GB389857A - Improvements in or relating to variable speed power transmission mechanisms - Google Patents

Abstract

389,857. Variable-speed friction gearing. HAYES, F. A., Middletown Township, New Jersey, U.S.A. Sept. 25, 1931, No. 26796. Convention date, Oct. 9, 1930. [Class 80 (ii).] In variable-speed gearing comprising toric discs such as 10, 11, Fig. 2, connected by planetary or other rollers which are tilted to vary the speed, each roller consists of two roller elements 14, 15 side by side capable of tilting to different angles. The capacity of the gearing is doubled with the number of rollers. In order that the rollers 14, 15 should transmit the same speed ratio, the geometrical ratio R<1>/R<2> should be equal to the ratio R<3>/R<4>, and therefore the rollers must be inclined at different angles and have conical engaging surfaces. The rollers are mounted so that they automatically take the correct relative positions and to this end use is made of " precession " as described in Specification 254,341, [Class 80 (ii), Gearing, Variable-speed &c.], in which the rollers precess on spiral tracks on the discs. Considering a single roller 14a, Fig. 3, if this roller is shifted bodily up from the plane of the figure, it will be caused by inherent frictional forces to rock counterclockwise on an axis perpendicular to its axis of rotation. The pair of rollers 14, 15, Fig. 2, precess in like manner automatically to positions of equilibrium at different angles. The rollers 14, 15 of a pair are mounted so that they can rock relatively to each other on the apexes A, Fig. 5, of their conical inner surfaces. The carrier for a pair of rollers is in two parts 32a, 32b, Fig. 4, which meet at their middles A and at both ends on knife-edges B, permitting the relative rocking. In the arrangement shown, precession is initiated by displacing angularly a helical gear 23 as described in Specification 380,485. A carrier bracket 25 is turnably supported in arcuate shoes 26 shiftable in guides 28 in a fixed housing 22, and on the bracket is a helical gear sector 30 engaging the gear 23. In the end of each bracket arm is a spherical recess containing a hemispherical balancing lever 31. Between the two hemispheres is the split carrier 32a, 32b. The rollers 14, 15 are mounted on studs 33, 34, Fig. 6, pinned in the carriers and meeting in a knife-edge A aligned with knifeedges B on the carriers. The stud 34 has a projecting end 35 forming a key connection with the bracket 25. Assume the disc 10 is turning anticlockwise and a control arm 20 is swung in the same direction. The bracket on the right is tilted clockwise with the shoes 26 so that the roller 15 is raised and the roller 14 depressed, the carrier halves sliding on their contacting knife-edges. The rollers begin to precess counterclockwise, as seen from above. The resulting rocking of the bracket 25 causes the sector 30 to glide through the inclined teeth of the sector 23, so screwing the bracket back from its tilted to its vertical position. At the same time, the roller 15 descends and the roller 14 rises, the hemispheres 31 equalizing the action. The rollers thus float in the bracket, precessing independently to different angular positions of equilibrium transmitting the same speed ratio between the toric discs.