推力滚针轴承

ThrustBearingsNomenclature............................................474Introduction.............................................476Identification.............................................476Construction.............................................477DimensionalAccuracy................................477-478PilotingandLocating......................................478BackUpSurfaces.........................................479TypeNTHAThrustCylindricalRollerBearing............................................479CoefficientofFriction......................................479Lubrication..............................................479SpecialDesigns..........................................479THRUSTNEEDLEROLLERANDCAGEASSEMBLIESAssemblyDimensions,LoadRatings,ThrustWasherandPilotingDimensions..................480-487THRUSTCYLINDRICALROLLERANDCAGEASSEMBLIESAssemblyDimensions,LoadRatingsandPilotingDimensions..............................488-489THRUSTCYLINDRICALROLLERBEARINGSBearingDimensions,LoadRatingsandPilotingDimensions..............................490-491PageThrustBearingsBore20=20mm16=16⁄16=1FMetricDesignationCageDesignAneedlerollerCneedlerollerHcylindricalrollerOutsideDiameter35=35mm25=25⁄16=19⁄16ThrustWashersTRthrustwasher,inchASthrustwasher,metricBore16=16⁄16=110=10⁄16=5⁄820=20mmA,B,Cetcwasherthickness,inchI&JborepilotedwashersID,JDoutsidediameterpilotedwashersOutsideDiameter18=18⁄16=11⁄835=35mm474FNTA2035NTcageassemblyTRB1018476INTRODUCTIONBeforeselectingspecificcageassembliesorcompletebearings,thegeneralengineeringsectionofthiscatalogshouldbereviewedfordetailedinformationconcerning:•bearingtypeselection•bearinglifeandreliability•definitionofloadratings•lifeandloadrelationships•lubrication•limitingspeeds•effectofracewayhardnessInadditiontothesegeneralconsiderations,reviewthematerialwhichfollowswhenselectingthrustneedlerollerandcageassembliesorthrustcylindricalrollerandcageassemblies.IDENTIFICATIONTheprefixlettersinthebearingdesignationoftheTorringtonthrustneedlerollerandcageassemblies,thrustcylindricalandcageassembliesandtheircorrespondingthrustwashersdenotewhethertheyaremadetoinchormetricnominaldimensions,andtheirmajorconstructionfeatures.Arollerandcageassemblyorwasherwithmetricnominaldimen-sionsisindicatedbythecodeletterFintheprefix.AbsenceoftheletterFintheprefixofthebearingdesignationindicatesinchnominaldimensions.NTAisthecompleteprefixcodeforanassemblywithinchnominaldimensionsandFNTandFNTAarethecompleteprefixcodesforthrustneedlerollerandcageassemblieswithmetricnominaldimensions.Thrustneedlerollerandcageassembliesuseneedlerollersofthesmallestpracticaldiameter.ThrustcylindricalrollerandcageassembliesidentifiedbytheprefixlettersNTHuselargediameterrollerstoobtainhigherloadratings.Theseassembliesareavailableonlyininchnominaldimensions.ThrustwashersofinchnominaldimensionsareidentifiedbytheprefixlettersTR,followedbyanotherlettersuchasA,B,C,etc.indicatingwasherthickness.TRAisthecompleteprefixcodeforthethinnestthrustwashermadetoinchnominaldimensions.ThrustwashersofmetricnominaldimensionsareidentifiedbytheprefixlettersASfor1.0mmthickness.Metricwashersofotherthicknessarealsoavailable.Mostthrustwashersareintendedtobepilotedontheirbores.Somewashers,however,aredesignedtobepilotedontheiroutsidediameters.SuchwashersareidentifiedbytheletterDfollowingthethicknesscodeletter.Thus,TRJDisthecompleteprefixcodeforathrustwasherwithinchnominaldimensionsofJthicknessanddesignedtobepilotedbyitsoutsidediameter.ThrustcylindricalrollerbearingswithprefixcodeNTHAaremadeupofoneNTHassembly,oneTRIorTRJborepilotedwasherandoneTRIDorTRJDoutsidediameterpilotedwasher.Sincethebearingdesignationforthrustassembliesdoesnotappearonthebearingitself,themanufacturer’spartslistoranotherreliablesourceshouldalwaysbeconsultedwhenorderingbearingsforserviceorfieldreplacement,tomakecertainthatthecorrectbearingwiththecorrectlubricantisused.ThrustBearingsTypeFNTTypesNTAandFNTATypeNTHTypesASandTRTypeNTHANeedleRollerandCageAssemblyCylindricalRollerandCageAssemblyThrustWashersCylindricalrollerThrustBearingsTHRUSTBEARINGS477CONSTRUCTIONTorringtonthrustneedlerollerandcageassemblies(NTA,FNTandFNTA)andthrustcylindricalrollerandcageassemblies(NTH)havehardenedcagesandthroughhardened,precisiongroundrollers.Thecagesaresecurelyfastenedassembliesoftwomatingpieces.ThisuniqueTorringtonconstructionminimizescagestressandassuresthattherollerretainingfunctionofthecageisunaffectedbynormalwear.Rollersareprecisiongroundandlappedtoclosetoleranceforoptimumloaddistribution.Table2Tolerancesforo.d.(Dc)ofnominalmetric(FNTandFNTA)thrustneedlerollerandcageassemblies.NominalO.D.Deviations(c12)mminchmminch(approx)overincloverincl.highlowhighlow18300.711.19-0.110-0.320-0.004-0.01230401.191.58-0.120-0.370-0.005-0.01540501.581.97-0.130-0.380-0.005-0.01550651.972.56-0.140-0.440-0.006-0.01865802.563.15-0.150-0.450-0.006-0.018801003.153.94-0.170-0.520-0.007-0.0211001203.944.73-0.180-0.530-0.007-0.0211201404.735.52-0.200-0.600-0.008-0.024Table2ATolerancesforborediameter(Dc1)ofnominalmetric(FNTandFN