113 N 310 EC M / C3 V W23B 1 2 3 4 5 Cylindrical roller bearings 6 C1 Clearance < C2 C2 Clearance < Normal (C0)* Normal internal clearance C3 Clearance > Normal C4 Clearance > C3 * Not marked on bearing or package N Two integral flanges on inner ring, flangeless outer ring NU Two integral flanges on outer ring, flangeless inner ring NJ One flange on inner ring, two flanges on outer ring NUP Two integral flanges on outer ring, one integral flange on inner ring and one loose flange on inner ring NCF Full complement, two flanges on inner ring, one flange on outer ring, with snap ring NJG Full complement with one flange on inner ring, and two flanges on outer ring NNCF Two-row, full complement, three flanges on inner ring, one flange on outer ring, with snap ring NNF Two-row, full complement NNCL Double row CRB with no outer ring integral flanges, only one centrally located snap ring NNC Double row CRB with one outer ring integral flange and one flange ring EC Increased capacity plus improved roller end to flange contact M Two piece machined brass cage, rolling element guided MA Two piece machined brass cage, outer ring flange guided MB Machined brass cage, inner ring flange guided ML/MP One piece window-type brass cage, inner or outer ring centered M2 Solid brass drilled cage, roller guided for traction motor bearings J Pressed steel cage, rolling element guided P Molded glass fiber reinforced polyamide 6.6 cage, roller centered PHA Injection molded cage of polyetheretherketone (PEEK), outer ring centered 1. Basic design: 2. Internal design: 4. Radial internal clearance: 3. Cage designs: V Full complement bearing without cage BV V + surface treated rollers 2LS Two land riding contact seals 5. Variations: W23B Special features for traction motor bearings VA301 Special bearing specifications for traction motors VL0241 INSOCOAT ® coating on inner ring for electrical insulation 6. Special features: Nomenclature
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113
N 310 EC M / C3 V W23B
12
34
5
Cylindrical rollerbearings
6
C1 Clearance < C2
C2 Clearance < Normal
(C0)* Normal internal clearance
C3 Clearance > Normal
C4 Clearance > C3
* Not marked on bearing or package
N Two integral flanges on inner ring, flangeless outer ring
NU Two integral flanges on outer ring, flangeless inner ring
NJ One flange on inner ring,two flanges on outer ring
NUP Two integral flanges on outer ring, one integralflange on inner ring andone loose flange on inner ring
NCF Full complement, two flanges on inner ring, one flange on outer ring, with snap ring
NJG Full complement with oneflange on inner ring, and twoflanges on outer ring
NNCF Two-row, full complement,three flanges on inner ring,one flange on outer ring, with snap ring
NNF Two-row, full complement
NNCL Double row CRB with no outerring integral flanges, only onecentrally located snap ring
NNC Double row CRB with one outerring integral flange and oneflange ring
EC Increased capacity plus improved roller end to flangecontact
M Two piece machined brass cage, rolling element guided
MA Two piece machined brass cage, outer ring flange guided
MB Machined brass cage, inner ring flange guided
ML/MP One piece window-type brass cage, inner or outerring centered
M2 Solid brass drilled cage,roller guided for traction motor bearings
J Pressed steel cage,rolling element guided
P Molded glass fiber reinforcedpolyamide 6.6 cage, roller centered
PHA Injection molded cage ofpolyetheretherketone (PEEK), outer ring centered
Axial load – max Contact SKF Applications Engineering
Seals 2LS seals on NNF series only
Technical features
Figure 1
115
IntroductionSKF manufactures many types and sizes ofcylindrical roller bearings, the majority beingsingle row bearings with a cage, but also single or double row bearings with a full complement of rollers.
All SKF cylindrical roller bearings representthe latest state of the art. The contact geome-try between roller and raceway has beenmuch improved by the introduction of the“logarithmic” profile that provides for optimumstress distribution in the bearing. Optimizedsurface finishes favor lubricant film formationand the correct rolling motion of the cylindricalrollers. These improvements have considerablyincreased the performance of SKF cylindricalroller bearings as well as their operational reliability in comparison with conventionalbearings, and have made them less sensitiveto misalignment.
