timken aerospace precision metric ball and cylindrical ......timken aerospace precision metric ball...

A TIMKEN COMPANY SUBSIDIARYA TIMKEN COMPANY SUBSIDIARY

Design Guidefor Precision Metric Ball and Cylindrical Roller Bearings

Design Guidefor Precision Metric Ball and Cylindrical Roller Bearings

pre

cis

ion

innovative design enhances performance

The Timken Company has the largest aerospace product offering in the

world. Our success is built upon the foundations of research, design and

manufacturing excellence. Aerospace customers around the world rely on

Timken for precision, performance and technical services that keep aircraft

running smoothly.

At Timken research facilities in the United States, Europe and Asia,

engineers develop and test aerospace bearings and components in the

conditions in which they will operate. Our approach to product development

governs our manufacturing direction and ensures that Timken products will

operate consistently and accurately in a host of aerospace applications.

One of The Timken Company’s competitive advantages is its knowledge

and experience in steel making. As the only aerospace bearing manufacturer

that develops and produces remelted aerospace steel, Timken understands

how slight variations in metallurgy can affect overall performance.

Timken is the world’s largest producer of bearing steel.

www.bearing.sg

www.bearing.sg

de

sig

n

customer-driven solutions

Our products – used in aircraft propulsion engines and APU’s, gear boxes,

helicopter transmissions, accessory subsystems, airframes, landing wheels and

instrumentation – continue to evolve to meet today’s high-performance

requirements. Timken engineers experiment with advanced materials,

engineered surfaces and modified internal geometry to identify the most

effective options for customers.

Collaboration has led to the development of enhanced products that are

helping customers produce new models and better maintain existing aircraft.

Timken regularly consults, designs prototypes and manufactures ball bearings

and cylindrical, spherical, needle and tapered roller bearings. While most

production quantities are made to order, many prototypes are

available with short lead times and are made from the newest

materials to meet customer demands.

Our engineers also offer advanced technical services to identify

and solve performance issues within aerospace operations, including:

• Application testing

• Material development and testing

• Metrology and measurement

• Advanced modeling and simulation

• Tribology and lubrication analysis

• Metallurgical services.

www.bearing.sg

www.bearing.sg

tech

no

log

yyour value-added resource

Throughout our global operations,

which include 90 manufacturing

facilities and 10 technical centers,

Timken maintains quality standards that

exceed industry norms. Our aerospace facilities have led the organization in

the implementation of Lean Manufacturing and Six Sigma techniques that

heighten quality and streamline production. Associates embrace continuous

improvement initiatives and regularly offer suggestions that enhance quality,

reduce waste and speed products to customers.

Our goal is to enhance our already strong reputation as an innovative

aerospace leader and a responsive resource for customers around the world.

We look forward to helping your company enhance its performance with

Timken products and services. www.bearing.sg

www.bearing.sg

TECHNICAL SERVICES

Timken Technical ServicesTimken offers a wide range oftechnical services to help customerssolve issues including gauging,metrology and lubrication. Timkenoffers its expertise and experience intechnical areas to customers aroundthe world. Technical Services (Order#1403) highlights how Timken canhelp your company.

Tribology & Lubrication AnalysisThe tribology and lubrication sell sheet(Order #1411) describes Timken’sservice offerings in analyzing friction.Timken can evaluate your lubricantproperties as well as perform rolling-contact fatigue tests and rolling-element performance evaluations.

Metrology & Measurement ServicesInformation regarding metrology andmeasurement services offered byTimken is included in this sell sheet(Order #1408), which highlights thecompany’s array of measurementcapabilities. Measurement servicesare tailored to meet your specificmetrology requirements.

Automated Bearing Setting &GaugingTimken Technical Services can helpyour company obtain bearing lateralsettings for your applications toachieve optimal system performance.The Automated Bearing Setting andGauging (Order #1405) sell sheetprovides more information.

Application TestingWith a broad range of testingcapabilities, Timken is able to developspecific parameters to measureperformance in a variety of conditions.We can evaluate your bearingsystems, seal performance, drivelinesystems, driveline components andmuch more. Timken’s ApplicationTesting (Order #1404) shares ourexperience in this field.

Metallurgical ServicesAs a bearing and steel manufacturer,Timken has the ability to provide value-added metallurgical services, includingsupplying of experimental materials,conducting mechanical testing, analyzingmaterial and failures and consultingregarding heat treating materials andthermal treatment processes. TheMetallurgical Services sell sheet (Order #1435) provides details.

se

rvic

e

AEROSPACE CAPABILITIES

Aerospace Capabilities BrochureTimken has the largest aerospaceproduct offering in the world. Weoffer in-depth research andtechnologically advanced productsto customers around the world. Thecapabilities brochure is available inEnglish, French, German, Italian andChinese (Order #5910).

Aerospace ServicesTimken offers comprehensiveservices for bearings used in aircraftengine mainshafts, gearboxes andaccessories. Timken aerospaceservices can restore bearings to like-new condition through cost-effectiveremanufacturing processes. To learnmore, request the AerospaceServices sheet (Order #5572) inEnglish, French, German or Italian.

Innovation in AerospaceAs a technology leader in theaerospace industry, Timkencollaborates with customers toengineer value-added solutions tomeet application requirements. Thecompany maintains global research,development and testing facilities for this purpose. This brochure isavailable in English, French, German,Italian and Chinese (Order #5952).

Aerospace ProductsTimken offers a broad range of ballbearings and cylindrical, spherical,needle and tapered roller bearingsspecifically for aerospaceapplications. This sell sheet offersdescriptions on all of the bearingproducts and services available. This brochure is available in English,French, German, Italian and Chinese(Order #5951).

Aerospace Landing WheelBearingsAerospace landing wheel bearingsoffer reliability and performance – ata cost-effective price. Timken'srange includes Code 629 bearings,made specifically for landing wheels,and bearings with engineeredsurfaces to decrease rib/roller endscuffing. (Order #5953)

TECHNICAL CAPABILITIES

Engineered SurfacesWork with Timken engineers to findout how engineered surfaces canimprove bearing and componentperformance and life. Engineeredsurfaces improve the wear, fatigueand frictional performance onprecision components. Learn morethrough this sales sheet. (Order #5673)

Tapered Roller Bearing Selection GuideThe interactive Tapered Roller Bearing SelectionGuide will help you locate the most appropriateTimken® bearing for your application. Users canvary size and performance data to predictbearing life and save application data for futurereference. Translations are available on the CDin French, German, English, Italian, Spanish andSwedish (Order #5667).

advanced products and servicesThe Timken Company offers an array of products and services to the aerospace industry. You canlearn more by requesting information from your Timken representative. Below are examples ofliterature available to you:

Timken Aerospace Precision Metric Ball andCylindrical Roller Bearings This is a design guide for aircraft gas turbine, transmission and accessorybearing applications, as well as other applications requiring the highestprecision and quality.

■ 10 mm bore to 300 mm outside diameter (O.D.)

■ 000,100,200,300,400 Series

■ ABEC/RBEC Classes 1,3,5,7,9

■ Standard and custom designs Contents

■ BASIC DESIGN CONSIDERATIONS

Bearing Design . . . . . . . . . . . . . . . . . . . . . . . . . . . 1Construction Selection . . . . . . . . . . . . . . . . . . . . . 2Size and Chassis Selection . . . . . . . . . . . . . . . . . . 3Special Designs . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

■ CYLINDRICAL ROLLER BEARINGS

Basic Construction Types . . . . . . . . . . . . . . . . . . . 3Separator Options . . . . . . . . . . . . . . . . . . . . . . . . . 4Part Numbers, Dimension and

Capability Table . . . . . . . . . . . . . . . . . . . . . . . . . 4

■ BALL BEARINGS

Basic Construction Types . . . . . . . . . . . . . . . . . . . 7Separator Options . . . . . . . . . . . . . . . . . . . . . . . . . 8Part Numbers, Dimension and

Capability Table . . . . . . . . . . . . . . . . . . . . . . . . . 9

■ ENGINEERING DATA

Tolerances . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12Non-Destructive Testing . . . . . . . . . . . . . . . . . . . 16Materials and Operating Temperatures . . . . . . 16Radial Play and Contact Angle . . . . . . . . . . . . . . 17Preloading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19Bearing Mounting Practices . . . . . . . . . . . . . . . . 20Dynamic Load Rating and Life Calculations . . . 20Static Load Ratings . . . . . . . . . . . . . . . . . . . . . . . 23Life Adjustment Factors . . . . . . . . . . . . . . . . . . . 23Modes of Failure . . . . . . . . . . . . . . . . . . . . . . . . . 24Lubrication . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

■ ULTRA-HIGH-SPEED PERFORMANCE FEATURES

Performance Features . . . . . . . . . . . . . . . . . . . . . 26

■ APPENDIX

Millimeter to Inch Equivalents . . . . . . . . . . . . . . 27Metric Conversion Factors . . . . . . . . . . . . . . . . . 28Celsius/Fahrenheit Temperature Conversion . . 31Torque Tension for Bolts, Capscrews,

Studs and Nuts . . . . . . . . . . . . . . . . . . . . . . . . .31Trigonometric Solutions . . . . . . . . . . . . . . . . . . . 32

1

From applications to specification – a logical approach.This design guide is prepared to help you choose theoptimum bearing for your specific application. Too oftenbearings are selected in a haphazard manner resulting inpoor performance, unexpected problems and earlyfailures. To help you avoid these and other issues,Timken has developed a four-step procedure thatsummarizes all key concepts that should be consideredwhen developing a specification. The interrelationship ofthese concepts covers the entire field of bearingengineering.

Many answers are provided in this design guide butmany others require the assistance of an experiencedbearing engineer. In unusual or state-of-the-artapplications, the solution is a carefully monitored testprogram. Bearing chassis sizes and capabilities listed inthis guide can be modified and optimized to meetspecific requirements including special features.

■ STEP 1 – Determine Performance RequirementsSimply stated, there are two basic performancerequirements, which if adequately defined, controleverything that a bearing must do within an application.Every bearing must: 1) Provide a defined level of rotational freedom.2) Provide a defined level of position control (from basic

free movement to high-frequency movement or noise).

It is important to determine the actual limits of theserequirements since bearing life is nothing more than howlong the bearing is statistically expected to operate withinthese limits. Of course, limits vary significantly from onetype of application to another, so thorough definitionsmust be established.

■ STEP 2 – Determine Application ParametersPerformance is governed by a number of applicationparameters. Although only a portion may be significantin any given application, meticulous review of each willensure that nothing important has been overlooked.

Performance application parameters can be categorizedfour ways:1) Physical Parameters 3) Environmental Parameters2) Operational Parameters 4) Economic Parameters

In any given application, many of these are fixed whileothers are variable and can be modified or controlledwhen necessary. Final selection is always a series ofcompromises.

Physical Parameters

These include:1) Space available for the bearing or bearing systems.2) Allowable weight for the bearing or bearing systems.3) The shape, material and tolerance control of the

housing and shaft.4) Combining features onto the bearing to simplify

mounting structures.5) Operational temperature.

The more space and weight that can be allowed to thebearing system, the more sophisticated and reliable itwill be. However, added weight may be an expensiveluxury unless absolutely necessary, as would be true ofsupplementary lubrication systems for high-speedturbine and accessory bearings. The housing and shaftdesign has a significant impact in ultimate bearingperformance. Ideally, the shaft will be a solid, perfectlyround cylinder made from material absolutely compatiblewith the thermal coefficient of expansion of the bearing.The housing cross section should be uniform, giving fullhoop support for the bearing. Both housing and shaftshould have precision-machined shoulders or seats toensure the bearing races are perfectly aligned.

But many compromises occur in actual applications.Timken’s extensive bearing design experience can provea valuable aid to a designer facing critical physicalrestrictions.

Operational Parameters

1) Speed governs the number of load cycles the bearingexperiences and is therefore related to life. Speed in termsof a relative guide parameter, called “dn” (inner ring borein mm x RPM) also influences many other aspects ofbearing operations. Included are lubricant flow patternsand film thickness, centrifugal rolling-element loads,skidding and excessive heat generation and removalmethod.

2) Loads can be broken down in three directions: radial,axial and moment. These in turn can be applied asconstant, variable, vibratory or impact loading. Thecombination must be carefully considered foroptimum life and performance.

Environmental Parameters

The environment is a fixed condition of the end product.However, the decision to protect or expose the bearing tothe environment is a design option. Temperature, eitherambient or internally generated, is a major consideration.The nature of the surrounding media, liquid or gas (forboth materials and lubrication), may establish the needfor seals, special corrosion protection or supplementallubrication. Any special environments such as magneticfields or radiation also should be considered for theirdesign impact.

Economic Parameters

Total system cost should be carefully weighed, not just thecost of the bearing, but the total cost of bearing, mountingand replacement if the bearing does not operatesatisfactorily. Special designs, while more expensiveinitially, may be most cost effective, since normally theywould result in simplified mounting structures.

■ STEP 3 – Evaluate Potential Failure ModesFailure in a particular application occurs when there issufficient performance degradation so that the bearingno longer meets the original requirements. There arenine commonly identified primary failure modes:1) Classic fatigue 6) Separator fracture2) True load brinell 7) Temper smearing3) False brinell (fretting corrosion) 8) Rotational4) Skidding interference5) Race or rolling element fracture 9) Wear

Bearing Design

2

Construction BEARING TYPES

SelectorChart

Conrad Angular Fractured Two-Piece Roller

DESIGN FUNCTION HK Contact HA Outer HD Inner HT Radial

Radial load S M E S E

Thrust – unidirectional S E S* E M

Thrust – reversing S N/A S* E N/A

Radial and unidirectional thrust S E E S M

Radial and reverse thrust S N/A E S N/A

Moment (cocking load) S N/A M* S N/A

High speed S E S* E E

Optimum design, one-piece retainer N/A E E E E

Ability to resist mishandling E S S S S

Ease of mounting E S E S S

Ability to resist housing distortion E S M E S

Continuity (life) after failure M E E E E

Ability to meet life with misalignment E M E S M

Ability to absorb axial expansion with M M M M Efixed races

CODES: E = excellent S = satisfactory M = marginal N/A = not adequate or not available*May be used with closely restraining housing fits and face clamping

ConstructionSelection

Evaluation of the design criteria contained in the following chart will help you choose theoptimum design construction. While no individual construction can satisfy all possibleservice functions, proper selections makes it possible to meet the most critical functions orconditions in each application. The chart rates each construction on a relative basis.

