Leonardo da Vinci’s early ball-bearing design used balls to reduce friction between two rings.
Leonardo illustrated a ball-bearing mechanism in the late 15th century. The design placed balls between an inner and outer ring so the rings could rotate with rolling contact rather than sliding directly against each other. This arrangement is the basic principle behind many modern bearings.
His drawing is often cited as an early ball-bearing concept, but it was not a complete modern bearing. Leonardo recognized that the balls needed to remain separated, and his sketches include a cage-like arrangement to prevent them from bunching together. Manufacturing accurate, durable bearings required later advances in metalworking and precision engineering.
Ball bearings reduce friction, but they do not eliminate it. The balls and races still deform slightly and require suitable materials and lubrication. Leonardo’s design is significant because it clearly expresses the rolling-element principle centuries before industrial production made such bearings widely practical.