Full complement cylindrical roller bearingsincorporate the maximum number of rollersand, as a rule, have a low sectional height inrelation to their width. This produces anextremely high load carrying capacity and permits space-saving designs to be achieved.Full complement cylindrical roller bearings aresuitable for very heavy radial loads; however,the different kinematic conditions in the bear-ing mean that they cannot operate at thesame high speeds as cylindrical roller bearingsof the conventional caged type.
SKF produces single and double row fullcomplement cylindrical roller bearings as partof the standard product range. The bearingsshown in the tables are standard range bear-ings but represent only part of the actualmanufactured range.
Basic design Single row cylindrical roller bearingsThe rollers of single row cylindrical roller bear-ings with cages are guided between integralflanges on one of the bearing rings. The ring
Introduction
a b c d
with integral flanges and the roller and cageassembly can be withdrawn from the otherring. This facilitates mounting and dismountingparticularly where both rings need to haveinterference fits because of the load conditions.
SKF single row cylindrical roller bearings havehigh radial load carrying capacity and also highspeed capability. They are produced in differentdesigns that differ in the configuration of theflanges (Figure 1).
The most popular of these bearings is the NU type which has two integral flanges on theouter ring and an inner ring without flanges(Figure 1a). The N type has two integralflanges on the inner ring and an outer ringwithout flanges (Figure 1b).
Axial displacement of the shaft with respectto the housing is permitted in both directionswithin certain limits (Table 3a, page 119 fordimension code “s”). For example, changes inlength because of thermal expansion can beaccommodated, and the bearings are thereforesuitable as non-locating bearings.
Cylindrical roller bearings of the NJ type havetwo integral flanges on the outer ring and oneintegral flange on the inner ring, so that axiallocation can be provided for the shaft in onedirection (Figure 1c).
Type NUP cylindrical roller bearings have twointegral flanges on the outer ring and the innerring has one integral and one loose flange,enabling the bearings to locate a shaft axially inboth directions (Figure 1d).
SKF Explorer class bearings SKF Explorer cylindrical roller bearings retainthe designation of earlier standard bearings,e.g. NU 216 ECP. However, each bearing and itsbox are marked with the name “SKF Explorer”, to avoid confusion. In the product tables, theSKF Explorer bearing designations are printedin blue. Additional details on the SKF Explorerperformance class bearings can be found onpage 23.
High speed performanceExtended benefits of the logarithmicprofile roller are the cooler runningconditions and reliable performancewhich allow for high speed runningconditions.
Precision-honed rollingcontact surfacesSKF cylindrical roller bearings also feature precision-honed inner andouter rings, raceways and rollers. TheSKF honing process results in optimumbearing performance and improvedlubricant effectiveness… and quieter,cooler, more reliable performance.
Large product assortmentSKF manufactures cylindrical rollerbearings in single, double and multiplerow designs which differ in thearrangement, design and constructionof the flanges. While caged bearingsare most common, several series witha full compliment of rollers are alsoavailable. Size range includes 25 to1,000 mm inside diameter.
Application flexibilityThe large variety of sizes and types of cylindrical roller bearings availablefrom SKF provides a wide degree ofapplication flexibility. Typical applicationsinclude compressors, industrial gear-boxes, transmissions, and final drives inboth on-road and off-road vehicles.
Customized solutionsSpecial cages are available from SKFfor special application conditions suchas ammonia compressors and railroadapplications.
Product highlights
Figure 2
116
Cylindrical roller bearings
Introduction
EC–design bearingsThe EC design contains improvements in theguiding surfaces of the flanges and of the rollerends which means that the EC bearings have ahigh axial load carrying capacity. The favorablecontact conditions also contribute to betterlubrication of the roller end/flange contact zoneand to lower operating temperatures. Thesecharacteristics make SKF cylindrical rollerbearings of the EC design particularly useful.They represent the standard design for themost popular sizes of bearing series 10, 2, 22,3 and 23.
Single row full complement cylindricalroller bearingsSKF full complement cylindrical roller bearingsare produced as standard in the single row NCF and NJG designs. (Figure 2).
Bearings of the NCF design are the mostpopular and have two integral flanges on theinner ring and one integral flange in the outerring and can thus locate the shaft in one direction (Figure 2a). A retaining ring at theflangeless side of the outer ring holds thebearing together. The axial internal clearance inthe bearing is designed to permit small axialdisplacements of the shaft in relation to thehousing to be accommodated within the bearing (Table 3b, page 120).
