General Catalogue
® SKF, CARB, INSOCOAT, NoWear andSensorMount are registered trademarks ofthe SKF Group. © Copyright SKF 2003The contents o...
Deep groove ball bearings        Angular contact ball bearings          Self-aligning ball bearings           Cylindrical ...
General Catalogue
The SKF brand now stands for more    than ever before, and means more to    you as a valued customer.    While SKF maintai...
GeneralForeword ………………………………………………………………………………………                   5SKF – The knowledge engineering company …………………………………...
Quantity    Unit              ConversionLength      inch              1 mm      0,039 inch         1 in           25,40 mm...
ForewordThe previous edition of the SKF General          General Catalogue overviewCatalogue was originally published in 1...
Significant innovations in the technical         • INSOCOAT® bearingssection                                          • No...
SKF Explorer bearings                               SKF Explorer bearings are characterized– the new performance class fro...
give reduced noise and vibration levels and       • Solid Oil bearings for applications whereimproved running accuracy. Si...
• system solution for automotive                   • basic and modified rating lives  transmissions                       ...
SKF – The knowledgeengineering companyThe business of the SKF Group consists of           The Group has global ISO 14001 e...
Evolving by-wire technologySKF has unique expertize and knowledge in fast-growing by-wire tech-nology, from fly-by-wire, t...
Delivering asset efficiency optimizationTo optimize efficiency and boost productivity,many industrial facilities outsource...
Developing a cleaner cleanerThe electric motor and its bearings are the heart ofmany household appliances. SKF works close...
ContentsPrinciples of bearing selection and application   Bearing terminology ………………………………………………………………………                 ...
Tolerances …………………………………………………………………………………                       120  Bearing internal clearance …………………………………………………………………...
Principles of bearingselection and applicationBearing types ………………………………………………………………………………           23Selection of bearin...
Principles of bearing selection and applicationA bearing arrangement consists of more than       Engineering Catalogue” on...
Product indexThe product range shown in this GeneralCatalogue comprises approximately 10 000bearings, bearing accessories ...
Principles of bearing selection and applicationBearing terminologyBearing arrangement                                     ...
Fig 3   14   Outer ring raceway                          15   Inner ring raceway                          16   Sealing gro...
Bearing types             Radial bearings             Deep groove ball bearings             single row, with or without fi...
Bearing types                          Radial bearings                          Four-point contact ball bearings (8)      ...
Radial bearings                           Cylindrical roller bearings                           double row1)              ...
Bearing types                                Radial bearings                                Drawn cup needle roller bearin...
Radial bearings                          Needle roller/cylindrical roller thrust bearings                            witho...
Bearing types                               Thrust bearings                               Thrust ball bearings            ...
Thrust bearings               Spherical roller thrust bearings               single direction (61)     61               Ta...
Bearing types                               Track runner bearings                               Cam rollers               ...
Y-bearings                                                                Y-bearings (insert bearings)4)                  ...
Selection of bearingtypeAvailable space ………………………………………………………………………………                      35Loads …………………………………………………………...
Selection of bearing typeEach bearing type displays characteristic           The matrix permits only a relatively super-pr...
Available space                                   Fig 1In many cases, one of the principal dimen-sions of a bearing – the ...
Selection of bearing type   When axial space is limited, certain series   Fig 4of cylindrical roller bearings and deep gro...
Fig 7        Loads        Magnitude of load        The magnitude of the load is one of the fac-        tors that usually d...
Selection of bearing type                            Fig 10      Angular contact thrust ball bearings can                 ...
Fig 12   loads of alternating direction these bearings                 must be combined with a second bearing.            ...
Selection of bearing typeMoment load                                       PrecisionWhen a load acts eccentrically on a be...
Fig 15Fig 16Fig 17   41
Selection of bearing typeSpeed                                              Fig 18The permissible operating temperature li...
Fig 21         Axial displacement         Shafts, or other rotating machine compon-         ents, are generally supported ...
Selection of bearing typeMounting and                                       Fig 24dismountingCylindrical boreBearings with...
Fig 27Integral sealsThe selection of a seal is of vital importance tothe proper performance of the bearing. SKFsupplies be...
Selection of bearing type The matrix can only provide a rough guide so that in each individual case it is                 ...
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Bearing

  1. 1. General Catalogue
  2. 2. ® SKF, CARB, INSOCOAT, NoWear andSensorMount are registered trademarks ofthe SKF Group. © Copyright SKF 2003The contents of this catalogue are the copy-right of the publisher and may not be repro-duced (even extracts) unless permission isgranted. Every care has been taken to en-sure the accuracy of the information con-tained in this catalogue but no liability canbe accepted for any loss or damage whetherdirect, indirect or consequential arising outof the use of the informationcontained herein.Catalogue 5000 E · June 2003Printed in Germany on environmentallyfriendly, chlorine-free paper (Novatech) byMedia-Print.
  3. 3. Deep groove ball bearings Angular contact ball bearings Self-aligning ball bearings Cylindrical roller bearings Taper roller bearings Spherical roller bearings CARB® toroidal roller bearings Thrust ball bearings Cylindrical roller thrust bearings Spherical roller thrust bearings Engineering products Mechatronics Bearing accessories Bearing housingsMaintenance and lubrication products Other SKF products
  4. 4. General Catalogue
  5. 5. The SKF brand now stands for more than ever before, and means more to you as a valued customer. While SKF maintains its leadership as the hallmark of quality bearings throughout the world, new dimensions in technical advances, product support and services have evolved SKF into a truly solutions-oriented supplier, creat- ing greater value for customers. These solutions encompass ways to bring greater productivity to cus- tomers, not only with breakthrough application-specific products, but also through leading-edge design simulation tools and consultancy services, plant asset efficiency maintenance programs, and the industry’s most advanced supply management techniques. The SKF brand still stands for the very best in rolling bearings, but it now stands for much more. SKF – The knowledge engineering company2
  6. 6. GeneralForeword ……………………………………………………………………………………… 5SKF – The knowledge engineering company …………………………………………… 10Contents ……………………………………………………………………………………… 14 3
  7. 7. Quantity Unit ConversionLength inch 1 mm 0,039 inch 1 in 25,40 mm foot 1m 3,281 ft 1 ft 0,3048 m yard 1m 1,094 yd 1 yd 0,9144 m mile 1 km 0,6214 mile 1 mile 1,609 kmArea square inch 1 mm2 0,00155 sq.in 1 sq.in 645,16 mm2 square foot 1 m2 10,76 sq.ft 1 sq.ft 0,0929 m2Volume cubic inch 1 cm3 0,061 cub.in 1 cub.in 16,387 cm3 cubic foot 1 m3 35 cub.ft 1 cub.ft 0,02832 m3 imperial gallon 1l 0,22 gallon 1 gallon 4,5461 l U.S. gallon 1l 0,2642 U.S. 1 U.S. 3,7854 l gallon gallonVelocity, foot per second 1 m/s 3,28 ft/s 1 ft/s 0,30480 m/sspeed mile per hour 1 km/h 0,6214 mile/h 1 mile/h 1,609 km/h (mph) (mph)Mass ounce 1g 0,03527 oz 1 oz 28,350 g pound 1 kg 2,205 lb 1 lb 0,45359 kg short ton 1 tonne 1,1023 short ton 1 short ton 0,90719 tonne long ton 1 tonne 0,9842 long ton 1 long ton 1,0161 tonneDensity pound per 1 g/cm3 0,0361 lb/cub.in 1 lb/cub.in 27,680 g/cm3 cubic inchForce pound-force 1N 0,225 lbf 1 lbf 4,4482 NPressure, pounds per 1 MPa 145 psi 1 psi 6,8948 × 103 Pastress square inchMoment inch pound-force 1 Nm 8,85 in.lbf 1 in.lbf 0,113 NmPower foot-pound per 1W 0,7376 ft lbf/s 1 ft lbf/s 1,3558 W second horsepower 1 kW 1,36 HP 1 HP 0,736 kWTemperature degree Celcius tC = 0,555 (tF – 32) Fahrenheit tF = 1,8 tC + 32
