This 3 speed automatic transmission was built out of Legos. The transmission is driven mechanically, as there is no motor or external device required to change gears. It works using a spinning wheel that contracts and expands. The spinning wheel is connected to a gear shaft that moves between 3 states. At rest, a rubber band holds the spinning wheel fully contracted. As the car’s wheels speed up, the centripetal force required to keep the spinning wheel contracted exceeds the force of the rubber band, causing the spinning wheel to expand. So as the spinning wheel increases speed, it expands and the gears are shifted.

The gear ratio for first, second, and third gear are respectively 1:2, 18:25, and 2:1.

Watch the video above to see it in action.