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A49LubricationMethodsoflubricationGreaselubricationandoillubricationaregenerallyusedforrollingbearings.Inspecialcases,solidlubri-cantsarealsoused.Ingeneral,greaselubricationrequiresthesimplestsealingstructure.Itisthereforeeconomicalandwidelyused.Also,oncefilledwithgrease,thebearingcanbeusedforalongperiodwithoutreplenishingthegrease.However,comparedwithoil,itsheatremovalpropertiesandcoolingcapacityareinferior,sincegreasehashighflowresistance,whichcauseshighchurningheat.Oilhasgreaterfluidityandsuperiorheatremovalproperties.Itisthereforesuitableforhigh-speedoperations.Inaddition,itissimpletofilteroutdustanddirtfromoil.Thusitcanpreventthegenerationofnoiseandvibrationandincreasebearinglife.Anotheradvantageofoillubricationisthatitoffersthepossibilityforselectingtheappropriatemethodforparticularoperatingconditionsfromamongvariousavailablelubricationmethods.However,measurestopreventoilleakagearerequired.Asaguidelineforselection,Table34comparesgreaseandoillubrica-tion.ForthelubricantsusedforIKOSphericalBushings,seepageK8.PurposeoflubricationThemainpurposeofbearinglubricationistoreducefrictionandwearandtopreventheatgenerationandseizure.Thelubricantandthelubricatingmethodhaveabiginfluenceontheoperatingperformanceofthebearing,anditisthereforenecessarytoselectthemsuitablyfortheoperatingconditions.Theeffectsoflubricationareasfollows.1ReductionoffrictionandwearAtthecontactsurfacesbetweentheracerings,rollingelementsandcageofthebearing,lubricationpreventsmetal-to-metalcontact,andreducesfrictionandwearduetoslidingandrolling,inthelatterofwhichmicro-slipsoccurbydifferentialslip,skew,spin,orelasticdeformation.2EliminationoffrictionalheatThelubricantremovestheheatgeneratedbyfrictionortransferredfromoutside,andpreventsoverheatingofthebearing.Circulatinglubricationisgenerallyusedforthispurpose.3InfluenceonbearinglifeThebearinglifeisextendediftherollingcontactsur-facesbetweentheraceringsandrollingelementsareseparatedbyanoilfilmofadequatethickness,andisshortenediftheoilfilmisinadequateduetolowoilviscosity,etc.4RustpreventionThelubricantpreventsrustformationontheinsideandoutsidesurfacesofthebearing.5DustpreventionGreaselubricationisparticularlyeffectivefordustpre-vention.Oilcirculatingorjetlubricationiseffectiveinwashingforeignparticlesawayfromtheareaaroundthebearing.Table34ComparisonbetweengreaselubricationandoillubricationItemSealingstructure,HousingstructureTemperatureRotationalspeedLoadMaintenanceLubricantreplacementLubricationperformanceDustfiltrationEntryofdustanddirtGreaselubrication(1)OillubricationSimpleHightemperaturenotallowedLowandmediumspeedsLowandmediumloadsEasySlightlycomplicatedGoodDifficultEasymeasuresforprotectionSlightlycomplicatedHightemperatureallowed(Coolingeffectbycirculation)HighspeedallowedHighloadallowedElaborate(Payspecialattentiontooilleaks.)SimpleVerygoodSimpleDustanddirtcanberemovedbyfilteringincirculatinglubrication.Note(1)Thisrepresentsbearinggreaseforgeneraluse.
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