This type of bearings is separable, which can only carry axial load. The single direction bearings of them can only carry axial load in one direction, while the double can carry alternat-ing axial load in either direction. Before using they have to be preloaded. The thrust ball are used in lathe centers, automobile clutches, reducer and so on. The double direction angular contact thrust ball bearings are suitable for machine toll spindles, while the single are used to support ball screws.