Trw Limited

Thomas William Luibrand

John Walter Spetz

An apparatus (,) includes a hydraulic fluid power cylinder (,) and a steering rack (,). The rack (,) is fixed to a piston (,) in the power cylinder (,), and extends outward through an open end (,) of the power cylinder (,). An annular hydraulic fluid seal (,) is received over the rack (,) in dynamic sealing contact with the rack (,). The seal (,) defines a fixed end of a variable volume hydraulic fluid chamber (,) extending from the piston (,) to the seal (,). The apparatus (,) further includes a housing part (,) which is mounted on the power cylinder (,). The housing part (,) supports the seal (,) at a location spaced outward from the open end (,) of the power cylinder (,). In this arrangement, the housing part (,) defines an end section (,) of the fluid chamber (,) extending outward from the open end (,) of the power cylinder (,) to the seal (,).

Vehicle steering apparatus

A power steering system (10) for use in a vehicle includes a power steering pump (12) which is driven by an engine (13) of the vehicle. The output from the power steering pump (12) is connected to a power steering valve (22). The power steering valve (22) is connected with a power steering motor (24). When the engine (13) is turned off, that is, in a non-operating condition, and the power steering pump (12) is not being driven, the fluid pressure in motor cylinder chambers (40, 42) is prevented from falling below a predetermined pressure to keep seals (64, 66) in sealing engagement with the power steering motor 24. To keep the fluid pressure in the motor cylinder chambers (40, 42) from falling below a predetermined pressure, a one-way valve (70) blocks the flow of fluid from the power steering valve (22) back to the reservoir (16). A pressure relief valve (72) blocks the flow of fluid from the power steering valve (22) to the reservoir (16) when the fluid pressure in the motor cylinder chambers (40, 42) is equal to or less than the predetermined pressure required to urge seals (64, 66) into sealing engagement with the power steering motor 24.

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Wytheville, VA, United States of America

Thomas William Luibrand