Standard SKF double row cylindrical roller bearings of series NN 30 and NNU 49 are usually produced with the high accuracy required for machine tools according to tolerance class SP. Suffix SP is included in the designation of these bearings in the tables. Some of these bearings are also available with even higher accuracy to tolerance class UP specifications. Details will be supplied on request.
The remaining standard bearings are produced, unless specially ordered, with Normal tolerances. Drawing number bearings are normally produced with dimensional accuracy to P6 and running accuracy to P5.
The actual values correspond to those specified in ISO 492:2014 for tolerance classes Normal, 6 and 5. Tolerance class SP specifies dimensional accuracy which corresponds approximately to tolerance class P5 and running accuracy to P4. Tolerance class UP is even more accurate, with a dimensional accuracy approximately to P4 and a running accuracy better than P4.
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