What transport device did Leonardo da Vinci design as a four-wheeled self-propelled cart?

Leonardo da Vinci designed a four-wheeled self-propelled cart powered by coiled springs.

The drawing, made around 1478–1480, shows a compact vehicle with a front steering arrangement and two large springs concealed inside its body. As the springs unwound, gears would transfer their force to the wheels. The cart may have been intended for theatrical performances or court spectacles rather than practical transportation.

It is often called Leonardo’s self-propelled cart, and sometimes described as an early robot because it could move without a person visibly pushing it. That label can be misleading: it was an automaton-like machine, not a programmable modern robot. Leonardo’s notes do not provide a complete surviving construction manual.

A full-scale reconstruction was built in the 21st century using the surviving drawings. The vehicle’s design demonstrates Leonardo’s understanding of springs, gearing, steering, and compact mechanical power, even though it did not use an engine.