DS EN 3290:1994 Aerospace Series - Bearings, Airframe Rolling - Single Row Self-Aligning Roller Bearings In Steel - Diameter Series 3 And 4 - Dimensions And Loads Defines the characteristics of single row self-aligning roller bearings in steel of diameter series 3 and 4 designed to withstand only slow rotations, oscillations and/or swivelling under load.