  8. 8. ForewordThe previous edition of the SKF General General Catalogue overviewCatalogue was originally published in 1989. This new SKF General Catalogue containsSince that time it has been translated into almost all of the standard rolling bearings and16 languages and over 1 million copies have accessories required by industrial equipmentbeen distributed worldwide. In the last edi- manufacturers, as well as those used for re-tion SKF introduced the “New Life Theory”, placement purposes. To provide the highestwhich since has become a major new tech- levels of service, SKF endeavours to have itsnical standard for the bearing industry. With standard assortment match virtually all cus-this broad usage and professional accep- tomer needs and to have products availabletance, the SKF General Catalogue is general- on a worldwide basis.ly considered to be the authoritative refer- The data in this catalogue relate to SKF’sence source of its type throughout industry. state-of-the-art technology and production The General Catalogue was subsequently capabilities as of early 2003. The data mayconverted to electronic formats for added differ from that shown in earlier cataloguesaccessibility and convenience – available in because of redesign, technological devel-a CD-ROM version, titled “SKF Interactive opments, or revised methods of calculation.Engineering Catalogue”, and online at SKF reserves the right to make continuingwww.skf.com. improvements to SKF products with respect This new edition of the General Catalogue to materials, design and manufacturingis also available electronically as well as in methods, as well as changes necessitatedprint and includes many revisions, additions by technological developments.and enhancements to make the catalogue The units used in this catalogue are in ac-even more useful and valuable. A familiariza- cordance with ISO (International Organizationtion with the information in this foreword, as for Standardization) standard 1000:1992,well as other annotated sections, enables and SI (Système International d’Unités).the user to obtain the maximum benefit fromthis comprehensive tool. Technical section – principles of bearing This foreword discusses the main sections selection and applicationof the catalogue with reference to major The technical section has a simplified indextechnical and product information as well as allowing for easy identification of the separateother available information of importance in chapters, which cover the basics of bearingunderstanding the overall capabilities of SKF. technology as required for the design of a bearing arrangement. These chapters are arranged in the order normally followed by a design engineer. 5
  9. 9. Significant innovations in the technical • INSOCOAT® bearingssection • NoWear® bearings• a new model for the determination of • Solid Oil bearings friction in rolling bearings.• revised speed ratings for the thermally Investigations have shown that factors such permissible reference speeds based on as mounting, lubrication and maintenance the new friction model. have a much greater influence on bearing• a new model for the determination of the life than previously assumed. For this reason, requisite lubricant viscosity based on new information has been included on the more accurate knowledge of the influence following: of raceway surface roughness and of the elastic deformation of the lubricant film. • SKF products for maintenance and• a new method to determine lubricant lubrication service life as well as the optimum relubri- • SKF condition monitoring equipment and cation intervals for grease-lubricated systems bearings.• the progress made in rolling bearing tech- Several SKF innovations are worthy of par- nology and the experience accumulated ticular note as they offer many advantages in practical applications in recent years for enhanced performance or greater pro- have been taken into consideration and ductivity. are referenced where appropriate in the For example, some of SKF product en- various sections of the technical part. hancements make it possible to build smaller• SKF technical services related to the machines having the same or even better bearing, the machine, or even the com- performance. Smaller size also implies lighter plete manufacturing plant – from bearing weight; meaning less friction, lower operat- selection and calculation, to installation, ing temperatures, reduced lubricant require- monitoring, maintenance and replace- ments and power consumption, and as a ment, are covered in a section referred to result, improved economy and added value. as Asset Efficiency Optimization. To facilitate easy reference to the various product innovations among the volume ofProduct section – bearing designations, information contained in this catalogue, thedescriptions and data specific products are identified as follows:The product section has a thumb index foreasy identification of bearing types. The • SKF Explorer bearings – the new perform-product tables contain all of the engineering ance class from SKF,data required for the selection of a bearing • application optimized bearings – standardand its application. Information relating to bearings tailored for specialized require-the specific types of bearings covered is ments,arranged in front of the relevant product • mechatronic components – combinationstable(s). of bearings and electronic sensors.Notable innovations in the product These innovations represent the most im-section portant new products in this catalogue andSignificant products included for the first will be explained in more detail under theirtime are: appropriate headings in the product section. For convenience, a summary description of• CARB® toroidal roller bearings these products is included hereafter.• stainless steel deep groove ball bearings• hybrid deep groove ball bearings• ICOS™ bearing/seal units• sealed spherical roller bearings• high-temperature ball bearings and Y-bearing units6
  10. 10. SKF Explorer bearings SKF Explorer bearings are characterized– the new performance class from SKF by a number of technical improvementsSKF Explorer is a new performance class of some of which are listed below. Dependingrolling bearings, of the types angular contact on the type of the SKF Explorer bearing oneball bearings, cylindrical roller bearings, or several of these below given examplesspherical roller bearings, CARB toroidal have been applied:roller bearings and spherical roller thrustbearings, which provide a substantial im- • Improved bearing steelprovement in key operational parameters SKF Explorer bearings feature an ex-relevant to the bearing type and its typical tremely clean and homogenous steelapplications. This new level of superior per- with a minimum number of inclusions.formance represents the blending of SKF’s This improved steel is so much cleanerapplications knowledge with its expertize in than the highest grades covered by pre-tribology, materials development, design sent classification methods that SKF hasoptimization and manufacturing. developed new calculation methods to Using advanced analytical and modelling take this factor into account.techniques and supporting testing, SKFengineers were able to confirm that SKF • The unique SKF heat treatment proceduresExplorer bearings provide a significant im- To maximize the benefits of SKF’s ultra-provement in key operational parameters. clean steel, engineers incorporatedThese parameters, according to bearing type unique heat treatment procedures. Theseand application, include noise, vibration, new procedures optimize the bearing’sservice life, dimensional stability, dynamic resistance to operational damage withoutload carrying ability and heat generation affecting heat stabilization. Wear resist-(friction torque). Because these parameters ance was improved so dramatically thatare not adequately factored into standard- SKF engineers were not able to accuratelyized life calculations, SKF Explorer bearing predict life expectancy using existing lifelife is calculated with modified factors, which factors for calculation methods.takes key operational parameters intoaccount. • Improved surface finish SKF Explorer bearings are interchange- The surface finish on all contact surfacesable with previously specified SKF standard (rolling elements and raceways) has beenbearings of the same type and size. These improved to maximize the effects of thebearings are included in the relevant product lubricant and reduce vibrations and noise.tables and are easily identified by an asterisk This has lead to a smoother, cooler run-(*) in front of the bearing designation. ning bearing that uses less lubricant and consequently the arrangement, includingThe making of an SKF Explorer bearing the seals, requires less maintenance.Achieving the outstanding levels of SKF Deep groove ball bearings and taper rollerExplorer bearings has only been possible bearingsdue to the basic sound engineering designof SKF products and by further improving For the rolling bearing types deep groovethe manufacturing of bearings to these ball bearings and taper roller bearings theredesigns. By studying the interrelationship have been many performance improvementsbetween each bearing component, SKF since the last SKF General Catalogue. Inengineers were able to maximize the effects line with the SKF product strategy, improve-of lubrication and minimize the effects of ments for deep groove ball bearings andfriction, wear and contamination. To do this, taper roller bearings have now sufficientlyan international research team looked at been implemented for certain sizes to qualifyeach component at micro level and then as SKF Explorer class bearings. For thesedeveloped new procedures to consistently selected deep groove ball bearings sizes im-manufacture this new standard of excellence. proved sealing, precision and surface finish, 7
