Which description best defines a plain bearing?

• A. A bearing with rolling elements such as balls or rollers.
• B. Consists of a simple bearing surface without rolling elements.
• C. Uses magnetic repulsion to locate the shaft.
• D. Operates using fluid bearings with a film.

Answer: (B)

Plain bearings are sliding bearings with a simple bearing surface and no rolling elements. The load is carried by the sliding contact between the bearing surface (like a sleeve or bushing) and the shaft, typically with lubrication to reduce friction and wear. This is different from bearings that use rolling elements (balls or rollers) to carry the load, magnetic bearings that support the shaft without contact, or fluid-film bearings that rely on a lubricating film to separate surfaces. Because a plain bearing lacks rolling elements, the description that best defines it is a simple bearing surface without rolling elements.