A complete discussion of these failure modes is beyondthe scope of this design guide. It is important to note thatonly classic fatigue and true load brinell have specificformulas that permit a believable theoretical calculationof life or numerical limit. All of the others are experiencefactors that are a function of the specific application,where temperatures, lubrication, overload orcontamination are contributors to decreased life.

■ STEP 4 – Determine Bearing Design Only after careful consideration of the foregoing should aspecific bearing selection be made. In many cases, it ispossible to select a size and type from this guide withoutdefining restrictions on other characteristics. In morecritical applications, specific decision and/or controls canbe developed on:

1) Lubrication type, method and/or quantity2) Use of shields and/or seals3) Separator configuration material and clearances4) Basic tolerance and modifications 5) Radial play or contact angle6) Preload 7) Material variation8) Contact area geometry modifications (curvature,

crowning, etc.)9) Special ball or roller complements 10) Complete special and/or integral designs

If the analysis has been completed properly, the final designwill function as intended. Reliability and life expectancy willbe optimized with minimum chance of premature failures orunanticipated problems. Timken aerospace product designengineers are ready to provide whatever assistance isnecessary toward achieving this goal.

Size and Chassis Selection

Timken aerospace ball and roller bearings are offered infive basic ABMA boundary dimension series(000,100,200,300 & 400). These series, presented in thespecification tables, include bearings ranging in size from10mm bore to 300mm O.D. The 000 (ABMA 1900) serieshas become increasingly popular with the aircraftindustry due to its very thin cross section and reducedweight. Should the need exist, Timken can also supplybearings in the ultra-light (1800) series.

Special Designs

Many special designs can be made to simplify mountingand improve performance in complex engine assemblies.

A typical design would include bearings with pullergrooves, self-aligning seats, flange mounts or double-rowduplex assemblies. To speed delivery and reduce cost, allspecialized bearings should be designed around standardbore, O.D. width or ball/roller complements as listed inthe bearing specification tables as a starting point.

Aerospace roller bearings are designed to meet the needfor improved quality bearings used in high-speedoperations. Attention to detail – including rollerconfiguration, separator design, guide flange finish andcontour and material stability – significantly reduces endwear and improves life at high speeds.

Conventionally designed roller bearings in standard52100 or VIM-VAR M-50 are normally manufactured in

RBEC 5 tolerance with high-strength machined cages.Any of at least seven race configurations may be selecteddepending on the application. All types (except RAA)provide precision control of the roller for operation overa wide speed range with precision-ground, double-ribbedguide flanges on one ring. Generally, the outside surfacesare also ground to close tolerances to offer a ridingsurface for the retainer to land clearance control.

3

Split-inner-race bearingwith puller groove

Roller bearingwith integral

flange mount

Roller bearing with self-aligning seat

Double-rowduplexassembly

Cylindrical Roller BearingsBasic Construction Types

Rollers

Rollers in all sizes over 3.5mm are contoured by crownblending for uniform stress distribution under load. Thelength is closely matched for uniform minimum clearancewithin the guide flanges to ensure optimum tracking at allspeeds. All rollers listed in the specification table have the

preferred equal length to diameter ratio. These “square”rollers have superior ability to accept thrust andmisalignment. Where theoretical capacity is critical, whenload conditions and O.D. restrictions dictate, rollers ofdiameter to length ratio less than 1 can be supplied.

RF RJ

For applications requiringaxial position control or

limited thrust capabilitiesin one direction, type RF is

most frequently used.Under light loads, type RFis less prone to skidding.

Under higher loads athigher speeds, type RJ iseasier to lubricate with anoil jet onto the inner race.

RU RN

These full-floatingconfigurations allow

limited axial motion duringoperation. Type RU is

easier to lubricate underheavy loads. Type RN isless prone to slip or skidunder lighter or varying

loads at high speeds.

RUS RNH

These configurations areused in integral designs

where the rollers rundirectly on a hardened andground shaft or housing.Nominal matching shaft

and housing diameters areshown in the tabulations.

Performancecharacteristics are similar

to types RU and RN.

RAA

Single-ribbed innerand outer rings are alower-cost version oftype RF for use at low

speeds or underoscillating conditions.This design generally

has high guide flangesto accept some thrust

in one direction (with well-lubricated

guide flanges).

Source: ABMA

ABMA Dimension Series

Timken Series

1819

10 0203

04

1800000

100 200300

400

Part Numbers,Dimensionand CapabilityTableCylindrical RollerBearingSpecifications

To Develop a Complete Bearing Part Number:

1) Select MATERIAL prefix (see page 17).2) Select CONSTRUCTION TYPE and SEPARATOR prefixes.

CONSTRUCTION TYPES

Separators RF RJ RU RN RUS RNH RAA

Machined Bronze B RFB RJB RUB RNB RUSB RNHB RAAB

Machined Si-Fe Bronze Z RFZ RJZ RUZ RNZ RUSZ RNHZ RAAZ

Machined Steel Silver plated H RFH RJH RUH RNH RUSH RNHH RAAH

Full roller complement F RFF RJF RUF RNF RUSF RNHF RAAF

3) Select basic bearing SIZE code (tabulation below)4) Add suffixes for TOLERANCE code (see pages 12-15), RADIAL PLAY code

(see page 17) and LUBRICATION code (see page 26). If any codes are omitted,standard values will be applied. For complex assemblies, Timken will substitute adash number (in lieu of suffixes) to cover all special features.

EXAMPLESRFZ201 P7(3) LY 240 5 RNF 109-28

Material – 52100 steel 5 = VIM-VAR M-50 steel

Construction RF = RF type RN = RN type

Separator Z = machined Si-Fe bronze F = full roller complement

Size 201 = size 201 109 = size 109

Tolerance P7 = ABEC 7 special featuresRadial Play (3) = Range 3 clearance -28 = detailed under

Lubrication LY240 = Shell Darina EP2 “dash” 28 code

4

AVAILABILITY: Most productionquantities are madeto order. Prototypesmay be available.Check with Timkenfor latest availability.

Separator OptionsSeparators are machined from high-strength, bearing-quality bronze with precision broached pockets. Therollers are retained through a Timken proprietary formedtab design. The floating ring can be removed to facilitate

inspection or assembly. Silicon-iron-bronze or silverplated 4340 steel may be specified for higher temperatureor speed conditions.

SeparatorMaterial & Type Design

Temp. Speed LimitDescriptionCode Limit dn 106

B Machined bronze 375°F190°C 1.0

Z AMS 4616 500°Fsilicon-iron-bronze 260°C 1.5

Machined and hardened 900°FH AMS 6415 alloy steel 480°C 3.0

silver plated

Full roller complement, Same as E no separator bearing 0.3.

material

Use in heavily loaded transmission, machine tool and accessoryapplications. Operates in oil lubrication. Excellent strength and wearperformance. Most readily available separator on most sizes.

Similar to standard bronze with better strength and wear resistance.Frequently used in combination with VIM-VAR M-50 rings wheretemperatures exceed the 375° limit for 52100 steel.

Silver plated to enhance run-in, wear life and to provide maximumcontinuity after lubricant loss. VIM-VAR M-50 bearings with silver-platedsteel cages are the first choice of the turbine industry for criticalperformance mainshaft and power train bearings.

Use primarily at low speeds under high radial loads. Provides themaximum possible static load capacity. Also use to reduce cost where aseparator is not required.

{

5

BasicSizeCode

BOUNDARY DIMENSIONS LOAD RATINGS

Roller

Diameter

x Lengthmm

DynamicRadial

CapacityCr (lbs.)

StaticRadial

CapacityCor (lbs.)

1,032 1,740 1,7722,8921,0381,7722,4603,2611,3332,1332,9064,2531,3272,4553,4345,3527,5822,7534,0065,1896,5699,1473,0204,6035,9789,341

12,6833,2615,1569,225

12,88514,554

4,5076,713

10,89814,95116,737

6,1538,456

12,92519,33421,323

6,5939,295

15,09821,25727,417

6,52810,08516,96526,36430,155

7,37413,46119,58030,46833,366

7,29814,63425,31233,68940,081

7,67314,55125,28640,44143,29512,11820,27927,69847,73254,842

3.5 x 3.55 x 55 x 5

6.5 x 6.53.5 x 3.5

5 x 56 x 67 x 7

3.5 x 3.55 x 56 x 68 x 8

3.5 x 3.55 x 56 x 69 x 9

11 x 115 x 57 x 7 8 x 8

10 x 1012 x 12

5 x 57 x 7 8 x 8

11 x 1113 x 13

5 x 57 x 7

10 x 1013 x 1314 x 14

6 x 68 x 8

11 x 1114 x 1415 x 15

7 x 7 9 x 9

12 x 1216 x 16 17 x 17

7 x 79 x 9

13 x 1317 x 1718 x 18

7 x 79 x 9

13 x 1319 x 1919 x 19

7 x 711 x 1114 x 1419 x 1920 x 20

7 x 711 x 1116 x 1620 x 2022 x 22 7 x 7

11 x 1116 x 1622 x 2223 x 23

9 x 913 x 1317 x 1724 x 2426 x 26

7461,2211,2682,449

7711,2682,0592,4061,1201,6682,2613,2221,1382,0532,7514,1405,9972,4443,3134,3325,1737,4782,8844,0365,2948,033

11,1673,3134,8908,460

11,37213,075

4,6536,522

10,19413,43815,372

6,4848,354

12,34817,77619,945

7,3169,751

14,62619,74427,306

7,39211,11617,36124,95630,415

8,98614,49620,37730,72634,163

9,05616,47426,75134,41041,527

9,87516,63927,24441,90545,23615,37520,40429,81250,01858,400

Outer No.

0.76770.90550.98421.18100.85330.98421.10241.26120.98431.13191.22051.45281.06301.23031.39071.63191.98821.32871.49611.64961.81102.28341.53611.69291.83002.18762.57811.72241.96262.24492.54532.91342.01972.24022.56102.81503.24812.28352.48032.85833.22052.62212.50002.73423.09653.52363.95682.67722.93113.29333.93504.29132.94683.30903.60244.23034.62603.13873.48424.00794.52755.00003.32683.68114.30314.94495.33473.71854.05514.50795.32285.9449

Bore d

mm

101010101212121215151515171717171720202020202525252525303030303035353535354040404040454545454550505050505555555555606060606065656565657070707070

Inch

10888

10888

141010

8141210

88

141010

88

1612121010181412101018141210101814121010201612101220181410122416141212241814121226181412122418141212

OutsideDiameter D

mm

222630352428323728323542303540476237424752724247526280475562729055627280

10062688090

110687585

100120

728090

110130

8090

100120140

8595

110130150

90100120140160100110125150180

Inch

Width W

mm

689

1168

1012

79

1113

710121417

912141519

912151721

91316192310141721251215182327121619252912162027311318212933131822313513182333371620243542

Inch Inner

Mounting ShoulderDiameter

Nominal RollerPath Diameter

Min.Shaft A

Max.Housing S

0.49210.51180.59050.66920.57780.59050.62990.71000.70870.73820.74800.82280.78740.83660.87890.92321.12200.93500.94491.01971.02361.33861.14241.14171.20001.32141.55581.32871.41141.45751.52171.91101.54721.61021.69491.71262.06691.73231.77161.91341.96062.28351.94882.02562.07282.18502.53942.12602.22242.26972.43902.79532.39572.44292.50002.73423.05122.58752.61812.74802.95273.26782.77562.81503.04333.21263.52373.00983.03153.16933.43313.8977

R

Radius

0.39370.39370.39370.39370.47240.47240.47240.47240.59060.59060.59060.59060.66930.66930.66930.66930.66930.78740.78740.78740.78740.78740.98430.98430.98430.98430.98431.18111.18111.18111.18111.18111.37801.37801.37801.37801.37801.57481.57481.57481.57481.57481.77171.77171.77171.77171.77171.96851.96851.96851.96851.96852.16542.16542.16542.16542.16542.36222.36222.36222.36222.36222.55912.55912.55912.55912.55912.75592.75592.75592.75592.7559

000100200300001101201301002102202302003103203303403004104204304404005105205305405006106206306406007107207307407008108208308408009109209309409010110210310410011111211311411012112212312412013113213313413014114214314414

0.86611.02361.18111.37800.94491.10241.25981.45671.10241.25981.37801.65351.18111.37801.57481.85042.44091.45671.65351.85042.04722.83461.65351.85042.04722.44093.14961.85042.16542.44092.83463.54332.16542.44092.83463.14963.93702.44092.67723.14963.54334.33072.67722.95283.34653.93704.72442.83463.14963.54334.33075.11813.14963.54333.93704.72445.51183.34653.74024.33075.11815.90553.54333.93704.72445.51186.29923.93704.33074.92135.90557.0866

0.23620.31500.35430.43310.23620.31500.39370.47240.27560.35430.43310.51180.27560.39370.47240.55120.66930.35430.47240.55120.59060.74800.35430.47240.59060.66930.82680.35430.51180.62990.74800.90550.39370.55120.66930.82680.98430.47240.59060.70870.90551.06300.47240.62990.74800.98431.14170.47240.62990.78741.06301.22050.51180.70870.82681.14171.29920.51180.70870.86611.22051.37800.51180.70870.90551.29921.45870.62990.78740.94491.37801.6535

0.4730.4890.5520.5690.5520.5640.6180.6710.6710.6860.7300.7960.7490.7630.8150.8790.9460.8740.9270.9720.9921.0641.0701.1281.1661.2051.3031.2681.3601.3741.4131.5001.5100.1561.5891.6831.6971.7071.7551.7931.8951.9881.9131.9591.9852.0872.1852.1092.1572.1802.3512.5182.3652.3982.4462.5582.7152.5602.5922.6482.7652.9122.7552.7872.8582.9493.1092.9632.9943.0543.1953.445

0.7860.9281.0231.2030.8661.0111.1141.2611.0221.1651.2391.4531.1021.2841.4291.6412.1641.3701.5141.6651.8432.5581.5681.7061.8662.2202.8311.7641.9872.2482.6023.2252.0342.2592.6232.8443.6192.3092.4972.9313.2233.9182.5362.7653.1333.6224.3112.6952.9613.3323.9484.5692.9503.3113.6574.3324.9623.1483.5104.0454.7165.3563.3473.7094.4265.1225.7503.7304.0924.6235.4666.397

0.0120.0120.0240.0240.0120.0120.0240.0390.0120.0120.0240.0390.0120.0120.0240.0390.0390.0120.0240.0390.0390.0390.0120.0240.0390.0390.0590.0120.0390.0390.0390.0590.0240.0390.0390.0590.0590.0240.0390.0390.0590.0790.0240.0390.0390.0590.0790.0240.0390.0390.0790.0790.0390.0390.0590.0790.0790.0390.0390.0590.0790.0790.0390.0390.0590.0790.0790.0390.0390.0590.0790.098

Part Numbers, Dimension and Capability Table continued

Cylindrical Roller Bearing Specifications

R = the maximum shaft or housing fillet radius that bearing corner will clearC = the dynamic radial capacity at 331⁄3 RPM for 500 hours minimum life

Co = the static non-brinell radial capacity.

