Leonardo da Vinci designed a ball-bearing arrangement to reduce friction between moving parts.
A ball bearing places hard spheres between surfaces so that rolling replaces much of the sliding friction. Leonardo’s sketches show balls arranged within a ring or raceway, an arrangement recognizably related to later bearing designs.
The idea did not immediately become a standardized industrial component. Suitable materials, manufacturing precision, lubrication, and reliable assembly were needed before ball bearings could be produced economically and consistently. Modern bearings therefore developed through later engineering advances rather than emerging fully formed from Leonardo’s drawing.
The bearing should not be confused with a gear, which transmits motion through toothed wheels, or a pulley, which redirects force using a wheel and rope. Leonardo’s concept addressed friction reduction and support for rotation.