Skf Bearing Selection

8/13/2019 Skf Bearing Selection

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Copyright SKF 2003

The contents of this publication are thecopyright of the publisher and may not bereproduced (even extracts) unlesspermission is granted. Every care hasbeen taken to ensure the accuracy of theinformation contained in this publicationbut no liability can be accepted for anyloss or damage, whether direct, indirector consequential arising out of the use

of the information contained herein.www.skf.com

Publication 5002 E2003 - 02

Principles of bearing selection and application 8

Angular contact ball bearings 112

Cylindrical roller bearings 180

Double direction angular contact thrust ball bearings 214

Single direction angular contact thrust ball bearings 234

Locking devices 260

Gauges 286

Other products and services 298

Products index 301


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11Principles of bearing

selection and applicationSelection of bearing types 8

A wide range of high-precision bearings 8Bearings materials 9Accuracy 10Rigidity 12Speed 12Available space 13

Loads 14Load carrying capacity and life 17

General 17Rating lives 17Rating life equation for hybrid bearings 18Load carrying capacity of bearing sets 19Equivalent bearing loads 19

Rigidity 21System rigidity 21Influence of a loose fit 22

Speed 23Rotational speed 23Speed ratings 25Speed capability of bearing systems 26

Bearing data general 27Dimension 27Tolerances 28Bearing internal clearance or preload 30Material for high-precision bearings 31

Application of bearings 34

Bearing arrangements 34Radial location of bearings 35Application examples 36Axial location of bearings 51Bearing preload 52Seals 57

Lubrication and maintenance 62General 62Grease lubrication 62Oil lubrication 71

Maintenance 78Dismounting and mounting 79

Dismounting 79Mounting 89Inspection 105

Contents


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26

1 Principles of bearing selection and application

Speed capabilityof bearing systems

When designing a spindle, a bearing

system will be used.The system may becomposed of various bearing arrangements,normally a set of bearings at the work side,and another set at the drive side (rear end).The spindle speed must be evaluated on

the most critical bearing set, normally theone at the tool side, which is bigger in borediameter, forcing it towards high values ofthe speed factor ndm. Table page 25provides a comparison of possible choices

in this respect.A comparison of temperature rise versusspeed for grease-lubricated spindlesbased on actual field results is shownin Diagram .3

1

27

1

Temperature rise from existing applicationsGrease lubrication

Dimension

High-precision bearings, similarly to rollingbearings in general, are manufactured withvery few exceptions, according toDimension Plans for the boundarydimensions issued by the InternationalOrganisation for Standardisation (ISO).

More precisely, boundary dimensionsfollow the ISO Dimension Plan for radialbearings ISO15: 1998, where a progressiveseries of standardised outside diameters(Diameter Series 7, 8, 9, 0, 1, 2 etc., inorder of increasing outside diameter), areset for every standard bore diameter.Withineach Diameter Series different Width Seriesare also established (Width Series 8, 0, 1,2, 3 etc., in order of increasing width).

The Width Series for radial bearingscorrespond to the Height Series for thrustbearings (Height Series 7, 9, 1 and 2 inorder of increasing height). By combininga Diameter Series with a Width or HeightSeries, Dimension Series, designated bytwo figures, are arrived at.The first figureidentifies the Width Series and the secondthe Diameter Series.

The bearings in this catalogue complywith the ISO Dimension Plans, with theexception of double direction angularcontact thrust ball bearings and singledirection angular contact thrust ballbearings belonging to metric series, whoseboundary dimensions are not standardised,but recognised by the market and used bythe manufacturers as such.

Bearing data general

Temperature rise above ambient, C

35

30

25

20

15

10

5

0

0,25

Speed factor, n dm(106)

0,3 0,41 0,49 0,57 0,66 0,74 0,82 0,99 1,15 1,2 1,35 1,45 1,57 1,62

70 CD/DBA

719 CD/QBCA

70 CD/TBTA

NN 30

70 CE/HCDBA

BTM 100 A/DB

70 CE/HC Spring

2344..

3Diagram


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37

Application examples

Spindle arrangements for heavy machining,CNC lathes and conventional millingmachines ( figs , and ).321

1

36


Bearing arrangement work side: 70 ACD/P4ATBT; drive side NN 30 K

2Fig

Bearing arrangement work side: N 10 KTN + BTM-A/HC; rear side N 10 KTN

3Fig

Bearing arrangement work side: NN 30 K + 2344(00); drive side NN 30 K

1Fig



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39

1

38


Bearing arrangement work side: 70 CD/P4AQBC; rear side 70 CD/P4A

Spindle arrangements for great rigidity andhigh speed machining centres, high speedturning centres and high speed milling( figs , , and ).7654

