CARB toroidal roller bearings – a revolutionary concept · 2021. 1. 26. · CARB bearing to...

CARB® toroidal roller bearings – a revolutionary concept

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Contents

1 Product information.................................................. 3The winning combination............................................. 3SKF toroidal roller bearings with revolutionary design characteristics.................................................. 4

SKF Explorer class bearings ....................................... 5The range for all requirements .................................... 6

Availability.................................................................... 7Bearing features and benefits ..................................... 7

The CARB toroidal roller bearing – the cornerstone of the new self-aligning system...... 8Successful in service ................................................... 10

2 Recommendations....................................................12Selection of bearing size ............................................ 12

Longer life or downsizing ............................................ 12Design of bearing arrangements ............................... 14

Radial location ............................................................ 14 Axial location .............................................................. 16Design of adjacent components ................................ 18Sealing the bearing arrangement ................................ 20

Lubrication ................................................................... 22Grease lubrication ...................................................... 22Deviating conditions ................................................... 24Oil lubrication .............................................................. 25

Mounting ...................................................................... 26Mounting on cylindrical seatings................................. 26Mounting on tapered seatings..................................... 27

Dismounting ................................................................. 34Dismounting from a cylindrical seating ....................... 34Dismounting from a tapered seating ........................... 35

SKF concept for cost saving ....................................... 36

3 Product data ..............................................................37Bearing data – general ................................................ 37Product tables .............................................................. 44

CARB toroidal roller bearings ..................................... 44Sealed CARB toroidal roller bearings.......................... 56CARB toroidal roller bearings on adapter sleeve ........ 58CARB toroidal roller bearings on withdrawal sleeve ... 68

Other associated SKF products ................................. 78

SKF – The knowledge engineering company ............ 82

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,creating greater value for customers.

These solutions encompass ways to bring greater productivity to customers, not only with breakthrough application-specific products, but also through leading-edge design simulation tools and consultancy services,plant asset efficiency maintenance programs, and theindustry’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 company

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The winning combination

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Self-alignment ...Self-aligning bearings are the hallmarkof SKF – not surprising since SKF wasfounded in 1907, based on the inventionof the self-aligning ball bearing by SvenWingquist. But the development didnot stop there, other SKF inventionsfollowed: the spherical roller bearing in1919 and the spherical roller thrustbearing in 1939.

Self-alignment is called for

• when misalignment exists as aresult of manufacturing or mountingerrors

• when shaft deflections occur underload

and these have to be compensated forin the bearing arrangement withoutnegative effects on performance orany reduction in bearing service life.

... and axial displacement ...SKF was also heavily involved in thedevelopment of bearings having ringsthat can be axially displaced withrespect to each other. In 1908, forexample, the cylindrical roller bearingin its modern version was largelydeveloped by Dr.-Ing. Josef Kirner ofthe Norma Compagnie in Stuttgart-BadCannstatt, which became a subsidiaryof AB SKF.

Cylindrical roller bearings are ap-plied when

• heavy radial loads and relativelyhigh speeds prevail and

• thermal changes in shaft lengthmust be accommodated in the bear-ing with as little friction as possible –provided, of course, that there is nosignificant misalignment.

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... combined for successPreviously, it was always necessary tocompromise. Because misalignment orshaft bending makes the use of self-aligning bearings essential – and,depending on load and speed, thechoice lay between self-aligning ballbearings and spherical roller bearings.

However, in contrast to cylindricalroller bearings, those bearings cannotaccommodate important axial dis-placements within the bearing.

Therefore, it was necessary for one of the bearings to move axially on itsseating in the housing. Such movementis always accompanied by considerablefriction, which produces internal axialforces in the bearing arrangement. The result is a shortened bearing servicelife and relatively high costs for main-tenance and repairs.

Today, this is a thing of the past.Because Magnus Kellström, a productdesigner at SKF, had a brilliant idea; he invented the toroidal roller bearing.This bearing not only can compensatefor misalignment without friction, butalso for changes in shaft length withinthe bearing. Thus a completely newtype of bearing for non-locatingarrangements has become available to the engineering world.

It is no longer necessary to com-promise, and there are added benefitstoo – much longer service life for thecomplete bearing arrangement andminimized maintenance and repaircosts.

Self-alignment …

… and axial displacement …

… combined in a toroidal rollerbearing

1 Product information 2 Recommendations 3 Product data

The winning combination Page ............. 12 Page ............. 37

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The SKF toroidal roller bearing rep-resents one of the most importantbreakthroughs in rolling bearing tech-nology over the past sixty years. Thebearing was introduced to the marketthe market in 1995 under the SKFtrademark CARB®.

The CARB toroidal roller bearing is a completely new type of roller bearing,which offers benefits that were previ-ously unthinkable. Irrespective of whether a new machine is to be design-ed or an older machine maintainedthere are benefits to be gained by usinga toroidal roller bearing. Which of thesebenefits is realized depends on themachine design and its operating para-meters.

The CARB bearing is a single rowroller bearing with relatively long, slightlycrowned rollers. The inner and outerring raceways are correspondinglyconcave and symmetrical (➔ fig ).The outer ring raceway geometry isbased on a torus (➔ fig ), hence the term toroidal roller bearing.

The SKF toroidal roller bearing isdesigned as a non-locating bearingthat combines the self-aligning abilityof a spherical roller bearing with theability to accommodate axial displace-ment like a cylindrical or needle rollerbearing. Additionally, if required, thetoroidal roller bearing can be made ascompact as a needle roller bearing.

An application incorporating an SKFtoroidal roller bearing provides bene-fits outlined in the following.

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Self-aligning capabilityThe self-aligning capability of theCARB bearing is particularly importantin applications where there is misalign-ment as a result of manufacturing ormounting errors or shaft deflections.To compensate for these conditions, a CARB bearing can accommodatemisalignment up to 0,5 degrees be-tween the bearing rings without anydetrimental effects on the bearing orbearing service life (➔ fig ).

Axial displacementPreviously, only cylindrical and needleroller bearings could accommodatethermal expansion of the shaft withinthe bearing. Today, however, the CARBbearing can be added to that list (➔fig ). The inner and outer rings of a CARB bearing can be displaced,with respect to each other, up to 10 %of the bearing width. By installing thebearing so that one ring is initially dis-placed with respect to the other one, it is possible to extend the permissibleaxial displacement in one direction. Incontrast to cylindrical and needle rollerbearings that require accurate shaftalignment, this is not needed for toroidalroller bearings, which can also copewith shaft deflection under load. Thisprovides a solution to many problemcases.

Long system lifeThe ability to accommodate misalign-ment plus the ability to accommodateaxial displacement with virtually nofriction enables a CARB bearing toprovide benefits to the bearing arrange-ment and its associated components(➔ fig ). 5

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The CARB toroidalroller bearing

SKF toroidal roller bearings with revolutionary design characteristics

1Fig

2Fig

3Fig

4Fig

5Fig

The torus

Angular misalignmentThe most frequentlyoccurring misalign-ments in operationare not a problemfor a CARB toroidalroller bearing

Axial displacement Changes in shaftlength are accom-modated within thebearing virtuallywithout friction

FreedomPermissible angularmisalignment + axialdisplacement withinthe bearing


Customer benefits Page ............. 12 Page ............. 37

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1• Internal axial displacement is virtually

without friction; there are no internallyinduced axial forces, thus operatingconditions are considerably im-proved.

• The non-locating bearing as well asthe locating bearing only need tosupport external loads.

• The bearings run cooler, the lubri-cant lasts longer and maintenanceintervals can be appreciably extended.

Taken together, these benefits con-tribute to a longer system life.

High load carrying capacityCARB toroidal roller bearings canaccommodate very high radial loads.This is due to the optimized design ofthe rings combined with the designand number of rollers. The large num-ber of long rollers make CARB bear-ings the strongest of all aligning rollerbearings. Due to their robust design,CARB bearings can cope with smalldeformations and machining errors ofthe bearing seating (➔ fig ). The ringsaccommodate these small imperfec-tions without the danger of edgestresses. The high load carryingcapacity plus the ability to compen-sate for small manufacturing or instal-lation errors provide opportunities toincrease machine productivity anduptime.

6

6Fig

7Fig

8Fig

Increased performance or downsizingFor bearing arrangements incorporatinga CARB toroidal roller bearing as non-locating bearing, internally induced axialforces are prevented. Together with highload carrying capacity this means that

• for the same bearing size in thearrangement, performance can beincreased or the service life extend-ed, or

• new machine designs can be mademore compact to provide the same,or even higher performance.

Reduced vibrationSelf-aligning ball or spherical rollerbearings in the non-locating positionneed to be able to slide within thehousing seating. This sliding, however,causes axial vibrations which can re-duce bearing service life considerably.

