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ENGINEERINGENGINEERINGThe following topicsare covered within thisengineering section: Tapered roller bearingdesign types. Cage design types. Lubrication recommendations.Fitting practice and mountingrecommendations.This engineering section is not intended to be comprehensive,but does serve as a useful guide in tapered roller bearingselection.To view the complete engineering catalog, please visitwww.timken.com. To order the catalog, please contact yourTimken engineer and request a copy of the Timken EngineeringManual, order number 10424.To view more Timken catalogs, goto www.timken.com/catalogsfor interactive versions, or todownload a catalog app for yoursmart phone or mobile devicescan the QR code or go totimkencatalogs.squawqr.com.TIMKEN TAPERED ROLLER BEARING CATALOG5

ENGINEERINGBEARING TYPES AND CAGESTAPERED ROLLER BEARINGS TYPES AND CAGESSINGLE-ROW BEARINGSDOUBLE-ROW BEARINGSTS - SINGLE-ROWTDO - DOUBLE OUTER RINGThis is the basic and the most widely used type of taperedroller bearing. It consists of the inner-ring assembly and theouter ring. It is usually fitted as one of an opposing pair. Duringequipment assembly, single-row bearings can be “set” to therequired clearance (endplay) or preload condition to optimizeperformance.This has a one-piece (double) outer ring and two single innerrings. It is usually supplied complete with an inner-ring spaceras a pre-set assembly. This configuration gives a wide effectivebearing spread and is frequently chosen for applications whereoverturning moments are a significant load component. TDObearings can be used in fixed (locating) positions or allowed tofloat in the housing bore, for example, to compensate for shaftexpansion. TDOCD outer rings also are available in most sizes.These outer rings have holes in the O.D. that permit the use ofpins to prevent outer ring rotation in the housing.Fig. 1. Single-row TS bearing.TSF - SINGLE-ROW, WITH FLANGEDOUTER RINGThe TSF type is a variation on the basic single-row bearing. TSFbearings have a flanged outer ring to facilitate axial location andaccurately aligned seats in a through-bored housing.Fig. 3. Double-row TDO bearing.TDI - DOUBLE INNER RINGTDIT - DOUBLE INNER RING WITHTAPERED BOREBoth comprise a one-piece (double) inner ring and two singleouter rings. They are usually supplied complete with an outerring spacer as a pre-set assembly. TDI and TDIT bearings can beused at fixed (locating) positions on rotating shaft applications.For rotating housing applications, the double inner ring of typeTDI can be used to float on the stationary shaft. Type TDIT hasa tapered bore to facilitate removal when an interference fit isessential, yet regular removal is required.Fig. 2. Single-row TSF bearing with flanged outer ring.TDITDITFig. 4. Double-row, double-inner-ring bearings.6TIMKEN TAPERED ROLLER BEARING CATALOG

ENGINEERINGBEARING TYPES AND CAGESTNA- NON-ADJUSTABLETNASW - NON-ADJUSTABLE WITHLUBRICANT SLOTSTNASWE - NON-ADJUSTABLE WITHLUBRICANT SLOTS AND EXTENDEDBACK FACE RIBThese three bearing types are similar to the TDO with a one-piece(double) outer ring and two single inner rings. The inner-ring frontfaces are extended so they abut, eliminating the need for aseparate inner-ring spacer. Supplied with a built-in clearance togive a standard setting range, these bearings provide a solutionfor many fixed or floating bearing applications where optimumsimplicity of assembly is required.Types TNASW and TNASWE are variations having chamfersand slots on the front face of the inner ring to provide lubricationthrough the shaft. Type TNASWE have extended back face ribson the inner rings which are ground on the O.D. to allow for theuse of a seal or stamped closure. These designs are typicallyused on stationary shaft applications.2SSRFig. 