Leonardo da Vinci sketched a ball bearing designed to reduce friction between moving parts.
His notebooks include a ring-shaped race containing balls that could roll as the surrounding parts moved. Rolling contact creates less resistance than sliding contact, so the arrangement could help machinery turn more smoothly. Leonardo’s drawing is generally dated to the late 15th or early 16th century.
The idea was not the first human use of rolling elements, and Leonardo did not create the modern industrial ball bearing. Ancient and earlier machines used rollers and related principles. His importance lies in clearly recording a compact bearing arrangement during the Renaissance.
Modern ball bearings use carefully manufactured races, balls, cages, and lubrication. Leonardo’s sketch lacks the precision and manufacturing systems required for modern mass-produced bearings, but it shows a sophisticated understanding of mechanical friction.