Hydraulic auxiliary power steering, especially for motor vehicles

Claim 1

In a power steering control device of the kind having a housing (9) with a steering spindle having a first section (1) and a second section (2), said sections being relatively rotative and connected by a torque rod (8) wherein the first section is for connection to a manually operated steering wheel to receive steering force and the second section is for mechanical connection to vehicle wheels, said sections having a coacting inner (3) and outer (4) valve sleeves for operation of a servomotor (7) having pressure chambers connecting to respective passages (14, 15) of said outer sleeve to be pressurized responsive to relative rotation of said steering spindle sections, including a steering reaction means responsive to operating pressure in said pressure chambers for simulating steering resistance; the improvement wherein: the steering reaction means comprises a reaction piston (18) carried coaxially on said first spindle section (1) and reaction chambers (20, 21) in said housing with the faces of said reaction piston exposed in respective reaction chambers; means whereby either reaction chamber receives pressure during operation of said servomotor so as to shift said reaction piston; helical gearing (22) intermediate said reaction piston and said first section of said steering spindle; a sliding keyway (25) intermediate said reaction piston and said second section (2) of said steering spindle to prevent relative rotation therebetween; whereby pressure acting on either face of said reaction piston is operative to shift said piston and thereby effect a rotative torque force on said first section of said steering spindle through said helical gearing to oppose steering force on said first section, simulating steering resistance.