pic: Inside the torque multiplier

[Dick Linn]

The way the harmonic drives operate is explained here in detail: http://www.harmonicdrive.net/referen...ingprinciples/

This is an interesting explanation of how a multi-speed planetary transmission operates: http://www.railcar.co.uk/mechanical/gears/work.htm This was actually for a locomotive: http://www.railcar.co.uk/mechanical/gears/intro.htm

And this is a great animation. You can click the buttons and see the different modes of operation: http://www.mekanizmalar.com/transmission.html

[Richard Wallace]

I usually don't like to revive dead threads. However, when I saw a description of how hypocycloidal gearing works, it immediately reminded me of the lugnut remover. The animation in the link above seems to capture the operation of that gadget better than any of the previous explanations.