Leonardo da Vinci sketched a ball bearing as a friction-reducing machine part using rolling balls.
His late-15th-century studies explored how circular objects could roll between surfaces instead of sliding across them. That arrangement reduces friction and helps rotating parts move more smoothly. Leonardo’s drawing is often cited as an early conceptual design for a modern ball bearing, although practical bearing technology developed gradually over later centuries.
A ball bearing is not itself a complete machine. It is a component placed between moving parts, commonly between a rotating shaft and a surrounding housing. The balls carry loads while allowing rotation.
Leonardo did not invent the modern standardized bearing industry. His importance lies in recognizing and illustrating the mechanical principle centuries before mass-produced bearings became common in machines, bicycles, vehicles, and industrial equipment.