What land vehicle did Leonardo da Vinci design with three wheels and a hand crank?

Leonardo da Vinci designed a three-wheeled self-propelled cart operated by stored spring power.

The cart appears in drawings from the late 15th century. Its mechanism used coiled springs to provide motion, while a system of gears controlled the wheels. Two front wheels supported the vehicle, and a smaller rear wheel helped balance it.

The design is often called Leonardo’s self-propelled cart. Because its springs could be wound before operation, it is sometimes described as an early programmable machine: pins on the control system could determine the route or movement. It was not powered by steam or an internal-combustion engine.

The cart’s original survival is uncertain, and no contemporary record proves that Leonardo built it. In the 20th century, museum researchers and engineers constructed working models from his drawings, demonstrating that the mechanism could move.