| 摘要 |
An automatic transmission for use on a bicycle is mounted on a bracket that is connected to the rear axle of the bicycle. A first chain connects the chain wheel with a sprocket fixed for rotation with the drive pulley of the transmission. A second chain transmits power from a sprocket fixed for rotation with the driven pulley to the rear wheel hub sprocket. A V-belt is used to transmit power between the driven and driven pulleys. Once a predetermined input torque is reached during pedalling, the transmission automatically changes the speed ratio between the chain wheel and the driven rear wheel of the bicycle. The gear ratio continues to change automatically and steplessly in response to increasing torque through the entire range of gear ratio change, which is approximately equal to the range provided by a standard ten speed bicycle. To selectively prevent the transmission from automatically changing the speed ratio, a hold system is provided. The hold system applies an axial force to lock the drive pulley in position, thus preventing further change in the speed ratio. The hold system can be actuated at any time during pedalling so that a desired speed ratio provided by the transmission may be maintained.
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