Bearings of the NJG design all belong to theheavy dimension series 23 and are intendedfor very heavily loaded, slow-speed applications(Figure 2b). In contrast to the other full complement bearings, the NJG bearings have a self-retaining roller complement. The outerring with its two integral flanges, together withthe roller complement, can be withdrawn fromthe inner ring and there is no need to provideany extra retention for the rollers. Mountingand dismounting of these bearings are there-fore simple operations. NJG design bearingscan support axial loads acting in one direction and can consequently locate the shaft in onedirection.
Double row full complement cylindricalroller bearingsThere are several designs of SKF double rowfull complement cylindrical roller bearings, all ofwhich have an annular groove and lubricationholes in the outer ring. This feature facilitatesthe provision of efficient lubrication.
Double row full complement cylindrical rollerbearings of the NNC, NNCL, and NNCF designsdiffer only in the number of flanges on theouter ring. The inner ring with its three integralflanges between which the two rows of rollersare accurately guided is common to all threedesigns. Outer ring flanges or retaining ringsinserted in the outer ring bore prevent thebearing from falling apart.
Bearings of the NNCL design (Figure 2c)have no integral flanges on the outer ring. Axialdisplacements of the shaft relative to the hous-ing are thus permitted, within certain limits.
Bearings of the NNCF and NNC designs (Figure 2d and 2e) have one integral flangeand a retaining ring in the outer ring. They canaccommodate axial loads in one direction andcan locate the shaft in one direction. Axial dis-placements of the shaft relative to the housingare permitted.
The rollers of bearings of the NNF design(series NNF 50) are guided between the integral flanges of the two-part inner ring,which is held together by a retaining ring. Theouter ring has a central integral flange. Thebearings can be used as locating bearings asthey can accommodate axial loads acting inboth directions. Because of the large distancebetween the roller rows, they are also suitablefor the accommodation of tilting moments.
The outer ring of the bearing is 1 mm narrower than the inner ring and has two snapring grooves in the outside diameter. It is thuspossible to dispense with spacer rings betweenthe inner ring and adjacent components with-out affecting outer ring rotation; for example in pulleys, or the housing (or hub) can be made narrower than the bearing and axialspace saved.
Bearings of the NNF design (Figure 2f) are pro-duced as standard with rubbing seals at bothsides. They are supplied filled with rust inhibitinglithium grease having a diester oil base, which issuitable for operation at temperatures between -58° and +230° F (-50° and +110° C). However, the permissible operating temperature for thesebearings is limited to -40° to +176° F (-40° to+80° C) by the material used for the seals.
Under certain conditions, the sealed NNFbearings are maintenance-free. However,where they operate in the presence of mois-ture or contaminants, or where speeds aremoderate or high, they must be relubricated.This can be achieved via both bearing rings. Ifbearings are required without one or both seals,they may be removed quite simply, for example,using a screwdriver.
For applications where oil lubrication is to beemployed, the bearings can be delivered withoutseals and grease if economic quantities areinvolved. Otherwise the seals should be removedand the bearings washed before use. If oil lubri-cation is adopted, the speed ratings can beincreased by approximately 30%.
a b c d e f
117
Introduction
Internal clearance Radial internal clearanceSKF single row cylindrical roller bearings areproduced with Normal radial internal clearanceas standard; the majority of the bearings arealso available with C3 radial internal clearanceand some with the appreciably greaterC4 clearance.
The values for the clearance correspond toDIN 620, Part 4 for the size range covered bythis standard and are given in Table 1. The values apply to bearings before mounting andunder zero measuring load.
SKF full complement cylindrical roller bearingsare manufactured with Normal or C3 radialinternal clearance as standard. The values forthe clearance limits correspond to ISO and areshown in Table 1.
Axial internal clearanceCylindrical roller bearings of the NUP type can serve to locate shafts in both directions, and are manufactured by SKF with axial internalclearance according to Table 2.