6

BasicSizeCode


Roller

Diameter

x Lengthmm

DynamicRadial

CapacityCr (lbs.)

StaticRadial

CapacityCor (lbs.)

12,03420,18430,95355,56763,19612,66720,28034,17363,01472,06417,56725,09737,90163,19281,46117,45428,59441,80972,11991,50118,40832,49450,27381,52498,06820,62832,63558,24188,623

101,72820,49135,44862,742

102,030107,270

21,62540,86971,220

113,129124,394

29,42243,90981,273

135,950155,479

33,54748,298

101,827155,082182,746

35,11851,451

101,406164,649197,341

43,78661,967

115,040212,423

48,94973,557

126,94548,52185,78459,822

104,21959,383

118,14781,25778,06884,399

9 x 913 x 1318 x 1826 x 2628 x 28

9 x 913 x 1318 x 1828 x 2830 x 3011 x 1114 x 1420 x 2028 x 2832 x 3211 x 1115 x 1520 x 2030 x 3034 x 3411 x 1116 x 1622 x 2232 x 3235 x 3512 x 1216 x 1625 x 2536 x 3636 x 3612 x 1217 x 1726 x 2636 x 3637 x 3712 x 1219 x 1928 x 2838 x 3840 x 4014 x 1419 x 1930 x 3042 x 4245 x 4515 x 1520 x 2030 x 3045 x 4549 x 4915 x 1520 x 2032 x 3250 x 5051 x 5117 x 1722 x 2236 x 3653 x 5318 x 1824 x 2436 x 3618 x 1826 x 2620 x 2030 x 3020 x 2032 x 3224 x 2423 x 2324 x 24

15,46623,61233,59158,83667,91716,85523,40338,74967,18078,12827,86630,90042,26867,91389,04322,99235,82948,81778,354

101,12325,03340,75359,25689,308

110,01327,71441,00066,53993,625

114,42427,83745,00772,519

113,826121,575

30,28050,73182,313

127,444142,445

41,67057,01095,415

154,869180,696

48,20463,838

124,889178,904215,492

52,24970,776

126,236183,357235,289

65,39686,184

140,314255,878

73,774102,906162,531

74,193121,387

92,241144,110

92,661164,257124,380123,735135,503

Outer No.

3.89764.25204.74415.70086.31904.09454.54725.03946.11696.69294.49014.78355.45276.31897.06694.68705.14765.70876.75207.53944.88395.38586.12607.12997.97205.19685.58276.49607.68908.30705.39375.91936.88197.98428.64185.59056.25987.20478.46069.25206.18906.69097.83469.2165

10.23636.69297.28358.32689.9311

11.18117.08667.67728.9370

10.728311.8504

7.75598.30709.6850

12.51978.18908.8189

10.27568.61819.48829.2519

10.23629.6456

10.708610.393710.793311.1811

Bore d

mm

75757575758080808080858585858590909090909595959595

100100100100100105105105105105110110110110110120120120120120130130130130130140140140140140150150150150160160160170170180180190190200210220

Inch

2418141212262016121224201412122420161212262016121224201410122420141212261814121226201412122620161212282216101228221412282216282228202820262828

OutsideDiameter D

mm

105115130160190110125140170200120130150180210125140160190225130145170200240140150180215250145160190225260150170200240280165180215260310180200230280340190210250300360210225270380220240290230260250280260290280290300

Inch

Width W

mm

1620253745162226394818222841521824304354182432455520243447582026364960202838506522284055722433405878243342628228354585283848284233463346383838

Inch Inner


Nominal RollerPath Diameter

Min.Shaft A

Max.Housing S

3.18903.22833.32683.65354.11423.38583.52363.62203.91214.33073.62403.68113.87794.11424.54733.82093.96654.13394.38984.86224.01774.12604.39374.61025.21654.25204.32284.52754.85435.47244.44884.58074.83465.14965.72844.64574.76385.00005.46856.10245.08665.19495.47245.90946.89295.51185.70875.96466.38787.32295.90556.10246.41736.79132.83466.41736.57506.85048.34656.77166.92917.44097.20087.44097.67717.87408.07098.18908.50398.98239.2913

R

Radius

2.95282.95282.95282.95282.95283.14963.14963.14963.14963.14963.34653.34653.34653.34653.34653.54333.54333.54333.54333.54333.74023.74023.74023.74023.74023.93703.93703.93703.93703.93704.13394.13394.13394.13394.13394.33074.33074.33074.33074.33074.72444.72444.72444.72444.72445.11815.11815.11815.11815.11815.51185.51185.51185.51185.51185.90555.90555.90555.90556.29926.29926.29926.69296.69297.08667.08667.48037.48037.87408.26778.6614

015115215315415016116216316416017117217317417018118218318418019119219319419020120220320420021121221321421022122222322422024124224324424026126226326426028128228328428030130230430032132232034134036136038138040042044

4.13394.52765.11816.29927.48034.33074.92135.51186.69297.87404.72445.11815.90557.08668.26774.92135.51186.29927.48038.85835.11815.70876.69297.87409.44885.51185.90557.08668.46469.84245.70876.29927.48038.858310.23625.90556.69297.87409.448011.02366.49617.08668.464610.236212.20477.08667.87409.055111.023613.38587.48038.26779.842511.81114.17328.26778.858310.629914.96068.66149.448811.41739.055110.23629.842511.023610.236211.417311.023611.417311.811

0.62990.78740.98431.45671.77170.62990.86611.02361.53541.88980.70870.86611.10241.61422.04720.70870.94491.18111.69292.1260.70870.94491.25981.77172.16540.78740.94491.33861.85042.28350.78741.02361.41731.92912.36220.78741.10241.49611.96852.55910.86611.10241.57482.16542.83460.94491.29921.57482.28353.07090.94491.29921.65352.44093.22831.10241.37801.77173.34651.10241.49611.88981.10241.65351.29921.8111.29921.81101.49611.49611.4961

3.1613.1903.2503.4033.6423.3563.3893.5193.6113.8393.5713.5933.7213.8764.2433.7673.8423.9714.0854.4393.9654.0394.1814.2944.6364.1724.2304.3914.5664.8334.3684.5224.6014.7745.0304.5644.7284.8115.0045.2264.9675.1235.2015.4486.1005.4505.5345.6975.9376.4945.8445.9316.1396.3536.8876.2976.3596.5617.2816.6886.7766.9877.0837.1927.4997.5847.8907.9888.3428.7349.126

3.9264.2904.8205.8496.7914.1244.6825.1426.2327.1854.5004.8725.5316.5577.3724.6985.2135.8726.9397.9624.8935.4106.2527.3208.5535.2775.6126.6337.8358.9465.4745.9117.0138.2189.3405.6726.2967.3938.775

10.1286.2546.6887.9889.513

10.8296.7547.4588.476

10.20412.010

7.1487.8499.215

10.97012.798

7.8768.4059.974

13.5858.2738.972

10.7308.6659.7379.430

10.5269.826

10.91010.55510.95111.346

0.0390.0390.0590.0790.0980.0390.0390.0790.0790.0980.0390.0390.0790.0980.1180.0390.0590.0790.0980.1180.0390.0590.0790.0980.1180.0390.0590.0790.0980.1180.0390.0790.0790.0980.1180.0390.0790.0790.0980.1180.0390.0790.0790.0980.1570.0590.0790.0980.1180.1570.0590.0790.0980.1180.1570.0790.0790.0980.1570.0790.0790.0980.0790.0790.0790.0790.0790.0790.0790.0790.079


Cylindrical Roller Bearing Specifications


Co = the static non-brinell radial capacity.

SealedBearingsConrad design bearings with molded ballriding crown separators (HKM) can besupplied with molded-lip Buna N rubber or

Viton® contact seals, indicated in the part number asHKMZZ for double seals. These unique, long-lip, lightcontact seals are normally used for high-speedapplications requiring adequate lubricant retention withminimum heat generation. Special seals with heavy-lippressure can be manufactured for severe contaminationenvironments under low-speed operation.

7

Ball BearingsBasic Construction Types

Any of four basic ball bearing constructions in size ranging from 10mm bore to300mm O.D. can be manufactured to meet the most demanding performancerequirements.

Selection of the construction best suited to the application must consider therelative importance of the various design functions (as listed on page 2). Thefollowing general description of each type will further assist in the proper selection.

HK SERIES

Conrad construction

The conventional Conradcontact bearing’s versatileload capability allows it tohandle radial, thrust,moment, reversible thrustor combination loadingconditions. Separators –either a two-piece (rivetedor welded) design or aone-piece, open-facecrown design – while nothaving the ultimatestrength and speedcapability of a one-piecesolid design, perform wellin most applications.Where speeds and loadsare severe, TimkenAerospace has developedhigh-strength Conradseparator options. Sealsand/or shields are readilyadaptable to this series,particularly with high-strength, non-metallicmolded crown separators.

HA SERIES

Angular contact

Conventional non-separable angular contactbearings with counter-bored outer rings and one-piece, high-strengthseparators are used inpreloaded and/or thrust-type applications. For ultra-high speeds, bearings withdeep-groove outer andrelieved inner races can besupplied. Two contactangle ranges are normallyspecified: 15° nominal forlightly preloaded, radialapplications; 25° nominalfor heavy preloads andhigh external thrust loads.Angular contact bearingsmay be supplied as duplex,triplex, etc., sets, which areaccurately preloaded toany specific level, withcontact angles that candeviate from thosenormally specified.

HD SERIES

Deep groove fractured race

The fractured outer ringdesign allows a maximumball complement in aradial- deep-groovebearing. This provides upto 56 percent greaterdynamic load capacityand 280 percent longerservice life over standardConrad types. One-piece,high-strength separatorsallow for higher speedsand loads while reducingthe chance of separatorfailure. While HD bearingsare used primarily forradial loads, high-strength17-4PH stainless holdingbands pressed on groundshoulders retain thefracture under moderatethrust at all but thehighest speeds. Normalmounting procedures areused except under severethrust or misalignment.Several stacked holdingbands can be used toincrease the holdingpower for loose fithousings. In this case,special precaution shouldbe observed to avoiddisplacement or openingof the fracture. Extensiveexperience has proventhere is no advancedtendency to fatigue at thefracture under normaloperation with a properlyretained outer ring.

HT SERIES

Two-piece inner ring

High-performance, two-piece inner ring bearingsare typically used on high-speed shafts withreversing thrust loads.Full deep groove outers,one-piece, high-strengthseparators and two extra-deep groove inner ringhalves provide themaximum level ofreliability with full thrustcapacity in eitherdirection. Simultaneousrace grinding assuresperfect matching betweenthe two inner ring halvesand a controlled offsetmay be specified toreduce end play. The HTseries can be readilydisassembled forinspection of the race andball components. Ballretaining separators or aremovable springretaining clip designed tohold inner halves togetherduring normal handlingalso are used. Operatingcontact angles are usuallyset between 25° and 35°but final selections ofdetailed characteristicsshould be developed withyour Timken engineer.

8

Conrad Bearing Separator Options Conrad separators are two-piece or open-face crown designs.

SeparatorMaterial & Type Design


M High-strength, fiber-reinforced 250°Fnylon; molded ball riding type 120°C 0.5

R Laminated cotton phenolic; 275°Fone-piece crown snap in 135°C 0.4

B Precision machined bronze; 375°Ftwo-piece riveted 190°C 1.0

Machined and hardened 900°FH AMS 6415 alloy steel; 480°C 2.0

silver-plated; two-piece riveted

Phosphor bronzes; stamped 375°FU two-piece riveted; land piloted; 190°C 1.0

with shaped pockets

Provides extra-quiet operation with most types of grease lubrication.Tooling available for limited number of sizes.

Specify for use with oil impregnation or where a light-weight, land-ridingseparator is required.

Use for high speeds in aircraft accessories and machine tools with forcedlubrication.

Use for ultra-high speeds in aircraft accessories and machine tools withforced lubrication. Silver plating improves wear under marginal lubrication.Normally used with M-50 daces and balls.

Allows rapid acceleration with minimum inertia and maximum exposure tooil flow. Tooling available for limited number of sizes

Ball BearingsSeparator Options

Following selection of the basic construction, selection of the proper separatorand ball complement will result in the optimum bearing for the application. Theball bearing separator is critical to bearing performance. While its prime purposeis to separate the balls in the bearing assembly, it must be evaluated for eachapplication as to:• Performance at various speed levels.• Compatibility with environmental conditions.• Compatibility with lubricant systems.• Cost and availability.

The tables below summarize separator options for metric ball bearings.

Special Separator Options

Conrad design bearings utilizing precision machined cages can be provided withstepped interfaces and detents to provide reliability with Timken’s unique “side wire” design to meet the needs of applications that experience extremeoperating conditions.

