Some uses of ball bearings

The purpose of a ball bearing is to determine the relative position of two parts (usually a shaft and a housing) and to ensure their free rotation, while transferring the load between them. At high rotational speeds (eg in gyro ball bearings) this use can be extended to include free rotation with little to no wear in the bearings. To achieve this state, the two parts of the bearing are separated by an adhesive fluid film called an elastohydrodynamic lubricating film. Denhard (1966) pointed out that the bearing can maintain elasticity not only when the bearing is loaded on the shaft, but also when the bearing is preloaded so that the positioning accuracy and stability of the shaft do not exceed 1 microinch or 1 nanoinch Hydrodynamic Lubricating Film.
Ball bearings are used in a variety of machines and equipment that have rotating parts. Designers often have to decide whether a ball bearing or a fluid film bearing should be used for a particular application. The following characteristics make ball bearings more desirable than fluid film bearings in many applications,
1. The starting friction is small and the working friction is suitable.
2. Can bear radial and axial joint load.
8. Insensitive to interruption of lubrication.
4. No self-excited instability phenomenon.
5. Easy to start at low temperature.