This International Standard specifies preferred boundary dimensions for single-direction and doubledirection thrust bearings with flat back faces. In addition@ it gives the minimum bore diameters of housing washers and maximum outside diameters of shaft washers of bearings in dimension series 11@ 12@ 13@ 14@ 22@ 23 and 24. Guidelines for the extension of this International Standard for single-direction thrust bearings are given in Annex A. NOTE Boundary dimensions for aligning thrust bearings (none flat back faces) and aligning seat washers are given in ISO 20516.[2]