What type of vehicle did Leonardo da Vinci sketch with four wheels and a spring-powered drive?

Leonardo da Vinci sketched a four-wheeled self-propelled cart with a spring-powered drive.

The cart’s design is one of Leonardo’s clearest studies of stored mechanical energy. Large coiled springs, comparable in principle to clock springs, were wound before operation. As the springs unwound, gears transferred the energy to the wheels. A steering system allowed the cart to follow a predetermined path rather than simply roll in a straight line.

Because the cart moved without an onboard animal or person pushing it, it is often described as an early automobile. That comparison is useful but limited. The machine did not have an internal-combustion engine, fuel tank, or passenger cabin. Its likely role was theatrical: it could enter a stage or court space as an apparently autonomous object.

The cart also illustrates Leonardo’s habit of adapting mechanisms from clocks and military engineering. Modern reconstructions have shown that the basic spring-and-gear system is mechanically plausible, although the original was never found.