6. Spacer assemblies.2S - TWO SINGLE-ROW ASSEMBLYOften referred to as snap-ring assemblies, type 2S consist oftwo basic single-row bearings (type TS). They are suppliedcomplete with inner-ring and outer-ring spacers to give a predetermined bearing setting when assembled. Type 2S have aspecified setting range to suit the duty of the application. Theyhave an inner-ring spacer and a snap-ring, which also serves asthe outer-ring spacer, to give axial location in a through-boredhousing.SR - SET-RIGHTTM ASSEMBLYType SR are made to a standard setting range, based on Timken’sSET-RIGHT automated setting technique suitable for mostindustrial applications. They have two spacers and an optionalsnap-ring that may be used for axial location. Because both typesare made up of popular sizes of single-row bearings, they providea low-cost option for many applications.There are two basic mounting arrangements for spacerassemblies.TNATNASWTNASWE Type 2TS-IM (indirect mounting)These consist of two single-row bearings with an inner-ringand outer-ring spacer. In some applications, the outer-ringspacer is replaced by a shoulder in the bearing housing. Type 2TS-DM (direct mounting)These consist of two single-row bearings, with inner ringsabutting and an outer-ring spacer. They are generally usedat fixed (locating) positions on rotating shaft applications.Fig. 5. Double-row, non-adjustable bearings.SPACER ASSEMBLIESAny two single-row bearings (type TS) can be supplied as adouble-row, pre-set, ready-to-fit assembly by the addition ofspacers, machined to pre-determined dimensions and tolerances.Spacer assemblies are provided in two types: "2S" and "SR". Thisconcept can be applied to produce custom-made double-rowbearings to suit specific applications. In addition to providinga bearing that automatically gives a pre-determined setting atassembly without the need for a manual setting, it is possibleto modify the assembly width to suit an application, simply byvarying the spacer widths.2TS-IM2TS-DMFig. 7. Basic spacer assemblies.TIMKEN TAPERED ROLLER BEARING CATALOG7

ENGINEERINGCAGESTAPERED ROLLER BEARING CAGESSTAMPED-STEEL CAGESMACHINED CAGESThe most common type of cage used for tapered roller bearingsis the stamped-steel cage. These cages are mass producedfrom low-carbon sheet steel using a series of cutting, formingand punching operations. These cages can be used in hightemperature and harsh lubricant environments.Machined cages for tapered roller bearings are robust in designand are suited for high-speed and high-load applications.Machined cages use alloy steels and are produced throughmilling and broaching operations. Assembly does not requirea close-in operation and rollers can be retained using nibs orstaking. Oil holes also can be easily added for extra lubricationfor demanding applications. Some designs are silver plated forspecial applications.PIN-TYPE CAGESFig. 8. Stamped-steel cage.POLYMER CAGESCages for tapered roller bearings made of polymer material areused primarily for pre-greased and sealed package designs. Themost common polymer materials used are Nylon thermoplasticswith glass reinforcement. Polymer cages can be mass producedin large quantities and offer more design flexibility than stampedsteel types. Polymer cages are lightweight and easy to assemble.In some instances, increased bearing rating can be achievedby allowing one or two extra rollers in the bearing complement.Care should be exercised when using aggressive lubricants withEP (extreme-pressure) additives in combination with elevatedtemperatures greater than 107 C (225 F).8TIMKEN TAPERED ROLLER BEARING CATALOGTapered roller bearing pin-type cages retain the rolling elementsby the use of a pin located through an axial hole in the center ofthe roller. Pin-type cages for tapered roller bearings consist oftwo rings with roller pins attached by screw threads at one endand welding at the other end. These types of cages are primarilyused for larger tapered roller bearing designs (greater than400 mm [15.7480 in.] O.D.). Pin-type cages are machined outof steel and typically allow for an increased number of rollingelements. Pin-type cages are restricted to low-speed applications(less than 20 m/sec [4000 ft/min] rib speed).

