Linear Motion Bearings

Linear Motion Bearings

Linear motion bearings are able to simultaneously bear loads and direct linear motion. There are four main categories of linear motion bearings: sliding contact linear motion bearings, rolling element linear motion bearings, hydrostatic or aerostatic linear motion bearings, and magnetic linear motion bearings.

Sliding contact linear motion bearings, also known as plain or journal bearings, carry a load by sliding. Due to their construction, they tend to produce more friction than other types of bearings. This aspect makes them less useful for precision work, although certain low-friction polymers make this type of bearing practical for an increasing number of applications.

Rolling element linear motion bearings, of which linear ball bearings and linear roller bearings are varieties, are far more accurate than sliding contact bearings. Because of their accuracy, low cost, and availability, these bearings are used in a variety of applications.

Hydrostatic or aerostatic linear motion bearings are used in applications requiring a great deal of precision. In hydrostatic or aerostatic bearings, the load is carried by a pressurized liquid which completely separates the two surfaces. These bearings are typically more costly and difficult to implement than rolling element bearings. As a result, they are usually only used in precision work.

Magnet linear motion bearings use magnetic forces from an electromagnet to keep one of the surfaces afloat. Because of the energy expenditure, this type of bearing has very limited applications. However, since they do not need lubrication or wear down from friction, these bearings are useful in clean environments such as semiconductor manufacturing.