Leonardo da Vinci is often credited with sketching an early ball-bearing principle for reducing friction. His design placed balls between moving surfaces so the parts could roll rather than slide directly against one another.
The idea appears in Leonardo’s studies of mechanical elements and dates to the late 15th century. Rolling contact can reduce sliding friction, making rotation easier and helping machinery operate more efficiently. Leonardo also considered cages or separators to keep the balls apart, an important feature in later bearing designs.
Leonardo did not invent the modern industrial ball bearing in its complete form. Reliable mass-produced bearings emerged much later through advances in materials, manufacturing, lubrication, and precision. His drawings are significant because they show an early understanding of the mechanical advantage of rolling elements.