ENGINEERINGMETRIC SYSTEM TOLERANCESMETRIC SYSTEM TOLERANCESTapered bearings are manufactured to a number of specifications with each having classes thatdefine tolerances on dimensions such as bore, O.D., width and runout. Metric bearings have beenmanufactured to corresponding standard negative tolerances.Boundary dimension tolerances for tapered roller bearing usage are listed in the following tables.These tolerances are provided for use in selecting bearings for general applications in conjunctionwith the bearing mounting and fitting practices offered in later sections.The following table summarizes the different specifications and classes for tapered roller bearings.TABLE 1. BEARING SPECIFICATIONS AND CLASSESSystemSpecificationMetricTimkenTapered Roller BearingsKNCBAISO/DINInchBearing TypeStandard Bearing ClassPrecision Bearing ClassAAAll Bearing TypesP0P6P5P4P2-ABMATapered Roller BearingsKNCBA-TimkenTapered Roller Bearings423000000ABMATapered Roller Bearings423000-TIMKEN TAPERED ROLLER BEARING CATALOG9

ENGINEERINGDETERMINATION OF APPLIED LOADS AND BEARING ANALYSISDETERMINATION OF APPLIED LOADS AND BEARING ANALYSISSUMMARY OF SYMBOLS USED TO DETERMINE APPLIED LOADS AND BEARING ANALYSISSymbolDescriptionaAxial Distance from Inner Ring Backface toEffective Load CenterUnits (Metric/Inch System)a1SymbolDescriptionDmWEffective Working Diameter of the WormUnits (Metric/Inch System)mm, in.DpGPitch Diameter of the Gearmm, in.Reliability Life FactorunitlessDpPPitch Diameter of the Pinionmm, in.a2Material Life FactorunitlessDpWPitch Diameter of the Wormmm, in.a3Operating Condition Life FactorunitlesseLife ExponentunitlesseLimiting Value of Fa/Fr for the Applicability ofDifferent Values of Factors X and YunitlessFree Endplaymm, in.mm, in.a3dDebris Life Factorunitlessa3kLoad Zone Life Factorunitlessa3lLubrication Life FactorunitlessEa3pLow-Load Life FactorunitlessfLubricant Flow RateaeEffective Bearing Spreadmm, in.f0Viscous Dependent Torque CoefficientunitlessA, B, Bearing Position (used as subscripts)unitlessf1Load Dependent Torque CoefficientunitlessBOuter Ring Widthmm, in.fbBelt or Chain PullB1Inner Ring Widthmm, in.fnSpeed FactorunitlessL/min, U.S. pt/minN, lbfbTooth Lengthmm, in.f2Combined Load Factorunitlessc1, c2Linear Distance (positive or negative).mm, in.f3Combined Load FactorunitlessCBasic Dynamic Radial Load Rating of a Double-RowBearing for an L10 of One Million RevolutionsN, lbfFGeneral Term for ForceN, lbfF1, F2, , Fn Magnitudes of Applied Force During a Loading CycleN, lbfN, lbfBasic Dynamic Thrust Load Rating of a Single-RowBearing for an L10 of 90 Million Revolutions or3000 Hours at 500 RPMFaApplied Thrust (Axial) LoadN, lbfFaiInduced Thrust (Axial) Load Due to Radial LoadingN, lbfBasic Static Radial Load RatingN, lbfFacInduced Thrust (Axial) Load Due to Centrifugal LoadingN, lbfCoaBasic Static Axial Load RatingN, lbfC90Basic Dynamic Radial Load Rating of a Single-RowBearing for an L10 of 90 Million RevolutionsC90(2)Basic Dynamic Radial Load Rating of a Double-RowBearing for an L10 of 90 Million RevolutionsN, lbfCaBasic Dynamic Axial Load RatingN, lbfCgGeometry Factor (used in a3l equation)unitlessClLoad Factor (used in a3l equation)unitlessCjLoad Zone Factor (used in a3l equation)unitlessCsSpeed Factor (used in a3l equation)unitlessCvViscosity Factor (used in a3l equation)unitlessCgrGrease Lubrication Factor (used in a3l equation)unitlessCpSpecific Heat of LubricantCtBasic