The operating speed of rolling bearings mainly depends on their allowable operating temperature. Bearings with low frictional resistance and less internal heat are suitable for high-speed operation. When only bearing radial load, deep groove ball bearings and cylindrical roller bearings can be used to achieve higher speeds. If bearing combined loads, angular contact ball bearings should be selected. Using specially designed high-precision angular contact ball bearings, extremely high rotational speeds can be achieved. The rotational speeds of various thrust bearings are lower than those of radial bearings.