Maximum Capacity Bearing Separator OptionsWith the exception of the special full-ball complement or stamped-steel design, all separators for maximum capacityball bearings are one-piece machined design for maximum strength and balance. They are normally designed to piloton the outer land to optimize oil jet lubrication of the inner race. Outer-land piloting separators provide a self-balancing effect since any wear improves balance.

SeparatorMaterial and Type Design


B Precision machined bronze; 375°Fdrilled; one piece 190°C 1.5

R Laminated cotton machined 275°Fphenolic; one piece 135°C 1.0

Z AMS 4616 silicon-iron-bronze; 500°Fmachined; one piece 260°C 2.0

Machined and hardened 900°FH AMS 6415 alloy steel; 480°C 3.0

silver-plated; one piece

S Stamped steel; 500°Fouter-land piloted 260°C 1.0

Same as F Full ball complement bearing 0.3

material

Use in heavily loaded transmission, machine tool and accessoryapplications. Operates in oil lubrication. Excellent strength and wearperformance. Most readily available separator on most sizes.

Use on lightly loaded grease or oil mist lubricated spindles. May bevacuum impregnated to enhance life in “one shot” oiled or greasedapplications.

Similar to standard bronze with better strength and wear resistance.Frequently used in combination with VIM-VAR M-50 races wheretemperatures exceed the 375°F limit for 52100 steel.

VIM-VAR M-50 bearings with silver-plated steel cages are first choice ofthe turbine industry for critical performance mainshaft and power trainbearings. Steel is silver-plated to enhance run-in, wear life and to providemaximum continuity after lubricant loss.

Unique design developed by Timken provides a lightweight land ridingseparator. This design crosses the pitch diameter to avoid “roll under”failures common to other thin-walled, high-speed land riding separators. All surfaces are treated with a diffusion hardening process to enhance wearand reduce friction. Tooling available for limited number of sizes.

Use primarily at low speeds under high radial loads. Provides themaximum possible static and dynamic load capacity. Use also to reducecost where a separator is not required. Should not be used under heavycombined or misaligned loads with continuous rotation since thedifferential ball speeds will cause ball-to-ball scrubbing and a substantial reduction in life.

Anti-rotation detents

Side wires

9

Part Numbers,Dimensionand CapabilityTableBall BearingSpecifications

To Develop a Complete Bearing Part Number:

1) Select MATERIAL prefix (see page 16).2) Select CONSTRUCTION TYPE, SEPARATOR and SEAL prefixes.

CONSTRUCTION TYPES

Separators and SealsConrad HK Angular Fractured Two-Piece

Contact HA Race HD Inner Ring HT

Molded Crown Open M HKM

Molded Crown Single Seal MZ HKMZ

Molded Crown Double Seal MZZ HKMZZ

Machined Phenolic R HKR HAR HDR HTD

Machined Bronze B HKB HAB HDB HTB

Stamped Bronze U HKU

Si-Fe Bronze Z HAZ HDZ HTZ

Silver-Plated Steel H HKH HAH HDH HTH

Stamped Steel S HAS HDS HTS

Full Ball Complement F HAF HDF HTF

3) Select basic bearing SIZE code (tabulation below).4) Add suffixes for TOLERANCE code (see pages 12-15), RADIAL PLAY code (see page

17), PRELOAD code (see page 19) and LUBRICATION code (see page 26). If any codesare omitted, standard values will be applied. For complex assemblies, Timken willsubstitute a dash number (in lieu of suffixes) to cover all special features.

EXAMPLES3HAH 104 P5(4)DB 10/20 HDB 306-91

Material 3 = 440C stainless steel — 52100 steel

Construction HA = Angular contact type HD = Fractured-race type

Separator/seal H = Silver-plated steel B = Machined bronze

Size 104 = Size 104 306 = Size 306

Tolerance P5 = ABEC 5

Radial Play (4) Range 4 clearance

Preload DB 10/20 = DB 10 lbs. min. to -91 = Special features detailed20 lbs. max under “dash” 91 code

Lubrication Standard dip

AVAILABILITY: Most productionquantities are madeto order. Prototypesmay be available.Check with Timkenfor latest availability.

BasicSizeCode


Maximum CapacityTypes HA, HD, HT

CONRAD Type HK

BallsNo. Cr Cor

Capacity (lbs.)

6881,0301,4731,821

7491,1561,5522,183

9721,5141,7132,6501,0331,5302,3593,1315,104

87669876

10886

118866

307443612774362549708941506725830

1,179573756

1,1721,4252,426

BallsNo.† Cr Cor

Capacity (lbs.)

8001,2411,8662,307

8941,3421,8642,5621,1331,7661,9993,3411,1791,8882,5923,9415,986

1110

99

131110

8141111

9151210

98

Bore d

mm

1010101012121212151515151717171717

Inch

0.39370.39370.39370.39370.47240.47240.47240.47240.59060.59060.59060.59060.66930.66930.66930.66930.6693

398601877

1,110487710954

1,204663942

1,0791,698

7271,0651,3812,0473,094

000100200300001101201301002102202302003103203303403

OutsideDiameter D

mm

2226303524283237283235423035404762

Inch

0.86611.02361.18111.37800.94491.10241.25981.45671.10241.25981.37801.65351.18111.37801.57481.85042.4409

Width W

mm

689

1168

1012

79

1113

710121417

Inch Inch

0.23620.31500.35430.43310.23620.31500.39370.47240.27560.35430.43310.51180.27560.39370.47240.55120.6693


BallDia.

Min.Shaft A

0.4730.4890.5520.5690.5520.5640.6180.6710.6710.6860.7300.7960.7490.7630.8150.8791.088

Max.Housing S

0.7860.928*

1.0231.2030.8661.0111.1141.2611.022

1.165*1.2391.4531.102

1.284**1.4291.6412.022

9⁄64

3⁄16

1⁄49⁄32

9⁄64

3⁄16

15⁄64

5⁄16

5⁄32

7⁄32

15⁄64

11⁄32

5⁄32

7⁄32

9⁄32

3⁄81⁄2

R

Radius

0.0120.0120.0240.0240.0120.0120.0240.0390.0120.0120.0240.0390.0120.0120.0240.0390.079

* Reduce by .025 for fractured race HD bearings† Ball complement is normally one less than the number listed when non-metallic separators or

separable HT and HA bearings with drop center separators for ball retention are specified.


Co = the static non-brinell radial capacity

** Reduce by .050 for fractured race HD bearings

10

BasicSizeCode



CONRAD Type HK

BallsNo. Cr Cor

Capacity (lbs.)

1,4342,1092,8773,5856,4611,5802,6123,1514,7658,3701,6282,9764,3746,087

10,4102,6503,5926,0127,527

11,5052,7353,7736,546

10,78911,7272,9384,4737,356

11,86715,9313,0125,2367,887

13,90117,1834,2406,9439,754

16,07318,4414,3696,892

11,79618,38519,7254,4867,210

13,99620,83422,7246,0929,227

13,98523,41725,6646,2719,159

13,96525,507

300,075

119876

139976

1411

977

1311

877

1412

977

1612

988

171210

88

151210

88

161210

88

171310

88

161310

88

171310

89

8271,1301,4791,7713,1801,0171,4481,7602,4544,2141,1261,8592,5303,2525,6491,8112,3083,4204,1196,4421,9992,5924,0216,5816,7712,3263,1424,5947,1169,7962,5073,7345,2078,504

10,7633,3865,0286,561

10,01511,7743,6495,1048,071

11,64912,8713,9285,5929,631

13,40515,6305,2377,2439,884

15,285177,787

5,6227,313

10,06317,29322,431

BallsNo.† Cr Cor

Capacity (lbs.)

1,7082,5213,7514,3226,8841,8753,2713,7686,1049,8021,9593,6915,2337,785

11,7933,1444,4507,4019,626

13,8903,3954,7258,590

12,35416,1973,5255,7979,211

13,85718,6453,6596,5589,614

16,22020,0505,3178,401

11,89618,74722,7435,3848,630

13,74321,43424,2565,4508,846

16,34325,73127,2237,309

10,94717,04328,91033,2727,618

11,23617,73031,47636,045

16131110

719141311

821171311

9191712111022191512102420141111261915111124181511122519141112262014121324191512132620161213

Bore d

mm

202020202025252525253030303030353535353540404040404545454545505050505055555555556060606060656565656570707070707575757575

Inch

0.78740.78740.78740.78740.78740.98430.98430.98430.98430.98431.18111.18111.18111.18111.18111.37801.37801.37801.37801.37801.57481.57481.57481.57481.57481.77171.77171.77171.77171.77171.96851.96851.96851.96851.96852.16542.16542.16542.16542.16542.36222.36222.36222.36222.36222.55912.55912.55912.55912.55912.75592.75592.75592.75592.75592.95282.95282.95282.95282.9528

1,1201,5252,2702,4033,5571,3722,0962,3783,6445,3731,5582,6743,4204,8176,9462,4443,3244,8336,1038,7562,8993,7886,2398,291

10,4303,2224,8336,6649,247

12,6913,5145,4587,299

11,04513,9794,9916,9829,205

13,00216,6655,2647,456

10,57515,11818,1625,4967,968

12,56418,97321,2077,2539,777

13,83921,63927,1567,900

10,42514,97524,48830,454

004104204304404005105205305405006106206306406007107207307407008108208308408009109209309409010110210310410011111211311411012112212312412013113213313413014114214314414015115215315415

OutsideDiameter D

mm

37424752724247526280475562729055627280

10062688090

110687585

100120

728090

110130

8090

100120140

8595

110130150

90100120140160100110125150180105115130160190

Inch

1.45671.65351.85042.04722.83461.65351.85042.04722.44093.14961.85042.16542.44092.83463.54332.16542.44092.83463.14963.93702.44092.67723.14963.54334.33072.67722.95283.34653.93704.72442.83463.14963.54334.33075.11813.14963.54333.93704.72445.51183.34653.74024.33075.11815.90553.54333.93704.72445.51186.29923.93704.33074.92135.90557.08664.13394.52765.11816.29927.4803

Width W

mm

912141519

912151721

913161923101417212512151823271216192529121620273113182129331318223135131823333716202435421620253745

Inch Inch

0.35430.47240.55120.59060.74800.35430.47240.59060.66930.82680.35430.51180.62990.74800.90550.39370.55120.66930.82680.98430.47240.59060.70870.90551.06300.47240.62990.74800.98431.14170.47240.62990.78741.06301.22050.51180.70870.82681.14171.29920.51180.70870.86611.22051.37800.51180.70870.90551.29921.45870.62990.78740.94491.37801.65350.62990.78740.98431.45671.7717


BallDia.

Min.Shaft A

0.8740.9270.9720.9921.2061.0701.1281.1661.2051.4671.2681.3601.3741.4131.6631.5101.5601.5891.6831.8601.7071.7551.7931.8952.2001.9131.9591.9852.0872.3972.1092.1572.1802.3512.8012.3652.3982.4462.5582.9982.5602.5922.6482.7653.1942.7552.7872.8582.9493.3912.9632.9943.0543.1953.8003.1613.1903.2503.4033.997

Max.Housing S

1.370*1.514*

1.6651.8432.4161.568

1.706*1.8662.2202.667

1.764**1.9872.2482.6023.061

2.034*2.2592.6232.8443.455

2.309*2.4972.9313.2233.705

2.536*2.7653.1333.6224.099

2.695*2.9613.3323.9484.2862.9503.3113.6574.3324.6803.1483.5104.0454.7165.0733.3473.7094.4265.1225.4673.7304.0924.6235.4666.0433.9264.2904.8205.8496.436

3⁄16

1⁄45⁄16

3⁄89⁄16

3⁄16

9⁄32

5⁄16

7⁄16

21⁄32

3⁄16

9⁄32

3⁄81⁄2

11⁄16

1⁄45⁄16

15⁄32

9⁄16

23⁄32

1⁄45⁄16

15⁄32

5⁄825⁄32

1⁄411⁄32

1⁄211⁄16

13⁄16

1⁄43⁄81⁄23⁄4

27⁄32

5⁄16

7⁄16

9⁄16

13⁄16

7⁄85⁄16

7⁄16

5⁄87⁄8

29⁄32

5⁄16

7⁄16

11⁄16

15⁄16

15⁄16

3⁄81⁄2

11⁄16

111⁄16

3⁄81⁄2

11⁄16

11⁄16

11⁄8

R

Radius

0.0120.0240.0390.0390.0790.0120.0240.0390.039

0.09810.0120.0390.0390.039

0.09810.0240.0390.0390.0590.0910.0240.0390.0390.0590.1180.0240.0390.0390.0590.1180.0240.0390.0390.0790.1570.0390.0390.0590.0790.1570.0390.0390.0590.0790.1570.0390.0390.0590.0790.1570.0390.0390.0590.0790.1970.0390.0390.0590.0790.197


Ball Bearing Specifications






11

BasicSizeCode



CONRAD Type HK

BallsNo. Cr Cor

Capacity (lbs.)

6,20211,38816,34027,64732,4437,989

11,31318,88027,80534,8618,237

13,74821,58329,99336,7388,477

13,66724,44432,22842,35610,52514,27427,46336,73944,96010,43816,21729,90439,10647,60810,75519,05032,40342,16552,98312,86919,81932,32846,82161,35515,62225,10637,12251,61375,16316,02026,15640,11761,79787,00020,97227,09445,58894,06621,59833,26350,53522,19637,58228,68139,09628,41542,24335,19936,34637,451

171310

89

161310

89

171310

88

181310

89

171410

89

171310

89

181310

79

171410

79

171311

710181410

811161510111714

9181317141714161718

5,6799,188

11,90719,43525,0007,1679,265

13,90419,93927,7097,686

11,36316,05322,22329,4838,194

11,44718,35624,63136,4999,994

12,43620,82629,48339,75710,07213,86023,45732,25743,15510,71016,40426,24435,05150,16212,77917,90826,93340,77061,71015,71422,36733,15746,91982,70416,74924,37536,63261,139

102,49021,16326,51243,681

114,69122,71731,83649,34724,13337,06030,74540,50530,95745,00737,62440,28842,840

BallsNo.† Cr Cor

Capacity (lbs.)