Thrust Dynamic Load RatingdBearing Bore Diametermm, in.dBall Diametermm, in.d1Spherical Diametermm, in.daShaft Shoulder Diametermm, in.Ca90CoN, lbfJ/(Kg - C), BTU/(lbf - F)N, lbfd0Mean Inner Ring Diametermm, in.dcDistance Between Gear Centersmm, in.dmMean Bearing Diametermm, in.dsiShaft Inside Diametermm, in.DBearing Outside Diametermm, in.D0Tapered Roller Bearing Outer RingMean Raceway DiameterDhDmHousing Outside DiameterFaGThrust Force on GearN, lbfFaPThrust Force on PinionN, lbfFaWThrust Force on WormN, lbfFazAllowable Axial LoadN, lbfFbBelt or Chain PullN, lbfF Load Term for Torque EquationN, lbfFcCentrifugal ForceN, lbfFrApplied Radial LoadN, lbfFrhResultant Horizontal ForceN, lbfFRSResultant Separating ForceN, lbfFRVResultant Vertical ForceN, lbfFSSeparating Force on GearN, lbfFsGSeparating Force on GearN, lbfFsPSeparating Force on PinionN, lbfFsWSeparating Force on WormN, lbfFtTangential ForceN, lbfFteTractive Effort on Vehicle WheelsN, lbfFtGTangential Force on GearN, lbfFtPTangential Force on PinionN, lbfFtWTangential Force on WormN, lbfFWForce of UnbalanceN, lbfFWBWeighted Average LoadN, lbfGGear (used as subscript)unitlessmm, in.G1Geometry Factor from Bearing Data Tablesunitlessmm, in.G2Geometry Factor from Bearing Data TablesunitlessHPowerkW, hpMean Diameter or Effective Working Diameterof a Sprocket, Pulley, Wheel or Tiremm, in.HsHousing Shoulder Inner Diametermm, in.DmTapered Roller Mean Large Rib Diametermm, in.HFsDmGMean or Effective Working Diameter of the Gearmm, in.Static Load Rating Adjustment Factor forRaceway HardnessunitlessDmPEffective Working Diameter of the Pinionmm, in.iNumber of Rows of Rollers in a Bearingunitless10TIMKEN TAPERED ROLLER BEARING CATALOG

ENGINEERINGDETERMINATION OF APPLIED LOADS AND BEARING ANALYSISSymbolDescriptioniBNumber of Bearing Rows Taking LoadUnits (Metric/Inch System)kCentrifugal Force ConstantSymbolDescriptionunitlessSShaft DiameterUnits (Metric/Inch System)mm, in.lbf/RPM2sShaft (used as subscript)unitlessmm, in.k1Bearing Torque ConstantunitlessSdInner Ring Reference Face Runoutk4, k5, k6Dimensional Factor to Calculate Heat GenerationunitlessSDOutside Cylindrical Surface Runoutmm, in.KTapered Roller Bearing K-factor; ratio ofbasic dynamic radial load rating to basic dynamicthrust rating in a single-row bearingSeaAxial Runout of Outer Ring Assemblymm, in.SiaAxial Runout of Inner Ring AssemblyunitlessKBall Bearing Constant Based on GeometryK1, K2Super Precision K-Factorsunitlessmm, in.KeaRadial Runout of Outer Ring AssemblyKoOuter Ring Contour Radius Expressedas a Decimal Fraction of the Ball Diameterdecimal fractionKiInner Ring Contour Radius Expressedas a Decimal Fraction of the Ball Diameterdecimal fractionKiaRadial Runout of Inner Ring Assemblymm, in.unitlessTApplied Thrust (Axial) LoadN, lbfTEEquivalent Thrust LoadN, lbfvVertical (used as subscript)VLinear Velocity or SpeedVBSInner Ring Width Variationmm, in.unitlessmm, in.km/h, mphVCSOuter Ring Width VariationVrRubbing, Surface or Tapered Roller BearingRib Velocitym/s, fpmWWorm (used as subscript)unitlessXDynamic Radial Load FactorunitlessStatic Radial Load FactorunitlessKNK-factor for Bearing #nunitlessKTRelative Thrust Load Factor – Ball BearingsunitlessLHLead – Axial Advance of a Helix for One CompleteRevolutionmm, in.X0LDistance Between Bearing Geometric Center Linesmm, in.Y, Y1, Y2, . Dynamic Thrust (Axial) Load FactorL10Bearing Liferevolutions or hoursmm, in.t1, t2, , tN Fractions of Time During a Loading CycleY0unitlessStatic Thrust (Axial) Load FactorunitlessLfLife FactorunitlessZNumber of Rolling ElementsmGearing RatiounitlessTCoefficient of Linear ExpansionMBearing Operating TorqueN-m, N-mm, lb.