Rex Engineering gearmotors are in stock at these two fine distributors.
search "electric motors Rex"
Prepare to drive yourself crazy!
Try "Gears", the on-line game.
Here is some fascinating history about
advanced gearing in the ancient world. Read up on the Antikathera
mechanism... and be amazed!
This site will direct you to a stocking
distributor in your area who carries valve actuators
search "gearmotor", then click "AC gearmotor"