Leonardo da Vinci drew a ball bearing using balls positioned between two rings.
His sketches from the late fifteenth century show rolling elements designed to reduce friction between moving parts. The balls were intended to keep surfaces apart so that motion would involve rolling rather than direct sliding contact.
Leonardo’s bearing concept is important because it illustrates his effort to understand friction mechanically. However, the drawing does not represent a complete modern bearing: it lacks some features needed to keep the balls evenly spaced and operating reliably under load.
Ball bearings later became important in machinery, bicycles, electric motors, vehicles, and industrial equipment. Leonardo is often credited with an early ball-bearing idea, but rolling bearings existed in simpler forms before his drawings. His contribution was a particularly clear Renaissance study of how enclosed rolling elements could improve mechanical movement.