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Timken Precision Tapered Roller BearingsSuperior Accuracy for Industrial Applications

Precisionbearings:superioraccuracy& controlSome applications demand a high level of precision thatcannot be achieved with standard tapered roller bearings.This includes many machining, printing press and rollingmill applications where combinations of tight tolerances,high speeds and radial and thrust loads are present. For morethan 50 years, The Timken Company has offered a wide arrayof precision-class tapered roller bearings that deliver superioraccuracy and control in critical applications.Standard vs. Precision:Making the Right ChoiceAlthough standard product issometimes used as a substitute forprecision class, there are many inherentdesign characteristics that uniquelyqualify precision tapered roller bearingsfor manufacturing and machiningoperations. In particular, precisiontapered roller bearings feature: tighter manufacturingspecifications resulting in greaterrotational accuracy; reduced tolerances on bore andoutside diameter creating improvedperformance in high speed, hightemperature applications; straight race and/or roller profiledesigns (versus crowned profile1designs) for increased accuracyand rigidity; controlled machining andassembly processes to ensurethat components are matchedproperly and exact specificationsare met; high load-carrying capabilitycompared to other bearing typesso that fatigue life is enhanced; the ability to be adjusted duringinstallation so that operatingtorque, shaft rigidity andoperating temperature can beprecisely controlled.Making the right choice betweenstandard and precision class productis an important decision. Equallyimportant is making sure the

company that manufactures precisiontapered roller bearings has theprocesses in place to produce reliablebearings on a consistent basis.and inch systems, that cover thefull range of precision applicationrequirements. In ascending orderof accuracy, they are identified inthe metric system as Class C, B, Aand AA, while in the inch system asClass 3, 0, 00 and 000.rotational accuracy combined withinherent stiffness and high loadcarrying properties.Our precision tapered roller bearingsare found wherever spindle, roll orcutting edge run-out and accuracy areessential. Typical applications includemachine tools, printing presses, backup rolls, optical grinders, profile cutters,indexing tables and many others.About Timken PrecisionTapered Roller BearingsTo provide high-level precision,Timken offers a full line of precisiontapered roller bearings up to 13inches outside diameter (33 cm).These bearings can be made withaccuracy equivalent to the width of ahuman hair split 600 times. Timken precision bearings offer extremeThe chart below summarizes theaccuracy of Timken precision bearingsas compared to standard bearings.All Timken precision bearings have anelectrolyte acid dot etched on bothfaces of each cone and cup. This dotindicates the high point of the coneand cup run-out, respectively, and isused when mounting to obtain thebest performance.Different Levels of PrecisionMeet Critical NeedsThe more demanding the precisionobjective, the more accurate thebearing must be. Timken providesfour precision classes, in both metricTimken Bearing Class Tolerance Range Example*Imperial Bearing Precision ClassAssembly Radial Run-OutCone Bore ToleranceCup OD Tolerance RangeHigh Point of Radial Run-OutRoller CrownData is for a 4.0000” cone bore and a 6.0000” cup ESYESYESNONONOData is for a 100.000 mm cone bore and a 150.000 mm cup OD.StandardMetric Bearing Precision ClassAssembly Radial Run-OutCone Bore Tolerance RangeCup OD Tolerance RangeHigh Point of Radial Run-OutRoller SNOinchmicron 0.001 mminchmicron 0.001 mminchmicron 0.001 0.0003YESNOAA10.00004-8-0.0003-8-0.0003YESNOmicron 0.001 mminchmicron 0.001 mminchmicron 0.001 mminch*Tolerance ranges vary with the size of the product.2

Precisionin everystep ofproductionDedicatedManufacturing FacilityPrecision must be incorporatedinto a bearing’s design andmanufacturing processes.It cannot be replicated after astandard bearing is made.That is why Timken has invested ina manufacturing facility dedicatedexclusively to the production ofprecision class bearings. Locatedin New Philadelphia, Ohio, this ISO9002 certified plant is temperatureand humidity controlled and equippedwith state-of-the-art machinery. Inaddition, our highly qualified andtrained associates implement cellmanufacturing techniques to ensureworld-class precision in every step ofthe process.Timken PrecisionBearings for MachineTool ApplicationsMachine tool builders mustrespond to customer demandsfor accuracy and quality, whilereducing downtime and increasingproductivity. Timken precisionbearings offer machine tool builders3an economical solution that meetsor exceeds most application needsfor rotational accuracy, consistencyand rigidity. Many of our precisionbearings are also designed to meetthe high-speed, low-heat demandsof the machine, enabling nonsynchronous run-outs below .00040inch ( 1 um). This capability, alsoknown as non-repetitive run-out,increases the accuracy, repeatabilityand resolution of the machine.The following special bearings areonly available in precision classes:HydraRib BearingThe Timken HydraRibTM bearingis a tapered roller design availablein any class of precision to maintainoptimum spindle system preload.The HydraRib has a floating outerrace rib, positioned by hydraulic orpneumatic pressure, and is in contactwith the large roller ends, insteadof the usual fixed inner race rib.This retains system stiffness whileallowing for thermal expansion. TheHydraRib bearing’s floating rib designallows it to compensate for thermalgrowth variations, while maintainingthe optimum setting and accuracy fora variety of speeds and loads.SpringRib BearingThe SpringRib bearing is similarto the HydraRib except the bearing

