Leonardo da Vinci sketched a ball bearing arrangement that helped inspire the modern ball bearing.
In his studies of friction, Leonardo explored ways to keep moving surfaces apart by placing balls between them. The principle is simple: rolling contact generally creates less resistance than sliding contact. His drawings show an early attempt to make the balls move without bunching together, a practical issue in any bearing design.
Leonardo’s sketch should not be treated as proof that he invented the complete modern bearing industry. Standardized manufacturing, hardened materials, precise races, and reliable lubrication developed much later. His contribution was an early documented study of rolling elements and friction reduction.
Ball bearings are now used in machines ranging from bicycles to electric motors. They support rotating shafts while reducing energy lost to contact between moving parts.