1.Selection of bearing types by speed A. Ball bearings have higher limit speed and rotation accuracy than roller bearings, so ball bearings should be preferred at high speeds. B. Under the condition of the same inner diameter, the smaller the outer diameter, the smaller the rolling body, and the smaller the centrifugal inertia force added by the rolling body to the outer raceway during operation, so it is suitable for working at a higher speed. Therefore, at high speed, bearings with smaller outer diameters in the same diameter series should be selected. If a bearing with a smaller outer diameter is used and the bearing capacity cannot meet the requirements, the same bearing can be installed in parallel, or a wide series of bearings can be considered. C. The material and structure of the cage have a great influence on the bearing speed. Solid cages allow higher speeds than stamping cages, and bronze solid cages allow higher speeds. Generally, in the workplace with high speed, deep groove ball bearings, angular contact bearings and cylindrical roller bearings should be used; Tapered roller bearings can be used in low-speed work situations. The limit speed of tapered roller bearings is generally about 65% of deep groove ball bearings, 70% of cylindrical roller bearings, and 60% of angular contact ball bearings. Thrust ball bearings have a low limit speed and can only be used at lower speeds. 2.Factors Affecting Bearing Speed The factors that affect the limit speed of the bearing include the size of the applied load; the direction of the force; the type of lubricant, the amount of lubricant; the manufacturing accuracy of the bearing, that is, the tolerance level of the bearing and the size of the bearing clearance. In addition, depending on the type and grade of lubricant, it may be superior to other properties but not suitable for high-speed rotation. The factors of the limit speed of the bearing are related to the type, load, precision, size, lubrication, clearance, cage and cooling conditions of the bearing. However, the most important factor is the allowable operating temperature or lubricant of the bearing material.