What wheeled machine did Leonardo da Vinci sketch as a self-propelled cart?

Leonardo da Vinci sketched a self-propelled cart, an early design for a vehicle that could move without being pushed or pulled by an animal.

The cart appears in Leonardo’s Codex Atlanticus and is generally dated to the late fifteenth century. Its motion came from coiled springs hidden inside the frame. When released, the springs transferred power through gears to the wheels, allowing the cart to travel forward.

A steering mechanism could be set before the cart began moving. That feature made the design useful for theatrical displays, where it might carry scenery or perform a programmed movement. It was not an automobile in the modern sense: there was no combustion engine, driver’s seat, or continuously adjustable steering.

Because the original machine has not survived, reconstructions are based on the drawing and on interpretations of its mechanism. The cart is often called the world’s first self-propelled vehicle, although similar claims depend on how “vehicle” and “self-propelled” are defined.