GB194161A - An automatically operated change speed gear - Google Patents

Abstract

194,161. Lechenaux, L. J. March 28, 1922. Variable-speed gearing of the kind comprising eccentrically-displaceable discs such as 1, 7 connected by pawls or hooks such as 5 is rendered automatic. In the application to a bicycle shown in Figs. 4 and 5, the disc or rim 1 is driven by a chain 2 from the pedal axle 4. This disc 1 turns upon a non-revoluble boss 12 supported on a spring-pressed lever arm 15. The hooks 5 are pressed by springs 10 against the toothed edge of the disc 7, which is secured to the hub of the road wheels 8. A spring 18 tends to hold the disc 1 in the position of maximum eccentricity transmitting the highest speed. As the tension in the chain 2 increases, the spring 18 yields, the disc 1 moves towards the disc 7, and the ratio decreases. A jockey pulley 20 is held in position by a detent 26 which is released by backpedalling. In a modification, the controlling spring is damped by fluid adjustably throttled. In the case of sub-normal speeds, the teeth of the disc 7 are screened by masks 33, 34, Fig. 6, so as to use the hooks 5 when moving at the speed required. The opening between these masks is controlled automatically by pins 35, 36 adapted to move in fixed grooves. In a form shown in Fig. 8, a screen 37 is formed so as to yield speeds above and below normal, and nodrive. Applications to machine tools and to hoisting-apparatus are mentioned.