>> P.47
1N=0.102kgf=0.2248lbs.1mm=0.03937inchABCDEFGHIJKLMShaftsandouterringsmayhavesomeinclinationbetweenthemduetodeflectionoftheshaft,machin-ingaccuracyofshaftsandhousings,errorsinmount-ing,etc.Inthiscase,theuseoftwoormorebearingsintan-demarrangementonasingleshaftshouldbeavoided.Instead,abearingwithlargeloadratingsshouldbeused.Itisrecommendedthatinclinationofshaftsbelessthan1/1000.Table27ToleranceclassITvaluesforbasicdimensionsBasicdimensionToleranceclass(1)mmIT5IT6IT710121518212530354046525763706891113161922252932364044Toleranceμm45689111315182023252730Incl.361018305080120180250315400500630Over-361018305080120180250315400500Note(1)BasedonJISB0401.AccuracyandroughnessofshaftandhousingAccuracyandroughnessoffittingsurfacetheirperformanceSincethebearingringsofneedlerollerbearingsarethin,iseasilyaffectedbypooraccuracyofshaftsorhousings.Undergeneraloper-atingconditions,fittingsurfacesofshaftsandhousingscanbefinishedbylatheturning.However,whenloadisgreatandhighaccuracyandlownoisearerequired,agrindingfinishisrequired.Table26showstheaccuracyandroughnessoffittingsurfacesforgeneraluse.thetheAccuracyandroughnessofracewaysurfaceIncaseofneedlerollerbearingsunlikeotherbear-ings,matingsurfacessuchasshaftandhousingboresurfacescanbeuseddirectlyastheracewaysur-faces.Forsuchuse,accuracyandroughnessoftheracewaysurfacesareimportantbecausetheywillinfluencebearinglife,noiseandaccuracy.Ingeneral,accuracyandroughnessofracewaysur-facesarebasedonTable26.DesignofShaftandHousingInclinationofshaftTable26SpecificationsofshaftsandhousingsforradialneedlerollerbearingsItemCircularityCylindricityFittingsurface0.3×IT6(1)or0.3×IT5(1)0.5×IT6(2)or0.5×IT5(2)SurfaceroughnessμmRa(μmRy)Hardness0.8(3.2)-ShaftHousingboreRacewaysurface0.3×IT6(1)or0.3×IT5(1)0.3×IT6(1)or0.3×IT5(1)0.2(3)(0.8)58〜64HRC(4)Fittingsurface0.3×IT7(1)or0.3×IT6(1)0.5×IT7(2)or0.5×IT6(2)1.6(6.3)-Racewaysurface0.3×IT7(1)or0.3×IT6(1)0.3×IT7(1)or0.3×IT6(1)0.2(3)(0.8)58〜64HRC(4)Notes(1)30%orlessofthedimensionaltoleranceforshaftsorhousingboresisrecommended.(2)50%orlessofthedimensionaltoleranceforshaftsorhousingboresisrecommended.(3)Whenrequiredaccuracyisnotcritical,asurfaceroughnesswithin0.8μmRa(3.2μmRy)isallowable.(4)Anappropriatethicknessofthehardenedlayerisrequired.RemarkFortoleranceclassIT,seeTable27.A44
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