Rolling-element bearing

Imagine you have a toy car with wheels. Each wheel has a little ball inside it that helps it roll smoothly. These balls are called rolling-element bearings. They're like tiny little helpers that make sure the wheels on your car don't get stuck or wobble around too much. The balls are usually made of metal, and they're held in place by a special cage that keeps them separated and evenly spaced. When the wheel turns, the balls roll around in the space between the cage and the inner and outer parts of the wheel. This rolling motion helps the wheel move smoothly and without much resistance, so your toy car can zip around and have fun! Rolling-element bearings are used in all kinds of machines and vehicles to make them run smoothly and efficiently.