This type of bearings is separable, which can only carry axial load. The single dirction bearings of them can only carry axial load in one direction, while the double can carry alternation axial load in either direction. Before using they have to be preloaded. The thrust ball bearings are used in lather centers, automobile clutches, reducers and so on. The double diretion angular contact thrust ball bearing s are suitable for machine toool spindles, while the single are used to support ball screws.