What powered the moving mechanism in Leonardo da Vinci’s self-propelled cart?

Leonardo da Vinci’s self-propelled cart was powered by coiled springs.

Leonardo designed the cart around 1478–1480. Two leaf springs, wound in advance, stored mechanical energy and released it through a system of gears. The mechanism could drive the cart forward, while a steering arrangement allowed its path to be set in advance. This made it an early example of a programmable or automatically moving machine.

The cart was not an automobile in the modern sense. It had no engine, fuel tank, pedals, or driver’s controls. Its motion came from stored spring energy, much like a large clockwork toy. Reconstructions have shown that the design could operate, although surviving drawings leave some mechanical details open to interpretation.

The cart is also sometimes described as a robot. That is broader than its original role: it was a vehicle-like automaton, not a human-shaped machine. Leonardo’s later mechanical lion and knight belong to the same wider tradition of Renaissance automata.