What are sliding bearings?

A bearing is a friction component that carries a load when it is in contact with and moves relative to another part. The motion can be sliding or rotating. There are two types of bearings: plain bearings and rolling bearings. Other types of bearings include fluid bearings that support their load on a thin layer of gas or liquid; magnetic bearings that use a magnetic field to carry the load; hinge-like flexure bearings, in which the load is supported by a flexure element; and jewel bearings used in clocks and watches.

Plain bearings, also called bushings, sleeves, or sleeve bearings, are usually cylindrical and contain no moving parts. Standard configurations include cylindrical bearings for radial loads, flanged bearings for radial and light axial loads, thrust washers and flanged washers for heavy axial loads, and sliders in various shapes. They can also be custom-designed to include special shapes, features (deep grooves, oil holes, notches, protrusions, etc.), and sizes. Plain bearings are used for sliding, rotating, oscillating, or reciprocating motion. In sliding applications, they are used as plain bearings, bearing strips, and wear plates. In these applications, the sliding surface is usually flat, but can also be cylindrical, and the motion is always linear, not rotating. Rotating applications involve cylindrical surfaces and one or two directions of travel. Oscillating and reciprocating applications involve flat or cylindrical surfaces but travel in both directions. Sliding bearings can be solid or split (wound bearings) for easier installation. It is important to match the bearing to the application. High loads require bearings with larger contact areas and high load-carrying capacity. Bearing designs with solid lubricants can operate at higher temperatures than oil/grease-lubricated bearings. High-speed applications require special lubricants to minimize heat build-up and friction. Sliding bearings are manufactured with different constructions and the choice of product depends on the operating conditions and performance requirements of the application.