| Summary: | 碩士 === 國立雲林科技大學 === 機械工程系 === 104 === A multi-speed transmission hub is one of key components in transmission systems of bicycles. It is a mechanical speed-changing device with several advantages, such as: compact size, high efficiency, long lifetime, high stability and available to change speed when the bicycle is stopped. The purpose of this study is to develop magnetic gear-shifting mechanisms for multi-speed transmission hubs for bicycles. Four different transmission hubs, including a Sturmey-Archer 7-speed transmission hub, a Sturmey Archer 8-speed transmission hub, a Shimano 7-speed transmission hub, and a Shimano 8-speed transmission hub, are introduced. The configurations of gear mechanisms and related mechanical gear-shifting mechanisms for these transmission hubs are introduced. The mechanical components, clutching sequence table, and the operation principle of the gear-shifting mechanism for each transmission hub are also analyzed. A design process for the implementation of magnetic gear-shifting mechanisms of multi-speed transmission hubs is proposed. Three examples including 5-speed, 7-speed, and 9-speed transmission hubs are presented to illustrate the embodiment design of related magnetic gear-shifting mechanisms associated with transmission mechanisms. Finally, a 5-speed transmission hub with a magnetic gear-shifting mechanism is manufactured and tested.
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