| 摘要 |
The system, which is especially applicable to a bicycle, incorporates means for supporting an endless chain 9, for actuation, which are capable of expansion or contraction, with combined variation of diameter, depending on the torque applied to the actuating shaft 11. It comprises individual plates 1, 2 wedged on the front shaft 11 and on the rear shaft 12 with toothed wheels 1a, 2a, of smaller diameter, which are superposed, free to rotate and engage with the toothed ends 3, 4 of respective levers 5, 6 which are radial and articulated to said first plates, urged by respective springs 7, 8 arranged inversely, those of the plate coaxial to the actuating shaft 11 in front and those of the other plate 2 behind, in the direction of forward motion of the vehicle, so that they act in combined form on the levers in accordance with whether said levers, via their other ends which are provided with teeth 5a, 6a, engage with the endless chain 9. <IMAGE>
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