Ball bearings are a type of bearing which use balls to separate the moving components. Bearings allow moving parts to work and bear weight. Ball bearings are used in all sorts of common products including inline skates, luggage wheels, and computer hard drives. Giant ball bearings are even used in some kinds of earthquake-proofing for modern buildings.
In General
Ball bearings work to make something spin. They are found in many different applications, and although the ball bearing itself is just a round metal ball, the appearance of a set of bearings can look vastly different from one application to another. Some are just ball bearings rolling free in bearing cups, some are in sealed setups that look more like a donut than a bearing, and some are hidden from view altogether, such as those in a fishing pole or bicycle wheel.
The Bearing
A ball bearing is a round, metal ball that works in unison with other bearings of the same shape and size to allow a spinning motion. They come in many different sizes, from extremely tiny to very large. Most bicycle wheel bearings are about the size of a green pea, for reference. Ball bearings actually roll around in their enclosure, which allows the object they are in to spin. Normally, the mechanism that ball bearings roll around in is called a race.
Lubrication
Ball bearings are used in many different things as a way of preventing friction. They are used in between two objects as a way to move one item over the other without creating excess wear and tear. Ball bearings are exactly what they sound like. They are balls and because of their shape, they create less friction than something that is flat or has edges. Edges tend to dig in or scrape against other edges. The roundness of ball bearings allows them to roll with the objects.
Friction causes heat, and steel ball bearings rolling around (sometimes at a very high rate of speed) are no exception. The most common cause of ball bearing failure is heat. If the bearing set is exposed to the elements, the combination of hot and cold weather mixed with rain and dew can break down the lubrication fast. This could cause the ball bearings to rust, preventing them from spinning freely. To combat the heat monster and vastly prolong the life of the bearings and the race, lubrication is needed. Keeping a bearing set well-greased exponentially cuts down on the heat caused from friction. Different lubricants are used in different types of bearings, so be sure you use the correct grease for the application.
