What are bearings?
A bearing is a machine element that constrains relative motion to only the desired motion, and reduces friction between moving parts. The design of the bearing may, for example, provide for free linear movement of the moving part or for free rotation around a fixed axis; or, it may prevent a motion by controlling the vectors of normal forces that bear on the moving parts.
Most bearings facilitate the desired motion by minimizing friction. Bearings are classified broadly according to the type of operation, the motions allowed, or to the directions of the loads (forces) applied to the parts.
Bearings are highly engineered, precision-made components that enable machinery to move at extremely high speeds and carry remarkable loads with ease and efficiency. Bearings must be able to offer high precision, reliability and durability, as well as the ability to rotate at high speeds with minimal noise and vibration.
Bearings are found in applications ranging from automobiles, airplanes, computers, construction equipment, machine tools, DVD players, refrigerators and ceiling fans. If something twists, turns or moves, it probably has a bearing in it.