  11. 11. give reduced noise and vibration levels and • Solid Oil bearings for applications whereimproved running accuracy. Similarly for conventional grease or oil lubricationselected taper roller bearing sizes, improved methods are not adequate or practical.surfaces for better lubrication and signifi-cantly reduced noise and vibration levels, Mechatronic components – bearingscleaner steel in combination with improved and sensors in combinationheat treatment give significantly longer life. SKF “plug and play” mechatronic bearingBecause all these parameters are not ad- units can be used to monitor or controlequately factored into standardized life calcu- operating sequences, motion or steeringlations, the bearing life of selected sizes SKF systems. Information in this catalogue pro-deep groove ball bearings and taper roller vides a brief overview of the mechatronicbearings is calculated with modified factors components and developments engineeredin line with all SKF Explorer class bearings. by SKF, which have already been well proven in a variety of industrial and automotiveApplication optimized bearings – tailored applications. More in-depth information onbearings SKF mechatronics products and capabilitiesThese bearings have standardized dimen- can be obtained through your SKF repre-sions but incorporate special features for sentative.specific applications. Properly applied, these Detailed information on Sensor-Bearingbearings make costly customized bearings Units, which are part of the SKF standardunnecessary, and they can also greatly line, will be found together with the appro-reduce lead times since they are generally priate product data.available from stock. This group of SKFbearings includes the following: Other SKF products In this section, all rolling bearings, plain• Hybrid deep groove ball bearings with bearings, linear bearings, and seals etc., not ceramic balls and rings of bearing steel. listed in the product section of the catalogue These bearings have good emergency are listed with a brief description. Where running properties and can cope with further information is available, reference is extreme conditions and high speeds. made to appropriate SKF printed and/or Their inherent resistance to the passage electronic media. of electric current means that they are very suitable for electric motors and SKF system solutions electrically powered tools. SKF has applied its extensive knowledge of• INSOCOAT bearings have an insulating particular industrial applications and their coating of aluminium oxide on the external demanding requirements, and developed surfaces of the inner or outer ring. These system solutions that yield cost-effective bearings can be used in difficult electrical results. applications with no additional design Some of these solutions do not even requirements and they can also be a drop- incorporate bearings. This underscores in replacement for conventional bearings SKF’s continuing efforts to expand its offer- in existing applications. ings beyond traditional bearing applications• Bearings and bearing units for extreme to other technologies from the fields of temperatures. Their operating temperature mechatronics and electronics. Some of the range covers –150 to +350 °C, making more important system solutions currently these products ideal for kiln trucks, roller available are listed here: hearth furnaces, bakery plants and re- frigeration rooms. • Copperhead system solution for vibrating• NoWear bearings. These bearings have screens been surface treated to withstand arduous • system solution for continuous casting operating conditions such as smearing, plants zero load or boundary lubrication condi- • system solution for paper machines tions. • system solution for printing machines8
  12. 12. • system solution for automotive • basic and modified rating lives transmissions (L10 and Lnm)• system solution for railway vehicles • requisite lubricant viscosity• system solution for wind power plants • equivalent bearing load • minimum bearing loadOther SKF catalogues • dynamic axial load carrying capacity ofEven though this General Catalogue con- cylindrical roller bearingstains more than 1 100 pages of core products • frictionand related information, it is by no means • bearing frequenciesall-inclusive of the total SKF product offering.Detailed information on many of the other In addition, 2 or 3-dimensional drawings canSKF products not covered in this General be supplied in some 50 CAD formats via theCatalogue is also available in separate, SKF internet site.individual printed catalogues which include: SKF – the supplier of choice• Needle roller bearings The SKF General Catalogue – as compre-• High-precision bearings hensive as it is – is just one of the many ad-• Y-bearings and Y-bearing units vantages provided to our customers. There• Spherical plain bearings and rod ends are many other capabilities that contribute• Bearing accessories to the overall value customers receive in• Bearing housings making SKF their supplier of choice:• CR seals • simplified bearing selection,A brief description of these products can be • short delivery times,found in the General Catalogue under the • worldwide availability,heading “Other SKF products” or online at • commitment to product innovation,www.skf.com. • state-of-the-art application solutions, Information on the comprehensive assort- • extensive engineering and technologyment of SKF linear bearing products, ball knowledge in virtually every industry.and roller screws, and linear actuators willbe found in the separate SKF catalogue“Linear Motion Product Range”, availablefrom your SKF Linear Motion representative.The SKF Interactive EngineeringCatalogueSKF provides this catalogue in electronicformats available on CD-ROM or online atwww.skf.com. The SKF Interactive Engineer-ing Catalogue contains comprehensivetechnical information on the following prod-ucts:• SKF rolling bearings inclusive accessories• SKF bearing units• SKF bearing housings• SKF plain bearings• CR sealsThe electronic catalogue formats allow foreasy navigation and also provide calcula-tions for critical design factors such as: 9
  13. 13. SKF – The knowledgeengineering companyThe business of the SKF Group consists of The Group has global ISO 14001 environ-the design, manufacture and marketing of mental certification. Individual divisions havethe world’s leading brand of rolling bearings, been approved for quality certification inwith a global leadership position in comple- accordance with either ISO 9000 or appropri-mentary products such as radial seals. SKF ate industry specific standards.also holds an increasingly important position Some 80 manufacturing sites worldwidein the market for linear motion products, high and sales companies in 70 countries makeprecision aerospace bearings, machine tool SKF a truly international corporation. Inspindles, plant maintenance services and addition, our 7 000 distributor and dealeris an established producer of high-quality partners around the world, e-businessbearing steel. marketplace and global distribution system The SKF Group maintains specialized put SKF close to customers for the supplybusiness operations to meet the needs of the of both products and services. In essence,global marketplace. SKF supports specific SKF solutions are available wherever andmarket segments with ongoing research and whenever our customers need them.development efforts that have led to a grow- Overall, the SKF brand now stands foring number of innovations, new standards more than ever before. It stands for theand new products. knowledge engineering company ready to serve you with world-class product compe- tences, intellectual resources and the vision to help you succeed.
