Cycloid gears are used in roots-style superchargers. I learned about the shape back in college when I thought I was going to build one from scratch. https://e

Cycloid gears are used in roots-style superchargers. I learned about the shape back in college when I thought I was going to build one from scratch. https://en.wikipedia.org/wiki/Roots-type_supercharger https://en.wikipedia.org/wiki/Roots-type_supercharger