The purpose of the ball bearing is to determine the relative position of the two parts (usually the shaft and the bearing seat) and to ensure their free rotation, while transmitting the load between them.
At high speeds (such as in gyro ball bearings), this use can be extended to include free rotation with almost no wear in the bearing. In order to achieve this state, an adhesive fluid film called an elastohydrodynamic lubricating film can be used to separate the two parts of the bearing.
Denhard (1966) pointed out that the elasticity can be maintained not only when the bearing bears the load on the shaft, but also when the bearing is preloaded so that the positioning accuracy and stability of the shaft does not exceed 1 microinch or 1 nanoinch. Hydrodynamic lubrication film.
