Abstract: A rotary valve having chamfers (26,39) at the groove edges (31) of its input shaft (10) which, in conjunction with axially extending troughs (44), form metering edge contours. The chamfers (26,39) and troughs (44) at the edges (31) of the grooves (18a,18b) interacting with sleeve slots (19) to reduce valve hiss and linearise the boost characteristic of the valve.

Abstract: Apparatus for machining an angularly disposed array of slots (FIG. 7) concentric with the axis (85) of a bore of a valve sleeve (1) which has a sleeve holder (3) which is rotatably indexed for locating the arcuate position of each slot of the array, a cutting tool (5) positioned on the apparatus to cut a slot in the bore of the sleeve at each indexed location and a boring device (80, 81, 82, 83, 90) for forming the bore co-axially with the array of slots; the operation of the cutting tool (5) and boring device (80, 81, 82, 83, 90) taking place while the sleeve (1) is mounted in the one orientatioln in the holder (3).

Abstract: A core for a rotary valve for a power steering system having in its periphery a plurality of blind ended longitudinally extending slots separated by lands for use in a sleeve member having in its bore a similar array of longitudinally extending blind ended slots matching those of the valve core but in an underlap relationship thereto, the slots of one being wider than the lands of the other so defining a set of longitudinally extending orifices which open and close when relative rotation in either direction from a neutral position occurs between the valve core and the sleeve in which at least two sets of valve core edges have along a substantial portion of their length a contour which extends substantially parallel to the core axis characterised in that the contour comprises in section a continuous curve wherein, at points near the high operating pressure zone thereof, it has a large radius of curvature and lies substantially parallel to the valve core periphery and wherein at a point along the curve approach

Abstract: A rotary valve (1) for hydraulic power steering of vehicles with arcuate slots (9,10) in the sleeve (2) and slots (11) in input-shaft (3) of the valve (1) where some of the slots (10) in the sleeve (2) are formed to provide hydraulic fluid return ports (13) axially of the valve (1) between the sleeve (2) and the input-shaft (3) while the axial extent of adjacent sleeve slots (10) and input-shaft slots (11) is the same at their ends remote from the return ports (13).

Abstract: A die for forming a Y-form rack portion of a steering rack bar from a blank by forging in which the die has at least three forming elements (44, 47, 48) relatively movable on application of forging pressure to the die to converge on a blank therein, a first of the forming elements (44) having in its cavities the shape of which corresponds to the shapes of the teeth to be formed, second and third forming elements (47, 48) having forming faces to form longitudinal guide faces (4, 5) on the Y-form rack portion on the side thereof opposite the teeth (8). The three forming elements (44, 47, 48) are shaped and arranged to move together to converge on the blank to transform it into the final form in such a manner as to inhibit escape of the material of the blank between the first and second or first and third forming elements up to substantially the last instant of closure of the die.

Abstract: Apparatus for manufacturing a master rack which in turn is employed in the manufacturing of forging dies to form nonuniform tooth configuartion, which includes an EDM machine having upper and lower platens and mechanism for raising and lowering the upper platen, rack blank support mechanism arranged for longitudinal movement in the rack blank axis and mounted on the lower platen, an electrode in the form of a facsimile of a helical pinion rotatably mounted in bracket attached to the upper platen, mechanism for rotating the electrode intermittently, mechanism causing axial movement of the rack blank past the electrode in accordance with the rotational movement of the electrode, a cam coordinating the position of the electrode in relation to the axis of the rack blank, and a cam follower attached to the bracket and contacting the last-named cam.

Abstract: A die head for a roll imprinting machine for the imprinting of edges of grooves performed in a valve core for a rotary valve for use in a power steering gear, the die head supporting a circular cluster of radially disposed rolling die holders, each die holder carrying at an inner end an arcuate imprinting die and being mounted for partial rotation on a transversely extending axle, partial rotation of all said die holders being effected synchronously by action on each die holder at a position on the idle holder more remote from the inner end of the die holder than the position of the axle and a valve core locator arranged to locate and hold the valve core at the center of the cluster for roll imprinting by the imprinting dies in a synchronous relationship and apparatus for actuating the die head including a number of racks, one for each die holder, supported for reciprocating motion in engagement with sectors of gear teeth formed on the die holders, a work spindle extending along the central axis of the cluste

Abstract: A machine for cutting the teeth of a rack for a variable ratio rack and pinion steering gear employing a helical pinion having a plurality of identical teeth engaged with a rack having some tooth gaps of varying form and angular disposition to the rack axis, the machine having a spindle carrying a tool with a single cutting tooth having cutting edges which lie on the surface of a single tooth of the helical pinion; the spindle is arranged for helical reciprocation in a housing between two predetermined limits about a mid position in which the tool is directed normally to the plane of the teeth of the rack, a rack holding fixture, the fixture or the housing being moveable with a relative translatory curvilinear motion during the cutting of a gap of the rack, the motion for any one gap being a part of the locus of the helical pinion when slid without rotation in the same gap of the rack.

Abstract: A rack and pinion steering gear of the kind in which a helical pinion engages a rack mounted in bearings, the rack being supported opposite the pinion by a spring loaded half round support journal, the spring acting to hold the pinion in contact with the teeth of the rack which are formed in such a manner as to provide in about the center of the rack a "ramp" in which there are tooth gaps of varying height providing a variation of slack free mesh center distance between the pinion and the rack, the maximum mesh center distance occurring in the mid travel portion of the rack and lesser mesh center distances occurring in positions of travel of the rack either side of the travel position of the present invention being characterized by the fact that the tooth gaps concerned are formed in such a manner as to form a ramp extending across the rack at an angle substantially the same as the angle made by the pinion axis with the rack axis whereby the possibility of an uneven distribution of the load between the teeth

Abstract: A die for forming a Y-form rack portion of a steering rack bar from a blank by forging in which the die has at least three forming elements (44, 47, 48) relatively movable on application of forging pressure to the die to converge on a blank therein, a first of the forming elements (44) having in it cavities the shape of which corresponds to the shapes of the teeth to be formed, second and third forming elements (47, 48) having forming faces to form longitudinal guide faces (4, 5) on the Y-form rack portion on the side thereof opposite the teeth (8). The three forming elements (44, 47, 48) are shaped and arranged to move together to converge on the blank to transform it into the final form in such a manner as to inhibit escape of the material of the blank between the first and second or first and third forming elements up to substantially the last instant of closure of the die.