Leonardo da Vinci drew a ball bearing using rolling spheres between two surfaces.
In studies made around 1498, Leonardo explored ways to reduce friction between moving parts. His bearing concept used balls positioned between rings or surfaces so that rolling replaced much of the sliding contact. This arrangement is recognizable as an early ball-bearing design.
The principle is simple but powerful: rolling resistance is generally lower than sliding friction. Bearings allow shafts and wheels to rotate more efficiently, which is essential in machines ranging from bicycles to turbines. Leonardo’s sketch shows that he understood the value of separating moving surfaces with rolling elements.
Leonardo did not invent every bearing concept, and his drawing was not necessarily manufactured or standardized. Modern ball bearings usually include precisely shaped races, cages, seals, and hardened steel or ceramic balls. The Renaissance design is best described as an early recorded proposal rather than a commercial bearing.