  14. 14. Evolving by-wire technologySKF has unique expertize and knowledge in fast-growing by-wire tech-nology, from fly-by-wire, to drive-by-wire, to work-by-wire. SKF pion-eered practical fly-by-wire technology and is a close working partnerwith all aerospace industry leaders. As an example, virtually all aircraft ofthe Airbus design use SKF by-wire systems for cockpit flight control. SKF is also a leader in automotive drive-by-wire, having jointly developed the revolutionary Filo and Novanta concept cars which employ SKF mechatronics for steering and braking. Further by-wire development has led SKF to produce an all-electric forklift truck which uses mechatronics rather than hydraulics for all controls. 11
  15. 15. Delivering asset efficiency optimizationTo optimize efficiency and boost productivity,many industrial facilities outsource some orall of their maintenance services to SKF,often with guaranteed performancecontracts. Through the specializedcapabilities and knowledge available fromSKF Reliability Systems, SKF provides acomprehensive range of asset efficiencyservices, from maintenance strategies andengineering assistance, to operator-drivenreliability and machine maintenanceprograms. Planning for sustainable growth By their very nature, bearings make a positive contribution to the natural environment. Reduced friction enables machinery to operate more effi- ciently, consume less power and require less lubri- cation. SKF is continually raising the performance bar, enabling a new generation of high-efficiency products and equipment. With an eye to the future, SKF’s global policies and manufacturing techniques are planned and implemented to help protect and preserve the earth’s limited natural resources. We remain committed to sustainable, environmentally responsible growth.Maintaining a 320 km/h R&D labIn addition to SKF’s renowned research and development facilities in Europe and theUnited States, Formula One car racing provides a unique environment for SKF to pushthe limits of bearing technology. For over 50 years, SKF products, engineering andknowledge have helped make Scuderia Ferrari a formidable force in F1 racing. (Theaverage racing Ferrari utilizes more than 150 SKF components.) Lessons learned hereare applied to the products we provide to automakers and the aftermarket worldwide.12
  16. 16. Developing a cleaner cleanerThe electric motor and its bearings are the heart ofmany household appliances. SKF works closelywith appliance manufacturers to improve theirproduct’s performance, cut costs, reduceweight, etc. A recent example produced anew generation of vacuum cleaners withsubstantially more suction. SKF’s knowledgein small bearing technology is also applied tomanufacturers of power tools and office equipment. Creating a new “cold remedy” In the frigid winters of northern China, sub-zero temperatures can cause rail car wheel assemblies and their bearings to seize due to lubrication starvation. SKF created a new family of synthetic lubricants formulated to retain their lubrication viscosity even at these extreme bearing tempera- tures. SKF’s knowledge of lubricants and friction are unmatched in the world.Harnessing wind powerThe growing industry of wind-generated electricpower provides an environmentally compatiblesource of electricity. SKF is working closelywith global industry leaders to develop efficientand trouble-free turbines, using SKF know-ledge to provide highly specialized bearingsand condition monitoring systems to extendequipment life in the extreme and often remoteenvironments of wind farms. 13
  17. 17. ContentsPrinciples of bearing selection and application Bearing terminology ……………………………………………………………………… 20Bearing types ………………………………………………………………………………… 23Selection of bearing type …………………………………………………………………… 33Available space ……………………………………………………………………………… 35 Loads ……………………………………………………………………………………… 37 Misalignment ……………………………………………………………………………… 40 Precision …………………………………………………………………………………… 40 Speed ……………………………………………………………………………………… 42 Quiet running ……………………………………………………………………………… 42 Stiffness …………………………………………………………………………………… 42 Axial displacement ………………………………………………………………………… 43 Mounting and dismounting ……………………………………………………………… 44 Integral seals ……………………………………………………………………………… 45 Matrix: Bearing types – design and characteristics …………………………………… 46Selection of bearing size ……………………………………………………………………… 49 System approach and reliability ………………………………………………………… 50 Load ratings and life ……………………………………………………………………… 51 Selecting bearing size using the life equations ………………………………………… 52 Dynamic bearing loads …………………………………………………………………… 73 Selecting bearing size using the static load carrying capacity ………………………… 76 Calculation examples ……………………………………………………………………… 78 SKF calculation tools ……………………………………………………………………… 82 SKF Engineering Consultancy Services ………………………………………………… 84 SKF life testing ……………………………………………………………………………… 85Friction ………………………………………………………………………………………… 87 Estimation of frictional moment…………………………………………………………… 88 More accurate calculation of frictional moment ………………………………………… 88 The new SKF model for calculation of the frictional moment ………………………… 89 Frictional behaviour of hybrid bearings ………………………………………………… 102 Starting torque ……………………………………………………………………………… 102 Power loss and bearing temperature …………………………………………………… 102 Calculation example ……………………………………………………………………… 103Speeds and vibration ………………………………………………………………………… 107 Reference speeds ………………………………………………………………………… 108 Limiting speeds …………………………………………………………………………… 114 Special cases ……………………………………………………………………………… 114 Vibration generation in a bearing ………………………………………………………… 115 Influence of the bearing on the vibration behaviour of the application………………… 115Bearing data – general………………………………………………………………………… 117 Dimensions ………………………………………………………………………………… 11814
  18. 18. Tolerances ………………………………………………………………………………… 120 Bearing internal clearance ………………………………………………………………… 137 Materials for rolling bearings ……………………………………………………………… 138 Cages ……………………………………………………………………………………… 144 Designations ……………………………………………………………………………… 147Application of bearings ……………………………………………………………………… 159 Bearing arrangements …………………………………………………………………… 160 Radial location of bearings………………………………………………………………… 164 Axial location of bearings ………………………………………………………………… 199 Design of associated components ……………………………………………………… 204 Bearing preload …………………………………………………………………………… 206 Sealing arrangement ……………………………………………………………………… 218Lubrication …………………………………………………………………………………… 229 Grease lubrication ………………………………………………………………………… 231 Lubricating greases………………………………………………………………………… 231 SKF greases ………………………………………………………………………………… 236 Relubrication ……………………………………………………………………………… 237 Relubrication procedures ………………………………………………………………… 238 Oil lubrication ……………………………………………………………………………… 242Mounting and dismounting…………………………………………………………………… 257 General information………………………………………………………………………… 258 Mounting …………………………………………………………………………………… 261 Dismounting ………………………………………………………………………………… 268 Storage ……………………………………………………………………………………… 273 Inspection and cleaning …………………………………………………………………… 273Reliability and services ……………………………………………………………………… 275 Achieving productivity goals is a challenge ……………………………………………… 276 SKF can help optimize asset efficiency ………………………………………………… 276 The Asset Efficiency Optimization concept ……………………………………………… 276 How the concept becomes reality………………………………………………………… 276 Condition monitoring equipment ………………………………………………………… 279Product dataDeep groove ball bearings …………………………………………………………………… 287Angular contact ball bearings………………………………………………………………… 405Self-aligning ball bearings …………………………………………………………………… 463Cylindrical roller bearings …………………………………………………………………… 497Taper roller bearings ………………………………………………………………………… 595Spherical roller bearings ……………………………………………………………………… 691CARB toroidal roller bearings ………………………………………………………………… 775Thrust ball bearings …………………………………………………………………………… 833Cylindrical roller thrust bearings …………………………………………………………… 859Spherical roller thrust bearings ……………………………………………………………… 873Engineering products ………………………………………………………………………… 889Mechatronics ………………………………………………………………………………… 951Bearing accessories ………………………………………………………………………… 969Bearing housings ……………………………………………………………………………… 1027Maintenance and lubrication products ……………………………………………………… 1065Other SKF products…………………………………………………………………………… 1077Product index ………………………………………………………………………………… 1114 15
