What did Leonardo da Vinci’s self-propelled cart use to store mechanical energy?

Leonardo da Vinci’s self-propelled cart used coiled springs to store mechanical energy.

Drawn around 1478 to 1480, the cart is often described as an early programmable machine or the ancestor of the modern automobile. Two large leaf springs beneath the vehicle could be wound to provide power, while gearing transferred that energy to the wheels.

A steering system and programmable cams helped determine the cart’s path. The design may have been intended for theatrical performances, court spectacles, or ceremonial events rather than transportation. It did not use an engine, fuel, or electricity.

The cart is sometimes called Leonardo’s robot, although that label is broader than the original object. In 2006, engineers built reconstructions and demonstrated that the design could move. Its importance is the combination of stored mechanical power, gearing, and programmed motion.