Leonardo da Vinci sketched a ball bearing using three interlocking spheres.
Leonardo studied the problem of friction and drew bearing arrangements around 1498. One design placed spherical elements between moving surfaces so that rolling, rather than sliding, would carry the load. Rolling contact can reduce friction, making machinery easier to move.
His sketch is often cited as an early ball-bearing concept, although it was not a standardized modern bearing. Leonardo’s arrangement included three balls and appears to have been intended to keep the spheres separated while allowing rotation.
Ball bearings later became essential in clocks, bicycles, motors, aircraft, and many other machines. Modern bearings use carefully manufactured steel or ceramic balls, races, cages, lubrication, and precise tolerances. Leonardo’s drawing did not create the complete industrial technology, but it clearly shows his interest in reducing friction through rolling motion.