I’ve posted a number of wind turbine ideas to this blog that have chain or belt drives, so I want to dedicate this post to a multi-speed drive for these turbines. It’s too hard to draw chains, so the diagram below illustrates the idea using belts and pulleys:
The purple wheels are behind the yellow wheels. Each set of coaxial orange and green wheels are mounted on the same shaft. The green wheels engage the front belt, and the orange wheels engage the rear belts. The diagram shows all three sets of coaxial (orange and green) wheels engaging the two belts at the same time, but this is just for the sake of clearly illustrating the geometric relationships. In reality, only one set of coaxial (orange and green) wheels would be lowered down until they engage the two belts, and the other two sets of coaxial (orange and green) wheels would be raised up a little so that they do not engage the belts.
I guess this drive might be useful for other applications, such as for a multi-speed drive for a bicycle.