single row angular contact ball bearings can accommodate axial loads in one direction only， and should always be adjusted against another bearing which accommodates the opposed thrust load. Their bearing rings have an upper and a lower shoulder and are non-separable.
Spindle bearings are a special design of the single row angular contact ball bearings; they were developed primarily for high-speed work spindles of machine tools. The spindle bearings differ from the angular contact ball bearings by the contact angle, the degree of accuracy, and the type of cage.
Single row angular contact ball bearings, which are intended for mounting in pairs (in sets) directly adjacent to each other, are manufactured in the so-called universal design.these bearings can be used in pairs in any arrangement without shims. Depending on the design selected, the mounted bearing pair has the required axial clearance, freedom from clearance or preload. This gives easier design of the bearing arrangement and mounting of the bearings.