Bearing arrangements that useCARB toroidal roller bearings as thenon-locating bearing are stiff becausethe CARB bearing can be radially andaxially located in the housing and onthe shaft. This is possible becausethermal expansion of the shaft isaccommodated within the bearing.The stiffness of the bearing arrange-ment, combined with the ability of theCARB bearing to accommodate axialmovement, substantially reducesvibrations within the application toincrease service life of the bearingarrangement and related components(➔ fig ).

Full dimensional interchangeabilityThe boundary dimensions of SKFCARB toroidal roller bearings are inaccordance with ISO 15:1998. This pro-vides full dimensional interchangeabilitywith self-aligning ball bearings, cylin-drical roller and spherical roller bear-ings in the same Dimension Series. TheCARB bearing range also covers widebearings with low cross sections nor-mally associated with needle rollerbearings (➔ fig ).

SKF Explorer classbearingsAll CARB bearings are manufactured tothe SKF Explorer performance class.

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Deviations fromcylindrical form areless problematicDemands on accur-acy of form of thebearing seatings are less stringent,making simpler andless costly arrange-ments possible

Axial vibrationWith a CARB bearing axial vibrations areconsiderably reduced, meaning longer service life and quieter operation

Full dimensional interchangeabilityCARB advantages can be fully exploitedwhen refurbishing non-locating bearingarrangements designed for self-aligning aswell as rigid bearings

time

axial vibration

– conventional arrangement– with CARB as non-locating bearing


Customer benefits Page ............. 12 Page ............. 37

The range for all requirements

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The SKFstandard range of CARB toroid-al roller bearings comprises bearings in13 ISO Dimension Series (➔ fig ). Thesmallest bearing has a bore diameter of25 mm and the largest one a bore dia-meter of 1250 mm. Bearings with a borediameter up to 1800 mm can be pro-duced. Whether a new bearing arrange-ment is to be designed or an existingarrangement upgraded most often thereis an appropriate CARB toroidal rollerbearing available or such a bearing couldbe manufactured.

SKF toroidal roller bearings are pro-duced in

• a caged version (➔ fig ) as well as• a full complement version (➔ fig )

with

• a cylindrical bore, or • a tapered bore.

The tapered bore has a taper of 1:12or 1:30, depending on the DimensionSeries.

In addition to the standard bearings,

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1

C 39 C 49 C 59 C 69 C 30 C 40 C 50 C 60 C 31 C 41 C 22 C 32 C 23

1Fig

Overview of product range

SKF also produces special executionsto suit particular applications, e.g.

• bearings with case hardened innerrings to allow a heavy interferencefit on the shaft/journal of dryer orYankee cylinders, for example;

• bearings with a surface hardenedcage for vibrating screens;

• sealed bearings, for example, forcontinuous casting plants (➔ fig ).The permissible misalignment andaxial displacement as well as theload carrying capacity are lowerthan for the corresponding bearingwithout seals.

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Assortment Page ............. 12 Page ............. 37

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AvailabilityThe product range is shown in theproduct tables starting on page 44.SKF recommends checking availabilityof those bearings marked with a triangle.To do that, contact your local SKF representative or SKF distributor. Thestandard range is being continuouslyextended and the intention is to manu-facture all the products shown in theproduct tables in a few years time.

Bearing benefitsAlready well proven in service, toroidalroller bearings enable all types ofmachines and equipment to be

• smaller,• lighter,• more cost-effective, and• more operationally reliable.

Replacing other non-locating bearingswith an equivalent CARB bearing can,depending on the application, improveperform-ance and uptime while de-creasing maintenance. Why not putCARB bearings to the test and reapthe benefits they can provide?

3Fig 4Fig

Sealed bearingLubricated for life and protected against contamination

Full complement bearingFor very heavy loads and low speeds

2Fig

Caged bearingFor heavy loads and relatively high speeds


Assortment Page ............. 12 Page ............. 37

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The CARB toroidal roller bearing– the cornerstone of the newself-aligning bearing systemThe conventional solutionUntil recently a self-aligning bearingsystem consisted of two self-aligningball bearings if there were high speedsand light loads, or two spherical rollerbearings when there were heavy loadsand moderate speeds. These bearingsystems are simple, have good loadcarrying capacity and can compensatefor misalignment resulting from manu-facturing or mounting errors as well asshaft deflections (➔ fig ). So far, sogood – but what happens if the shaftwere to expand axially?

In a traditional bearing arrangement,axial expansion of the shaft is accom-modated by the non-locating bearing.The fits for this bearing are selected sothat one of the bearing rings will beable to move axially on its seating asthe shaft expands. Generally thismovement is between the outer ringand the housing seating. This move-ment is always accompanied by fric-tion, which gives rise to induced axialforces in both the bearings (➔ fig ).In addition, the movement of the loosebearing on its seating can create dam-aging vibrations because the movementis ”stick-slip” and not smooth (➔fig ).

The loose fit has a negative effecton the stiffness of the bearing arrange-ment. The bearing ring with the loosefit can also begin to “wander”, whichcan wear the seating and lead to fret-ting corrosion and possibly “weld” the ring to its seating (➔ fig ).

The new solutionToday, the CARB toroidal roller bearingis available for the non-locating posi-tion in a self-aligning bearing system.It is no longer necessary to compro-mise.

4

3

2

1

1Fig

Fr

2Fig

0,2

0,1

0

3Fig

1

1,5

0,5

0

4Fig

Conventional solutionTwo spherical rollerbearings (or self-aligning ball bear-ings) compensateeasily for angularmisalignment of the inner ring withrespect to the outer ring

Axial expansion of the shaft caninfluence the loaddistribution in thebearings

Load conditions in a conventionalsolutionChanges in axialforce in a non-locat-ing bearing duringthe machine start-upphase; internal axialforces of corres-ponding magnitudeare produced in thelocating bearing

In a non-locating bearing which has been clamped in itshousing bore seat-ing, heavy axialforces prevail in thebearing arrange-ment after the start-up phase and dra-matically shortenbearing service life

Fa/Fr

Fa/Fr

t

t


Self-aligning bearing system Page ............. 12 Page ............. 37

Fr

9

1

5Fig

6Fig

7Fig

CARB toroidal roller bearings areable to compensate for misalignmentand accommodate axial displace-ments within the bearing (➔ fig ).This means that both rings of the non-locating bearing can be axially locatedin the housing and on the shaft (➔ fig

). If it is necessary to secure therings so that they cannot “creep”, theycan be mounted with an interferencefit, thus enhancing the radial stiffnessof the bearing arrangement.

This is an optimal solution for appli-cations with undetermined load direc-tion, e.g. vibrating applications, becauseinternal preload and wear to the bear-ing seating in the housing are elimin-ated. No longer is there a compromisebetween a tight fit and axial freedom.

A CARB toroidal roller bearing isdesigned to accommodate axial dis-placement without inducing additionalaxial internal forces or friction (➔ fig ).This means that the loads acting on thebearing are determined exclusively by external radial and axial forces.Because of this, a bearing systemincorporating a CARB bearing willhave lower loads and better load dis-tribution than a conventional bearingsystem. This translates into lower oper-ating temperatures, higher operatingviscosities, extended relubricationintervals, and a significantly longerservice life for both the bearings andthe lubricant (➔ fig ).

With a CARB toroidal roller bearing in the non-locating position, the manyexcellent design characteristics andproperties of SKF spherical roller bear-ings and self-aligning ball bearings canbe fully exploited. This provides newopportunities to further optimizemachine design.

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6

6

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The new solutionA spherical roller bear-ing or a self-aligningball bearing as thelocating bearing and a CARB toroidal rollerbearing as the non-locating bearing com-pensate for angularmisalignment of therings resulting fromerrors of alignment ordeflection under loadas well as thermalchanges in shaftlength, virtually with-out friction

There are no intern-ally induced axialforces. The rings of the non-locatingbearing should beaxially and radiallylocated

Lower operatingtemperatures extendrelubrication inter-vals and bearingservice life

°C


Self-aligning bearing system Page ............. 12 Page ............. 37

Successful in service

One of the major application areasfor CARB toroidal roller bearings is insteelmaking and particularly in continu-ous casters where the multitude ofguide rollers are subjected to the mostdifficult operating conditions. Papermachines are another important applica-tion where shaft deflections and thermalchanges in roll length of up to 10 mmhave to be accommodated.

Although a recent invention, the CARBtoroidal roller bearing can be found ina variety of applications spanningalmost every industry. This bearinghas already proven itself and in manycases has outperformed expectationsby

• extending service life,• increasing reliability,• reducing maintenance, and• providing more compact designs.

Main application areas• Steelmaking and rolling mills• Conveyors and roller beds • Paper machines • Fluid machinery • Crushers• Gearboxes of all types • Textile machines • Food and beverage

processing machines • Agricultural machinery• Vibrating screens

Major demands• Freedom• High load carrying capacity • High operational reliability• Long service life • Reduced maintenance• Low operational costs • Compact design • Enhanced performance • High power density

Solution

These are not the only fields whereCARB toroidal roller bearings performsuccessfully. They are also in servicein gearboxes, large electric motors,wind power plants, water turbines, bowthrusters, crane wheels, separators,centrifuges, presses, staking machinesfor tanneries, rotary cultivators andmulchers.