  19. 19. Principles of bearingselection and applicationBearing types ……………………………………………………………………………… 23Selection of bearing type………………………………………………………………… 33Selection of bearing size ………………………………………………………………… 49Friction ……………………………………………………………………………………… 87Speeds and vibration …………………………………………………………………… 107Bearing data – general …………………………………………………………………… 117Application of bearings ………………………………………………………………… 159Lubrication ………………………………………………………………………………… 229Mounting and dismounting ……………………………………………………………… 257Reliability and services ………………………………………………………………… 275 17
  20. 20. Principles of bearing selection and applicationA bearing arrangement consists of more than Engineering Catalogue” on CD-ROM orjust the bearings. Associated items such as online at www.skf.com.the shaft and housing are integral parts of In the following sections of this generalthe overall assembly arrangement. The im- technical introduction, the designer of aportance of lubricant and sealing elements bearing arrangement will find the necessarycannot be overestimated. Deploying a full basic information presented in the order inbearing’s performance relies on the pres- which it is generally required. Obviously it isence of appropriate lubrication and adequate impossible to include all the informationprotection from corrosion and the ingress needed to cover every conceivable bearinginto the assembly of foreigen matter. Clean- application. For this reason, in many places,liness has a profound effect on bearing ser- reference is made to the comprehensivevice life – which is why lubricants and seals SKF application engineering service, whichhave become part of the SKF business. includes technical support regarding the To design a rolling bearing arrangement it selection of the right bearing as well as cal-is necessary culations of the complete bearing arrange- ment. The higher the technical demands• to select a suitable bearing type and placed on a bearing arrangement and the• to determine a suitable bearing size, more limited the available experience of using bearings for particular applications,but that is not all. Several other aspects have the more advisable it is to make use of thisto be considered: service. The information contained in the general• a suitable form and design of other com- technical section generally applies to rolling ponents of the arrangement, bearings, or at least to a group of bearings.• appropriate fits and bearing internal clear- Special information specific to one bearing ance or preload, type only will be found in the text preceding• holding devices, the appropriate individual product section.• adequate seals, Additional special catalogues and brochures• the type and quantity of lubricant, covering specific application areas are• installation and removal methods, etc. available on request. Detailed information on almost all SKF rolling bearings, bearing units,Each individual decision affects the perform- bearing housings, plain bearings, seals etc.ance, reliability and economy of the bearing can also be found in the “SKF Interactivearrangement. Engineering Catalogue” on CD-ROM or The amount of work entailed depends on online at www.skf.com.whether experience is already available It should be noted that the values given inabout similar arrangements. When experi- the product tables for load and speed ratingsence is lacking, when extraordinary de- as well as for the fatigue load limit are heavilymands are made or, when the costs of the rounded.bearing arrangement and any subsequentoutline have to be given special consider- Bearing terminologyation, then much more work is needed in- To better understand frequently used bear-cluding, for example, more accurate calcu- ing terms, definitions are provided on pageslations and/or testing. 20 and 21 and explained with help of draw- As the leading bearing supplier SKF manu- ings. A detailed collection of bearing spe-factures a large number of bearing types, cific terms and definitions is to be found inseries, designs, variants and sizes. The most ISO 5593:1997:Rolling bearings – Vocabu-common of them are introduced in the sec- lary.tion “Product index”, starting on page 1114.There are also bearings which are not in-cluded in this catalogue. Information aboutmost of these bearings will be found in spe-cial catalogues or in the “SKF Interactive18
  21. 21. Product indexThe product range shown in this GeneralCatalogue comprises approximately 10 000bearings, bearing accessories and bearinghousings. So that users can find the tech-nical data for a product known only by itsdesignation, e.g. 6208-2RS1, the seriesdesignations are listed in the index startingon page 1114. In this case 62-2RS1 is used.Designations in this index are in alphanumer-ical order. The page listing for each designa-tion is the start of the introductory text forthat particular product type. 19
  22. 22. Principles of bearing selection and applicationBearing terminologyBearing arrangement Fig 1(➔ fig 1 )1 Cylindrical roller bearing2 Four-point contact ball 13 1 2 bearing 33 Housing4 Shaft5 Shaft abutment shoulder6 Shaft diameter 127 Locking plate8 Radial shaft seal 11 49 Distance ring 510 Housing bore diameter 1011 Housing bore 612 Housing cover 9 713 Snap ring 8Radial bearings (➔ figs 2 Fig 2and 3 )1 Inner ring2 Outer ring3 Rolling element: ball, 6 2 10 11 18 cylindrical roller, needle roller, tapered roller, 9 12 spherical roller4 Cage 135 Capping device 4 14 Seal – made of elastomer, contacting (shown in figure) 5 15 or non-contacting Shield – made of sheet 16 steel, non-contacting 8 176 Outer ring outside diameter7 Inner ring bore 7 18 1 38 Inner ring shoulder diameter9 Outer ring shoulder diameter 1910 Snap ring groove11 Snap ring12 Outer ring side face13 Seal anchorage groove20
  23. 23. Fig 3 14 Outer ring raceway 15 Inner ring raceway 16 Sealing groove 17 Inner ring side face6 18 Chamfer2 α 19 20 Bearing mean diameter Total bearing width 21 Guiding flange12 14 22 Retaining flange3 23 Contact angle 214 1522 α 171 237 20 Fig 4 Thrust bearings (➔ fig 4 ) 24 24 Shaft washer 25 Rolling element and 25 cage assembly 26 Housing washer 27 Housing washer with 26 sphered seating surface 28 Seating support washer 27 24 28 24 25 26 21
  24. 24. Bearing types Radial bearings Deep groove ball bearings single row, with or without filling slots open basic design (1) with shields with contact seals (2) with snap ring groove, with or without 1 2 snap ring single row with fixed section open basic design (3) with contact seals double row (4) 3 4 Angular contact ball bearings single row design for universal matching (5) basic design for single mounting single row high precision1) standard design for single mounting (6) 5 6 design for universal matching matched bearing sets double row with one-piece inner ring (7) open basic design with shields with contact seals with two-piece inner ring 7 Footnote ➔ page 31 23
