Leonardo da Vinci designed a ball bearing using rolling spheres between surfaces to reduce friction.
His studies included a bearing arrangement in which balls moved within a cage-like structure. The rolling elements prevented the surfaces from rubbing directly against each other, allowing smoother rotation. This was a significant mechanical insight because friction was a central problem in machines, vehicles, and lifting equipment.
Leonardo’s design is often credited as an early ball-bearing concept, not as the first complete modern bearing manufactured to industrial standards. Modern ball bearings use carefully made rings, balls, cages, and lubricants, usually produced to precise tolerances. Leonardo’s sketches demonstrate the principle clearly, but surviving evidence does not show widespread production or use of his version during his lifetime.