ABSTRACT
A major problem in dynamic machinery occurs due to friction, which causes loss of energy. From the viewpoint of sustainability considerations, this is a major challenge. It has been estimated that from one-third (1/3) to one-half (1/2) of all the energy produced in the world is wasted in friction. Friction may be defined as the opposing force that is developed when two surfaces move relative to each other. Lubrication reduces the friction developed, but it has its own pitfalls; lubricants, which may be in the liquid, solid, or gaseous state, can be toxic and hazardous to health. Plain bearings, as distinguished from rolling-element bearings, are usually classified as plain journal or sleeve, thrust, spherical, pivot, or shoe-type thrust. Sometimes, bearings are classified based on the type of lubricant used. A hydrodynamically lubricated bearing is one that uses a fluid lubricant (liquid or gas) to separate the moving surfaces completely. When this ideal condition is attained, it is commonly called a thick film. Other commonly used terms for this type of lubrication are fluid film, stable, or perfect. Bearings are essential components of practically all systems, ranging from automobiles to CD players to industrial production machinery. Virtually any application involving moving elements contains one or more bearings.
