What spring-powered machine did Leonardo da Vinci design to move without animals?

Leonardo da Vinci designed a spring-powered self-propelled cart that could move without animals.

The cart used coiled springs to store energy, much like the mechanism of a clock. Cams and other mechanical parts translated the spring’s unwinding into wheel movement and steering. The surviving drawings are associated with Leonardo’s studies of automata and mechanical engineering in the late 15th century.

The vehicle is often called a precursor to the automobile, but that description needs care. It was not powered by an internal-combustion engine, and it was not a road vehicle intended for ordinary transport. Its short, controlled movement was better suited to a theatrical or ceremonial setting.

A full-scale replica built in the 21st century demonstrated that the mechanism could operate when constructed according to the drawings. The cart is distinct from Leonardo’s armored vehicle: the armored design was a military machine, while this spring-powered cart was an automaton-like device.