at the other end of said power cylinder, means mounting said bushing for radial movement relative to said outer sleeve, means mounting said bushing for axial movement relative to said power cylinder, said piston rod slidably registering with the opening in said bushing thereby providing a first support bearing point, a seal and bushing assembly at the other end of said inner sleeve in the interior of said power cylinder, said seal and bushing assembly being piloted on said piston rod and having a radial clearance relative to said power cylinder, means mounting said one end of said inner sleeve on said housing for angular movement relative thereto whereby slight tolerances and misalignments of the center lines of said piston rod and said inner sleeve may be accommodated while maintaining uniform sliding bearing contact for said bushing and said seal and bushing assembly with said piston rod, said steering gear housing including a pair of pressure passages, one pressure chamber on one side of said piston communicating with one pressure passage through said annular pressure passage and the other passage communicating with the other pressure chamber on the other side of said piston through the annular space defined by said inner sleeve and said power cylinder, a rotatable steering shaft journalled in said housing, a pressure port and an exhaust port in said housing, valve means in said housing responsive to movement of said steering shaft for controlling distribution of pressure from said pressure port to either of said pressure passages and for controlling communication between said pressure passages and said exhaust port.