Which Leonardo da Vinci invention was a self-propelled cart powered by wound springs?

Leonardo da Vinci’s self-propelled cart was a spring-powered vehicle designed to move without being pushed or pulled.

Leonardo sketched the cart around 1478–1480, making it one of his early mechanical designs. Two symmetrical leaf springs stored energy, while a system of gears transferred that energy to the wheels. A steering device could be set in advance, allowing the cart to follow a predetermined route rather than being driven by a person.

The cart was probably intended for theatrical or ceremonial effects, perhaps to surprise an audience or carry a figure onto a stage. It was not an automobile: it had no engine, pedals, brakes, or steering wheel. A full-scale reconstruction displayed in 2006 demonstrated that the basic mechanism could work. Because the surviving drawings are incomplete, reconstructions necessarily involve interpretation, but the spring-powered principle is clear.