Thrust ball bearings are classified into those with flat seats or aligning seats depending on the shape of the outer ring seat (housing washer).They can sustain axial loads but no radial loads. For Single-Direction Thrust Ball Bearings, pressed steel cages and machined brass cages are usually used The cages in Double- Direction Thrust Ball Bearings are the same as those in Single-Direction Thrust Ball Bearings of the same diameter series.