What Leonardo da Vinci machine used a coiled spring to power a moving cart?

Leonardo da Vinci’s self-propelled cart used coiled springs to power its movement.

Drawn around 1478–1480, the cart is often described as a predecessor of the automobile or robot. Two large spiral springs hidden in drums stored energy; gears transferred that energy to the wheels. A programmable steering system using blocks or pegs could make the cart follow a preset path, allowing it to perform at court ceremonies.

The cart had no fuel engine and carried no rider. Its motion came from stored mechanical energy, much like a large clock. Leonardo’s surviving sketch is incomplete, so historians and engineers have reconstructed different versions. A 2006 Italian reconstruction demonstrated that the basic mechanism could move.

This machine should not be confused with Leonardo’s later mechanical lion, another spring-powered automaton. The cart’s significance lies in combining energy storage, gearing and programmable steering in one compact design.