Examples of suffix code content DB Paired double (back-to-back) 7208ADBDBB Four-pair combination 7318ADBBDBD Three-row combination 7318ADBDDBT Four-row combination 7318ADBTDBTD Five-row combination 7318ADBTDDF Paired double (series) 7320ADFDFD Three-row combination 7320ADFDDFF Four-row combination 7320ADFFDFT Four-row combination 7320ADFTDT For duplex (face-to-face) 7320ADTDTD three-row combination 7320ADTDDTT three-row combination 7320ADTT universal combination In order to make the same type of bearing, no matter how the combination can achieve the set preload, the width difference between the front and back is controlled and made during manufacturing. Equal, this is the universal combined bearing. At this time, in order to avoid mistaking the bearing installation direction and get the correct combination method, a V-shaped mark is made on the outer ring outer diameter of a single bearing. The direction of the arrow tip of the V-shaped mark indicates the direction of the axial load (contact angle) screwed on the inner ring. Front width difference f u003d back width difference b Therefore, it is suitable for various combinations. Pre-tightening clearance: 2f Pre-tightening clearance: 2bDB combination back width difference × 2u003d2b (u003d2f) can get the set preload force DF combination front width difference × 2u003d2f (u003d2b) can get the setting The fixed pre-tightening force DT combines the front width difference f u003d the back width difference b, and there is no play between DTs like the usual DT combination.