Anti-Friction Bearings

Anti-friction bearings, also called rolling contact bearings, are not widely used in the engine proper. They are used more prevalently in the transmission and drivetrain. Nonetheless, they are found in several engine components such as alternators and water pumps. Their primary function is to support a rotating shaft. Figure 5.1 shows a selection of types of anti-friction bearings.

Anti-friction bearings offer very low coefficients of friction. Furthermore, some types are able tosupport axial (thrust) loads in addition to the radial, or shaft, loads. Deep groove ball bearings can support small thrust loads. Tapered roller bearings are specifically designed to support significant thrust loads; hence, they are used as wheel bearings. The rollers or balls are made of hardened, high carbon chromium alloy steels, and their construction is somewhat complicated. Furthermore, these bearings do not handle shock loads very well, and their performance is greatly reduced by the presence of dirt. Thus, anti-friction bearings must be well sealed to keep in the lubricant and keep out dirt and other contaminants.