Application areas Page ............. 12 Page ............. 37

To facilitate the incorporation ofCARB toroidal roller bearings in newas well as existing machines, pleaseconsult the SKF application engineer-ing service.


Application areas Page ............. 12 Page ............. 37

Selection of bearing size

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To calculate bearing size or the basicrating life for a toroidal roller bearing it is possible to use all the known andstandardized (ISO 281) calculationmethods. However, it is recommendedthat the SKF Life Method be appliedso that the enhanced performance ofSKF bearings can be fully exploited.Detailed information can be found in theSKF General Catalogue in the section“Selection of bearing size” or in the“SKF Interactive Engineering Cata-logue” available on CD-ROM or onlineat www.skf.com.

For a self-aligning bearing systemthat uses an SKF Explorer sphericalroller bearing and a CARB bearing,system life can be calculated using theSKF rating life equation:

whereLnm,Sys = SKF rating life for the bear-

ing system (at 100 – n %reliability), millions of revo-lutions

Lnm,SRB = SKF rating life for the locat-ing spherical roller bearing(at 100 – n % reliability), millions of revolutions

Lnm,CARB = SKF rating life for the non-locating CARB toroidalroller bearing (at 100 – n %reliability), millions of revo-lutions

Longer life or downsizingWhen used in a self-aligning bearingsystem, the CARB bearing preventsinternally induced axial forces fromoccuring. This is in contrast to con-ventional self-aligning bearing systemswith two spherical roller bearings orself-aligning ball bearings where theinduced internal axial forces can be 20 % or more of the radial load actingon the non-locating bearing. Theseadditional forces represent a sizeableproportion of the total load that cannotbe neglected and can result in

• the bearing system not achieving therequisite life, or

• larger bearings being used to com-pensate for the additional forces.

Because a CARB toroidal roller bear-ing prevents internally induced axialforces from occuring, the load condi-tions in the bearing arrangement canbe predicted accurately since thelocating bearing is only subjected to itsportion of the external radial and axialloads, while the non-locating bearingis only subjected to its portion of theradial load.

Whether a spherical roller bearing (➔ diagram ) or a self-aligning ballbearing (➔ diagram ) is used in thelocating position, the new self-aligningbearing system can substantiallyincrease the service life of a bearingarrangement. It is also worth notingthat, even if smaller bearings are used,it is often possible to achieve systemlives that are longer compared to thetraditional systems. This can beexploited by downsizing adjacentcomponents and reducing costs.

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To take full advantage of the bene-fits offered by the new self-aligningsystem it is necessary to carefullyselect the bearing size – at the non-locating as well as the locating side.For assistance, contact the SKF appli-cation engineering service.

Lnm,Sys =9/8�

11

+1

Lnm,SRB9/8 Lnm,CARB

9/8


Page ............. 3 System life Page ............. 37

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2

1Diagram

2Diagram

Compare the life of a conventional self-aligning bearing system with sphericalroller bearings with a bearing systemcontaining a CARB toroidal roller bear-ing and a spherical roller bearing

Compare the life of a conventional self-aligning bearing system with self-align-ing ball bearings with a bearing systemcontaining a CARB toroidal roller bear-ing and a self-aligning ball bearing

Coefficient of friction µ

Coefficient of friction µ

Rel

ativ

e lif

e of

the

sys

tem

Rel

ativ

e lif

e of

the

sys

tem

0 0,05 0,1 0,15* 0,2 0,25 0,3 0,35 0,40

1

C 3148 23148

C 3144 23144

23148 23148

0 0,05 0,1 0,15* 0,2 0,25 0,3 0,35 0,4

6

5

4

3

2

1

0

C 2222 2222

22222222

C 2220 2220

* Typical value for steel on cast iron

* Typical value for steel on cast iron

0,5


Page ............. 3 System life Page ............. 37

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Design of bearing arrangements

1Fig 2Fig

Two bearings are generally required tosupport, guide and locate a shaft inthe radial and axial directions. To dothis, one bearing is designated thelocating bearing and the other is thenon-locating bearing.

In traditional self-aligning bearingsystems, the locating bearing locatesthe shaft axially in its housing whilethe non-locating bearing typicallymoves in its housing to accommodateaxial expansion of the shaft.

With the new SKF self-aligningbearing system, a CARB toroidal rollerbearing is used in the non-locatingposition and either a spherical rollerbearing (➔ fig ) or a self-aligningball bearing (➔ fig ) is used in thelocating position. Because a CARBbearing can accommodate axialexpansion internally like a cylindricalroller bearing, it prevents internallyinduced axial forces from occuring thatwould otherwise that would otherwisebe present if the bearing had to slideon its seating in the housing. This abilityto accommodate internal axial forcesallows the bearing rings to be axiallylocated on the shaft and in the housing.

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Radial location To take advantage of the very high loadcarrying capacity and full life potential ofa toroidal roller bearing, the bearingrings must be fully supported aroundtheir whole circumference and acrossthe full width of the outer ring.

Selecting the proper fitTo locate a shaft radially, most applica-tions require an interference fit betweenthe bearing rings and their seatings.However, if easy mounting and dis-mounting are required, the outer ringwill have a looser fit.

Recommendations for suitable shaftdiameter and housing bore tolerancesfor CARB toroidal roller bearings aregiven in tables , and . Theserecommendations apply to solid steelshafts and housings made from castiron or steel.

Generally, CARB toroidal roller bear-ings follow the fit recommendationsfor spherical roller bearings on shaftsand in housings. However, a sphericalroller bearing on the non-locating sidemust be axially free, which requires a

321

loose housing fit – this is not necessaryfor bearing arrangements using a CARBtoroidal roller bearing. CARB bearings(and locating spherical roller bearings)can therefore utilise the advantages oftight outer ring fits if mounting and dismounting allow this, but for normal,stationary outer ring load it is not neces-sary. For example a K7 fit is applied tobearings in the split housing for a fanwith an unbalanced fan rotor and a P7fit applied to a non-split housing.

Bearings with a tapered bore aremounted either directly on a taperedjournal or on an adapter or a with-drawal sleeve on cylindrical shaft seat-ings. The fit of the inner ring in thesecases depends on how far the ring isdriven up the tapered seating.

Accuracy of associated componentsThe accuracy of the cylindrical seatingson the shaft and in the housing boreshould correspond to that of the bear-ing. For CARB toroidal roller bearingsthe shaft seating should be tolerancegrade 6 and the housing seating grade7. For an adapter or withdrawal sleeve,wider diameter tolerances can be

SKF self-aligning bearing system with a spherical roller bearing at the locating side and a CARB toroidal roller bearingat the non-locating side

SKF self-aligning bearing system with a self-aligning ball bearing at the locating side and a CARB toroidal roller bearingat the non-locating side


Page ............. 3 Radial location Page ............. 37

Conditions Examples Shaft diameter (mm) Toleranceover incl.

Bearings with cylindrical boreRotating inner ring load or direction of load indeterminate

Normal and General 40 k5heavy loads engineering, 40 65 m5(P > 0,06 C) electric motors, 65 100 m6

pumps, 100 140 n6gearboxes 140 280 p6

280 500 r61)500 r71)

Very heavy loads and shock loads 50 100 n61)with difficult working conditions 100 140 p61)(P > 0,12 C) 140 r61)

Bearings with tapered bore on adapter or withdrawal sleevesNormal loads and/or normal speeds h10/IT7/2Heavy loads and/or high speeds h9/IT5/2

Stationary inner ring loadEasy dismounting unnecessary h6Easy dismounting desirable g62)

1) Bearings with radial internal clearance greater than Normal may be necessary2) Tolerance f6 can be selected for large bearings to provide easy displacement

Conditions Examples Tolerance Remarks

Rotating outer ring loadHeavy loads and Crushers, N6 Bearing outside diameter < 160 mmshock loads vibrating P6 Bearing outside diameter ≥ 160 mm

screens, fans

Stationary outer ring loadLoads of all kinds General H7

engineering

Direction of load indeterminateHeavy shock loads M7

Normal and General K7heavy loads engineering,(P > 0,06 C) electric motors, H7 Easy mounting of bearing required

pumps

15

2

1Table

2Table

Conditions Examples Tolerance

Stationary outer ring load Loads of all kinds General H7

engineering

Direction of load indeterminateLoads of all kinds General J7

engineering,electric motors,pumps

3Table

Fits for solid steelshafts

Fits for non-splitcast iron and steelhousings

Fits for split castiron and steelhousings

adopted for the cylindrical seating onthe shaft, e.g. grade 9 or 10.

The cylindricity as defined in ISO 1101-1996 for the bearing seatingshould be 1 or 2 grades better thanthe recommended dimensional toler-ance depending on the requirements.For example, a shaft seating machinedto tolerance m6 should have a cylin-dricity grade 5 or 4.


