Zahnradfabrik Friedrichshafen, Ag.

Zf Friedrichshafen Ag

Zf Friedrichshafen

Helmut Knodler

Armin Lang

Stefan Frohlich

Wilfried Leutner

Wolfgang Abele

Power steering gear intended in particular for motor vehicles

Servo-assisted steering system

Hydraulic steering arrangement

Control device for steering-rack equipped auxiliary power steering

Rack and pinion auxiliary steering mechanism, especially for motor

A compact power steering device is provided wherein the power steering valving is actuated by axial movement of a pinion having helical teeth engaging a rack in a steering housing. The valving utilizes head and seat valves with valve heads and coacting valve seats which are actuated on axes parallel to the pinion axis within the housing and requiring no more than the overall distance occupied by axial movement of the pinion as effected by rotation of a steering wheel during steering. Opposed springs effect a centered position for the pinion in neutral position of the valving for straight ahead steering. Thus, a centering spring is dominant and limited in movement to fix the valving as biased by other springs to a precise neutral position.

Rack and pinion auxiliary power steering

Pressure agent control arrangement for auxiliary power steering

A hydraulic power steering system having an unbalanced piston servomotor and a pair of identical control valve pistons controlling flow of pressurized fluid to the servomotor for balanced directional displacement of the servomotor piston and to separately control depressurization of feedback chambers acting on the control valve pistons. Pressurized fluid is supplied directly to the feedback chambers from the servo-steering pump through flow restrictors, one of which is externally adjusted to select the degree of road sensing feedback generated to oppose manual actuation of the control valve pistons.

Hydraulic steering

An auxiliary fluid power steering device having a servomotor (8) and a control valve (13) in a common steering gear housing (1). In order to relieve the control valve of axial pressure forces, the valve body (14) of the control valve has four surfaces (24, 25, 26, 27) of equal area respectively exposed exclusively to fluid in the inlet port (22), in the outlet port (23), in one of the servomotor pressure chambers (9) adjacent the control valve and in the other pressure chamber (10) of the servomotor.

Axial thrust compensating means for power steering control valve

Growing community of inventors

Lorch, Germany

Helmut Knodler