Thrust ball bearing is separable , which can only carry axial load . The single direction Thrust ball bearing of them can only carry axial load in one direction , while the double an carry alternating axial load in either direction . Before using Thrust ball bearing have to be preloaded. The Thrust ball bearing are used in lathe centers , automobile clutches, reducers and so on . The double direction angular contact Thrust ball bearing are suitable for machine tool spindles , while the single direction angular contact Thrust ball bearing are used to support ball screws .