The values given in Table 2 for axial internalclearance should be considered as guideline values. Because of roller tilting during measure-ment of the axial internal clearance, increases inthe clearance are possible. These correspond:
• For bearings of series 10, 2, 3 and 4 to approximately the radial internalclearance, and
• For bearings of series 22 and 23 to approximately 2/3 of the radial internal clearance
Special solutions using cylindrical roller bearingsSKF also manufactures:
• Precision single and double row cylindrical roller bearings for machine toolapplications
• Double and multi-row cylindrical rollerbearings for rolling mill and other heavy engineering applications
• Special traction roller bearings for railroad applications
Details on these special solution products areavailable in other SKF publications, which can besupplied upon request
Table 1
Radial internal clearance of cylindrical roller bearings
Bore Radial internal clearancediameterd C2 Normal C3 C4over incl. min max min max min max min max min max min max min max min maxmm µm in µm in µm in µm in
Loads Equivalent dynamic bearing load forsingle row cylindrical roller bearingsWhen cylindrical roller bearings are used asnon-locating bearings and are only subjected toradial loads, the equivalent dynamic bearingload is
P = FrIf cylindrical roller bearings with flanges on
inner and outer rings are used to axially locatethe shaft in one or both directions, as is frequently the case, the equivalent dynamic bearing load should be calculated using
P = Fr when Fa / Fr ≤ eP = 0.92 Fr + YFa when Fa / Fr > e
wheree = calculation factor
= 0.2 for bearings of series 10, 2, 3 and 4= 0.3 for bearings of series 22 and 23
Y = axial load factor= 0.6 for bearings of series 10, 2, 3 and 4= 0.4 for bearings of series 22 and 23
Since axially loaded cylindrical roller bearingswill only operate satisfactorily when they aresubjected to a simultaneously acting radial load,the ratio Fa / Fr should not exceed 0.5 for ECdesign bearings and 0.4 for the other bearings.
Equivalent dynamic bearing load for full complement cylindrical roller bearingsWhen cylindrical roller bearings are used asnon-locating bearings and are only subjected to radial loads, the equivalent dynamic bearing load
P = FrIf cylindrical roller bearings with flanges
on inner and outer rings are used to axiallylocate the shaft in one or both directions, as isfrequently the case, the equivalent dynamicbearing load should be calculated using
Table 2
Axial internal clearance of single row cylindrical roller bearings
P = Fr when Fa / Fr ≤ eP = 0.92 Fr + YFa when Fa / Fr > e
wheree = calculation factor
= 0.15 for double row bearings= 0.2 for bearings of series 18= 0.3 for all other single row bearings
Y = axial load factor= 0.6 for bearings of series 18= 0.53 for double row bearings= 0.4 for all other single row bearings
Since axially loaded full complementcylindrical roller bearings will only operate satisfactorily when they are subjected to asimultaneously acting radial load, the ratio Fa / Fr should not exceed 0.5 for single rowbearings or 0.25 for double row bearings.
Table 3a
Axial displacement(s) of NU, NJ and N bearing ring relative to opposite ring
Minimum load In order to provide the satisfactory operationof all ball and roller bearings they mustalways be subjected to a given minimumload. This is also true of cylindrical roller bear-ings, particularly if they run at high speedswhere the inertia forces of the rollers and cage,and the friction in the lubricant can have adetrimental influence on the rolling conditionsin the bearing and may cause damaging slidingmovements to occur between the rollers andthe raceways.
However, the weight of the components supported by the bearing, together with theexternal forces, often exceeds the requisiteminimum load. If this is not the case, an additional radial load must be applied to thebearing, for example, by increasing belt tensionor similar means.
The requisite minimum radial load to beapplied in such cases can be determined byusing the Interactive Engineering Catalog onthe SKF website www.skf.com or by contactingSKF Applications Engineering.
