Andrew Gorman
Cruisin' on my Bluebird
A lot of people- myself included have had a hard time wrapping our brains around how planetary gearbox/hub like a Sturmey Archer hub actually works. Here is a US Army training film from 1953 that does a good job of explaining how planetary gears work on a tank transmission which is just larger and easier to see than a bicycle hub. Basic mechanisms are explained well, although the method of locking parts is different. I hope other folks out there find it helpful- a tank transmission is not the first place I'd look for bicycle information, but there is always serendipity.