Leonardo da Vinci sketched a ball bearing using spheres between moving surfaces.
Around 1498, Leonardo produced drawings showing balls arranged so that two surfaces could move with less friction. The idea is generally recognized as an early ball-bearing concept. Instead of allowing surfaces to slide directly against each other, the balls would roll between them.
Leonardo’s sketches also explored cages or separators to keep the balls from crowding together. Modern bearings use carefully manufactured rolling elements, races, lubrication, and precise tolerances, so Leonardo’s drawing was an important concept rather than a modern finished component.
Ball bearings later became essential in clocks, machines, vehicles, and industrial equipment. Leonardo’s work is often mentioned in histories of bearings because it demonstrates a clear understanding of rolling friction. It should not be confused with the invention of every later bearing design, which developed through many engineers and manufacturers.