| 摘要 |
The invention relates to a drive hub for six speeds, with an integral back-pedal brake device (28, 31) for bicycles or the like. The gear system comprises two separate planetary gear units (5b, 6a, 7b and 16, 26, 27 respectively), each of which comprises one stage and of which a primary gear unit (5b, 6a, 7b) is incorporated in the drive member (5), while a secondary gear unit (16, 26, 27) is disposed in the hub sleeve (1). The coupling elements (2, 3, 23 29) of the drive hub are constructed in such a manner that lost motion positions are avoided both during driving and during braking. During braking the torque flow is always guided through the secondary gear unit (16, 26, 27) in the hill speed position by means of separate detents (23) which come into operation only during the backward rotation of the drive member (5), so that the back-pedal brake is operated with a stepped-up brake force.
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