-in.oMOMomentN-m, N-mm, lb.-in.Tapered Roller Bearing Half IncludedOuter Ring Raceway Angledeg.nBearing Operating Speed or General Termfor SpeedBall Bearing Nominal Contact Angledeg.ΔTTemperature Difference Between Shaft/Inner Ring/Rollers and Housing/Outer RingΔBsInner Ring Width Deviationn1, n2, , nn Rotation Speeds During a Loading Cyclerot/min, RPMrot/min, RPMunitlessmm/mm/ C, in./in./ F C, Fmm, in.NAReference Speedrot/min, RPMnGGear Operating Speedrot/min, RPMΔCsOuter Ring Width Deviationmm, in.Deviation of Mean Bore Diameter in a Single Planemm, in.nPPinion Operating Speedrot/min, RPMΔdmpnWWorm Operating Speedrot/min, RPMΔDmpDeviation of Mean Outside Diameter in a Single Plane mm, in.unitlessbsInterference Fit of Inner Ring on Shaftmm, in.unitlessbhInterference Fit of Outer Ring in Housingmm, in.ƺEfficiency, Decimal FractionNcNiNumber of Rotations of the Ball and Cage AssemblyNumber of Rotations of the Inner RingNGNumber of Teeth in the GearunitlessNPNumber of Teeth in the Pinionunitlesse1, e2, e3Gear Mesh Angles Relative to the Reference Planeunitlessei, eoOil Inlet or Outlet TemperatureunitlesshWorm Gear Lead Angleunitless Coefficient of FrictionN, lbf Lubricant Dynamic ViscositycPLubricant Kinematic ViscositycStNSNfNumber of Teeth in the SprocketSpeed FactorPPinion (used as subscript)PoStatic Equivalent Loaddeg., rad C, Fdeg.unitlessPoaStatic Equivalent Thrust (Axial)N, lbfvPorStatic Equivalent Radial LoadN, lbfmoApproximate Maximum Contact StressPaDynamic Equivalent Axial LoadN, lbfƪGNormal Tooth Pressure Angle for the Geardeg.PrDynamic Equivalent Radial LoadN, lbfƪPNormal Tooth Pressure Angle for the Piniondeg.N, lbfMPa, psiPeqEquivalent Dynamic Loaddeg.Generated Heat or Heat Dissipation RateW, BTU/minƬGƬPHelix (Helical) or Spiral Angle for the GearQHelix (Helical) or Spiral Angle for the Piniondeg.QgenGenerated HeatW, BTU/minlLubricant DensityW, BTU/minƩGQoilHeat Dissipated by a Circulating Oil SystemrRadius to Center of Massmm, in.RPercent Reliability, Used in the Calculationof the a1 FactorunitlessRadial Internal Clearancemm, in.RICƩPkg/m3, lb./ft3Bevel Gearing – Gear Pitch Angledeg.Hypoid Gearing – Gear Root Angledeg.Bevel Gearing – Pinion Pitch Angledeg.Hypoid Gearing – Pinion Face Angledeg.TIMKEN TAPERED ROLLER BEARING CATALOG11

ENGINEERINGMETRIC SYSTEM TOLERANCESMETRIC SYSTEM BEARINGS (ISO AND J PREFIX PARTS)tolerances lie within those currently specified in ISO 492 withthe exception of a small number of dimensions indicated in thetables. The differences normally have an insignificant effect onthe mounting and performance of tapered roller bearings.Timken manufactures metric system bearings to six toleranceclasses. Classes K and N are often referred to as standardclasses. Class N has more closely controlled width tolerancesthan K. Classes C, B, A and AA are precision classes. TheseTABLE 2. TAPERED ROLLER BEARING TOLERANCES – IN

please refer to the respective Timken product catalog reference. Timken offers an extensive range of bearings and accessories in both imperial and metric sizes. For your convenience, size ranges are indicated in millimeters and inches. Contact your Timken engineer to learn more about our