7,72713,50720,76234,10438,8809,845

13,87822,99536,04541,77610,00616,87126,29738,88145,21410,41417,31929,79241,77650,78412,78617,18833,47945,21453,90413,00320,54536,46248,12157,07613,20823,37439,51753,75763,54716,03124,61741,04663,23373,62819,46230,80246,03769,68084,12020,13832,48950,94176,29391,35226,52833,03057,93598,75226,90641,31666,10627,87947,62735,73048,53136,26452,45544,52445,27845,992

271916121325201513132620151312282115131326211512132721151213282015111327221612132720171213292216121326231613272215292127222822262728

Bore d

mm

8080808080858585858590909090909595959595

100100100100100105105105105105110110110110110120120120120120130130130130130140140140140140150150150150160160160170170180180190190200210220

Inch

3.14963.14963.14963.14963.14963.34653.34653.34653.34653.34653.54333.54333.54333.54333.54333.74023.74023.74023.74023.74023.93703.93703.93703.93703.93704.13394.13394.13394.13394.13394.33074.33074.33074.33074.33074.72444.72444.72444.72444.72445.11815.11815.11815.11815.11815.51185.51185.51185.51185.51185.90555.90555.90555.90556.29926.29926.29926.69296.69297.08667.08667.48037.48037.87408.26778.6614

8,22912,41217,73127,51233,94010,32413,21119,42230,45437,61510,76716,16722,45333,94041,65411,61417,14325,71532,61549,58414,04417,24629,19741,65454,00614,61820,75432,89845,56758,61815,15223,35936,82052,00868,18018,51426,01740,08165,96883,94822,83031,87047,70975,893

101,29824,48035,41254,51986,555

114,09931,59837,43665,055

127,66032,91446,25276,90735,21455,48744,72458,72146,45765,32056,17558,47160,606

016116216316416017117217317417018118218318418019119219319419020120220320420021121221321421022122222322422024124224324424026126226326426028128228328428030130230430032132232034134036136038138040042044

OutsideDiameter D

mm

110125140170200120130150180210125140160190225130145170200240140150180215250145160190225260150170200240280165180215260310180200230280340190210250300360210225270380220240290230260250280260290280290300

Inch

4.33074.92135.51186.69297.87404.72445.11815.90557.08668.26774.92135.51186.29927.48038.85835.11815.70876.69297.87409.44885.51185.90557.08668.46469.84245.70876.29927.48038.8583

10.23625.90556.69297.87409.4480

11.02366.49617.08668.4646

10.236212.2047

7.08667.87409.0551

11.023613.3858

7.48038.26779.842511.811

14.17328.26778.8583

10.629914.9606

8.66149.4488

11.41739.0551

10.23629.8425

11.023610.236211.417311.023611.417311.8110

Width W

mm

162226394818222841521824304354182432455520243447582026364960202838506522284055722433405878243342628228354585283848284233463346383838

Inch Inch

0.62990.86611.02361.53541.88980.70870.86611.10241.61422.04720.70870.94491.18111.69292.12600.70870.94491.25981.77172.16540.78740.94491.33861.85042.28350.78741.02361.41731.92912.36220.78741.10241.49611.96852.55910.86611.10241.57482.16542.83460.94491.29921.57482.28353.07090.94491.29921.65352.44093.22831.10241.37801.77173.34651.10241.49611.88981.10241.65351.29921.81101.29921.81101.49611.49611.4961


BallDia.

Min.Shaft A

3.3563.3893.5193.6114.1943.5713.5933.7213.8764.7033.7673.8423.9714.0854.9003.9654.0394.1814.2945.0974.1724.2304.3914.5665.2944.3684.5224.6014.7745.4904.5644.7284.8115.0045.6884.9675.1235.2015.4486.3945.4505.5345.6975.9376.7885.8445.9316.1396.3537.1816.2976.3596.5617.5756.6886.7766.9877.0837.1927.4997.5847.8907.9888.3428.7349.126

Max.Housing S

4.1244.6825.1426.2326.8304.5004.8725.5316.5676.9115.2135.8726.9394.8937.5024.8935.4106.2527.3208.0925.2775.6126.6337.8358.4865.4745.9117.0138.2188.8795.6726.2967.3938.7759.6676.2546.6887.9889.513

10.5356.7547.4588.476

10.20411.716

7.1487.8499.215

10.97012.504

7.8768.4059.974

13.2918.2738.972

10.7308.6659.7379.430

10.5269.826

10.91010.55510.95111.346

3⁄89⁄16

3⁄411⁄813⁄16

7⁄16

9⁄16

13⁄16

11⁄811⁄47⁄16

5⁄87⁄8

13⁄16

13⁄87⁄16

5⁄8

15⁄16

11⁄417⁄16

1⁄25⁄81

13⁄811⁄2

1⁄2

11⁄16

11⁄16

17⁄16

19⁄16

1⁄2

3⁄411⁄815⁄8

111⁄16

9⁄16

3⁄411⁄813⁄417⁄8

5⁄8

7⁄813⁄16

17⁄821⁄16

5⁄87⁄8

15⁄16

223⁄16

3⁄47⁄8

17⁄16

25⁄16

3⁄41

15⁄83⁄4

11⁄87⁄8

11⁄87⁄8

13⁄16

111

R

Radius

0.0390.0390.0790.0790.1970.0390.0390.0790.0980.2560.0390.0590.0790.0980.2560.0390.0590.0790.0980.2560.0390.0590.0790.0980.2560.0390.0790.0790.0980.2560.0390.0790.0790.0980.2560.0390.0790.0790.0980.3150.0590.0790.0980.1180.3150.0590.0790.0980.1180.3150.0790.0790.0980.3150.0790.0790.0980.0790.0790.0790.0790.0790.0790.0790.0790.079






12

BoreDiameter

Mean Bore Diameter(+.0000 to minus value below)

ABEC/RBEC Classes

Bore Diameteral Taper, MaxABEC/RBEC Classes

Ring Width (+.0000 to minus value below)

0.09840.39370.70871.18111.96853.14964.72445.90557.08669.8425

12.401615.748019.685024.8031

0.39370.70871.18111.96853.14964.72445.90557.08669.8425

12.401615.748019.685024.803131.4961

334

4.568

1010121416182030

3334

4.5677

8.510121416-

22

2.53

3.5455679---

1.51.52

2.53344

4.5-----

1111

1.52333-----

2.52.53

3.54.56

7.57.59

10121315-

22

2.53

3.54.55.55.56.57.59

1012-

111

1.522333

3.54.5---

1111

1.51.522

2.5-----

0.50.50.50.511

1.51.51.5-----

4747474759799898

118138157177197295

98989898

150150197197197197248

---

1631474759799898

118138157

---

9898989898

150150150197197248

---

Over Includ. 1 3 5 7 9 1 3 5 7 9 1,3 5,7,9 1,3 5,7,9

BoreDiameter

Bore 2pt Diametral Roundness, Max000 (1900) Diameter Series

ABEC/RBEC Classes

Bore 2pt Diametral Roundness, Max100 Diameter SeriesABEC/RBEC Classes

Bore 2pt Diametral Roundness, Max200, 300, 400 Diameter Series

ABEC/RBEC Classes

Over Includ. 1 3 5 7 1 3 5 7 9 1 3 5 7 9

Tolerances

Single BearingABEC/RBEC

Preloaded SingleBearing ABEC/RBEC

INNER RING

0.09840.39370.70871.18111.96853.14964.72445.90557.08669.8425

12.401615.748019.685024.8031

2.51018305080

120150180250315400500630

0.39370.70871.18111.96853.14964.72445.90557.08669.8425

12.401615.748019.685024.803131.4961

1018305080

120150180250315400500630800

4456

7.51012121517202225-

10101315192531313844505663-

3.53.5456

7.599

1112151720-99

1013151923232831384450-

22

2.53

3.5455679---55689

101313151823---

1.51.52

2.53344

4.5-----445678

101012-----

334

4.57.51012121517202225-88

1012192531313844505663-

33346

7.599

1112151720-778

10151923232831384450-

1.51.52

2.53344

4.55.57---445678

1010121418---

11

1.522

2.533

3.5-----334556889-----

1111

1.52333-----

2.52.52.52.545778-----

2.52.53

3.54.56

7.57.59

10121315-6689

111519192326303438-

1.51.52

2.53344

4.55.57---445678

1010121418---

11

1.522

2.533

3.5-----334556889-----

22

2.53

3.54.55.55.56.57.59

1012-55689

1114141719232630-

1111

1.52333-----

2.52.52.52.545778-----

INCH

ES

2.51018305080

120150180250315400500630

1018305080

120150180250315400500630800

88

101215202525303540455075

778

10121518182225303540-

55689

101313151823---

445678

101012-----

2.52.52.52.545778-----

6689

111519192326303438-

55689

1114141719232630-

3334557789

12---

22

2.53

3.54556-----

1.51.51.51.52

2.53.53.54-----

120120120120150200250250300350400450500750

250250250250380380500500500500630

---

4080

120120150200250250300350400

---

250250250250250380380380500500630

---

MIL

LIM

ETER

SIN

CHES

MIL

LIM

ETER

S

Inch

tole

ranc

e in

.000

1 in

ches

Met

ric to

lera

nce

in m

icro

met

ers

Inch

tole

ranc

e in

.000

1 in

ches

Met

ric to

lera

nce

in m

icro

met

ers

13

BoreDiameter

Radial Runout, MaxABEC/RBEC Classes

Axial Runout, MaxABEC/RBEC Classes

0.09840.39370.70871.18111.96853.14964.72445.90557.08669.8425

12.401615.748019.685024.8031

2.51018305080

120150180250315400500630

0.39370.70871.18111.96853.14964.72445.90557.08669.8425

12.401615.748019.685024.803131.4961

1018305080

120150180250315400500630800

44568

1012121620242628311010131520253030405060657080

2.533445778

10121416-678

10101318182025303540-

1.51.51.522

2.533456---44455688

101315---

111

1.51.52

2.52.53-----

2.52.53445668-----

0.50.51111122-----

1.51.52.52.52.52.52.555-----

88

10121214161618222630353920202530303540404555657590

100

6888

101012121416182022-

15202020252530303540455055-

33333

3.544568---778889

1010131520---

11

1.51.522333-----334455778-----

0.50.51111122-----

1.51.52.52.52.52.52.555-----

Over Includ. 1 3 5 7 9 1 3 5 7 9

BoreDiameter

Face to Bore Runout, MaxABEC/RBEC Classes

Face Parallelism, MaxABEC/RBEC Classes

0.09840.39370.70871.18111.96853.14964.72445.90557.08669.8425

12.401615.748019.685024.8031

2.51018305080

120150180250315400500630

0.39370.70871.18111.96853.14964.72445.90557.08669.8425

12.401615.748019.685024.803131.4961

1018305080

120150180250315400500630800

NRNRNRNRNRNRNRNRNRNRNR

---


---


---


---

33333

3.544

4.556---778889

1010111315---

11

1.51.522

2.52.53-----334455667-----

0.50.50.50.50.511

1.52-----

1.51.51.51.51.52.52.545-----

6888

101012121214162024281520202025253030303540506070

6888

101012121214161820-

15202020252530303035404550-

2222

2.5333456---55556788

101315---

1111

1.51.522

2.5-----

2.52.52.5344556-----

0.50.50.50.50.511

1.52-----

1.51.51.51.51.52.52.545-----

Over Includ. 1 3 5 7 9 1 3 5 7 9

INNER RING

INCH

ESM

ILLI

MET

ERS

INCH

ESM

ILLI

MET

ERS

All bearings described inthis design guide can bemanufactured toABEC/RBEC 1,3,5,7 or 9tolerances. Generally,ABEC/RBEC 5 is thepreferred tolerance levelfor high-reliability aircraftsystems. ABEC 7 and 9 arenormally specified only onball bearings where closermounting tolerances andrunout are essential forprecise position control.Otherwise, performance issimilar to ABEC/RBEC 5,which is available at alower cost.

ABEC/RBEC 1 and 3 aregenerally used in industrialand less critical aircraftaccessory applications. To facilitate selection, thetolerance charts belowsummarize mean bore,outside diameter, widthtolerance and maximumradial runout of each ringfor all classes. Please referto ABMA Standard 20 for acomplete table of alldimensions.

How to specifyABEC/RBEC precisiontolerance levels 1through 9 are indicatedin split ball bearing partnumbers by the suffixesP1, P3, P5 or P9.

Inch

tole

ranc

e in

.000

1 in

ches

Met

ric to

lera

nce

in m

icro

met

ers

Inch

tole

ranc

e in

.000

1 in

ches

Met

ric to

lera

nce

in m

icro

met

ers

14

Tolerances continued

OUTER RING

OutsideDiameter

(O.D.)

O.D. 2pt Diametral Roundness, Max000 (1900) Diameter Series

ABEC/RBEC Classes

O.D. 2pt Diametral Roundness, Max100 Diameter SeriesABEC/RBEC Classes

O.D. 2pt Diametral Roundness, Max200, 300, 400 Diameter Series

ABEC/RBEC Classes

Over Includ. 1 3 5 7 1 3 5 7 9 1 3 5 7 90.70871.18111.96853.14964.72445.90557.08669.8425

12.401615.748019.685024.803231.4961

18305080

120150180250315400500630800

1.18111.96853.14964.72445.90557.08669.8425

12.401615.748019.685024.803231.496139.3701

305080

120150180250315400500630800

1000

4.55.56.57.59

1215172022253749121416192331384450566394

125

44.55.56.57.59

1012141619223010111416192325313541485675

2.53

3.54

4.556789

1114-679

101113151820232835-

22.533

3.54

4.556----56789

10111315----

3.54.55

7.59

12151720222537499

1113192331384450566394

125

33.54.56.57.59

1012141619223089

1116192325313541485675

223334

4.55.56

6.58.510-55788

10111415172126-

1.522

2.53334

4.5----4556788

1011----

1.51.51.5223334----44455788

10----

334

4.55.57.59

10121315223078

1011141923263034385575

223334

4.55.56

6.58.510-55788

10111415172126-

1.522

2.53334

4.5----4556788

1011----

2.5334

4.55.56

7.58.510111318678

10111415192125293445

1.51.51.5223334----44455788

10----

OutsideDiameter

(O.D.)

