What power source drove Leonardo da Vinci’s self-propelled cart?

Coiled springs were the power source in Leonardo da Vinci’s self-propelled cart.

Leonardo’s cart design stored energy in two large springs. When wound, the springs could unwind and turn mechanical components. A system of gears connected that stored energy to the cart’s wheels, allowing the vehicle to move without an animal or a person supplying continuous force.

This detail matters because the cart is sometimes loosely described as an early car. It was not powered by gasoline, electricity, or steam. Its mechanism was closer to a large clockwork device, using stored mechanical energy rather than generating power continuously. The arrangement shows Leonardo applying familiar Renaissance clockwork principles to a wheeled vehicle.

The cart’s exact construction remains partly interpretive because Leonardo left a drawing rather than a complete modern engineering specification. Reconstructions have tested how the springs, gears, and steering could work together. They support the basic idea that a spring-driven cart was mechanically plausible, while leaving its intended use open to discussion.