Bearings and bushings are machinery components that consist on a support, guide, or locating piece for a rotating oscillating, or sliding mechanical part. Their main function is improve efficiency, accuracy, service intervals, reliability and speed of operation thereby reducing costs of purchasing and operating machinery. These components depending of his design can resist thrust loading, radial loading, or a combination of both.

Exist two principal types of bearings: frictional bearing and roller bearing.

Bushings can be categorized into three groups depending of his lubrication system:

• Class I. Are bearings that require the application of a lubricant from an external source (oil, grease, etc.).
• Class II. This type of bearings contain a lubricant within the walls of the bearing (bronze, graphite, etc.). Typically these bearings require an outside lubricant to achieve maximum performance.
• Class III. Bearings made of materials that are the lubricant. These bearings are typically considered "self-lubricating" and can run without an external lubricant. Typical lubricants for this class are PTFE, graphite, etc.