Mean O.D. Diameter(+.0000 to minus value below)

ABEC/RBEC Classes

O.D. Diameteral Taper, MaxABEC/RBEC Classes

Ring Width (+.0000 to minus value below)

1.18111.96853.14964.72445.90557.08669.8425

12.401615.748019.685024.803231.496139.3701

305080

120150180250315400500630800

1000

3.54.5567

10121416182030399

1113151825303540455075

100

33.54.55678

10111315182489

1113151820252833384560

2.53

3.54

4.556789

1114-679

101113151820232835-

22.533

3.54

4.556----56789

10111315----

1.51.51.5223334----44455788

10----

334

4.55.57.59

10121315223078

1011141923263034385575

2.5334

4.55.56

7.58.510111318678

10111415192125293445

11.522

2.533

3.54

4.55.57-34556789

10121418-

11

1.51.522

2.533----

2.53

3.5455678----

11111

1.51.51.52----222

2.52.53.5445----

47474759799898

118138157177197295120120120150200250250300350400450500750

989898

150150197197197197248

---

250250250380380500500500500630

---

31474759799898

118138157

---

80120120150200250250300350400

---

98989898

150150150197197248

---

250250250250380380380500500630

---

Over Includ. 1 3 5 7 9 1 3 5 7 9 1,3 5,7,9 1,3 5,7,9

Single BearingABEC/RBEC

Preloaded SingleBearing ABEC/RBEC

INCH

ESM

ILLI

MET

ERS

INCH

ESM

ILLI

MET

ERS

0.70871.18111.96853.14964.72445.90557.08669.8425

12.401615.748019.685024.803231.4961

18305080

120150180250315400500630800

Inch

tole

ranc

e in

.000

1 in

ches

Met

ric to

lera

nce

in m

icro

met

ers

Inch

tole

ranc

e in

.000

1 in

ches

Met

ric to

lera

nce

in m

icro

met

ers

15

OutsideDiameter

(O.D.)

Radial Runout, MaxABEC/RBEC Classes

Axial Runout, MaxABEC/RBEC Classes

0.70871.18111.96853.14964.72445.90557.08669.8425

12.401615.748019.685024.803231.4961

18305080

120150180250315400500630800

1.18111.96853.14964.72445.90557.08669.8425

12.401615.748019.685024.803231.496139.3701

305080

120150180250315400500630800

1000

68

101416182024283139475515202535404550607080

100120140

3.545789

101214162024309

101318202325303540506075

2.5334

4.556789

1012-678

101113151820232530-

1.522

2.5334

4.55----455678

101113----

11

1.5222333----

2.52.54555778----

10121416182226303539434749253035404555657590

100110120125

688

1012141618202224262815202025303540455055606570

334

4.55

5.56789

1012-88

10111314151820232530-

222

2.533445----555678

101013----

11

1.5222333----

2.52.54555778----

Over Includ. 1 3 5 7 9 1 3 5 7 9

OutsideDiameter

(O.D.)

OD to Face Runout, MaxABEC/RBEC Classes

Face Parallelism, MaxABEC/RBEC Classes

0.70871.18111.96853.14964.72445.90557.08669.8425

12.401615.748019.685024.803231.4961

18305080

120150180250315400500630800

1.18111.96853.14964.72445.90557.08669.8425

12.401615.748019.685024.803231.496139.3701

305080

120150180250315400500630800

1000

NRNRNRNRNRNRNRNRNRNRNRNR

-NRNRNRNRNRNRNRNRNRNRNRNR

-

NRNRNRNRNRNRNRNRNRNRNRNR

-NRNRNRNRNRNRNRNRNRNRNRNR

-

333

3.544

4.555678-8889

1010111313151820-

1.51.51.5222334----44455578

10----

0.50.50.5111

1.523----

1.51.51.52.52.52.5457----

888

1010121212141620242820202025253030303540506070

888

101012121214161820-

202020252530303035404550-

22

2.53334

4.55678-556888

101113151820-

111

1.522333----

2.52.53455778----

0.50.50.5111

1.523----

1.51.51.52.52.52.5457----

Over Includ. 1 3 5 7 9 1 3 5 7 9

OUTER RINGIN

CHES

MIL

LIM

ETER

SIN

CHES

MIL

LIM

ETER

S

Inch

tole

ranc

e in

.000

1 in

ches

Met

ric to

lera

nce

in m

icro

met

ers

Inch

tole

ranc

e in

.000

1 in

ches

Met

ric to

lera

nce

in m

icro

met

ers

16

3) M-50 extends life in “oil out” or marginal lubricantconditions. Under these conditions, surfacetemperatures immediately rise causing surfacetempering, deformation and seizure. Even afterexposure to temperatures as high as 1100°F (593°C) M-50 will not soften significantly (compared to 500°F[260°C] for 52100) providing an extra margin of fail-safe life.

4) M-50’s moly-carbides provide greater hardness toreduce fretting and wear under slow-speed oroscillating conditions.

VIM-VAR M-50 NIL (AMS 6278) is a carburized case-hardened variation of M-50 which provides improvedfracture toughness due to its softer core. All properties ofconventional M-50, including high-temperature stabilityand rolling contact fatigue life, are retained. Potentialapplications include ultra-high-speed (2.4 million dn andabove) mainshaft and other applications limited by lowfractures toughness.

440C Stainless steel (AMS 5880), a 16 percent chromiumsteel common to miniature and instrument bearings, isalso used in special metric bearings requiring corrosionresistance. Special tempering and subcooling cyclesprovide stable operating temperatures through 375°F(190°C). Optional high-temperature draw cycles providestability at temperatures to 800°F (425°C). However, thisoption reduces corrosion resistance. Typical applicationsinclude large instrument bearings, reactor controlbearings, bearings immersed in jet fuel and lightly loadedhigh-temperature thrust reverse controls.

Modified 440C alloys, similar to 440C, contain additionalmolybdenum to improve hot hardness at high temperingtemperatures for applications requiring corrosion andoxidation resistance. In some applications, they providethe best features of both 440C and M-50. However, theirhigh alloy content has led to unpredictable variations inexperienced fatigue life. Examples of modified 440Cinclude BG 42 and CRB7.

CSS42L® (AMS 5932) is a case-carburized, stainless-steelalloy suitable for use up to 800°F (427°C) in high-performance, rolling-element bearings. This alloy combineshigh hardness, fracture toughness, corrosion resistanceands rolling contact fatigue resistance to optimize bearingperformance for demanding application. This alloy wasdeveloped by Timken Latrobe Steel Co. The roomtemperature case hardness is 68 Rc minimum, maintainingcase hardness of 62 Rc at 800°F (427°C).

Standard Material—High Chrome 52100 Bearing Steel (AMS 6440)Unless otherwise indicated, all bearings listed in thisdesign guide are manufactured from vacuum-degassed,bearing-quality, 52100 steel (AMS 6440). Rings androlling elements are thoroughly heat treated undercontrolled atmospheres to provide the uniform stablestructure required for antifriction bearings. AllABEC/RBEC 3 and better bearings are stabilized withspecial tempers and 120°F (-84°C) sub-cooling cycles.This permits operating temperatures ranging fromcryogenic temperatures to 375°F (190°C) with a hardnessof Rockwell C60 minimum on most standardconfigurations and Rockwell C58 minimum on morecomplex shapes or where higher temperatures arerequired. Retained austenite is held well within 5 percent.

Special MaterialsCEVM 52100 (AMS 6444) consumable electrode vacuumremelt improves reliability and fatigue life over 52100 attemperatures under 375°F (190°C). A life improvementfactor of 5 can be applied in most applications. Timkengenerally recommends that in an application criticalenough to require CEVM 52100, the slight additional costof VIM-VAR M-50 is more than justified by its manyadditional benefits.

VIM-VAR 52100 (AMS 6444) vacuum induction melt,followed by a vacuum arc remelt, further improvesreliability and fatigue life. Hardness and heat treatmentare similar to other 52100 grades.

VIM-VAR M-50 High-Speed (AMS 6491)

Vacuum induction melt-vacuum arc remelt M-50 hasproven to be the most satisfactory advancedperformance material for demanding aircraft engine andaccessory positions. VIM-VAR M-50 provides four specificareas of improved performance:1) M-50 permits operation at or exposure to

temperatures to 900°F (482°C) with no permanent sizechange or loss of hardness. Retained austenite isunder 3 percent.

2) M-50 provides extended fatigue life (more than 10times that of air melt 52100) in the 150° to 400°F (66°to 204°C) range common to most aircraft applications.It compensates for application conditions that maycause severe reduction in experienced life, e.g., rapidacceleration, marginal housing or shaft support,differential temperatures, misalignment and otherunavoidable conditions.

Materials and Operating Temperatures

Non-Destructive TestingIn addition to the basic dimensional characteristics definedby the ABMA, many aspects of quality and reliabilityassurance are dependent upon the integrity of themanufacturer as well as supplemental tests that are agreedupon in the final specification. Controls on finish, racewaywaviness, lobing, roller-path flatness and many other minutevariables are carefully defined as a function of tolerance levelby Timken. Non-destructive testing techniques are used on a

sample basis to ensure reliability against cracks, materialdefects and grinding temper marks.

For critical bearings, 100 percent non-destructive testingusing fluorescent penetrant, magnetic particle inspection,nital etch testing, Barkhausen noise testing or EddyCurrent testing is available on a contract basis to ensureultimate reliability of all components.

17

How to specifyTo select material, choose one of the following as theprefix to the Timken part number:

None – 52100 34 – CEVM 440C3 – 440C 35 – VIM-VAR M50 Nil5 – VIM-VAR M50 58 – Pyrowear 675®

25 – BG42® 59 – CSS42L®

26 – CEVM 52100 303 – Noralide‚ NBD 200

BG-42® (AMS 5749) VIM-VAR, a high-performance Cr-Mo-V alloy, is ideal for bearing applications where ahardenable martensitic stainless steel is needed forcorrosion resistance, with a combined hot hardness lessthan 440°C. It performs similar to M-50 but with addedproperties described above. Multiple remelting enhancesmaterial cleanliness and provides a more reliableperformance and fatigue life. It is suitable for use whereapplication temperatures are up to 800°F (427°C).

Pyrowear 675® (AMS 5930) is a carburizing grade ofstainless, corrosion-resistant steel developing a HRc 60case with a tough ductile core. It has corrosion resistanceequivalent to 440C steel.

Ceramics, Norton Noralide‚ NBD 200 is available for fullceramic and hybrid bearings. This is a high-performanceceramic, proven to be beneficial for certain high-temperature, high-corrosive environments. When corrosive

environments or exceptionally non-typical bearingtemperatures or very high speeds are anticipated in adesign, it may be useful to apply a “hybrid” construction,whereby properly designed race and cage materials can bemated with ceramic rolling elements – balls or rollers – toobtain the maximum benefits of each. These specialapplications should be discussed with a Timken engineerfor guidance.

Radial play or free internal clearance is one of the mostcritical bearing design parameters. Contrary to a commonmisconception, it has nothing to do with quality or ABECtolerance level. In both ball and roller bearings, radial play isdefined as the free radial displacement of the outer ring withrespect to a fixed inner ring. In ball bearings, it directly affectsand controls the operating contact angle and free axial or endplay. In some ball bearing applications, contact angle or endplay may be the controlling specification. In these cases,radial play is not designated but is offered as a “reference.”

Radial Play Selection – HK, HD and R TypesBall bearings are normally manufactured to one of the fivestandard ABMA ranges shown in the chart, page 18. Unlessotherwise specified, Timken HK (Conrad) and HD (fracturedouter race) ball bearings and R-series roller bearings aresupplied with ABMA Group N standard clearances. Thisstandard range has excellent radial stability and loadcapacity. In ball bearings, Group N provides good resistanceto cocking loads and a reasonable degree of axial locationwithout preloading. It also allows for a light press fit on theinner ring for normal rotating shaft applications.

Looser fits – Group 3 and Group 4 clearances may bespecified in a bearing for a number of reasons: 1) To allow for a press fit on the outer race and where

necessary on both races. Keep in mind that 50 to 75percent of an interference fit is reflected in loss ofradial play. Temperature extremes cause additionalchanges in radial play occur when dissimilar materialsare used for shaft and housing materials.

2) To provide higher contact angles under thrust loadsthereby reducing stress level which increases fatiguelife, reduces torque and improves operating efficiency.

3) To provide greater axial stability, particularly inpreloaded bearings.

4) To allow greater static and dynamic misalignment.

Tighter fits – Group 2 clearance may be specified fora bearing slip-fit mounted in both the housing and on theshaft and operating under straight radial loads. If cockingloads are unavoidable, Group 2 provides the greatest

resistance and angular control. If preloading between twobearings is impractical it also provides the most preciseaxial location.

Relationship Between Radial Play, End Play and Contact Angle (HK and HD Series Ball Bearings)The following graph provides the designer with themeans to calculate the relationship between radial play,contact angle and end play for Timken bearings withstandard inner and outer race curvatures. Since curvaturesignificantly affects this relationship, any bearing withinverse curvature or reduced curvature for extra-highload capacity will have a different relationship. Thevalues obtained with this graph are averages and shouldnot be interpreted as acceptance or manufacturing limits.

Example: Determine the average contact angle andthe average end play on an HD 106 bearing with Group 3(loose) internal clearance:1) From table of dimensions (see Ball Bearing Specifications

page 9) the ball diameter is found to be 9⁄32” (0.28125”).

