>> P.238
E5■AxialLoadCapacityAxialloadcapacityisnotdeterminedfromthebasicdynamicloadratingbasedonrollingfatigue,butisdeterminedbytheamountofheatgeneratedbyslid-ingcontactbetweentheendsofrollersandguideshouldersoftheinnerandouterrings.Itisthereforelimitedbytheloadconditions,slidingspeeds,lubrica-tionmethods,etc.TheaxialloadcapacityofRollerBearingsisobtainedfromthefollowingequation.Iftheaxialloadincreasesincomparisonwiththeradi-alload,itwillstarttointerferewiththesmoothrollingmotion.Theaxialloadshouldthereforebewithin20%oftheradialload.CalculationexampleWhenarollerbearingforsheavesNAS5016ZZNRisrunatn=250min-1undergreaselubricationandsubjectedtoanintermittentaxialload,theaxialloadcapacityiscalculatedasfollows.Asthebearingborediameteris80mm,fA=18000isobtainedfromtheaxialloadcapacitylineofFig.1(ii). a=1 dm≒ 80+125=102.52 dmn=102.5x250≒25600FromFig.2,fv≒0.87Therefore,theaxialloadcapacityCAisobtained.CA=fvafA=0.87×1×18000≒15700N8000006000004000002000001000008000060000400002000010000800060004000200010008006004002001001020406080100200400CA=fvafA……………………………………(1)where,CA:AxialloadcapacityN fv:SpeedcorrectionfactorfvisobtainedfromFig.2bycalculat-ingthedmnvalue.dmn = dm×ndm: Meanvalueofbearingboreandoutsidediametersmmn:Rotationalspeedmin-1Whendmn≦ 1000,fv = 1.a: Valuedeterminedbytypeofbearing(SeeTable5.)fA:Axialloadcapacityfactor(SeeFig.1.)Fig.1AxialloadcapacityfactorTable5ValuebytypeofbearingTypeofbearingNAS50NAG49NAU49,TRU10.780.7a(dm≒d+D)2
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