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Showing posts from February, 2018

Split-ring compound epicyclic/planetary gearboxes

A while ago, I came across this strange thing called ‘split-ring compound epicyclic/planetary gearboxes’. They seemed really nice, extremely high gear ratios in compact, stackable modules. But the already existing models were not enough. I wanted to be able to design my own, and due to the lack of information on the subject, I had to do a little research and some math. Here is most of what I would have liked to find on the first place: 1. What is a planetary gearbox? Planetary gearboxes, as their name says, resemble planets orbiting around a “sun”. They are composed of a sun gear, in the center, two or more planet gears around it -and often fitted to a carrier- and a ring/annulus gear on the outside. As an image is worth a thousand words: Source Their main feature is a high reduction ratio in a small, flat space, and also, it is easy to couple the output of one gearbox to the input of another one, getting a two or more stage gearbox with such a high reduction ratio. But where is the i