Trw Limited

William T Rabe

Wendell L Gilbert

Jim L Rau

Maurice P Roberts

A vehicle steering for turning the steerable wheels of a vehicle having a fluid motor with a housing defining a fluid chamber and a piston in the chamber dividing the chamber into first and second chamber portions. A rotatable steering input member is supported by the housing. A rotatable follow-up member is associated with the piston and rotatable upon movement of the piston in the chamber. A valve controls pressurized fluid flow to the first and second chamber portions. The valve comprises first and second relatively movable valve parts. One of the valve parts is connected with the input member and the other of the valve parts is connected with the follow-up member forming a unit therewith. The unit has a surface against which fluid pressure in the first and second chamber portions acts tending to create an axial force on the unit. Pressure is applied to another surface area of the unit to balance the axial force acting on the unit.

Steering gear with pressure-balanced valve

Steering gear with recirculation check valve

A power assist steering gear for use in vehicles having a housing that defines a chamber. A piston dividing the chamber into first and second chamber portions. The piston is movable through a work stroke in opposite directions in the chamber. A steering valve directs fluid pressure into the first chamber portion and vents the second chamber portion to effect piston movement in a first direction and directs fluid pressure into the second chamber portion and vents the first chamber portion to effect piston movement in a second direction. An input shaft moves to effect actuation of the steering valve. A relief valve for communicates the first and second chamber portions when the piston is near the end of its work stroke. The relief valve has a valve member and valve seat which are movable between a closed position blocking communication between the first and second chambers and a fully open position establishing communication between the first and second chambers when the piston reaches the end of its work stroke. A press-fit connection effects adjustment of, in response to movement of the input shaft, the position in the piston path at which the valve member and valve seat move relatively to an open position.

Unloading valve for power steering piston with integral gear

An improved power steering control apparatus includes a power steering motor having a piston rod which extends through one end of the motor cylinder. This results in the rod end of the piston having a smaller working area than the head end of the piston. In order to equalize the fluid pressure forces on opposite sides of the piston when the motor is in an inactive condition, a power steering control valve vents both sides of the piston to atmospheric pressure when the control valve is in a neutral or unactuated condition. Three conduits are connected with the control valve; a supply conduit which conducts fluid from a pump to the control valve to effect operation of the motor upon actuation of the control valve; a return conduit through which fluid is returned to a reservoir when the control valve is in the neutral condition; and a vent conduit which connects the control valve and opposite sides of the motor cylinder piston directly with the reservoir and atmospheric pressure when the control valve is in the neutral condition.

Power steering control apparatus

An improved steering apparatus includes a piston and cylinder type motor having a hollow piston rod extending out of one end of a motor cylinder. Since the piston rod extends out of only one end of the motor cylinder, the working area on the head end of the piston is greater than the working area in the rod end of the piston. The head end working area is exposed to fluid pressure during turns in one direction and the rod end working area is exposed to fluid pressure during turns in the opposite direction. A compensator chamber is provided in the hollow piston rod. The compensator chamber has a working area on the rod end of the piston. The compensator chamber working area is exposed to fluid pressure during turns in both directions. The size of the compensator chamber working area is equal to the cross sectional area of a tubular wall of the piston rod. Since the compensator chamber working area is the same size as the cross sectional area of the piston rod and is on the rod end of the piston, exposing the compensator chamber working area to fluid pressure during turns in both directions tends to equalize the steering forces in both directions.

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Lafayette, IN, United States of America

William T Rabe