Leonardo da Vinci drew a ball bearing as a mechanical component for reducing friction between moving surfaces.
His notebooks contain sketches of balls placed between rings, allowing one surface to rotate more freely against another. The idea is commonly dated to the late 15th century and is one of the earliest known designs for a modern-style rolling-element bearing.
A ball bearing works by replacing sliding contact with rolling contact. The balls sit between inner and outer races, reducing resistance and helping support radial or axial loads. Leonardo’s drawings show that he understood the value of separating moving surfaces with rolling bodies.
The sketch was not a mass-produced industrial bearing. Modern bearings require precise materials, cages, lubrication, and manufacturing tolerances. Leonardo’s design is important as an early mechanical concept, not as the complete technology used today.