  25. 25. Bearing types Radial bearings Four-point contact ball bearings (8) 8 Self-aligning ball bearings with cylindrical or tapered bore open basic design (9) with contact seals (10) 9 10 with extended inner ring (11) 11 Cylindrical roller bearings single row NU type (12) N type (13) 12 13 NJ type (14) NUP type (15) 14 15 angle ring (16) for NU and NJ type bearings 1624
  26. 26. Radial bearings Cylindrical roller bearings double row1) with cylindrical or tapered bore NNU type (17) NN type (18) NNUP type 17 18 four-row2) with cylindrical or tapered bore open design (19) with contact seals 19 Full complement cylindrical roller bearings single row NCF type (20) NJG type (21) 20 21 double row with integral flanges on the inner ring (22) with integral flanges on the inner and outer rings with contact seals (23) 22 23 Needle roller and cage assemblies3) single row (24) double row (25)24 25 Drawn cup needle roller bearings, open ends3) single and double row open basic design (26) with contact seals (27) 26 27 Footnote ➔ page 31 25
  27. 27. Bearing types Radial bearings Drawn cup needle roller bearings, closed end3) single and double row open basic design (28) with contact seal (29) 28 29 Needle roller bearings with flanges3) single and double row without inner ring (30) with inner ring open basic design with contact seals (31) 30 31 Needle roller bearings without flanges3) single and double row with inner ring (32) without inner ring (33) 32 33 Alignment needle roller bearings3) without inner ring with inner ring (34) 34 Combined needle roller bearings3) Needle roller/angular contact ball bearings single direction (35) double direction (36) 35 36 Needle roller/thrust ball bearings with full complement thrust ball bearing (37) with cage-guided ball set with or without (38) cover 37 38 Footnote ➔ page 3126
  28. 28. Radial bearings Needle roller/cylindrical roller thrust bearings without cover (39) with cover (40)39 40 Taper roller bearings single row single bearings (41) matched bearing sets face-to-face (42) back-to-back 41 42 in tandem double row2) TDO configuration (back-to-back) (43) TDI configuration (face-to-face) (44)43 44 four-row2) TQO configuration (45) TQI configuration 45 Spherical roller bearings with cylindrical or tapered bore open basic designs (46) with contact seals (47) 46 47 CARB toroidal roller bearings with cylindrical or tapered bore open basic designs with cage-guided roller set (48) with full complement roller set with contact seals (49) 48 49 Footnote ➔ page 31 27
  29. 29. Bearing types Thrust bearings Thrust ball bearings single direction with flat housing washer (50) with sphered housing washer with (51) or without seating washer 50 51 double direction with flat housing washers (52) with sphered housing washers with (53) or without seating washers 52 53 Angular contact thrust ball bearings1) high precision bearings single direction standard design for single mounting (54) design for universal matching matched bearing sets (55) 54 55 double direction standard design (56) high-speed design (57) 56 57 Cylindrical roller thrust bearings single direction single row (58) double row (59) components cylindrical roller and cage thrust assemblies 58 59 shaft and housing washers Needle roller thrust bearings3) single direction (60) needle roller and cage thrust assemblies raceway washers thrust washers 60 Footnote ➔ page 3128
  30. 30. Thrust bearings Spherical roller thrust bearings single direction (61) 61 Taper roller thrust bearings2) single direction with or without (62) cover screw down bearings double direction (63)62 63 Footnote ➔ page 31 29
  31. 31. Bearing types Track runner bearings Cam rollers single row ball bearing cam roller (64) double row ball bearing cam roller (65) 64 65 Support rollers3) without axial guidance with or without contact seals without inner ring with inner ring (66) 66 with axial guidance by thrust washers with or without contact seals with cage-guided needle roller set (67) full complement 67 with axial guidance by cylindrical rollers with labyrinth seals (68) with contact seals (69) with lamellar seals 68 69 Cam followers3) with axial guidance by thrust plate with or without contact seals with concentric seating (70) with eccentric seating collar 70 with cage-guided needle roller set with full complement needle roller set with axial guidance by cylindrical rollers with labyrinth seals (71) with contact seals with concentric seating with eccentric seating collar 71 Footnote ➔ page 3130
  32. 32. Y-bearings Y-bearings (insert bearings)4) with grub screw locking inner ring extended on one side (72) inner ring extended on both sides (73) 72 73 with eccentric locking collar inner ring extended on one side (74) inner ring extended on both sides (75) 74 75 with tapered bore inner ring extended on both sides (76) for adapter sleeve mounting 76 with standard inner ring for locating by interference fit on the shaft (77) 771) See SKF catalogue “High-precision bearings” or “SKF Interactive Engineering Catalogue”2) See “SKF Interactive Engineering Catalogue”3) See SKF catalogue “Needle roller bearings” or “SKF Interactive Engineering Catalogue”4) See SKF catalogue “Y-bearing units” or “SKF Interactive Engineering Catalogue” 31
  33. 33. Selection of bearingtypeAvailable space ……………………………………………………………………………… 35Loads …………………………………………………………………………………………… 37 Magnitude of load …………………………………………………………………………… 37 Direction of load …………………………………………………………………………… 37Misalignment ………………………………………………………………………………… 40Precision ……………………………………………………………………………………… 40Speed …………………………………………………………………………………………… 42Quiet running ………………………………………………………………………………… 42Stiffness ………………………………………………………………………………………… 42Axial displacement …………………………………………………………………………… 43Mounting and dismounting ………………………………………………………………… 44 Cylindrical bore ……………………………………………………………………………… 44 Tapered bore ………………………………………………………………………………… 44Integral seals ………………………………………………………………………………… 45Matrix: Bearing types – design and characteristics …………………………………… 46 33
  34. 34. Selection of bearing typeEach bearing type displays characteristic The matrix permits only a relatively super-properties, based on its design, which ficial classification of bearing types. Themakes it more, or less, appropriate for a limited number of symbols does not allowgiven application. For example, deep groove an exact differentiation and some propertiesball bearings can accommodate moderate do not depend solely on bearing design. Forradial loads as well as axial loads. They have example, the stiffness of an arrangementlow friction and can be produced with high incorporating angular contact ball bearingsprecision and in quiet running variants. or taper roller bearings also depends on theTherefore they are preferred for small and applied preload and the operating speedmedium-sized electric motors. which is influenced by the precision of the Spherical and toroidal roller bearings can bearing and its associated components ascarry very heavy loads and are self-aligning. well as by the cage design. In spite of itsThese properties make them popular for limitations, the matrix on pages 46 and 47example for heavy engineering applications, should enable an appropriate choice ofwhere there are heavy loads, shaft deflec- bearing type to be made. It should also betions and misalignments. considered that the total cost of a bearing In many cases, however, several factors arrangement and inventory considerationshave to be considered and weighed against could also influence the final choice.each other when selecting a bearing type, Other important criteria to be observedso that no general rules can be given. when designing a bearing arrangement The information provided here should including load carrying capacity and life,serve to indicate which are the most impor- friction, permissible speeds, bearing internaltant factors to be considered when selecting clearance or preload, lubrication and sealinga standard bearing type and thus facilitate are dealt with in depth in separate sectionsan appropriate choice: of this catalogue. The complete SKF product range is not shown in this General Catalogue.• available space Specific catalogues and brochures are avail-• loads able for bearings not covered here – please• misalignment consult SKF.• precision• speed• quiet running• stiffness• axial displacement• mounting and dismounting• integral seals A comprehensive overview of the standardbearing types, their design characteristicsand their suitability for the demands placedon a given application will be found in thematrix on pages 46 and 47. Detailed infor-mation on the individual bearing types,including their characteristics and the avail-able designs, will be found in the sectionsdealing with individual bearing types. Bearingtypes that are not included in the matrix aregenerally only used for a few well-definedapplications.34
