Leonardo da Vinci designed an early ball bearing to reduce friction between moving parts.
His Codex Atlanticus contains a sketch of balls arranged between rings, allowing one component to rotate while the balls roll instead of the surfaces sliding directly against each other. This is the basic principle of a ball bearing: rolling contact can greatly reduce friction compared with sliding contact.
Leonardo’s bearing was part of his wider interest in machines, including gears, pulleys, and rotating mechanisms. The design also tried to prevent the balls from bunching together, an important practical issue in bearing construction.
The sketch is often described as an early ball-bearing design, not as proof that Leonardo invented every later form of bearing. Modern bearings use carefully manufactured materials, cages, lubrication, and precise tolerances. Leonardo’s drawing nevertheless shows a clear understanding of a mechanical solution that remains central to engines, wheels, turbines, and many other machines.