What Leonardo da Vinci machine used a spring-powered cart to move without a person pushing it?

Leonardo da Vinci designed a self-propelled cart powered by wound springs.

Drawn around 1478 to 1480, the cart used two large coiled springs hidden inside its body. The springs drove the wheels through a system of gears, allowing the vehicle to move forward without an animal or visible driver. Steering could be set in advance with wooden blocks placed on a control system.

The machine is sometimes described as an early automobile, although it was not an automobile in the modern sense. It carried no engine, had limited stored energy, and was intended primarily as a theatrical or ceremonial device. Some reconstructions suggest it may have been used to create a dramatic entrance at a court event.

The surviving design is incomplete, so details of its exact operation remain debated. In 2006, engineers at the Museo Nazionale della Scienza e della Tecnologia in Milan built a working reconstruction based on Leonardo’s drawings. The cart is also called Leonardo’s self-propelled cart.