ABSTRACT
Wide variety of unique tribological systems with their peculiar attributes and performance requirements are in use in all kinds of machineries. Likewise sliding bearings are prominent in high volume items such as low-cost electric motors, home appliances, and farm machinery. There are many types of rolling element bearings as may be seen by consulting the sales brochures of bearing makers. On the other hand, custom-built or low-production equipment and machinery often have rolling element bearings throughout. The lead and babbitt bearing materials are used mostly in low speed and lightly loaded machinery. Thrust loads can also be carried on sliding bearings, but there must be tilting pads to capture lubricant. Three main modes of failure on gear are connected to lubrication. These are wear, contact fatigue and scuffing. The predominant failure mode is dependent on the tooth contact conditions, the gear material, surface finish and texture, the lubricant properties and supply, as well as the operating environment.