preload is maintained by springsrather than hydraulic pressure. Itis ideal for applications where loadand speed conditions are relativelyconstant, such as a transfer linespindle. Three different spring packpre-loads are available: light, mediumand heavy.Crossed Roller Bearing-TXRTimken precision crossed rollerbearings (TXR) are designedto offer the highest levels ofrotational accuracy and rigidity,while conserving space and savingmaterial costs.The bearing features two sets of racesand rollers brought together at rightangles, with alternate rollers facing inopposite directions. This allows twohalf rows of rollers to fit into the spaceof one. The steep-angle, taperedgeometry results in a total effectivebearing spread much greater than thewidth of the bearing itself.Able to withstand high overturningmoments, the crossed roller bearingis ideal for the table bearing ofmachine tools, including verticalboring and grinding machines. It isalso uniquely suited to many otherpivot and pedestal applicationswhere space is limited or the lowestpossible center of gravity of arotating mass is required.Single Row with Axial OilProvision-TSMAThe single-row bearing with aspecial provision for lubrication(TSMA) ensures adequate lubricationat high speeds at the importantroller-rib contact area. Oil is capturedin a manifold attached to the innerrace and is then directed to theroller-rib contact area through holesdrilled axially in the inner race. TheTSMA bearing is used on machinetool spindles.Single Row withRadial Oil Provision-TSMRThe TSMR type single-row bearingalso has a special provision forlubrication of the critical rollerrib contact area in high-speedapplications. With this bearingdesign, the oil is directed to therib-roller contact area through holesdrilled radially into the inner race.This ensures proper lubrication athigh speeds – and enhances bearingfatigue life.Increased Productivityfor Rolling MillsThe performance of roll neckbearings affects not only the qualityof rolled steel or aluminum, butalso a mill’s profitability. Usingprecision bearings may helpmeet your customer’s demandsfor increased productivity, whilereducing costs and material waste.Precision bearings – applied to theback-up roll – help ensure stripuniformity by minimizing variationsin thickness along the strip’s length.For applications where the aestheticappeal of the strip is important,precision bearings help improve gageaccuracy, resulting in a smoother andless wavy finish.Timken provides several precisionbearings for rolling mill operations.This includes the non-adjustable,heavy duty, double outer racebearing (TNASWH). This type ofbearing is similar to a two-row, nonadjustable bearing (TNA), but the cupis made with a self-supporting, heavywall section. Like TNA bearings, thecones of TNASWH bearings are nonadjustable, so that the front facesof the cones are in contact. Becausethey are pre-set, this saves assemblytime. The heavy outer rings of theTNASWH are self-supporting forheavy-duty applications. This typeof bearing also allows oil lubricationfrom the shaft.Four-row bearings combine theinherent high-load, radial/thrustcapacity and direct/indirect mountingvariables of tapered roller bearings intoassemblies that provide maximum4

Precisionbearings:performance& productivityload rating in a minimum space.For low- and medium-speedrolling mills, a four-row, straightbore assembly with coneface lubrication slots (TQOW)precision bearing is often used.TQOW assemblies have slots in thefront faces of the cones to providecritical lubrication between the conebore and roll neck. For high-speedapplications, four-row, tapered boreassembly (TQITS) is the ideal choice.This type of bearing allows theoperator to minimize roll body runout. The tapered bore on the TQITSbearing allows a tight fit on the rollneck, which further increases itsprecision capabilities.High-Quality Performancefor Printing PressesToday’s print shops must respond tocustomer demands for high-quality,fast, cost-effective printing by usingpresses that are not only extremelyaccurate and reliable, but capableof high levels of productivity. Theperformance of any printing pressis directly impacted by the bearingsthat support the print cylinders,5drives and ancillary equipment.Precision tapered roller bearings helpto ensure precise alignment of theprinting rolls so that print quality isachieved, run after run.Timken Products andServices for PrecisionApplicationsIn addition to our precision taperedroller bearing line, Timken offersseveral other programs to reducedowntime and keep your machineryrunning smoothly, day after day, yearafter year. Through our network ofTimken authorized distributors, wehelp meet your needs for relatedcomponents, repair and replacementproducts in a timely, efficient manner.Timken LubricantsIdeal for machining and printing pressapplications-among others, Timkenoffers the G-Power and M-Powersingle-point lubricators. Thesedevices dispense precise amounts ofgrease into your equipment, resultingin time and cost savings over manuallubrication practices.Timken also offers severallines of lubricants that not onlyoutperform other lubricants inindustry-recognized tests, but offertremendous value to our customers.