Page 21 of Roller Bearings by RBC Bearings

if the bearing is subject to repeated shock or impact loads the equivalent load pe or its individual components should be multiplied by a suitable shock load factor the product of load and shock load factor should not exceed the bearing static capacity to prevent brinelling of raceways and rollers loading uniform and constant variable and light shock vibration and moderate shock heavy and severe shock shock load factor 1.00 1.50 2.00 3.00 table 3 load modification factors 4 limiting speed the limiting speed values in the dimensional tables apply to bearings lubricated with oil of proper viscosity operating under low to medium load poor cooling conditions bearing misalignment and improper diametral bearing clearance will cause the bearing to heat up and reduce the maximum permissible speed grease lubricated bearings should not exceed 65 of the values given in the tables the maximum speed of bearings with contacting lip seals is generally limited to a lip surface speed of 1000 ft/min 5 shaft housing fits the dimensional tables list loose and interference fits for inner and outer rings the correct fit depends on type and severity of the load to prevent rotation and wear the ring subject to rotating loads must be press fitted this will be the inner ring in most applications the ring subject to a stationary load may be loosely fitted the housing interference fit iso n7 given in the tables covers most applications with normal loads to 25 of dynamic capacity and light to moderate shock loads higher loads or heavy shock loads or thin-walled housings may require a tighter interference fit e.g iso p7 likewise loads above 25 of dynamic capacity or heavy shock loads or a hollow shaft may require a shaft interference fit per iso n6 to determine tolererances per p7 or n6 proceed as follows the nominal housing bore is the maximum bearing outside diameter the nominal shaft diameter is the maximum inner ring inside diameter find the nominal housing bore diameter or shaft diameter respectively in table 4 and add the tolerances to the nominal dimension nominal bearing od range[in 3/4 1 1/8 1 3/16 1 15/16 upper lower tolerance iso p7 0006 0007 0008 0009 0011 0013 0014 0016 0014 0017 0020 0023 0027 0031 0035 0039 nominal inner ringid range[in upper lower tolerance iso n6 0005 0006 0007 0008 0009 0011 0012 0013 2-3 3 1/4 4 1/2 4 3/4 7 7 1/8 9 3/4 10 12 3/8 12 1/2 15 5/8 1/2 11/16 0009 3/4 1 1/8 0011 1 3/16 1 15/16 0013 2-3 3 1/4 4 1/2 4 3/4 7 7 1/8 9 3/4 10 12 3/8 0015 0018 0020 0024 0026 table 4 housing tolerance p7 and shaft tolerance n6 19

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