Page ............. 3 Radial location Page ............. 37

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4Fig

3Fig

Axial location The rings of CARB toroidal roller bear-ings should be axially located on bothsides on the shaft as well as in thehousing. SKF recommends arrangingthe bearing rings so that they abut ashoulder on the shaft or in the hous-ing. Inner rings can be locked in posi-tion using

• a shaft (lock) nut (➔ fig ),• a retaining ring (➔ fig ) or • an end plate screwed to the shaft

end (➔ fig ).

Outer rings are usually secured inposition in the housing by the endcover (➔ fig ).

Instead of integral shaft and housingshoulders CARB toroidal roller bear-ings can be mounted against

• spacer sleeves (➔ fig ) or• retaining rings (➔ fig ).

Bearings with a tapered bore that aremounted

• directly onto a tapered journal areusually secured to the shaft with anut on the threaded section (➔ fig ),or

• on an adapter sleeve and a steppedshaft are secured against a spacerring (➔ fig ), or

• on a withdrawal sleeve against a shaft shoulder are secured by a shaft nut (➔ fig ) or an endplate (➔ fig ).12

11

10

9

87

6

5

43

Abutment and fillet dimensionsThe abutment and fillet dimensions,which include the diameters of shaftand housing shoulders, spacer sleevesetc. have been determined so thatadequate abutment surfaces are pro-vided for the side faces of the bearingrings without any danger of the rotatingparts being fouled. The recommendedabutment and fillet dimensions for eachindividual bearing can be found in theproduct tables.

Inner ring locatedaxially with ashaft nut

Inner ring locatedaxially with aretaining ring


Page ............. 3 Axial location Page ............. 37

17

2

5Fig

6Fig

7Fig

8Fig

9Fig

10Fig

11Fig

12Fig

Inner ring locatedaxially with an endplate

Outer ring locatedaxially with an endcover

Spacer sleevesused to axiallylocate the innerand outer rings

Retaining ringsused to axiallylocate the bearingrings

Inner ring on atapered shaft heldin place by a shaftnut

Inner ring on anadapter sleeveand a steppedshaft, axially located against a spacer ring

Inner ring on a with-drawal sleeve and a stepped shaft, axially located by a shaft nut

Inner ring on a with-drawal sleeve and a stepped shaft,axially located by an end plate


Page ............. 3 Axial location Page ............. 37

18

13Fig

14Fig

15Fig

16Fig

Design of adjacent components Space on the sides of the bearingTo enable axial displacement of theshaft relative to the housing, spacemust be provided on both sides of the bearing as indicated in fig . The actual value for the width of thisspace can be estimated based on

• the value Ca (from the producttables),

• the axial displacement of the bearingrings from the central position expected in operation, and

• the displacement of the rings causedby misalignment

Careq = Ca + 0,5 (s + smis)

or

Careq = Ca + 0,5 (s + k1 B α)

whereCareq = width of space required on each

side of the bearing, mmCa = minimum width of space required

on each side of the bearing, mm (➔ product tables)

s = thermal change in shaft length,mm

smis = axial displacement of rollercomplement caused by mis-alignment, mm

k1 = misalignment factor (➔ product tables)

B = bearing width, mm(➔ product tables)

α = angular misalignment, degrees

See also under “Axial displacement” onpage 40.

Normally, the bearing rings aremounted so that they are not dis-placed with respect to each other. How-ever, if considerable thermal changes in shaft length can be expected, theinner ring can be mounted offset rela-tive to the outer ring up to the permis-sible axial displacement s1 or s2 in thedirection opposite to the expectedthermal elongation (➔ fig ). In thisway, the permissible axial displace-ment can be appreciably extended, anadvantage which is made use of in thebearing arrangement of drying cylin-ders in papermaking machines.

14

13

Free space on both sides of thebearing

By mounting theouter ring pur-posely displacedwith regard to theinner ring the permissible axialdisplacement canbe extended

CARB toroidalroller bearing on a tapered journalwith oil duct anddistributor groove

CARB toroidalroller bearingarrangement withoil ducts and dis-tributor grooves inthe shaft andhousing

It is particularly important whendesigning large bearing arrangementsto take steps so that the mounting anddismounting of the bearings are facili-tated or actually made possible.

Ca

s1s2


Page ............. 3 Associated components Page ............. 37

19

2

Recommended dimensions for oil ducts and distributor grooves Threaded connection holes

Bearing seating Dimensionsdiameter ba ha ra Nover incl.

mm mm

100 3 0,5 2,5 2,5100 150 4 0,8 3 3150 200 4 0,8 3 3

200 250 5 1 4 4250 300 5 1 4 4300 400 6 1,25 4,5 5

400 500 7 1,5 5 5500 650 8 1,5 6 6650 800 10 2 7 7

800 1 000 12 2,5 8 8

4Table

Thread Design DimensionsGa Gb Gc

1) Namax

– – mm

M 6 A 10 8 3

G 1/8 A 12 10 3

G 1/4 A 15 12 5

G 3/8 B 15 12 8

G 1/2 B 18 14 8

G 3/4 B 20 16 8

1) Effective threaded length

5Table

L3

L

N

hara

ba Na

Ga

c bG G

Na

Gac

b

G

G60°

Design A Design B

Threaded holes for the oil injectionmethodIf the oil injection method is to be used

• for mounting and dismounting bearings on tapered journals (➔ fig ) or

• for dismounting bearings on or in cylindrical seatings on the shaft or in the housing

it is necessary to provide oil ducts anddistributor grooves in the seating onthe shaft or in the housing (➔ fig ).The distance of the distributor groovefrom the side at which the bearing is tobe mounted and/or dismounted shouldcorrespond to approximately a third ofthe bearing width. Recommended

16

15

dimensions for the distributor grooves,the oil ducts and the appropriatethreads for the connections are givenin tables and .54


Page ............. 3 Associated components Page ............. 37

20

ReferenceAdditional information about radialshaft seals, V-ring seals or mech-anical seals can be found in theSKF catalogue 4006 “CR seals” orin the “SKF Interactive EngineeringCatalogue” on CD-ROM or onlineat www.skf.com.

CR seals

Sealing the bearingarrangementWhen selecting the most suitable sealing arrangement for a self-aligningbearing arrangement it is necessary topay particular attention to

• the angular misalignment of theshaft and

• the magnitude of the axial displacement.

Otherwise the general selection criteriapresented in the SKF General Cata-logue (and the “SKF Interactive Engin-eering Catalogue”) apply and all typesof seals can be used.

Non-contact seals are to be pre-ferred when the operating conditionsinvolve

• high speeds,• large axial displacements,• high temperatures,

and the sealing position is not directlyexposed to contamination. The shaftshould be horizontal.

The simple gap-type seal (➔ fig )is very suitable for sealing the non-locating arrangement of self-aligningbearing systems. The size of the gapcan be adapted to the misalignment ofthe shaft and is not limited in any way.

Single or multi-stage labyrinth sealsare obviously more efficient than thesimple gap-type seal, but are moreexpensive. With CARB toroidal rollerbearings, the labyrinth passages shouldbe arranged axially in order to providefreedom of axial movement for theshaft in operation. If considerable misalignment is expected in operation,the passages should be angled (➔ fig

). When split housings are used,labyrinth seals with radially arrangedpassages can be used, provided axialmovement of the shaft relative to thehousing is not limited (➔ fig ).

Radial shaft seals are contact sealsthat are suitable for sealing greased oroil lubricated CARB toroidal roller bear-ings, provided misalignment is slightand the seal lip counterface is suffi-ciently wide (➔ fig ).20

19

18

17

Some seal types are supplied asstandard with SKF bearing housingsand include a double-lip contact seal,a labyrinth seal as well as a Taconiteseal (➔ fig ). Additional informationcan be found in the brochure 4403“SNL plummer block housings solvethe housing problems”.

21


Page ............. 3 Seals Page ............. 37

21

2

18Fig

19Fig

20Fig

21Fig

17Fig Gap-type seal

Labyrinth sealwith angled passages

Labyrinth sealwith radiallyarranged passages

Radial shaft seal

Taconite seal


Page ............. 3 Seals Page ............. 37

22

1FigCARB toroidal roller bearings can belubricated with grease as well as oil.There is no strict rule for when greaseor oil should be used.

Grease has the advantage over oilthat it is more easily retained in thebearing than oil and grease is better ifthe shaft is at an angle or arrangedvertically.

On the other hand, oil lubricationallows higher operating speeds andtemperatures and can contribute toheat removal from the bearing position,which is particularly important whereexternal heating is involved. Very smallquantities of lubricant are required tolubricate the bearing surfaces.

Since CARB toroidal roller bearingscannot be relubricated via the outerring, lubricant has to be supplied fromthe side of the bearing. This is bestdone via a duct that opens immediatelyadjacent to the side face of the bear-ing outer ring. To force the lubricant topass through the bearing, a drainageopening should be provided on theopposite side of the bearing (➔ fig ).