  35. 35. Available space Fig 1In many cases, one of the principal dimen-sions of a bearing – the bore diameter – ispredetermined by the machine’s design andthe shaft diameter. For small-diameter shafts all types of ballbearings can be used, the most popular be-ing deep groove ball bearings; needle rollerbearings are also suitable (➔ fig 1 ). Forlarge-diameter shafts, cylindrical, taper,spherical and toroidal roller bearings areavailable, as well as deep groove ball bear-ings (➔ fig 2 ). When radial space is limited, bearingswith a small cross section, particularly thosewith a low cross-sectional height, should bechosen, i.e. bearings in the 8 or 9 DiameterSeries. Needle roller and cage assemblies, Fig 2drawn cup needle roller bearings and needleroller bearings without or even with innerring (➔ fig 3 ) are very appropriate as well ascertain series of deep groove and angularcontact ball bearings, cylindrical, taper,spherical and toroidal bearings. Fig 3 35
  36. 36. Selection of bearing type When axial space is limited, certain series Fig 4of cylindrical roller bearings and deep grooveball bearings can be used for radial or com-bined loads respectively (➔ fig 4 ) as well asthe various types of combined needle rollerbearings (➔ fig 5 ). For purely axial loads,needle roller and cage thrust assemblies(with or without washers) as well as thrustball bearings and cylindrical roller thrustbearings can be used (➔ fig 6 ). Fig 5 Fig 636
  37. 37. Fig 7 Loads Magnitude of load The magnitude of the load is one of the fac- tors that usually determines the size of the bearing to be used. Generally, roller bear- ings are able to support heavier loads than similar sized ball bearings (➔ fig 7 ) and bearings having a full complement of rolling elements can accommodate heavier loads than the corresponding caged bearings. Ball bearings are mostly used where loads are light or moderate. For heavy loads and where shaft diameters are large, roller bearings are usually the more appropriate choice. Direction of loadFig 8 Radial load NU and N types cylindrical roller bearings, needle roller bearings and toroidal roller bearings can only support pure radial loads (➔ fig 8 ). All other radial bearings can ac- commodate some axial loads in addition to radial loads (➔ “Combined loads”). Axial load Thrust ball bearings and four-point contact ball bearings (➔ fig 9 ) are suitable for light or moderate loads that are purely axial. Single direction thrust ball bearings can only accommodate axial loads acting in one di- rection; for axial loads acting in both direc- tions, double direction thrust ball bearingsFig 9 are needed. 37
  38. 38. Selection of bearing type Fig 10 Angular contact thrust ball bearings can support moderate axial loads at high speeds; here the single direction bearings can also accommodate simultaneously acting radial loads, while double direction bearings are normally used only for purely axial loads (➔ fig 10 ). For moderate and heavy axial loads acting in one direction, needle roller thrust bearings, cylindrical and taper roller thrust bearings are suitable, as are spherical roller thrust bearings (➔ fig 11 ). Spherical roller thrust bearings can also accommodate simultan- eously acting radial loads. For heavy alter- nating axial loads, two cylindrical roller thrust bearings or two spherical roller thrust bear- ings can be mounted adjacent to each other. Combined load A combined load comprises a radial and an axial load acting simultaneously. The ability of a bearing to carry an axial load is deter- mined by the angle of contact α – the greater the angle, the more suitable the bearing for axial loads. An indication of this is given by the calculation factor Y, which becomes Fig 11 smaller as the contact α increases. The values of this factor for a bearing type or for individual bearings will be found in the intro- ductory text of the product table sections, or in the actual product tables. The axial load carrying capacity of a deep groove ball bearing depends on its internal design and the internal clearance in the bearing (➔ sec- tion “Deep groove ball bearings”, starting on page 287). For combined loads, single and double row angular contact ball bearings and single row taper roller bearings are most common- ly used although deep groove ball bearings and spherical roller bearings are suitable (➔ fig 12 ). In addition, self-aligning ball bearings and NJ and NUP type cylindrical roller bearings as well as NJ and NU type cylindrical roller bearings with HJ angle rings can be used for combined loads where the axial component is relatively small (➔ fig 13 ). Single row angular contact ball bearings and taper roller bearings, NJ and NU+HJ type cylindrical roller bearings and spherical roller thrust bearings can only accommodate axial loads acting in one direction. For axial38
  39. 39. Fig 12 loads of alternating direction these bearings must be combined with a second bearing. For this reason, single row angular contact ball bearings are available as “universal bearings” for paired mounting and singleα row taper roller bearings can be supplied as matched sets comprising two single row bearings (➔ sections “Single row angular contact ball bearings”, starting on page 407, and “Paired single row taper roller bearings”, starting on page 667). When the axial component of combined loads is large, it may be supported independ- ently from the radial load by a separate bearing. In addition to the thrust bearings, some radial bearings, e.g. deep groove ball bearings or four-point contact ball bearings α (➔ fig 14 ) are suitable for this task. To make sure that the bearing is only subjected to the axial load in such cases, the bearing outer ring must be mounted with radial clearance. Fig 13 Fig 14 39
