Abstract: A power-assist device for an automotive steering system employs an easy-to-assemble hydraulic pressure control valve to compensate for differential forces on opposite sides of an actuating piston in an unbalanced hydraulic cylinder. The piston divides the cylinder into first and second working chambers which are each connected to a hydraulic pump and a return reservoir via first and second spool valves, respectively. The spool valves are actuated axially by a torsion bar connected to the stub shaft of the steering column, so that they reciprocate axially within bores through the valve body as the steering wheel is turned back and forth. Lands on the spool valves oppose slightly larger lands the bores to define orifices which control the rates of hydraulic supply and drain to and from the working chambers of the cylinder.

Abstract: A rack-and-pinion steering gear structure for a vehicle including a rack housed within a cylinder and driven by means of a pinion shaft, comprises an annular piston received with suitable axial clearance in an annular groove defined by three surfaces, namely the end face of one end of the rack, a seating surface of a head of a bolt screwed into a boss projecting from the end of the rack, and the outer periphery of the boss itself. An elastic annular seal member is interposed between the inner periphery of the piston and the outer periphery of the boss.

Abstract: A rack-and-pinion steering gear structure for a vehicle including a rack housed within a cylinder driven by means of a pinion shaft, comprising: a bolt having a threaded portion screwed in a threaded hole formed in one end face of the rack and a shoulder linked integrally with the threaded portion and smaller in diameter than the rack but greater in diameter than the threaded portion; and a piston housed within a groove formed by the shoulder of the bolt, the seating surface of the bolt head, and the end face of the rack, with clearances with respect to the groove in the axial and radial directions.