CP Washer’s act as supporting face in thrust bearings. These are the plate incorporated in the thrust bearing and are made from hardened bearing steel and forms one of the raceways for the rolling elements The opposing raceway is generally provided by a separate thrust plate of similar design. When the thrust bearing is centered by the revolving part, the thrust plate must be centered by the stationary part and vice versa.
For smooth running operation of needle or roller thrust bearings, it is necessary that their supporting faces should be parallel. Thin needle thrust bearings and thin thrust plates must be supported on a flat, rigid and continuous face throughout the area of circulation of the needles.