What moving device did Leonardo da Vinci sketch as a four-wheeled, spring-powered cart?

Leonardo da Vinci sketched a self-propelled cart powered by coiled springs.

The four-wheeled mechanism appears in drawings from the late fifteenth century. Large leaf springs stored energy, while a system of gears and control mechanisms transferred that energy to the wheels. A steering arrangement also allowed the cart to follow a programmed path rather than simply travel in a straight line.

The cart is often called an early automobile, but it had no engine and was not designed for carrying passengers over long distances. It was closer to a clockwork automaton: a machine that could move through stored mechanical energy. The design may have been intended for theatrical effects or court entertainments.

Because Leonardo left drawings rather than a confirmed surviving original, details of its operation have been reconstructed by engineers and historians. In 2006, a working replica was built in Italy and showed that the basic mechanism could move as intended. The cart is therefore a notable example of Renaissance automation.