Improvements in or relating to steering gears particularly for motor vehicles

摘要

1,073,477. Cam steering mechanisms. ZAHNBADFABRIK FRIEDRICHSHAFEN A.G. Aug. 4, 1964 [Aug. 3, 1963], No. 31413/64. Heading F2K. In a vehicle steering gear comprising a globoidal worm 2 engaged by an annularly toothed roller 3 rotatably mounted in a cavity 261 in a steering shaft 21, the roller is displaced about the worm axis S by an angle (α), (Fig. 1, not shown) from a plane (EE) containing the worm axis and normal to the rocker arm axis (W), and, when the steering gear is in the central position, the roller axis R is displaced relative to a plane FF containing the rocker arm axis (W) and normal to the worm axis S by by an angle #1 about an axis (MN), (Fig. 3, not shown) contained in the plane FF and normal to the rocker arm axis (W), the point M being the centre of the cavity 261, and the roller centre M1 is offset along the roller axis a distance m from the point M so that the roller maintains correct mesh with the worm as the rocker arm is turned from the centre position. The pitch circle envelope curve of the worm has a greater radius than the pitch circle envelope curve of the roller. The roller has needle bearings and is spaced from the walls of the cavity 261 by bearing washers (29), (Fig. 2, not shown). The roller may have an integral or separate spacer ring (39 (Fig. 6, not shown) at one end. The flank angles of the outer flanks of the asymmetrical tooth profiles of the toothed roller are about 2 degrees smaller than the angles of the worm flanks co-operating therewith, and the flank clearance between the outer flanks of the roller tooth profiles and the worm flanks cooperating therewith is in the range 0.1 to 0À5 mm., the flanks of the roller teeth and/or the profile of the worm being generally straightsided with a convex portion adjacent the tip.