Which Leonardo da Vinci design used a spring-powered mechanism to move a cart without horses?

Leonardo da Vinci’s spring-powered cart design was a self-propelled cart.

Leonardo sketched the mechanism around 1478–1480, making it one of his earliest known mechanical designs. Wound springs inside the cart stored energy, while a system of gears and cams converted that energy into controlled wheel movement.

The cart was probably intended for theatrical displays rather than practical transport. It could travel a predetermined distance, and its steering arrangement may have allowed it to follow a set path. The design is sometimes described as an early robot or automaton because it could perform a programmed movement without a driver.

Leonardo did not build a surviving full-size original. In 2006, a reconstruction in Florence demonstrated that the mechanism could work. It is often confused with Leonardo’s later mechanical lion, which was a walking ceremonial automaton rather than a wheeled vehicle.