GB464664A - A transmission variable speed gearbox applicable to pedal operated cycles - Google Patents

Abstract

464,664. Change-speed gearing. NEW, D. Aug. 11, 1936, No. 22060. [Class 80 (ii)] A three - speed gear suitable for cycles is operated by back-pedalling half a turn and manually moving a countershaft 7 towards and from a pedal shaft 2. Keyed at 3<1> on the shaft 2 is a toothed wheel 3 with through pins 6 upon which slide outer toothed wheels 4, 5 biassed outwards by springs 13, 14. Mating wheels 8, 9, 10 are fast on the shaft 7 which is mounted in a sliding box 40 which can be raised and lowered of Fig. 1 by a manual control 11. Keyed on the shaft 2 are two bosses 18 each with a finger 17 projecting inwardly against a cam sleeve of which there are two, 15, 15<1>. The parts are shown in highspeed position, the drive passing through the pair 3, 10, then on through a chain from a sprocket 30 and through a toothed pair which causes the road wheel to turn in the forward direction of pedalling. The sleeves 15, 15<1> are allowed to turn freely forwards by detent pawls 28. To change to middle speed, the box 40 is lowered until the wheel 5 slips left into mesh with the wheel 9, the wheel 4 being held at its inner position by its overlap of the wheel 8. To bring in low speed, the box 40 is lowered until the wheel 4 slips right into the position of Fig. 2 so as to drive the wheel 8. To return to high speed, the pedals 47 are given a half turn backwards which causes the fingers 17 to cam the sleeves 15, 15<1> both inwards so as to thrust the wheels 4, 5 together against the wheel 3. The pawls 28 have held the sleeves 15, 15<1> against backward turning so that the fingers 17 can thrust them axially. The box 40 is then raised to bring the pinion 10 into mesh with the wheel 3 as shown. By a combination of momentary back-pedalling and sliding of the box 40, any speed can be engaged.