Which Leonardo da Vinci invention was a four-wheeled vehicle driven by gears and springs?

Leonardo da Vinci’s self-propelled cart was a four-wheeled vehicle driven by coiled springs and gears.

Leonardo designed the cart in the late fifteenth century. Two symmetrical springs stored energy, while a system of gears transferred that energy to the wheels. A steering mechanism could set the cart to follow a predetermined path, making it more like a programmable machine than a modern automobile.

The vehicle may have been intended for theatrical effects at court, rather than transportation. Leonardo’s notebooks do not provide a complete surviving construction record, so modern reconstructions have been important in understanding how the mechanism might have worked.

The cart is sometimes described as an early robot because it could move without a person pushing it and could be arranged to follow a set course. It was not powered by an engine or fuel; its motion came from stored mechanical energy in the springs.