GB1112225A - Improvements in or relating to power steering mechanism - Google Patents

Abstract

1,112,225. Power-assisted vehicle steering. BENDIX CORPORATION. 16 Sept., 1965, No. 39661/65. Heading B7H. In a power-assisted steering mechanism including within a housing 24 an hourglass worm 14 with a stepped bore 17 which accommodates one end of a rotary open-centre valve 48 and extends almost to the bottom of a cam track 16 engaged by a follower 20 connected to an output member 26, the valve 48 controls fluid flow to a steering motor or ram 38 and comprises a pair of nested relatively rotatable tubular elements 56, 58 the inner element 56 being externally grooved and formed on an input member 12 and the outer element 58 being internally grooved and secured to the worm 14, the input shaft 12 being connected to the worm by a loose spline coupling 117 permitting limited relative rotation, which is resisted by a torsion bar 114, between the valve elements 56, 58. Pressure fluid supplied through an inlet 60 in the housing 24 flows through axial bores 89 and 91 of the worm and the input shaft and through radial passages 98 to the interior of the outer elements 58 wherein the external grooves 68, 70 of the element 56 and the internal grooves 76, 78 of the element 58 co-operate to selectively direct fluid, in the neutral valve position, along the grooves 70, and a chamber 72 at one end of the valve to an exhaust outlet 62 or, on relative rotation of the valve elements, either through radial passages 96, an external annulus 88 of the element 58 and a passage 44 to one end of the steering motor 38 or through radial passages 94, a ball race 18, the interior of the worm housing and a port 46 to the other end of the steering motor 38. The element 58 is angularly adjustable relative to the worm 14 by rotation of a screw 104 with an eccentric spherical head and vibration of the element 56 is suppressed by an O-ring 107.