Internal gears or Ring gears are cylindrical disks which have involute shaped teeth cut into their interior face. KHK's stock internal ring gears are designed for use in planetary gear trains and are suitable wherever you require high-speed reduction. including speed reducers and other industrial machinery. Our internal ring gears are offered in carbon steel, with many configurations of modules and numbers of teeth. All of the internal ring gears that we offer allow for secondary operations such as opening the adding of tapped holes.