GB662724A - Improvements in power assisted steering mechanisms - Google Patents

Abstract

662,724. Fluid-pressure servomotor control systems; fluid-actuated valves. BENDIX AVIATION CORPORATION. Oct. 12, 1949 [Nov. 17, 1948] No. 26241/49. Class 135. A servo-assisted steering gear comprises a piston 48 having a rack 54 coacting with a gear quadrant 56 connected to the steered members and a screw-thread connection 44, with a rotatable and axially movable steering column 38, the latter carrying spaced discs 98, 100 for actuation of valves 20, 22 upon axial displacement of the column. The steering column is centred by coned spring washers 124 which are pre-loaded to permit of direct manual actuation of the piston through its screwed connection with the column if the resistance to movement is low. In the event of high resistance the column is displaced so that one of the discs 98, 100 operates one of the valves. Thus the disc 98, when displaced to the right moves a valve seat member 91 which normally permits communication between a chamber 52, to the right of the piston, and a reservoir 12 through a conduit 66, a passage through a tubular valve member 101, a chamber 74 and a conduit 72. Such movement of the member 91 interrupts this communication and subsequently moves the valve member 101 away from a fixed seat 78 to permit passage of pressure liquid from an accumulator 18 through a conduit 24 and the conduit 66 to the chamber 52. The consequent movement of the piston recentres the steering column. The valve 22 is similar to the valve 20 and directs pressure liquid to a chamber 50 upon displacement of the steering column in the opposite airection. A spring-loaded valve 132 prevents the formation of a partial vacuum in the pressure supply conduits 24, 26 should the steering gear be operated during a failure of the supply pressure.