Which term describes a bearing in which the moving surface slides over a plain bearing surface with a lubrication film between them?

• A. Plain
• B. Ball
• C. Roller
• D. Needle

Answer: (A)

The moving surface sliding over a plain bearing surface with a lubrication film describes a plain (sliding) bearing. In this type, the faces slide against each other and a lubricant film—oil or grease—keeps them separated, which greatly reduces friction and wear. This is the hallmark of plain bearings, which are often bushings or sleeves made to ride on a lubricated surface.

The other options involve rolling elements, where small balls or rollers between inner and outer races carry the load. That means the contact is rolling, not sliding over a flat bearing surface, so they don’t fit the description of a plain bearing with a lubrication film between sliding surfaces.