What propulsion method did Leonardo da Vinci’s self-propelled cart use?

Leonardo da Vinci’s self-propelled cart used wound springs for propulsion.

Leonardo designed the cart around 1478 to 1480, making it one of his earliest mechanical devices associated with self-directed movement. The springs stored energy when wound, then released it through a system of gears and cams. The cams regulated the motion so that the vehicle could follow a programmed path rather than simply roll freely.

This mechanism made the cart fundamentally different from a horse-drawn wagon. It also did not use steam, gasoline, electricity, or an internal-combustion engine. The machine was probably intended for entertainment or ceremony, perhaps carrying scenery or appearing to move on its own during a performance.

Because Leonardo’s surviving drawings are incomplete, reconstruction details vary. Nevertheless, the use of wound springs is central to the accepted interpretation. The cart is often called an early robot or automobile, but those labels are modern comparisons rather than names Leonardo used.