GB224449A - Improvements in toothed gearing - Google Patents

Abstract

224,449. Holdener, S. March 17, 1924. Variable-speed epicyclic gearing of the type in which an eccentric planet wheel has two or more toothed faces engaging with corresponding concentric surfaces on other members. The teeth employed are of circular arc form, or the teeth of the larger of two interengaging wheels are partly formed as circular arcs and partly straight. Fig. 16 shows a rim 9a on the eccentric planet wheel 9 gearing with a rim 8 concentric with the shaft 1. The required tooth dimensions are set out along the pitch circle T of the rim 9<a> and points P, P<1> are selected equidistantly from the pitch point N as the points of intersection of the surfaces of a tooth O with the pitch circle. With centres P and P<1>, arcs R, R' are drawn with radii equal to that of the pitch circle T to cut the circle at S and S<1> respectively. The surfaces both of the tooth 0 and of the teeth X in the rim 8 engaging with the tooth 0 are struck with the points S and S' as centres. The faces above the pitch circle, however, of the teeth X may lie along the tangents W, W<1> from the points P, P<1> to a circle Q concentric with the circle T and of half its radius. A circle T<2> is drawn concentric with the rim 8 and contains the centres of the faces of all the teeth on the said rim. In the form shown in Fig. 1, a planet ring 9 loose on an eccentric 2 on the shaft 1 carries external teeth gearing with a stepped casing 4 coaxial with the shaft 1 and formed as a pulley, toothed wheel, &c. and also carries external or internal teeth gearing with a sleeve 10 loose on the shaft 1. Any of the parts 1, 4, 10 may drive, either of the others be held stationary, and the third constitute the driven member. Fig. 5 shows a three speed and reverse gear for automobiles. The planet wheel 9 loose on the eccentric 2 on the driving-shaft 1 carries four sets of teeth gearing with a drum 12' on the driven shaft 12 and with drums 10, 13, 14, which can be braked to provide two forward speeds and a reverse, a clutch (not shown) connecting the drum 12<1> and eccentric 2 for solid drive.