What Leonardo da Vinci machine used stored spring energy to move without an animal pulling it?

Leonardo da Vinci’s self-propelled cart used stored spring energy to move without an animal pulling it.

Leonardo sketched the cart around 1478–1480. Two large, coiled leaf springs stored energy, while a system of gears and cams controlled the wheels. The cart was probably intended for theatrical or ceremonial use rather than ordinary transport.

The design could travel along a predetermined route because adjustable blocks controlled the steering. That feature has led some writers to describe it as an early programmable vehicle, although the term refers to its mechanical control rather than to electronic programming.

The cart was not an automobile in the modern sense. It had no combustion engine, battery, or motor. In 2006, the Istituto e Museo Nazionale della Scienza e della Tecnologia in Milan built a working replica, helping researchers study how Leonardo’s mechanism may have operated.