This orbital reduction box uses only 19-tooth and 20-tooth gears, and achieves a reduction ratio of about 10 : 1 (and, unlike many planetary gearing arrangements, does NOT use an internal ring-gear).
I originally needed it to demonstrate the compactness of this arrangement for use in an electric starter project I am working on for Indian Motocycles.
It was such fun as a toy that I made this cut-away version, for visitors and friends to fiddle with, when they visit.
7.116 w x
6.6 d x
2.802 w x
2.598 d x