Cam Gears Limited

Trw Cam Gears Limited

Peter R Rogers

David H Allen

John Whitney

A variable ratio rack has a linear array of teeth. The teeth in the linear array are disposed at a plurality of final tooth angles. In order to form the rack, a linear array of teeth is cut in a workpiece. The teeth in the linear array of cut teeth have a tooth angle which is less than the largest tooth angle of the plurality of final tooth angles and greater than the smallest tooth angle of the plurality of final tooth angles. After the linear array of teeth has been cut in the workpiece, the cut teeth are deformed to have tooth angles corresponding to the final tooth angles.

Method of forming a rack member

This invention relates to methods of making valve sleeves. The valve sleeve 35 is manufactured from a tube 10 which is initially placed on a mandrel 20, which is formed with axially-extending projections 23 spaced about it circumferentially. The tube is then swaged on to the mandrel to form grooves 28, which have the shape and the dimensions of 23. The mandrel 20 is then replaced by a cylindrical mandrel 30 and the open ends of grooves 28 are then closed by a further swaging operation. This method enables valve sleeves, having stopped axially-extending grooves in their inner surface with accurately located lips, to be formed from a single piece of metal.

Method of making valve sleeves

A rack and pinion gear assembly 10 (FIG. 1) includes a resilient bushing which urges the rack into meshing engagement with the pinion. An arcuate inside bearing surface 54 (FIG. 4) of the bushing 18 has a larger radius of curvature than the curved outside surface 52 of the rack 12 against which it bears. The rack thus makes tangent contact with the bushing 18. When one portion of the bushing 18 is worn and therefore excessive play appears in the steering gear assembly 10, the bushing may be removed from the housing 16 of the assembly and rotated 180.degree. and then reinserted into the housing to thereby provide an unworn bearing surface which slidably engages the rack 12. The bushing 18 includes a plurality of axially extending grooves 70, 72, 74, and 76 through which lubricant is supplied to the bearing surfaces 52 and 54. In a second embodiment (FIG. 5) the aperture 50b in the bushing 18b through which the rack 12b extends has a square cross section and is in tangent contact with the rack at two locations 84 and 86. In a third embodiment (FIG. 3) the aperture 50c in the bushing through which the rack 12c extends is composed of four arcuate segments 100, 102, 104, and 106 each having the same radius of curvature, and each having a different center of curvature 110, 112, 114, and 116, respectively. This provides tangent contact between the rack 12c and the bushing 18c at two axially extending areas 120 and 122.

Rack and pinion gear assembly

A ball joint comprises a housing having a bore. A ball is received in the bore. Means is provided to restrain the ball against withdrawal from the bore and another means restrains the ball against excessive penetration into the bore. The housing material is recessed at the region of the bore on which the ball bears in its restrained position. The recess receives a bearing annulus of synthetic plastics material having low friction and good wearing characteristics.

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Chepstow, United Kingdom

Peter R Rogers