GB1112283A - Gear coupling - Google Patents

Abstract

1,112,283. Universal joints. SIER-BATH GEAR CO. Inc., and E. WILDHABER. 30 June, 1966, No. 29430/66. Heading F2U. In a. gear-toothed coupling, wherein internal longitudinally straight teeth 13 of a sleeve (12) engage external longitudinally convexly crowned teeth 15 of a hub (14), the crowning of the sides of the teeth 15 is increased adjacent both ends of said teeth by abruptly changing the radius of crowning curvature, to provide for abovenormal angularities, between the sleeve (12) and the hub (14), occurring under little or no. intended. load, e.g. on assembly. The top lands of the hub teeth are spherical. At maximum normal shaft angularity under full load the centre of the contact zone is at a point 24. The abrupt change in radius of crowning curvature starts at a point 30 which is spaced from the point 24 at about half the width of said contact zone centred at point. 24. The normal working portion, 30-30<SP>1</SP>,of the crowning may, as shown, be of approximately constant radius; may, Fig. 4 (not shown), be of gradually increasing radius from the centre (e.g. a hyperbola) so as to increase surface capacity with increasing angularity, to offset the decreased number of teeth in contact and increased sliding; or may, Figs. 5, 6 (not shown), comprise two branches intersecting at a central ridge (54), this form being for a coupling intended to operate at an angularity only. The inclination of the crowned tooth profile in planes perpendicular to the hub axis, and at points equidistant from the hub axis decreases from the tooth centre to the ends. The increased crown portions are widest adjacent the tooth root. The profiles at the centres of the external teeth crowns match those of the sleeve teeth, as shown, and. in Fig. 4 (not shown). The profiles of the central ridges (54) of Figs. 5, 6 (not shown), touch the corresponding sleeve teeth profiles only adjacent the roots of the latter, inwardly tapering surfaces connecting the otherwise intersecting branches being necessary if profile matching is required in this embodiment. The crowning is mechanically produced by uniform feed of a hob along the hub axis with an additional feed in the depthwise direction to obtain the resultant curved feed. This additional feed is controlled by a templet the ends of which may be cut off at an obtuse angle so as to produce, in co-operation with an arcuate abutment, the increased crowning. The profiles of the straight teeth 13 are concavely curved, e.g. involute. A seal (17) is provided for lubricant retention.