| 摘要 |
The invention relates to a pedal-crank drive for two- and multi-wheeled vehicles, in particular bicycles, the crank arms of which are connected to the commercially available chain drive in such a manner that the effective length of a crank is considerably larger during the downwards pedalling than during the upwards movement. This is intended to exploit the fact that the rider can exert a stronger force on the pedal crank during its downwards movement than during the upwards movement of the same for an increase in the torque which can be generated during the downwards movement. By means of the invention, the pedal-crank drive is intended to be of such a design that only the front crank semicircle with extended lever arm be available for exerting the torque whereas the rear crank semicircle is completely free of torque and passed through quickly. This object is achieved by virtue of the fact that the pedal crankshaft (6) is divided and the two coaxial pedal crankshafts (6) which, in the direction of travel, lie before the shaft (13) of the large sprocket wheel (10), are mounted in a carrier (1) attached to the front oblique tube (3) of the frame, at least one pedal crankshaft (6) being connected via a crank (7) having a sliding piece (8), which engages in a profile rail (9) attached diametrically to the sprocket wheel (10), to the conventional chain drive. <IMAGE>
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