Four row tapered roller bearingsare specially designed for rolling mill applications where their thin cross-section height and increased width provide higher capacity. The difference between a TQO bearing and a 2TDIW bearing design is relatively minor, as each uses two TDI cones.

The TQO design uses two TDI cones, one double cup in the middle, two single cups one on each end, two cup spacers, and a cone spacer.
The 2TDIW design uses two TDI cones, four single cups, three cup spacers. The cones are match ground, therefore no cone spacer is required.
Either design can be supplied depending on the preference of the mill; however, the TQO is the most commonly used design.

There are a variety of special features that can be incorporated in the design of four row tapered rolling bearings, such as face notches, helical bore grooves, extended cones, re-lubrication accommodations, cups and/or cone seals, etc.