Thrust ball bearings are separable, which support only axial load. One-direction thrust ball bearings only carry axial load, while twp-direction thrust ball bearings carry alternating load from two directions. Thrust ball bearings are normally used in machine tool spindles and must be preloaded in operation, one-direction thrust angular contact ball bearings for ball screws, two-direction thrust angular contact ball bearings for spindles in grinders, lathes, milling and drilling machines, especially for precision spindles when matched with double-row roller bearings.