GB439540A - Improvements in and relating to change speed gears for cycles - Google Patents

Abstract

439,540. Variable-speed ratchet gearing. VINCENZONI, A., 30, Viale del Vignola, Rome. March 11, 1935, No. 7530. Convention date, March 9, 1934. [Class 80 (ii)] A cycle-driving chain-wheel 12 is adjusted eccentrically relative to the pedal-shaft 2, for speed increase or reduction, the variable drive being effected through transmission links 23, pivoted near the periphery of the chain-wheel, and pivotally carrying at their inner ends, friction pawls 25, adapted to wedge in an annular groove in a disc 5, secured to the pedal-shaft 2. In order to provide for speed reduction, the pawls 25 are only allowed to assume a wedging position during part of the upper arc of their travel, a stationary cam 28, Fig. 7, being provided to engage lateral projections 26 on the pawls, so as to tilt them, against spring-bias 27, into an idle position for the remaining arc. The chain-wheel is rotatably mounted on a ball-bearing 11 in a chain-case 9, which, when the chain wheel is adjusted, swings about a pivot 10, near the rear hub of the cycle and is guided by forward posts 16, hinged to the cycle frame. Adjustment is effected by turning a hinged bolt 20, screwing through a lug 19, pivotally carried by the chain case 9. For cycles having back-pedalling hub brakes, there is a disc 29, rotating with the pedal-shaft and bearing, through balls, against inclines on a stationary disc 31. When the pedal-shaft is reversely rotated, the balls ride up the inclines, forcing the disc 29 axially, so as to apply pressure, through a spring disc 7, against the pawls 25, thereby holding them against the disc 5 and providing for a reverse transmission to the back-pedal brake. There is a small permanent horizontal eccentricity between the chain wheel and pedal-shaft.