Simplest automatic LEGO transmission in the world? Really functional. Principle explained. - YouTube
This Remarkably Complex Lego 5-Speed Transmission Video Is A Great Way To Learn Transmission Basics - The Autopian
Someone Made a Working Six-Speed Gearbox Out of Legos
The greatest gearbox
Amazon.com: LEGO Technic COMPLETE GEARBOX ASSEMBLY 2 x 4 x 3 1/3 Trans-Clear Wormbox gear motor REDUCER block Mindstorms robotics ev3 NXT transparent robot building power functions part 6588
LEGO Technic 4 Speed Forward Transmission Gearbox -car truck NXT EV3 - new parts | eBay
Amazon.com: LEGO Technic COMPLETE GEARBOX ASSEMBLY 2 x 4 x 3 1/3 Trans-Clear Wormbox gear motor REDUCER block Mindstorms robotics ev3 NXT transparent robot building power functions part 6588
LEGO MOC 6-speed sequential gearbox by Whathetech | Rebrickable - Build with LEGO