What Leonardo da Vinci machine used a crank and gears to move itself without an external animal?

Leonardo da Vinci designed a self-propelled cart driven by springs, gears and a steering mechanism.

The cart appears in drawings from the late fifteenth century and is often described as an early ancestor of the automobile or robot. Two large, wound leaf springs supplied stored energy. As the springs unwound, gearing transferred motion to the cart’s wheels, allowing it to travel without a horse or person pushing it.

A programmable feature was built into the steering system. Pegs placed on one of the wheels could determine the cart’s path, making it possible to set a turn in advance. The design may have been intended for theatrical performances at court rather than transportation.

Leonardo’s drawings do not show every construction detail, and scholars debate some aspects of the mechanism. Even so, the cart clearly demonstrates a Renaissance attempt to store mechanical energy and release it through controlled motion.