Radial Play and Contact Angle

18

BoreDiameter

Group 2 Group N Group 3 Group 4 Group 5

0.23620.39370.70870.94491.18111.57481.96852.55913.14963.93704.72445.51186.29927.08867.87408.85839.8425

11.023612.401613.976415.748017.716519.685022.047224.803127.952831.496135.433139.370144.0945

61018243040506580

100120140160180200225250280315355400450500560630710800900

10001120

0.39370.70870.94491.18111.57481.96852.55913.14963.93704.72445.51186.29927.08667.87408.85839.8425

11.023612.401613.976415.748017.716519.685022.047224.803127.952831.496135.433139.370144.094549.2126

1018243040506580

100120140160180200225250280315355400450500560630710800900

100011201250

000

0.50.50.50.50.50.5

1111111111111448888880001111112222222223333

1010202020202020

33.5

44.54.54.5

60.5

7899

101214161822242831353943515563677175

79

1011111115151820232325303540455560708090

100110130140160170180190

Over Includ. Min. Max.1122

2.52.5

36

4.56778

1010121416182224283135434755596367

2355668

1012151818202525303540455560708090

110120140150160170

578889

114

14161921242833374145495767758391

102114126138150161

13182020202328303641485361718595

105115125145170190210230260290320350380410

Min. Max.3

4.555679

121214161821253033353943515967758394

106118130142

z8

11131315182325303641465363758590

100110130150170190210240270300330360390

910111113141710232632364046556367758394

106118130142157177197217236256

232528283336435158668191

102117140160170190210240270300330360400450500550600650

Min. Max.6789

1112152021242832364249576169778998

110122134150169189209228248

14182023283038465361718191

107125145155175195225250280310340380430480530580630

1113141618202418333845515864778996

106118134150165185205224248276303335362

29333641465161718497

114130147163195225245270300340380420470520570630700770850920

Min. Max.8

1011121618222830354147535969818996

108124138154173193213236264291323350

20252830404555657590

105120135150175205225245275315350390440490540600670740820890

1518192125293526475563717991

104118134146161181201224248272299331370409453496

37454853647390

105120140160180200230265300340370410460510570630690760840940

104011501260

Min. Max.

Radial Play and Contact Angle continuedIN

CHES

MIL

LIM

ETER

S

19

There are three basic reasons for preloading a ballbearing: 1) to define more precisely a shaft position.2) to keep the balls in contact with the race to prevent

skidding and reduce noise.3) to share a load, thrust or radial equally between two

bearings.

Preloading methodsConventional radial separator (HK) or angular contact(HA) bearings may be preloaded in an application usingone of the following basic techniques:1) Increase axial load to a predetermined torque range

by using adjustable face clamping, for example a nutor screw.

2) Select a shim to create a predetermined torque valueor axial deflection value under reversing gage load.

3) Mount bearings with a preload spring, either betweeninner or outer rings or at one end of the assembly.

4) Use factory preloaded duplex pairs of bearings whichprovide exact “built-in” preload when face-clamped ina DB, DF or DT configuration.

In categories 1 through 3, where opposed single bearingsare involved, two types of preload mounts are possible:“DB” (back- to-back) and “DF” (face-to-face). The type ofmount is usually predicated on unit assemblyconsiderations. “DB” mounts are most desirable whereoverturning moment loading is encountered.

Factory duplexed pairs – Timken supplies pairs ofradial bearings that have precision-matched offset. Whenface-clamped together or against equal length spacers, apredetermined preload value is obtained. Duplex pairsare available in “DB” or “DT” configurations with preload

values as selected for individual applications. To avoidunloading of either bearing in a two bearing “DB” or“DF” set, the minimum preload value should equal 1/3 ofthe applied axial load. The maximum preload limitshould then be specified as at least 1.5 times theminimum preload.

Advantage of Each MethodDB – Provides excellent radial, axial and moment stabilitywhen there are no additional bearings on the shaft.DF – Provides radial and axial stability and aligns readilywith additional bearings mounted on the same shaft.DT – Shares extra-high thrust loads equally between twobearings. Does not provide stability unless furtherpreloaded with additional bearings.

MarkingBearings of DB, DF, and DT duplex sets have two axial linesforming a 30° included angle “V” etched across the outerrings of the pair (with the point of the “V” at the outer ringface to which the load is applied in the case of DT pairs).

Preloading

2) From the chart on page 17, the internal clearance forrange 3 for a 106 bearing is .0005” to .0011”.

3) The conditions for average internal clearance (.0008”)or the extremes (.0005” and .0011”) may be read offthe graph on page 17. First determine the value of fr.

fr = radial play = .0008 = .00285ball diameter .281254) Extend a vertical line from fr = .00285 through curves

labeled “Contact Angle” and “fe” to determineintersection points “A” and “B”.

5) Extend horizontal line to left from “A” to determineaverage contact angle of 14 degrees.

6) To obtain end play, extend horizontal line to right frompoint “B” to determine value; fe = .024. Solve equation

fe = end play ball diameter

end play = ball diameter x fe = .28125 x .024 =.0067”

Note: An interference fit will reduce the internal clearance by approximately 50 to 75percent of the amount of interference, giving operating conditions of a tighter internal fit-up.If interference fits are used, first determine the reduced internal clearance, then thecontact angle or the average end play of the bearing.

The graph may also be used to determine the requiredinternal clearance range from predetermined axial play orcontact angle values.

How to specify: To specify radial play or contact angle choose one of thefollowing alternatives. Then add the suffix to the basicbearing part number. For standard ABMA Range O,code may be omitted.1)To specify an ABMA radial play range: select code

number from table on page 18. Example: IndicatesGroup 3

2)To specify radial play: Express in ten thousandths(.0001) of an inch x 10,000. Example: (5/15) indicates.0005/.0015 radial play.

3)To specify contact angle code (HA type angularcontact bearings only) use letter code in parentheses.Suffix (D) is equivalent to normal contact angle of 25°.

Radial Play Selection – HA and HT TypesAngular contact (HA) bearings are normallymanufactured to a contact angle tolerance, rather than aspecified radial play. The two standard contact angles are15° and 25°; 15° should be used for radial loadapplications and 25° for high-thrust-load applications.

Split inner race (HT) series bearing are normallymanufactured to a contact angle of 25° or higher. Due tothe special nature of these bearings, your Timkenengineer should be consulted before specifying.

How to specifyTo specify preload, show preload type DB, DF or DTand min/max preload value desired.Example: “DB” preload, 8 lbs. min. to 12 lbs. max.Specify as: DB 8/12Add this suffix to the standard chassis part number.

Roller bearings may be radially preloaded by applicationof bi-lobe or tri-lobe geometry to the outer ring, throughuse of specialized grinding techniques: consult The Timken Company for advice and applicability.

20

Bearing fits are generally established based upon theapplication data such as loads, materials, temperaturesand speed. Every bearing must be properly fitted beforeit can meet its performance requirements. Preferably,housing and shaft tolerances should be selected inmagnitude approximately equal to the diametertolerances of the bearing (see tolerance chart on pages12-15). The normal fitting procedure is to press fit therotating member from line to tight. The non-rotatingmember is usually slip fitted from line to loose.

Heavier or out-of-balance loads may require tighter fits toavoid fretting damage to housing or shaft. In these cases,additional radial play is required to compensate for thepress fit.

Shaft and housing shoulders should be of adequateheight to properly support the face of the bearing. Seesuggested minimum shaft and maximum housingdimensions in the bearing specifications tables.Shoulders should be carefully machined to preventmisalignment and have a corner fillet radius notexceeding the radius dimension listed in thespecifications.

It is always preferable to use shaft and housing materialshaving compatible coefficients of expansion with thebearing. Whenever this is impractical due to weight orother material consideration, use the adjacent chart todetermine the possible degree of looseness orinterference at temperature extremes. This additionallooseness or tightness can be partially compensated forby adjusting fits and radial play.

Effect of Fitting Practice on Radial Playand PreloadKeep in mind that 50 to 75 percent of the interference fitat any temperature extreme is reflected in loss of radialplay. Press fits are even more significant in their effect onincreasing preload in factory-duplexed fits. For example,with an HA 107 having a 10-pound preload, a .0006”press fit of the inner race on a solid steel shaft wouldincrease the preload in excess of 100 pounds. To avoidexcessive as-mounted preloads, pairs are either mountedwith loose fits or specified as “matched and coded” onthe bores and/or O.D.s so that a fit of .0001” tight on therotating member can be established. Contact Timken forspecific application assistance.

Bearing Mounting Practices

Linear or diametral expansion in inches from 70°F.

To determineexpansion orpotential fitvariation fordissimilarmaterials:Multiply bore orO.D. diametertimes theexpansion foreach materialat the maximumtemperaturerequired.Contraction attemperaturesbelow 70°F isequal to theexpansion for acomparabletemperaturedifferentialabove 70°F.

The dynamic load rating for all ball and roller bearingsdescribed in this design guide (see bearing specificationtables) are based on an average (L50) life of 2500 hours ora minimum (L10) life of 500 hours when rotating at 331⁄3RPM. In a large group of bearings operating at 331⁄3 RPMat the rated load, approximately 90 percent would still beoperating at the end of 500 hours and 50 percent at theend of 2500 hours. Reference: ABMA Std. 9 and 10.

To calculate L10 rating life for other loads and speeds:

Determine Cr—P

Cr = rated dynamic capacity (see bearing specificationtables pages 5, 6, 9, 10 and 11)

P = equivalent radial load (see page 22)

Enter the nomogram at N (the desired RPM). Draw astraight line through the Cr—

Pvalue. The intersection point

with the right hand line equals the L10 life.

To select a bearing size:

Knowing the required L10 life, RPM and load, thenomograms can be solved for Cr—

P. Enter the nomogram at

N RPM and draw a straight line to the L10 value. Theintersection with the center line is the Cr—

Pratio. Multiply

Cr—P

by P (equivalent load) and obtain Cr. Using this value,enter the Cr column in the bearing dimension andcapacity tables and select a bearing with the propercapacity to suit the shaft and housing requirements.

Dynamic Load Rating and Life Calculations

Temperature in Degrees Fahrenheit

21

Roller Bearings

Cylindrical bearing L10 lifeL10 = ((Cr/P)10/3 x 106)———————-

N x 60

Basic dynamic capacityCr = fcm (i Lw cos α)7/9 Z3/4 Dwe

29/27

Basic static capacityCor = 6430 (1 - Dwe cos α / Dpw) i Zlwe Dwe cos α

See ABMA std 11 for use or contact application engineer

Ball Bearings

Radial and angular contact bearing L10 lifeL10 = ((Cr/P)3 x 106)——————-

N x 60

Basic dynamic capacityCr = fcm (i cos α).7 Z2/3 Dw

1.8

Basic static capacityCor = foiz Dw

2 cos α

See ABMA std 9 for use or contact application engineer

Alternate Direct Calculation Method

Where:

1) L = rating life in hours2) N = bearing speed in RPM3) Cr = rated dynamic capacity (see Column Cr bearing

specifications table, pages 5, 6, 9, 10 and 11)4) P = equivalent radial load (see next page)

To find L10 life of BALL BEARINGS(A) N = 500 RPM(B) Cr/P = 2.45(C) then L10 = 500 hours

To find Bearing Size(with the followingrequirements)(X) Shaft = 35 mm (1.3780")

Load = 550 lbs.L10 = 4000 hours

(Y) Speed = 1000 RPM(Z) then Cr/P = 6.3

C = 6.3 x 550 = 3465

Select HDB 107 whereCr = 4450 and shaftdiameter is compatible.

NOMOGRAPH EXAMPLES

To find L10 life of ROLLER BEARINGS(A) N = 5000 RPM(B) Cr/P = 10(C) then L10 = 7300 hours

22

Dynamic Load Rating and Life Calculations continued

Variable Mean Cubic Load Calculation

Variable load constant speed

P = 3 P13 (( ) + P2

3 ( ) + P33 ( ) + - - - + Pn

3 ( ) )Variable load and variable speed

P = 3 (P13 (f1) ( ) ( ) + P2

3 ( ) + P33 ( ) + ( ) )

Sm is the mean speed equivalence where:

Sm = S1 ( ) + S2 ( ) + S3 ( ) …. Sn ( ) ( )where: P1, P2, etc., equals each discrete load (lbs)

f1, f2, etc., equals time in constant units when load is applied.The complete fraction sums must equal 1.0 exactly.Resulting value P is then the cubic equivalentmean load to be used for life calculation. This format can be used for both radial and axialloads individually.

Example: A roller bearing has a variable load of 50 lbs. radialfor 2 minutes, 25 lbs. for 3 minutes and 100 lbs. for 5 minutes.

The equivalent load given the speed is constant is calculated as follows:

P = 3 503 ( ) + 253 ( ) + 1003 ( ) = 80.88 lbs.

In the given example, each load has a varying speed of2000 RPM; 5000 RPM; 3000 RPM respectively.

Sm = 2000 ( ) + 5000 ( ) + 3000 ( ) = 3400 RPM

P = 3 503 ( ) ( ) + 253 ( ) ( ) + 1003 ( ) ( )P = 77.32 lbs.

If this were a ball bearing, a similar analysis could be made forthe axial loads.

(f1)—-n∑f

(f2)—-n∑f

(f3)—-n∑f

(f3)—-n∑f

(S1)—-(Sm)

(f1)—-n∑1f

(f2)—-n∑f

(fn)—-n∑f

(f3)—-n∑f

2—-10

3—-10

5—-10

2000——-3400

5000——-3400

3000——-3400

2—-10

3—-10

5—-10

(f1)—-n∑1f

(f2)—-n∑2f

(f3 )—-

n∑3frev—--min

(f3 )—-

n∑3f

Equivalent Radial Load (P) – In bothrating life formulas, the equivalent radial load (P)equals the constant stationary radial load, which,if applied to a bearing with a rotating inner ringand stationary outer ring, would give the samelife as that which the bearing will attain underactual conditions of load and rotation.

Roller Bearings Ball Bearings:

(cylindrical) P=FR (radial loads)P= FR P=XFR + YFA

(radial and axialcombined loads)

Check both formulas.Use the largest value of P

as the equivalent radial load.

Where

1) FR = calculated radial load2) Fa = calculated axial thrust load3) X = 0.50 radial factor for ball bearings4) Y = thrust factor under combined

loads

Y is a function of Fa/Co (axial force divided bythe radial static capacity) and the radialclearance factor, fr.

where fr = average radial play in inchesball diameter in inches

To determine the value of Y for single-row ballbearings, compute fr and select the curveclosest to this value in the chart at right. Solvefor Fa/Co and determine Y using the selectedcurve.