Grease lubricationFor the lubrication of CARB toroidalroller bearings good quality rustinhibiting greases that are resistant to ageing and have a consistency of 2 or 3 are suitable. Many factors influ-ence the choice of grease. To assist inthis process, SKF greases that aresuitable for CARB bearing lubricationare listed in table .1

1

Recommended SKF greases

Lubrication

Operating conditions SKF greaseDesignation Temperature Viscosity at

range 40/100 ˚C

– – ˚C mm2/s

Standard bearing LGMT 2 –30/+120 110/11arrangements

Standard bearing arrange- LGMT 3 –30/+120 125/12ments but with relativelyhigh ambient temperatures

Operating temperatures LGHB 2 –20/+150 420/26,5always over 100 ˚C

High operating temperatures, LGHP 2 –40/+150 96/10,5smooth operation

Shock loads, heavy loads, LGEP 2 –20/+110 200/16vibration

High demands on LGGB 2 –40/+120 110/13environmental friendliness

Full details on the mentioned SKF greases as well as the complete range of SKF greases will be found in– SKF catalogue MP3000 “SKF Maintenance and Lubrication Products” or online at www.mapro.skf.com – “SKF Interactive Engineering Catalogue” on CD-ROM or online at www.skf.com

1Table

The correct quantity of greaseFor the majority of applications the following guidelines apply:

• Caged CARB toroidal roller bearingsshould be filled with grease toapproximately 50 %. In bearingsthat are to be greased beforemounting it is recommended just tofill the space between the inner ringand the cage (➔ fig ).

• The free space in the bearing hous-ing should be filled with grease tobetween 30 and 50 %.

• Full complement CARB toroidalroller bearings should be completelyfilled with grease.

For bearing arrangements that turnslowly but where good protectionagainst corrosion is required, all thefree space in the housing can be filledwith grease as there is little risk of theoperating temperature increasing.

2

Lubricant supply to the bearing


Page ............. 3 Grease lubrication Page ............. 37

23

2

2Fig

Bearing grease fillCaged CARB toroidal roller bearings shouldnot be completely filled with grease; forhigh speed operation fill only the spacebetween the inner ring and the cage

The tf value is then derived consider-ing the load magnitude, given by thevalue of C/P. The relubrication interval(tf) is an estimated value, valid for anoperating temperature of 70 °C, usinggood quality lithium base greases.

Different conditions are covered indetail in “Deviating conditions”.

If the value of “n × dm” approachesthe limit value (> 70 %) or if ambienttemperatures are high, then the use of

300 000 400 000100 000 600 000

1 000

100

C/P ≥ 15

C/P ≈ 8

C/P ≈ 4

10 000

100 000

200 000 500 000 700 000 800 000

500

5 000

50 000

0

1Diagram

Example: CARB toroidal roller bearing C 2220 KThe bearing has a bore diameter d = 100 mm, an outside diameter D = 180 mm and rotates at a speed n = 1 000 r/min. The load ratio C/P is 4 and the operating temperature lies between 60 and 70 °C. What is therelubrication interval?

The bearing factor n × dm is obtained as follows: n × dm = 1 000 × 0,5 (d + D) = 1 000 × 0,5 (100 + 180) = 140 000. Follow a vertical line from the x-axis from the point n × dm = 140 000 until it intersects the line of the load ratio C/P = 4. The relubrication interval can then be read off on the y-axis by drawing a horizontal line from the point of intersection with 3 000 operating hours.

Bearing factor n × dm

Relubrication intervals for CARB toroidal roller bearings at 70 °C

t f,op

erat

ing

hour

sRelubricationCARB toroidal roller bearings have to be relubricated if the service life of thegrease is shorter than the expected ser-vice life of the bearing. Relubricationshould always be undertaken at a timewhen the existing lubricant is still satis-factory.

The time at which relubrication shouldbe undertaken depends on many relatedfactors. These include bearing type andsize, speed, operating temperature,grease type, space around the bearingand the bearing environment.

It is only possible to base recommen-dations on statistical rules; the SKFrelubrication intervals are defined as thetime period, at the end of which 99 % ofthe bearings are still reliably lubricated.This represents L1 for grease life.

SKF recommends using experiencedata from running applications andtests, together with the estimated relu-brication intervals provided in the nextsection.

Relubrication intervals (tf)The relubrication intervals tf for normaloperating conditions are provided indiagram . The diagram is valid forbearings on horizontal shafts underclean conditions.

The value on the horizontal axis isobtained from “n × dm” (rotationalspeed × bearing mean diameter) (unit: mm/min) multiplied by the relevantCARB toroidal roller bearing factor,which depends on the applied CARBtoroidal roller bearing execution andloading situation. The bearing factorand recommended maximum “n × dm”values for CARB toroidal roller bearingsare given in table .2

1

Bearing design Bearing Maximum n × dmfactor C/P ≥ 15 C/P ≈ 8 C/P ≈ 4

CARB bearings with cage 2 350 000 200 000 100 000CARB bearings – full complement1) 4 N.A3) N.A3) 20 0002)

1) The tf value obtained from diagram 1 needs to be divided by a factor 10 2) For higher speeds oil lubrication is recommended 3) For these C/P values a caged bearing is recommended instead

2Table

Bearing factors and recommended maximum speed limits

the calculations presented in the SKFGeneral Catalogue, section “Speedsand vibration”, is recommended tocheck the operating temperature andthe proper lubrication method.



24

3Fig 4Fig

Grease valveExcess grease is caused to enter a circular channel in the housing cover

Supplying grease to a CARB bearingWhen using a hand-operated grease gun, excess pressure shouldbe avoided or the seals may be damaged

Deviating conditionsOperating temperatureTo account for the accelerated ageingof grease in hot running applications,SKF recommends halving the intervalsobtained from the diagram for every 15 °C increase in bearing temperatureabove 70 °C.

The relubrication interval tf may beextended at temperatures below 70 °C.In many cases the interval may also beprolonged if the load is low (C/P = 30 to50). Extending the relubrication intervaltf by more than a factor of two is notrecommended.

For full complement bearings, tfvalues obtained from the diagramshould not be prolonged.

Moreover, it is not advisable to userelubrication intervals in excess of 30 000 hours.

For many applications, there arepractical grease lubrication limits,when the bearing ring with the highesttemperature reaches an operating tem-perature of 100 °C. Above this tempera-ture special greases should be used. In addition,temperature stability of thebearing and premature seal failureshould be taken into consideration.

For high temperature applications,contact the SKF application engin-eering service.

Vertical shaftsFor bearings on vertical shafts, theintervals obtained from the diagramshould be halved.

The use of a good seal or retainingshield is a prerequisite or grease willleak from the bearing arrangement.

VibrationsMild vibrations will not have a negativeeffect on grease life, but high vibrationand shock levels, such as those invibrating screen applications, will causethe grease to churn. In these cases therelubrication interval should be reduced.If the grease becomes too soft, agrease with a better mechanical stability(e.g. LGHB 2) and/or a stiffer grease(NLGI 3) should be used.

Outer ring rotationIn applications where there is outer ringrotation, the value of the bearing factorn × dm is calculated by applying thevalue of the bearing outside diameter Dinstead of dm. The use of a good seal-ing mechanism is a prerequisite in orderto avoid grease loss.

Under conditions of high outer ringspeeds (i.e. > 50 % of the speed rat-ing in the bearing tables), greases witha reduced bleeding tendency shouldbe selected (e.g. lithium complex andpolyurea).

ContaminationIn case of ingress of contamination, amore frequent relubrication interval willreduce the negative effects of foreignparticles on the bleeding characteristicsof grease while reducing the damagingeffects caused by overrolling of par-ticles. Fluid contaminants (water, pro-cess fluids) also call for a reduced inter-val. In case of severe contamination,continuous relubrication should be considered.

Requisite grease quantities for relubricationThe used grease in a CARB toroidalroller bearing should be replaced byfresh grease. The quantity of greaserequired for this depends on the bear-ing size; this can be determined using

Gp = 0,005 D B

whereGp = grease quantity required for

periodic lubrication, gD = bearing outside diameter, mmB = bearing width, mm



25

2

5Fig

Oil level in CARBtoroidal rollerbearing arrange-mentsMax.: middle of thelowest rollerMin.: 2 to 3 mmabove the lowestpoint of the outerring smallest diam-eter, D1 in the product tables

Grease valveIf CARB toroidal roller bearings are tobe relubricated frequently, there is arisk that too much grease will collect inthe housing. This risk can be avoidedby using a grease valve that allowsexcess grease to leave the housing (➔ fig ).

The so-called grease valve consistsof a washer that rotates with the shaftand forms a narrow gap to the housingcover. Excess grease is carried by thewasher into this gap and leaves thehousing by a grease escape hole inthe base.

