The goal of a bearing is to provide relative positioning and rotational freedom while transmitting a load between two parts, commonly a shaft and its housing. The object of lubrication is to reduce the friction, wear, and heating between two surfaces moving relative to each other. This is done by inserting a substance, called lubricant, between the moving surfaces. The study of lubrication and the design of bearings are concerned mainly with phenomena related to the oil film between the moving parts. Note that tribology may be defined as the study of the lubrication, friction, and wear of moving or stationary parts. The literature on this complex subject is voluminous. Much is collected in the CRC Handbook of Lubrication, sponsored by the American Society of Lubrication Engineers [1]. Also see [2–4]. The website www.machinedesign.com includes general information on bearings and lubrication.