Care must be used to select bearings, whichare of sufficient size for the application. Abearing, which appears to have adequate life,may require a shaft so small that shaftdeflection could lead to misalignment andfitting problems. A further analysis issometimes required.

2—-10

3—-10

5—-10

Fa = Axial ForceCor = Radial Static Capacity

Radial The radial static capacity Cor is defined by the ABMA asthe maximum static radial load that may be imposed ona bearing without causing total permanent deformationin excess of .0001” of the ball or roller diameter.Experience shows that this load can be tolerated withoutimpairing performance under subsequent operation.Where smooth operation is not critical, the Cor valuemay be exceeded. For example, air frame bearings arefrequently rated at 5.7 times the Timken Cor limits.Contact your Timken representative for specificapplication information.

Thrust The static thrust capacity of metric series ball bearings isgenerally higher than their radial static capacity. Thespecific value depends upon the initial contact angle(radial play), groove depth and race curvature(conformity).

The use of fractured outer-race bearings (HD series)under axial loads is also determined by the ability of theholding wire to keep the fracture closed. Thrust loads inexcess of approximately 200 pounds (depending onbearing size) may tend to open the fracture causing earlyfailure. Where the housing fit can be maintained line toline to tight, the holding wires are no longer the limitingfactor and higher thrust loads may be applied equivalentto HK construction.

The static thrust capacity of cylindrical roller bearings(where guide flange configuration allows thrust) is alsohigher than the radial capacity. However, the use of thistype of bearing under dynamic thrust loading is restrictedto less than 10 percent of the radial Cr value because ofthe sliding rather than rolling contract between the endsof the rollers and the guide flanges. Continuousoperation under thrust should be avoided.

If the static load (radial or thrust) exceeds the catalog Corrating, Timken should be consulted.

23

Static Load Ratings

Life Adjustment FactorsLife adjustment factors can be used to further define therating life in terms of (1) reliability, (2) material and

(3) application conditions. The fatigue life formulaembodying these adjustment factors is:

Ln = a1 x a2 x a3 x L10

A1 = Reliability Factor

It may be desirable for reliability(a1) to determine the life whenmore than 90 percent of thebearings must still be operating.

Reliability L10 Reliability

(Rating Life) Factor (a1)

90% L10 1.00

95% L5 .62

96% L4 .53

97% L3 .44

98% L2 .33

99% L1 .21

Example – If the L10 rating life of abearing in a specific application is4000 hours, the L1 life for 99%reliability would be a1 x L10 = .21 x 4000 = 810 hours.

A3 = Application Factor

Life adjustment factors forapplication conditions, such aslubrication, quality, misalignment,temperature, etc., are morecomplex and may require morediscreet analysis. For example,low viscosity oil (less than 70 ssu)and high temperatures (varieswith steel) and speeds insufficientto generate a hydrodynamic oilfilm will require the use of an a3value of less than 1. Actual testexperience in a particularapplication is the best way todevelop accurate a3 factors.

A2 = Material Factor

Certain materials have proven tohave greater fatigue life thanothers operating under identicalconditions. The theoretical L10

dynamic life is based on air-meltsteel and standard ABMAformulas. The life adjustmentfactors for materials frequentlyused are shown below. These areconservative values for use incritical aircraft applications.

Material Material Factor (a2)

Air Melt 440C 1

Std. VacuumDegassed 52100 3

BG 42 5

CEVM 52100 5

VIM-VAR M-50 10

VIM-VAR 52100 10

CSS 42L 20

In all discussions of the calculated dynamic capacity andL10 life, the mode of failure is always considered to befatigue spalling of the inner or outer raceway or one ofthe rolling elements. Fatigue results from cyclic stressreversals on the rolling contact surfaces and ischaracterized by actual loss of metal. Initially, only thevibration level of the bearing increases but morecatastrophic failure may follow if operation is allowed tocontinue. The wear rate of the separator substantiallyincreases and the ring or one of the balls may fracturecausing a total lock-up. For this reason, magnetic chipdetectors are used in many critical applications tohighlight early stages of fatigue in gear or bearingcomponents.

Other modes of failure that are not statisticallypredictable by the conventional ABMA formulas canaffect performance. Depending on the criticality of torqueand noise level, they may cause a “failure” long beforethe L10 rating has been achieved.

These include:

• True load brinells caused by either radial or axialimpacts in excess of the static rating. Results:roughness and noise

• False brinells (fretting corrosion) caused by vibrationunder static conditions with inadequate lubrications.

• Wear caused by loss of lubrication or introduction ofabrasive particles (contamination).

• Ball skidding caused by rapid acceleration withinadequate preload. Results: flats and noisy bearings

• Ring or ball fracture or separator fracture caused byimproper mounting techniques or extreme loads.

• Rotational interference caused by debris, lubricantoxidation, loss of radial play due to improper fittingprocedures, corrosion, etc.

In summary, to achieve rated fatigue life the bearingmust be given an adequate chance. Most prematurefailures are the results of improper use. An in-depthanalysis will usually reveal steps that can be taken bothin the application and in the design of the bearing toremedy the cause.

24

LubricationSelection of the lubricant type and the method ofdistribution are critical in achieving successful life.Lubrication has four basic purposes:1) To provide fluid film or boundary layer separation

between the bearing components.2) To cool the bearing.3) To clean the bearing.4) To prevent corrosion.

The relative importance of each depends upon theapplication, particularly on the speed and load. Effect ofspeed on different bearings can be related by the dnvalue (bore diameter mm x RPM).

High-Speed Applications (Over 1 Million dn)Lubrication of high-speed (over 1 million dn) applicationsis most critical. Centrifugal force tends to throw lubricantfrom the heavily stressed inner ring into the outer race.Lubricant accumulation creates additional drag and heatcausing slippage or wear on the inner race. In high-speedapplications, the most effective means of lubrication usesone or more high-velocity jets of oil directed at the innerrace contact area with adequate escape for usedlubrication around the outer ring shoulders. In someapplications this can be achieved by bringing oil throughholes at critical locations in the inner ring. If loads are notsevere, air can be mixed with oil in a non-recirculating oilmist system. With mist lubrication, air provides thecooling and cleaning functions.

Medium-Speed Applications (10,000 to 1 Million dn)In this broad range, which encompasses most bearingapplications, the lubricant’s cooling function is lesscritical. A circulating or replenishment oil system is stillpreferable for optimum life, but a controlled quantity ofgrease may be used if temperatures are low. With aboveambient temperatures, grease frequently deteriorateslong before the predicted fatigue life of the bearing.Unless the bearings are periodically regreased with theproper amount of lubricant, early failure may result. Newdevelopments in high-temperature greases provide apartial solution to the problem.

Bearing fatigue life can be prolonged beyond thatpredicted in this design guide if full fluid filmelastohydrodynamic lubrication is established at thecontact surface. To achieve this, the fluid film thicknessmust be equal to or greater than contact surface finish ormicrogeometry variations at the most heavily loadedcontact area. Without full fluid separation, metal contactoccurs causing higher surface sheer stress, possible wearand reduced life.

Fluid film separation is influenced by: 1) size design andquality of the bearing; 2) speed; 3) applied load; and 4) viscosity characteristics of the oil at operatingtemperatures.

Most medium-speed bearings operating with high-qualitymineral oils under average loads establish full fluid film

Modes of Failure

separation. However, where low viscosity fluids orlubricants are required, fluid film may not be establishedresulting in reduced life (e.g., hydraulic pumps and fuelcontrol systems). Bearings operating in JP4 or higher fuelwill function at less than 10 percent of predicted life.Timken aerospace computer programs utilizing the abovevariables are available to assist designers in determiningadequacy of the lubricant. Then, design or applicationmodifications can be reviewed to compensate for oraccept potential life reductions.

Where fluid film cannot be maintained due to low speedsand bearing loads, grease lubrication may proveadvantageous. Extreme pressure additives in somegreases provide good boundary lubrication and lubricityeven though the viscosity characteristics of the oilprovide marginal fluid film support.

In lubrication, the most important property is viscosity.Within limits, the higher the better, the lower the worse.Since viscosity is affected by temperature and bearingloads, it is important to supply the proper “consistency”(viscosity) in the proper quantity and to remove built upheat effectively.

The measure of viscosity uses multiple units that dependupon the test method used in the evaluation. There areseveral viscosity terms, such as absolute, kinematic andapparent. The units used in most modern analysisprograms are the kinematic viscosity expressed incentistokes (CS). It can be related to the absoluteviscosity, expressed in centipoise (CP) by the oil density.The purpose of the lubrication ideally is to interact byseparating the moving elements in a bearing bydeveloping a protective film, thereby keeping metal-to-metal contact at the surface finish asperities from cominginto contact. Lubricants are temperature limited wherethe mineral oils may be utilized at temperatures notexceeding -40°F to 225°F (-40°C to 107°C).

Synthetic esters and di-esters may be utilized attemperatures not exceeding -65°F to 350°F (-54°C to176°C).

Degradation of the lubrication film is most affected byoxidation and is accelerated at higher temperatures.

Lubrication FiltrationTo obtain the greatest benefit from the lubricationsupplied, it is of the utmost importance that thelubrication system is properly filtered. For oil lubricationin critical applications where speeds are moderate tohigh, use of a 3⁄5 micron filter is advised. Be aware that ahard particle greater than .0001⁄.0003 inches (2.5⁄7.5 microns)can cause wear, scuffing and other surface distress.When grease is used, it should also be filtered prior toinstallation, since unfiltered grease may be highlycontaminated. Filtering the grease with a 5 micron filteris recommended.

Low-Speed ApplicationsUnder slow speed or oscillating conditions, bearings nolonger depend on fluid film separation but operate withmetal-to-metal contact. Wear is minimized by greaselubricants with high lubricity and extreme pressureadditives providing effective “boundary layer”separation. Thin, dry-film coatings may be added tofurther improve wear resistance.

Standard lubrication – Most aircraft turbine andtransmission bearings operate with supplementalreplenishment lubricant systems. Therefore, unlessotherwise specified, all open bearings with separatorswill be supplied with a preservative coating meeting MIL-PRF-32033. Open bearings with nonmetallic separatorswill be supplied with a light oil preservative per MIL-PRF-6085. These are non-operating coatings rather thanlubricants. They are, however, compatible with mostlubricants and do not need to be removed prior tomounting.

Sealed HKMZZ bearings are normally lubricated with acontrolled quantity of long-life sodium soap grease. Thisprovides excellent channeling characteristics resulting inminimum torque and heat generation.

Special lubricants – Timken maintains a large inventoryof oils and grease for use in special applications exposedto extreme conditions of temperature, vacuum, moistureor radiation. Where initial lubrication must last the life ofthe bearing, grease is preferable to oil (except forinstrument-type applications having sensitive torquerequirements). The choice of grease is a function of oiland thickener type as well as the additive package tomeet many special requirements.

How to SpecifyThe greases listed with the Timken lubricant code aretypical of those frequently specified. The lubricant codeshould be added as a suffix to the end of standardbearing part numbers when required. For a morecomplete list, consult with your Timken sales engineer.

25

To successfully break the 2 million dn barrier,specifically engineered designs are developed throughclose cooperation between the manufacturer and thebearing user. Lubrication flow pattern is one of the mostimportant factors. Timken has the manufacturingtechnology to fabricate both ball and roller bearings inVIM-VAR M-50 steel with integral inner race lubrication.Two-piece inner race mainshaft bearings with lubricantdirected between the halves, and mainshaft rollerbearings with lubrication holes in precision undercuts(adjacent to guide flanges and to the separator pilotsurface) efficiently provide lubricant to critical locations.Both wear and fatigue life are improved while less oil is needed resulting in higher efficiency and less heat generation.

Where the application warrants:

1) Ultraprecise rollers can be manufactured by Timkenwith end squareness as low as 50 millionths of an inchand corner radius runout as low as .0005”.

2) Slight roller end crown, low guide flange angles and reduced clearances can be combined to furtherimprove roller tracking and permit even higherspeeds.

3) Special roller crowns can be used to allow for greatermisalignment.

4) The one-piece broached separator can be modifiedwith relieved areas to improve lubrication and reduce wear.

The extensive use of VIM-VAR M-50 in many turbine andaccessory positions testifies to its value as the preferredmaterial for ultra high speed bearings.

In all cases where special designs are required, consultyour Timken field sales engineer for assistance inselecting the necessary features.

26

Ultra-High-Speed Performance Features

Timken LubricationBrand Name

Manufacturers’CommentsCode Suggected Temp. Range

LY 263 Aeroshell 22 -85 to +400°F-65 to +204°C

LY 231 Mobil 28 -85 to +350°F-65 to +177°C

LY 240 Shell Darina E P 2 -20 to +350°F-30 to +175°C

LY 270 Shell Alvania E P 2 -20 to +300°F-30 to +149°C

LG 38 Exxon Andok B -20 to +225°F-30 to +110°C

LY 189 Dupont Krytox 240 AC -10 to +600°F-25 to +315°C

Non-melting, inorganic thickener with synthetic hydrocarbon oil for excellentfatigue life over wide temperature ranges. General-purpose lubricant, meetsthe MIL-PRF-81322.

Organic Bentonite clay binder with synthetic hydrocarbon oil. Has EPadditives. Meets the MIL-PRF-81322.

Similar to LY 270 except uses non-melting, inorganic thickener to enhancehigh-temperature operation.

Lithium soap, mineral oil, extreme pressure lubricant. Excellent waterresistance for long life under adverse operating conditions.

Long life, sodium soap, mineral oil grease with excellent channelingcharacteristics for low torque after run in at all speeds. Limited operatingtemperature range.

Teflon®-type thickener with fluorocarbon oil for maximum high-endtemperatures. Chemically inert and insoluable in all fuels and most solvents.Premium price. Meets the MIL-PRF-27617.

Lubrication continued

Two-piece, inner-racemainshaft bearing

Mainshaft roller bearing

timken aerospace precision metric ball and cylindrical ......timken aerospace precision metric ball...

Documents