Table 3b
Axial displacement(s) of full complement NCF and NJG bearing ring relative to opposite ring
Designation Axial displacementsmm in
1830 V 1.5 0.0591832 V 1.5 0.0591834 V 1.5 0.0591836 V 1.5 0.0591838 V 1.8 0.0711840 V 1.8 0.0711844 V 1.8 0.0711848 V 1.8 0.0711852 V 1.8 0.0711856 V 2.5 0.0981860 V 3 0.1181864 V 3 0.1181868 V 3 0.1181872 V 3 0.1181876 V 3.5 0.1381880 V 3.5 0.1381884 V 3.5 0.1381888 V 3.5 0.1381892 V 5 0.1971896 V 5 0.19718/500 V 5 0.19718/530 V 5 0.19718/560 V 5 0.19718/600 V 7 0.27618/630 V 8 0.31518/670 V 8 0.31518/710 V 8 0.31518/750 V 8 0.315
2207 V 1 0.0392209 V 1 0.0392210 V 1 0.0392218 V 2.5 0.0982220 V 2.5 0.0982224 V 4 0.157
2912 V 0.5 0.0202914 V 0.75 0.0302916 V 0.75 0.0302918 V 0.75 0.0302920 V 0.75 0.0302922 V 0.75 0.0302924 V 0.75 0.0302926 V 0.75 0.0302928 V 0.75 0.0302930 V 0.8 0.0312932 V 0.8 0.0312934 V 0.8 0.0312936 V 1 0.0392938 V 1 0.0392940 V 3 0.118
Designation Axial displacementsmm in
2944 V 2.5 0.0982948 V 2.5 0.0982952 V 5 0.1972956 V 4 0.1572960 V 5 0.1972964 V 5 0.1972968 V 5 0.1972972 V 5 0.1972976 V 5 0.1972980 V 5 0.1972984 V 5 0.1972988 V 6 0.2362992 V 6 0.2362996 V 7 0.27629/500 V 7 0.27629/530 V 7 0.27629/560 V 7 0.27629/600 V 7 0.276
3004 V 0.5 0.0203005 V 0.5 0.0203006 V 0.8 0.0313007 V 1 0.0393008 V 1 0.0393009 V 1 0.0393010 V 1 0.0393011 V 1.2 0.0473012 V 1.2 0.0473013 V 1.2 0.0473014 V 1.5 0.0593015 V 1.5 0.0593016 V 1.8 0.0713017 V 1.8 0.0713018 V 2 0.079
Designation Axial displacementsmm in
3020 V 2 0.0793022 V 3 0.1183024 V 3.5 0.1383026 V 3.5 0.1383028 V 3.5 0.1383030 V 3.5 0.1383032 V 4 0.1573034 V 7 0.2763036 V 5 0.1973038 V 6 0.2363040 V 6.5 0.2563044 V 7 0.2763048 V 7 0.2763052 V 8 0.3153056 V 9 0.3543060 V 10 0.3943064 V 12 0.4723068 V 12 0.4723072 V 12 0.4723076 V 12 0.4723080 V 14 0.551
121
Frequency vibration data Frequency vibration data is available on theSKF website www.skf.com in the InteractiveEngineering Catalog or by contacting SKFApplications Engineering.
Table 3c
Axial displacement (s) of full complement NNC, NNCF and NNCL bearing ring relative to opposite ring
Designation Axial displacementsmm in
4830 V 1.1 0.0434832 V 1.1 0.0434834 V 1.1 0.0434836 V 1.1 0.0434838 V 1.5 0.0594840 V 1.5 0.0594844 V 1.5 0.0594848 V 2 0.0794852 V 2 0.0794856 V 2 0.0794860 V 2.1 0.0834864 V 2.1 0.0834872 V 2.1 0.0834876 V 2.1 0.083
Designation Axial displacementsmm in
4912 V 1 0.0394914 V 1 0.0394916 V 1 0.0394918 V 1.1 0.0434920 V 1.1 0.0434922 V 1.1 0.0434924 V 1.1 0.0434926 V 1.5 0.0594926 V 1.5 0.0594928 V 1.5 0.0594930 V 2 0.0794932 V 2 0.0794934 V 2 0.0794936 V 2 0.0794938 V 2 0.079
Designation Axial displacementsmm in
4940 V 2.1 0.0834944 V 2.1 0.0834948 V 2.1 0.0834952 V 2.1 0.0834956 V 2.1 0.0834960 V 3 0.1184964 V 3 0.1184968 V 3 0.1184972 V 3 0.1184976 V 4 0.1574980 V 4 0.1574984 V 4 0.1574988 V 4 0.1574992 V 4 0.1574996 V 5 0.19749/500 V 5 0.197
Designation Axial displacementsmm in
5013 V 1.1 0.0435015 V 1.1 0.0435017 V 1.1 0.0435024 V 2 0.0795056 V 4 0.157
Cylindrical roller bearings
122
Designation Principal dimensions Basic load ratings Speed rating Mass Diameter
Bore Outside diameter Width Dynamic Static Reference Limiting Under rollerd D B C C0 speed speed F
mm in mm in mm in N lbf N lbf r/min r/min kg lb mm in
Single rowStandardSeries: 1005 — 1052Size: 25 mm — 260 mm0.9843 in — 10.2362 in