Designed to support high-speed axial thrusts, NSK thrust ball bearings comprise flat washers which enclose the balls. Thrust ball bearings are classified into two families: flat or spherical housing washers. In all cases, no axial forces can be maintained. NSK thrust ball bearings can be single-acting or double-acting. The single type comprises two washers (shaft and housing) and a cage and ball assembly. The double version has three washers and two cage and ball assemblies (the two rows of balls are separated by the shaft washer).