The grease should always be supplied from the side of the bearingopposite to the grease valve so that itis forced to pass through the bearing.When the bearing is mounted on anadapter sleeve, the lock nut with lock-ing washer acts as a grease valve, so that grease should be supplied atthe side opposite to the lock nut (➔ fig ).4

3

Oil lubricationOil lubrication is recommended ormust be used if

• the relubrication intervals for greaseare too short,

• speeds and/or operating tempera-tures are too high for grease,

• heat must be removed from thebearing position, or

• adjacent components are lubricatedwith oil.

For CARB toroidal roller bearingsthe following methods are normallyemployed:

• Oil bath lubrication where the oil isdistributed by rotating machinecomponents to the bearing arrange-ment and runs back to the sump.

• Circulating oil lubrication where thecirculation is achieved by a pumpand where the oil is filtered andcooled before being returned to the sump. The use of this methodrequires efficient sealing to preventoil leakage.

The oil level should be checked regu-larly. The appropriate level should notbe higher than the middle of the low-est roller when the bearing is station-ary.

The lower limit should be 2 to 3 mmabove the lowest point of the outerring smallest diameter, D1 in the producttables (➔ fig ).

The same oils can be used for CARBtoroidal roller bearings as for sphericaland cylindrical roller bearings. Theyshould

• have good thermal and chemicalstability,

• contain anti-wear additives and• provide good protection against

corrosion.

Oils of viscosity class

• ISO VG 150 and ISO VG 220 can beused under normal conditions and

• ISO VG 320 and VG 460 may bemore appropriate at high tempera-tures, under heavy loads and slowspeeds.

5


Page ............. 3 Oil lubrication Page ............. 37

26

1Fig 2Fig

Mounting dolly with abutment faces for both bearing rings in the same plane

A CARB toroidal roller bearing on an induction heater

A variety of mechanical and hydraulictools and heaters can be used to mounta CARB bearing. The procedures youchoose will depend on the size of thebearing and the application. The onebasic rule in any installation procedureis to avoid hitting the bearing rings,the rollers or cage.

Detailed information on mountingrolling bearings will be found in thepublication 4100 “SKF BearingMaintenance Handbook”, as well asonline at www.skf.com/mount.

Mounting on cylindricalseatingsWith CARB bearings, the ring that is tohave the tighter fit should be mountedfirst. If the bearing is to be cold mount-ed on the shaft and in the housing atthe same time a tool of the type shownin fig should be used. This toolabuts both bearing rings to apply evenpressure without damaging the rollingelements.

As a rule, larger bearings cannot becold mounted, as the force required topress a bearing into position increasesconsiderably with size. Therefore it isrecommended

• to heat the bearing before it ismounted on the shaft, and

• to heat non-split housings beforeinserting the bearing.

1

To mount a bearing on the shaft, a temperature differential of 80 °C (be-tween ambient temperature and heatedinner ring) is usually sufficient. Forhousings, the appropriate differentialdepends on the degree of interferenceand the seating diameter. However, a moderate increase in temperature willusually suffice. An even and risk-freeheating of CARB bearings can beachieved using an induction heater (➔ fig ).2

Mounting


Page ............. 3 Cylindrical seating Page ............. 37

27

2

Bearing Clear- Axial Turningdesig- ance drive-up angle nation reduc- α

tion

– mm mm degrees

C 2205 0,011 0,42 100C 2206 0,013 0,45 105C 2207 0,016 0,48 115C 2208 0,018 0,52 125C 2209 0,020 0,54 130

C 2210 0,023 0,58 140C 2211 0,025 0,60 110C 2212 0,027 0,65 115C 2213 0,029 0,67 120C 2214 0,032 0,69 125

C 2215 0,034 0,72 130C 2216 0,036 0,77 140C 2217 0,038 0,80 145C 2218 0,041 0,84 150C 2219 0,043 0,84 150

C 2220 0,045 0,87 155C 2222 0,050 0,95 170

C 2314 0,032 0,72 130C 2315 0,034 0,75 135C 2316 0,036 0,78 140C 2317 0,038 0,81 145C 2318 0,041 0,86 155

C 2319 0,043 0,87 155C 2320 0,045 0,90 160

1Table

3

Move the blade backwards and forwardsbetween roller and outer ring

4Fig

Measuring clearance reduction

Mounting on taperedseatingsA CARB toroidal roller bearing with a tapered bore is always mounted onthe shaft with an interference fit. Todetermine the degree of interferenceeither the reduction in radial internalclearance or the amount by which theinner ring is driven up on its seatingcan be used.

Suitable methods for mounting aCARB bearing with a tapered bore are:

• measuring the clearance reduction,• measuring the lock nut tightening

angle,• measuring the axial drive-up and• measuring the inner ring expansion.

For CARB toroidal roller bearings withbore diameters greater than or equalto 50 mm, SKF recommends the SKFDrive-up method. This method is moreaccurate and takes less time than theprocedure based on clearance reduc-tion.

Measuring clearance reductionPrior to mounting, the internal radialclearance must be measured with afeeler gauge between the outer ringand an unloaded roller. Before meas-uring, the bearing should be rotated afew times to make sure that the rollershave assumed their correct position.For the first measurement a bladeshould be selected that is slightly thin-ner than the minimum value for the

clearance. During the measurement,the blade should be pushed back-wards and forwards (➔ fig ) until itcan be inserted to the middle of theroller. The procedure should be repeat-ed using slightly thicker blades eachtime until a certain resistance is felt.

During mounting, the reduction inclearance should be measured be-tween the outer ring raceway and the lowest roller (➔ fig ). Again thebearing should be rotated a few timesbetween each measurement.

Guideline values for the clearancereduction and axial drive-up are given intable on page 28. They are valid forsolid steel shafts and normal operatingconditions (C/P > 10). Where loads areheavy (C/P < 5), speeds high or there isa considerable temperature gradientacross the bearing, greater clearancereductions or axial drive-up are requiredand thus bearings with greater initialradial internal clearance might be needed.

The minimum values given in tableon page 28 for the clearance reduc-

tion apply mainly to bearings having initial clearances close to the lower limits for clearance given in tableon page 39. This will provide that thefinal clearance will not be less than thepermissible minimum. For bearings withC3 or C4 clearance to have a sufficientdegree of interference on their seating, it is recommended that the maximumclearance reductions be applied.

2

2

2

4

3

Fig

Measuring the lock nut tighteningangleSmaller bearings can easily be mount-ed using the tightening angle α throughwhich the nut has to be turned to driveup the bearing properly on to its taperedseating. Where applicable, the tighten-ing angle α is listed in table . Beforemounting, the thread and side face ofthe nut should be coated with a molyb-denum disulphide paste or similarlubricant and the seating should belightly oiled with thin oil. The bearing isthen pushed on to the tapered seating

1

Angular drive-up for CARB bearings

α

180°


Page ............. 3 Tapered seating Page ............. 37

Bearing bore Reduction of Axial drive-up s1) Permissible residualdiameter radial internal Taper Taper radial clearance2)d clearance 1:12 1:30 after mounting

bearings with initial clearance

over incl. min max min max min max Normal C3 C4

mm mm mm mm

24 30 0,012 0,018 0,25 0,34 0,64 0,85 0,025 0,033 0,04730 40 0,015 0,024 0,30 0,42 0,74 1,06 0,031 0,038 0,05640 50 0,020 0,030 0,37 0,51 0,92 1,27 0,033 0,043 0,063

50 65 0,025 0,039 0,44 0,64 1,09 1,59 0,038 0,049 0,07465 80 0,033 0,048 0,54 0,76 1,36 1,91 0,041 0,055 0,08880 100 0,040 0,060 0,65 0,93 1,62 2,33 0,056 0,072 0,112

100 120 0,050 0,072 0,79 1,10 1,98 2,75 0,065 0,083 0,129120 140 0,060 0,084 0,93 1,27 2,33 3,18 0,075 0,106 0,147140 160 0,070 0,096 1,07 1,44 2,68 3,60 0,085 0,126 0,173

160 180 0,080 0,108 1,21 1,61 3,04 4,02 0,093 0,140 0,193180 200 0,090 0,120 1,36 1,78 3,39 4,45 0,103 0,150 0,209200 225 0,100 0,135 1,50 1,99 3,74 4,98 0,113 0,163 0,228

225 250 0,113 0,150 1,67 2,20 4,18 5,51 0,123 0,175 0,251250 280 0,125 0,168 1,85 2,46 4,62 6,14 0,133 0,186 0,276280 315 0,140 0,189 2,06 2,75 5,15 6,88 0,143 0,198 0,292

315 355 0,158 0,213 2,31 3,09 5,77 7,73 0,161 0,226 0,329355 400 0,178 0,240 2,59 3,47 6,48 8,68 0,173 0,251 0,358400 450 0,200 0,270 2,91 3,90 7,27 9,74 0,183 0,275 0,383

