| 摘要 |
A drive wheel for pulling a chain has a diameter that can be changed continuously as the drive wheel rotates. The drive wheel has a drive shaft and there are at least 2 chain-engaging means (teeth or blades) positioned around the drive shaft for engaging a chain. The wheel has a number of modules that support the chain-engaging means and permit the chain-engaging means to move slightly in a circumferential direction a distance sufficient to engage the chain. Module locks prevent such movement when the chain is engaged, but permit it when the chain is not engaged. Extenders connect the modules to the drive shaft and can change the distance between the modules and the drive shaft while the drive shaft is rotating. Extender locks prevent the extenders from changing that distance when the chain is engaged but permit such change when the chain is not engaged. A transmission can be made by connecting the drive wheel to a sprocket wheel with a chain.
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