In terms of its role, it should be a support, that is, a literal interpretation used to support the axis, but this is only part of its role, supporting its essence is to be able to bear the radial load. It can also be understood that it is used to fix the shaft. Bearing quick and easy excellent automatic selection is included. It is the fixed shaft that allows it to rotate only and control its axial and radial movement. Motors do not work at all if they do not have bearings. Because the shaft may move in any direction, the motor requires that the shaft only rotate when it is working. Theoretically speaking, it is impossible to achieve the role of transmission, not only that, the bearing will also affect the transmission, in order to reduce this effect in the high-speed shaft bearings must achieve good lubrication, and some bearings have lubrication, called pre-lubricated bearings, and Most bearings must have lubricating oil, responsible for high-speed operation, because friction will not only increase energy consumption, but more terrible is that it is easy to damage the bearings. The idea of turning sliding friction into rolling friction is one-sided because there is something called sliding bearings.