450 500 0,225 0,300 3,26 4,32 8,15 10,80 0,210 0,295 0,433500 560 0,250 0,336 3,61 4,83 9,04 12,07 0,225 0,327 0,467560 630 0,280 0,378 4,04 5,42 10,09 13,55 0,250 0,364 0,508

630 710 0,315 0,426 4,53 6,10 11,33 15,25 0,275 0,386 0,560710 800 0,355 0,480 5,10 6,86 12,74 17,15 0,319 0,430 0,620800 900 0,400 0,540 5,73 7,71 14,33 19,27 0,335 0,465 0,675

900 1 000 0,450 0,600 6,44 8,56 16,09 21,39 0,364 0,490 0,7401 000 1 120 0,500 0,672 7,14 9,57 17,86 23,93 0,395 0,543 0,8231 120 1 250 0,560 0,750 7,99 10,67 19,98 26,68 0,414 0,595 0,885

1) Only valid for solid steel shafts2) The residual clearance must be measured when the initial radial internal clearance (before mounting) lies in the lower

half of the clearance range and if large temperature differences between inner and outer rings are to be expected inoperation; the residual clearance should not be less than the minimum values quoted here. When measuring clearancecare must be taken to see that both bearing rings and the roller complement are centrically arranged with respect toeach other

2Table

28

and the nut screwed on. By turning thenut through the recommended angle αthe bearing will be pressed up on thetapered seating. As the bearing has atendency to skew when being pressedinto place it is advisable to repositionthe hook spanner in a slot at 180° tothat used for tightening and then apply-ing a light hammer blow to the hookspanner. The bearing will straightenup on its seating. Finally the residualclearance of the bearing should bechecked.

In all cases, before mounting, therust inhibiting oil should be wiped fromthe bore and outside diameter of newbearings and sleeves. The shaft seat-ing and outside diameter of the sleeveshould then be lightly oiled with thin oil.

The SKF Drive-up MethodThe SKF Drive-up Method is based onmeasuring axial displacement of thebearing inner ring on its tapered seat-ing from a reliably determined startingposition.

The SKF Drive-up Method (➔ fig )requires the use of an HMV..E hydraulicnut, that can accommodate a dialgauge.A pressure gauge, appropriate to themounting conditions, mounted on asuitably sized hand pump, allowsaccurate pressure measurement todetermine the starting position. Thetools required are shown in fig .

Guideline values for

• the requisite oil pressure and • the axial displacement

for the individual bearings are providedin table on page 30.3

6

5

s

Guideline values for clearance reductionand axial drive-up



One sliding interfaceCase 1

One sliding interfaceCase 2

Two sliding interfacesCase 3

Two sliding interfacesCase 4

29

2

5Fig

6Fig

Suitable tools for the SKFDrive-up Method

1. Check whether the bearing size and the HMV .. E hydraulic nut coincide. Otherwisethe values for the pressure given in table 2 must be adjusted (➔ note on page 32).

2. Check the number of sliding interfaces (➔ above).

3. Lightly coat the sliding surfaces with a thin oil, e.g. SKF LHMF 300, and place thebearing on the tapered journal or sleeve. Screw the hydraulic nut on to the thread ofthe journal or sleeve so that it abuts the bearing and connect the appropriate oilpump (➔ fig ).

4. Bring the bearing to its starting position. Pump oil into the hydraulic nut until thepressure quoted in table on page 30 is reached.

5. Set the dial gauge to “zero” (➔ fig ) and pump more oil into the hydraulic nut untilthe bearing has been driven up the distance prescribed in table on page 30 and isin its final position.

6. After mounting has been completed, release the return valve of the oil pump, so that oil under high pressure in the nut can flow back out of the nut.

7. To completely empty the oil, bring the piston of the hydraulic nut to its original position. This is most simply done by screwing the nut further up the threaded portion of the journal or sleeve.

8. Remove the nut from the shaft by unscrewing and replace with a lock nut and a locking device.

36

3

6

Dial gauge

SKF hydraulic nut HMV .. E

SKF pump 729124 SRB (for nuts up to and including HMV 54 E)SKF pump TML 50 SRB (for nuts up to and including HMV 170 E)

The SKF Drive-up Method

s

s

s

Zeroposition

Startingposition

Finalposition



30

Basic bearing Starting position Final position Hydraulic nut designation Requisite oil pressure for Axial displacement from Radial clearance Desig- Piston

one sliding two sliding starting position reduction from nation areainterface* interfaces* one sliding two sliding zero position

interface* interfacesss ss ∆r

– MPa mm mm – mm2

Series C 22C 2210 K 0,67 1,15 0,34 0,41 0,023 HMV 10 E 2 900C 2211 K 0,57 0,98 0,35 0,42 0,025 HMV 11 E 3 150C 2212 K 1,09 1,86 0,39 0,47 0,027 HMV 12 E 3 300

C 2213 K 0,82 1,40 0,40 0,47 0,029 HMV 13 E 3 600C 2214 K 0,76 1,29 0,43 0,50 0,032 HMV 14 E 3 800C 2215 K 0,70 1,20 0,45 0,52 0,034 HMV 15 E 4 000





C 2244 K 1,95 3,34 1,15 1,22 0,100 HMV 44 E 14 400



C 2320 K 2,56 4,36 0,59 0,66 0,045 HMV 20 E 5 100C 2326 K 2,71 4,62 0,73 0,81 0,059 HMV 26 E 6 400







* The quoted values are for hydraulic nuts, the thread diameter of which corresponds to the bore diameter of the bearing to be mounted and for applications with lightly oiled slidingsurfaces

3Table



31

2







C 30/500 K 1,56 2,66 2,47 2,54 0,225 HMV 100 E 51 500C 30/530 K 1,54 2,63 2,60 2,68 0,239 HMV 106 E 56 200C 30/560 K 2,26 3,85 2,84 2,91 0,252 HMV 112 E 61 200




C 30/1000 K 1,93 3,30 4,85 4,92 0,450 HMV 200 E 145 800








Series C 31C 31/500 K 3,54 6,04 2,57 2,64 0,225 HMV 100 E 51 500C 31/530 K 3,40 5,81 2,71 2,79 0,239 HMV 106 E 56 200C 31/560 K 3,11 5,30 2,83 2,90 0,252 HMV 112 E 61 200



3Continuation table



32





Series C 31


C 31/850 K 4,02 6,86 4,32 4,39 0,383 HMV 170 E 114 600C 31/1000 K 3,69 6,30 4,97 5,04 0,450 HMV 200 E 145 800

Series C 32C 3224 K 2,46 4,20 0,69 0,76 0,054 HMV 24 E 6 000C 3232 K 2,68 4,58 0,87 0,94 0,072 HMV 32 E 8 600

C 3234 K 3,87 6,60 0,96 1,03 0,076 HMV 34 E 9 400C 3236 K 3,69 6,30 1,01 1,09 0,081 HMV 36 E 10 300

Series C 39C 3972 K 0,63 1,08 1,74 1,81 0,162 HMV 72 E 31 300C 3976 K 1,06 1,81 1,88 1,95 0,171 HMV 76 E 33 500C 3980K 0,74 1,27 1,93 2,00 0,180 HMV 80 E 36 700


C 3996 K 1,18 2,01 2,37 2,44 0,216 HMV 96 E 48 600C 39/500 K 0,95 1,63 2,43 2,50 0,225 HMV 100 E 51 500C 39/530 K 0,73 1,25 2,52 2,59 0,239 HMV 106 E 56 200




C 39/950 K 1,04 1,77 4,50 4,57 0,428 HMV 190 E 135 700


3Continuation table

NoteThe values given in table for therequisite oil pressure and the axialdisplacement ss apply to bearingsmounted on solid steel shafts for thefirst time. For the case 4 shown infig on page 29, “Two slidinginterfaces” (bearing on a withdrawalsleeve), the guideline values given intable do not apply as a smallernut is used than that shown for the

3

5

3 bearing in table . The requisite oilpressure can be calculated from

AreqPreq = · Pref

Aref

where Preq = requisite oil pressure for

hydraulic nut used, MPa

3 Pref = oil pressure specified for thestandard hydraulic nut (➔ table ), MPa

Areq = piston area of hydraulic nutused (➔ table ), mm2

Aref = piston area of the specifiedstandard hydraulic nut (➔ table ), mm23

3

3



33

2

Measuring inner ring expansionMeasuring inner ring expansion allowslarge size CARB bearings with atapered bore to be mounted simply,quickly and accurately without meas-uring the radial internal clearancebefore and after mounting. The SKFSensorMount® Method uses a sensor,integrated into the CARB toroidal rollerbearing inner ring, and a dedicatedhand-held indicator (➔ fig ).

The bearing is driven up the taperedseating using common SKF mountingtools. Information from the sensor isprocessed by the indicator. Inner ringexpansion is displayed as the relation-ship between the clearance reduction(mm) and the bearing bore diameter (m).

Aspects like bearing size, smooth-ness, shaft material or design – solid orhollow do not need to be considered.

