What Leonardo da Vinci invention used a spring to move itself without an animal pulling it?

Leonardo da Vinci's self-propelled cart used springs to move itself without an animal pulling it.

Leonardo designed the cart in the late 15th century, probably for theatrical performances or court spectacles. Two large, coiled springs stored energy, while a system of gears transferred that energy to the wheels. Adjustable mechanisms could control the distance traveled and help the cart follow a planned path.

The machine is sometimes described as an early automobile, but that comparison can mislead. It had no engine, fuel system, or steering wheel like a modern car. Its motion came from wound springs, making it closer to a large clockwork device.

The original drawing is preserved in Leonardo's codices, and modern reconstructions have demonstrated that the mechanism can move. The exact intended use is uncertain, but stage machinery is a leading interpretation because Leonardo worked on elaborate court entertainments.