Leonardo da Vinci’s studies of friction included an early ball-bearing design.
His sketches show balls placed between surfaces so that one part could move with rolling contact rather than sliding contact. Rolling reduces friction because the contact points continually change, making movement easier than rubbing two flat surfaces together.
The design is often described as an early ball bearing, but Leonardo did not create the standardized, mass-produced bearings used in modern machines. His notes explored the principle and showed how it could be applied to rotating mechanisms. Later engineers refined cages, races, materials, lubrication, and manufacturing methods.
A roller bearing uses cylindrical rollers rather than spherical balls, while a flywheel stores rotational energy. Leonardo’s contribution belongs to the long history of friction reduction, linking Renaissance mechanical observation with modern machine design.