Leonardo da Vinci studied a ball bearing using rolling spheres to reduce friction.
Leonardo’s notebooks include designs in which balls move between surfaces so that one part can rotate with less sliding friction. The arrangement is an early form of a ball bearing, a machine element that separates moving surfaces with rolling bodies.
Rolling contact generally produces less friction than direct sliding contact. Leonardo’s studies recognized this mechanical advantage, although his sketches did not create the standardized, sealed bearings used in modern machines.
The idea was part of Leonardo’s wider work on mechanical transmission, gears, axles, and motion. His bearing studies are often linked to a rotating platform or similar mechanism. Later engineers refined bearing geometry, materials, lubrication, and manufacturing, turning the basic principle into a crucial component of vehicles and machinery.