Leonardo da Vinci sketched a ball bearing arrangement to reduce friction between moving surfaces.
In studies made during the late fifteenth century, Leonardo explored the use of round balls placed between rings or tracks. As the balls roll, they can reduce sliding friction, allowing one component to move more easily against another. His drawings show an early understanding of the principle behind rolling-element bearings.
Leonardo did not create the standardized, enclosed ball bearings used in modern machines. Manufacturing precise balls, races, cages, and lubrication systems required later engineering developments. The modern ball bearing became practical through industrial production and improvements in metallurgy and machine tools.
The idea is often credited to Leonardo because his notebooks contain unusually clear bearing sketches, but rolling supports were not entirely unknown before him. His importance lies in analyzing and documenting a useful mechanical arrangement. The design illustrates how his notebooks connected observation, geometry, and practical machine construction.