  40. 40. Selection of bearing typeMoment load PrecisionWhen a load acts eccentrically on a bearing, Bearings with higher precision than Normala tilting moment will occur. Double row bear- are required for arrangements that mustings, e.g. deep groove or angular contact ball have high running accuracy (e.g. machinebearings, can accommodate tilting moments, tool spindle arrangements) as well as thosebut paired single row angular contact ball applications where very high speeds arebearings or taper roller bearings arranged required.face-to-face, or better still back-to-back, The introductory text to each table sectionare more suitable (➔ fig 15 ). contains information regarding the tolerance classes to which the bearings in that section are produced. SKF produces a comprehen-Misalignment sive range of high precision bearings, includ- ing single row angular contact ball bearings,Angular misalignments between the shaft single and double row cylindrical roller bear-and housing occur, for example, when the ings and single and double direction angularshaft bends (flexes) under the operating load, contact thrust ball bearings (➔ the SKF cata-when the bearing seatings in the housing logue “High-precision bearings”).are not machined to the same height orwhen shafts are supported by bearings inseparate housings that are too far apart. Rigid bearings, i.e. deep groove ball bear-ings and cylindrical roller bearings cannotaccommodate any misalignment, or can onlyaccommodate very minor misalignments,unless by force. Self-aligning bearings, i.e.self-aligning ball bearings, spherical rollerbearings, toroidal roller bearings and spher-ical roller thrust bearings (➔ fig 16 ), on theother hand, can accommodate misalign-ment produced under operating loads andcan also compensate for initial errors ofmisalignment resulting from machining ormounting errors. Values for the permissiblemisalignments are given in the introductorytext of the table section. If the expected mis-alignment exceeds the permissible values,please contact the SKF applicationengineering service. Thrust ball bearings with sphered hous-ing washers and seating rings, Y-bearingunits and alignment needle roller bearings(➔ fig 17 ) can compensate for initial mis-alignment arising from machining or mount-ing errors.40
  41. 41. Fig 15Fig 16Fig 17 41
  42. 42. Selection of bearing typeSpeed Fig 18The permissible operating temperature limitsthe speed at which rolling bearings can beoperated. Bearing types with low friction andcorrespondingly low heat generationinside the bearing are therefore the mostsuitable for high-speed operation. The highest speeds can be achieved withdeep groove ball bearings and self-aligningball bearings (➔ fig 18 ) when loads are purelyradial and with angular contact ball bearings(➔ fig 19 ) for combined loads. This is particu-larly true of high precision angular contactball bearings or deep groove ball bearingswith ceramic rolling elements. Because of their design, thrust bearingscannot accommodate as high speeds asradial bearings. Fig 19Quiet runningIn certain applications, e.g. small electricmotors for household appliances or officemachinery, the noise produced in operationis an important factor and can influence thebearing choice. SKF deep groove ball bear-ings are produced specifically for theseapplications (➔ fig 18 ).StiffnessThe stiffness of a rolling bearing is charac-terised by the magnitude of the elasticdeformation (resilience) in the bearing under Fig 20load. Generally this deformation is very smalland can be neglected. In some cases, how-ever, e.g. spindle bearing arrangements formachine tools or pinion bearing arrange-ments, stiffness is important. Because of the contact conditions be-tween the rolling elements and raceways,roller bearings e.g. cylindrical or taper rollerbearings (➔ fig 20 ), have a higher degree ofstiffness than ball bearings. Bearing stiff-ness can be further enhanced by applyinga preload (➔ section “Bearing preload”,starting on page 206) .42
  43. 43. Fig 21 Axial displacement Shafts, or other rotating machine compon- ents, are generally supported by a locating and a non-locating bearing (➔ section “Bear- ing arrangements”, starting on page 160). Locating bearings provide axial location for the machine component in both direc- tions. The most suitable bearings for this are those that can accommodate combined loads, or can provide axial guidance in com- bination with a second bearing (➔ matrix on page 46 and 47). Non-locating bearings must permit shaft movement in the axial direction, so that the bearings are not overloaded when, for ex- ample, thermal expansion of the shaft occurs. The most suitable bearings for the non-Fig 22 locating position include needle roller bear- ings and NU and N design cylindrical roller bearings (➔ fig 21 ). NJ design cylindrical roller bearings and some full complement design cylindrical roller bearings can also be used. In applications where the required axial displacement is relatively large and also the shaft may be misaligned, the CARB toroidal roller bearing is the ideal non-locating bear- ing (➔ fig 22 ). All of these bearings permit axial displace- ment of the shaft with respect to the housing within the bearing. Values for the permissible axial displacement within the bearing are given in the relevant product tables. If non-separable bearings, e.g. deep groove ball bearings or spherical rollerFig 23 bearings (➔ fig 23 ) are used as non-locating bearings, one of the bearing rings must have a loose fit (➔ section “Radial location of bearings”, starting on page 164). 43
  44. 44. Selection of bearing typeMounting and Fig 24dismountingCylindrical boreBearings with a cylindrical bore are easier tomount and dismount if they are of separabledesign rather than non-separable, particu-larly if interference fits are required for bothrings. Separable bearings are also prefer-able if frequent mounting and dismountingare required, because the ring with rollingelement and cage assembly of these separ-able bearings can be fitted independently ofthe other ring, e.g. four-point contact ballbearings, cylindrical, needle and taper rollerbearings (➔ fig 24 ) as well as ball and rollerthrust bearings.Tapered boreBearings with a tapered bore (➔ fig 25 ) caneasily be mounted on a tapered journal or ona cylindrical shaft seating using an adapteror withdrawal sleeve (➔ fig 26 ) or a steppedsleeve. Fig 25 Fig 2644
  45. 45. Fig 27Integral sealsThe selection of a seal is of vital importance tothe proper performance of the bearing. SKFsupplies bearings with integral• shields (➔ fig 27 ),• low-friction seals (➔ fig 28 ),• contact seals (➔ fig 29 ).that can provide an economic and space-saving solution for many applications. A largenumber of sizes are available for• deep groove ball bearings• angular contact ball bearings• self-aligning ball bearings• cylindrical roller bearings• needle roller bearings Fig 28• spherical roller bearings• CARB toroidal roller bearings• cam rollers• Y-bearings and Y-bearing unitsAll bearings with integral seals on both sidesare filled with a grease of appropriate qualityand quantity. Fig 29 45
  46. 46. Selection of bearing type The matrix can only provide a rough guide so that in each individual case it is Bearing types – design and characteristics necessary to make a more qualified selection referring to the information given on the preceding pages or the detailed information in the text preceding each Design table section. If several designs of the bearing type are shown adjacent to each other, the relevant information is indicated by the same small letter used to identify the individual design. Symbols: + + + excellent − poor + + good − − unsuitable + fair ← single direction shields or seals non-seperable ← → double direction tapered bore self-aligning separable Bearing type Deep groove ball bearings a a b Angular contact ball bearings, single row matched single row, double row b a, b c a b c four-point contact Self-aligning ball bearings Cylindrical roller bearings, with cage a a b b full complement, single row a b a b full complement, double row a a a b c Needle roller bearings, with steel rings a c a b c assemblies/drawn cups b, c a b c combined bearings b, c a b c Taper roller bearings, single row matched single row a b Spherical roller bearings CARB toroidal roller bearings, with cage full complement Thrust ball bearings a b with sphered housing washer a b Needle roller thrust bearings Cylindrical roller thrust bearings a b Spherical roller thrust bearings46

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