>> P.238
Calculation exampleWhen a roller bearing for sheaves NAS 5016 ZZ NR is run at n = 250 min-1 under grease lubrication and subjected to an intermittent axial load, the axial load capacity is calculated as follows.As the bearing bore diameter is 80 mm, fA = 18000 is obtained from the axial load capacity line of Fig. 1 (ii). a=1 80+125dm≒2=102.5 dmn=102.5 x 250 ≒ 25600From Fig. 2, fv ≒ 0.87Therefore, the axial load capacity CA is obtained.CA=fv a fA = 0.87×1×18000 ≒ 15700 N8000006000004000002000001000008000060000400002000010000800060004000200010008006004002001001020406080100200400Fig. 1 Axial load capacity factor■Axial Load CapacityAxial load capacity is not determined from the basic dynamic load rating based on rolling fatigue, but is determined by the amount of heat generated by slid-ing contact between the ends of rollers and guide shoulders of the inner and outer rings. It is therefore limited by the load conditions, sliding speeds, lubrica-tion methods, etc.The axial load capacity of Roller Bearings is obtained from the following equation.If the axial load increases in comparison with the radi-al load, it will start to interfere with the smooth rolling motion. The axial load should therefore be within 20% of the radial load.CA=fv a fA ……………………………………(1)where, CA:Axial load capacity N fv:Speed correction factorfv is obtained from Fig.2 by calculat-ing the dmn value. dmn = dm×n dm: Mean value of bearing bore and outside diametersmm(dm≒ 2d+D) n :Rotational speedmin-1 When dmn ≦ 1000, fv = 1. a: alue determined by type of bearing (See Table 5. ) fA:Axial load capacity factor (See Fig.1.)Table 5 Value by type of bearingType of bearingNAS 50NAG 49NAU 49,TRUa10.780.7E5
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