| 摘要 |
A variable ratio transmission for a bicycle or other purposes includes an automatically controlled variable diameter sprocket 12 comprising a rotary support disc 101 carrying a number of pivoted arms 102, two of which have toothed sectors 104 while the remainder have smooth sectors 105, the arms being interlocked to move in unison inwards and outwards. They are urged outwards by mechanical spring units 109 or gas accumulators 174 and the movement is controlled either by adjustable brakes 118, which are preferably unidirectional, or by crank operated brakes 131 under the control of the foot cranks 127. The position of the chain contact elements is also controlled automatically by a ratchet detent mechanism 152 and an hydraulic damper 157 and wear in the brakes is compensated automatically by the rotary ratchet mechanism 158,159. |