For detailed information about SKFSensorMount please contact SKF.

7

Additional mounting informationAdditional information on mountingCARB toroidal roller bearings can befound

• in the handbook “SKF Drive-upMethod” on CD-ROM,

• in the “SKF Interactive EngineeringCatalogue” on CD-ROM or online atwww.skf.com, or

• online at www.skf.com/mount.

ON0FF

CLR MAX

0,450

TMEM 1500SensoMount Indicator

7Fig


Page ............. 3 SKF Drive-up Method Page ............. 37

34

If CARB toroidal roller bearings are tobe re-used after dismounting, theforce used for dismounting shouldnever pass through the rollers. Thering with the looser fit should be with-drawn from its seating first. There arethree methods available to dismountthe bearing ring that has been mountedwith an interference fit: mechanical,hydraulic or the oil injection method.

Detailed information on the dis-mounting of bearings is contained inpublication 4100 “SKF Bearing Main-tenance Handbook”.

Dismounting from a cylindrical seatingCARB toroidal roller bearings having a bore diameter up to approximately120 mm that have been mounted withan interference fit on the shaft can beremoved using a conventional puller.The puller should be applied to theface of the ring to be dismounted (➔fig ). By turning the puller spindlethe bearing is easily removed from thecylindrical seating.

For larger bearings, the withdrawalforces are considerable. In these cases,the use of pullers with hydraulic assist-ance (➔ fig ) or the SKF oil injectionmethod should be used.

CARB toroidal roller bearings thathave an interference fit for both ringsshould be pressed out of the housingtogether with the shaft. On the otherhand it is also possible to withdraw thebearing with the housing from the shaft,particularly if the oil injection method isapplied (➔ fig ).

Small CARB toroidal roller bearingsmounted with an interference fit in ahousing bore without shoulders canbe removed using a dolly applied tothe outer ring. Larger bearings requiremore force to remove them and apress is required.

3

2

1

1Fig

3Fig

2Fig

Dismounting

The puller isapplied to the sideface of the innerring

SKF puller with hydraulicassistance

CARB toroidalroller bearing on acylindrical seatingbeing removedusing the oil injection method


Page ............. 3 Cylindrical seating Page ............. 37

35

2

Various larger CARB toroidal rollerbearings that have a loose or a transi-tion fit in the housing can be removedusing a tool with hooks that passbetween the rollers and grip the outerring from behind (➔ fig ), so that thewithdrawal forces are applied directlyto the outer ring and the rollers do notbecome jammed between the rings.

Dismounting from a tapered seatingAs bearings with a tapered bore comefree from their seating very suddenly itis necessary to provide a stop of somesort to limit their axial movement. Anend plate screwed to a shaft end or alock nut (➔ fig ) serve this purpose.The lock nut should be unscrewed afew turns.

Small CARB toroidal roller bearingscan be removed with the aid of a dollyor a drift of special design (➔ fig ).A few blows directed at the dolly aresufficient to drive the inner ring fromits tapered seating.

Medium-sized CARB toroidal rollerbearings can be withdrawn using amechanical puller or a puller with ahydraulic assistance. To avoid damag-ing the bearing, the puller should beapplied centrically.

The removal of large bearings isgreatly facilitated if the oil injectionmethod is employed.

.

6

5

4

4Fig

Schematic sketch of tool for removal of CARB bearings from a non-split housing

5Fig

The lock nut is left on the shaft thread to provide a stop

6Fig

Removal of a small CARB toroidal roller bearing using a drift of special design



36

SKF concept for cost saving

A daily occurrenceWhatever the branch of industry – un-planned stoppages are still not a thingof the past. They are not only annoying,but costly too. And with the heighteneddemands for prompt and just-in-timedeliveries they may be even moreexpensive.

The SKF answerThe bearings in a machine can belikened to the heart of a living being.When the bearing comes to a stand-still, the machine does too.

And just as a doctor will listen to theheart of a patient, so it is possible tolisten to the bearings in order to judgethe condition of the machine. It is pos-sible to determine whether the bearingis in danger of failing prematurelybecause of faulty mounting, poorlubrication or other causes.

If the importance of the bearings isneglected this will inevitably lead tohigh costs, unnecessary stoppagesand, in the worst case, damage toother components of the machine.

Instead, SKF recommends to makeuse of one of its services: an IMS(Integrated Maintenance Solutions)contract, which consists of linkingcustomers with SKF resources.

This involves a multi-stage pro-gramme that includes the followingpoints:

• common problem definition and target setting,

• optimization of spares stocked,• reduction of purchasing costs,• choosing the right bearings,• caring for the bearings,• monitoring the machine condition,• having the correct tools and

lubricants on hand,• customer-specific training, and• a repair service.

Obviously it is possible to accept thewhole programme or to select onlyparts of it. Whatever the choice, it willbe a win-win situation. More informa-tion can be obtained from the nearestSKF office or authorised distributor.

Monitoring temperature Monitoring noiseSKF experts bring their experience to lubricant analysis


Page ............. 3 Integrated maintenance Page ............. 37

37

3DesignsCARB toroidal roller bearings are available

• with a caged roller assembly (➔ fig ) and

• in a full complement version (➔ fig ).

They are both produced with a cylin-drical bore, but the caged bearings arealso produced with a tapered bore.Depending on the bearing series, thetaper is either 1:12 or 1:30.

2

1

Sealed bearingsToday, the range of sealed bearings(➔ fig ) consists of small and mediumsize full complement bearings for lowspeeds. These bearings with seals onboth sides are filled with a high tempera-ture long life grease and are mainten-ance-free.

The double lip seal suitable for hightemperature operations is sheet steelreinforced and made of hydrogenatedacrylonitrile butadiene rubber (HNBR).It seals against the inner ring raceway.The outside diameter of the seal isretained in an outer ring recess andprovides proper sealing also in appli-cations with outer ring rotation.The sealscan withstand operating temperaturesin the range of –40 and +150 °C.

The sealed bearings are filled with a premium quality, synthetic ester oilbased grease using polyurea as athickener. This grease has good corro-sion inhibiting properties and can beused at temperatures between –25and +180 °C. The base oil viscosity is 440 mm2/s at 40 °C and 38 mm2/s at100 °C. The grease fill is 70 to 100 %of the free space in the bearing.

Sealed bearings with other lubricat-ing greases or degrees of greasefillcan be supplied on request.

DimensionsThe boundary dimensions of CARBtoroidal roller bearings are in accord-ance with ISO 15:1998. The dimen-sions of the adapter and withdrawalsleeves correspond to ISO 2982-1:1995.

TolerancesSKF CARB bearings are manufacturedas standard to Normal tolerances.Bearings up to and including 300 mmbore diameter are produced to higherprecision than the ISO Normal toler-ances. For example

3

• the width tolerance is considerably tighter than the ISO Normal toler-ance,

• the running accuracy is to toleranceclass P5 as standard.

For larger bearing arrangementswhere running accuracy is a key oper-ational parameter, SKF CARB bearingswith P5 running accuracy are also avail-able. These bearings are identified bythe suffix C08. Their availability shouldbe checked.

The values of the tolerances are inaccordance with ISO 492:2002.

Internal clearanceCARB toroidal roller bearings are produced as standard with Normalradial internal clearance. Many of thebearings are also available with C3clearance and some with the smallerC2 or the much larger C4 clearance.

The radial internal clearance limitsfor

• bearings with cylindrical bore aregiven in table on page 38 and for

• bearings with tapered bore in table on page 39.

They are valid for bearings beforemounting and under zero measuringload.

Axial displacement of one ring inrelation to the other will graduallyreduce the radial internal clearance ina CARB toroidal roller bearing. How-ever, for the amount of axial displace-ment found in standard applications,this is not an issue.

CARB toroidal roller bearings areoften used together with sphericalroller bearings. In these cases theoperational internal clearance of boththe bearings should be the same.

2

1

Bearing data – general

1Fig

2Fig

3Fig

Caged CARBtoroidal rollerbearing

Full complementCARB toroidalroller bearing

Sealed CARBtoroidal rollerbearing


Page ............. 3 Page ............. 12 Bearing data

38

Bore Radial internal clearance diameter C2 Normal C3 C4 C5dover incl. min max min max min max min max min max

mm µm

18 24 15 27 27 39 39 51 51 65 65 8124 30 18 32 32 46 46 60 60 76 76 9430 40 21 39 39 55 55 73 73 93 93 117

40 50 25 45 45 65 65 85 85 109 109 13750 65 33 54 54 79 79 104 104 139 139 17465 80 40 66 66 96 96 124 124 164 164 208

80 100 52 82 82 120 120 158 158 206 206 258100 120 64 100 100 144 144 186 186 244 244 306120 140 76 119 119 166 166 215 215 280 280 349

140 160 87 138 138 195 195 252 252 321 321 398160 180 97 152 152 217 217 280 280 361 361 448180 200

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