Bearing arrangement work side: 70 CD/P4ADB; rear side N 10 KTN

75

Bearing arrangement work side: 70 CE/HCP4AQBC; rear side 70 CE/HCP4A

6

Bearing arrangement work side:70 CE/HCP4ADB; rear side N 10 KTN

4Fig

Fig Fig

Fig



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41

1

40


Spindle arrangements for maximum speed,internal grinding machines ( figsand ).9

8

Bearing arrangement for live centres( fig ).10

Bearing arrangement work side: 70 CD/HCP4ADT; rear side 70 CD/HCP4ADT

9Fig

Bearing arrangement work side: 70 CE/HCP4A; rear side 70 CE/HCP4A

8Fig

Bearing arrangement work side:NN 30 K ; rear side 72 ACD/P4AQBT

10Fig



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43

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42

p g pp

Bearing type Operating conditions ToleranceBearings of tolerance classP4A, SP, P4C PA9A, UP

Angular contact Non-locating bearings, displacement of outerball bearings ring desired H51) H41)

Locating bearings, displacement of outer ringnot required JS5 JS4Rotating outer ring load M5 M4

Cylindrical rollerbearings Normal and light loads K5 K4

Heavy loads, rotating outer ring loads M5 M4

Angular contactthrust ball bearingsSingle direction H5 Double direction2) K5 K4

1) The upper half of the recommended tolerance range should be used, especially when impor tant drive loads (belts,gears) are acting at the spindle drive side

2) The 2344(00) and BTM series bearings are mounted with radial clearance in the same housing bore seating as theappropriate cylindrical roller bearing. Fits tighter than those recommended should never be used even if they arerequired for cylindrical roller bearings

2Table

Fits for cast iron and steel housings

Preferred fits on the shafts

Bearing type Bearing bore Interferenceover incl.

mm mm m

Angular contact ball bearings 50 0 250 80 1 380 120 1 4120 150 2 5150 200 2 6

3Table

Recommended fitsAppropriate shaft and housing tolerancesfor high-precision bearings are shown inTables and . However, in the specificcase of spindle applications with normal

load and speed conditions, the interference/clearance fit between bearings, shaft andhousing shown in Tables and page44 are recommended.

The table of housing tolerancerecommendations also gives informationas to whether the outer ring can be axiallydisplaced in the housing bore.

For extreme conditions, such as veryhigh speed or exceptional loading, pleaseconsult SKF application engineering

services.

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21

Fits for steel shafts (solid and hollow)

Bearing type Shaft diameter ToleranceBearings of tolerance class

over incl. P4A, SP, P4C PA9A, UP

mm mm

Angular contact ball bearingswith rotating outer ring load 240 h4 h3with rotating inner ring load 240 js4 js3

Cylindrical roller bearings

with cylindrical bore 40 js4 40 140 k4 140 200 m5 200 240 n5

Angular contact thrustball bearingsSingle direction 130 h4 Double direction 200 h4 h3

1Table



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45

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44

Tolerances for shaft and housingAppropriate shaft and housing tolerancesfor high-precision bearings will be foundin the Table page 46 : ISO shaft limitsand Table page 47 : ISO housing limits.

The positioning of tolerance zones givenin the tables, in relation to the nominal boreand outside diameter of the bearings isshown in Diagram .1

6

5

Specific recommendations for singledirection angular contact thrust ball bearingseatings are given in the relevant bearingsection.

0

+

h4 h3 js3 js4 js5 js6 k4 k5 m5 n5 H5 H4 JS4 JS5 K4 K5 M4 M5

1

ISO shaft and housing limits, position

of the tolerance zones

Preferred fits in the housings

Bearing type Outside diameter Recommended clearancefor bearings axially

over incl. located free (non-located)

mm mm m

Angular contact 50 0 2 5 8ball bearings 50 120 0 3 6 10

120 150 0 4 8 12150 250 0 5 10 15

Bearing type Outside diameter Recommended interference

over incl.

mm mm m

Cylindrical roller 460 0 2bearings

4Table

Diagram



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47

1

46

Housing bore Tolerancesdiameter H5 H4 JS4 JS5Nominal Deviationsover incl. high low high low high low high low

mm m

18 30 +9 0 +6 0 +3 3 +4,5 4,530 50 +11 0 +7 0 +3,5 3,5 +5,5 5,550 80 +13 0 +8 0 +4 4 +6,5 6,580 120 +15 0 +10 0 +5 5 +7,5 7,5120 180 +18 0 +12 0 +6 6 +9 9180 250 +20 0 +14 0 +7 7 +10 10250 315 +23 0 +16 0 +8 8 +11,5 11,5315 400 +25 0 +18 0 +9 9 +12,5 12,5400 500 +27 0 +20 0 +10 10 +13,5 13,5

Housing bore Tolerancesdiameter K4 K5 M4 M5Nominal Deviationsover incl. high low high low high low high low

mm m

18 30 0 6 +1 8 6 12 5 1430 50 +1 6 +2 9 6 13 5 1650 80 +1 7 +3 10 8 16 6 1980 120 +1 9 +2 13 9 19 8 23120 180 +1 11 +3 15 11 23 9 27

180 250 0 14 +2 18 13 27 11 31250 315 0 16 +3 20 16 32 13 36315 400 +1 17 +3 22 16 34 14 39400 500 0 20 +2 25 18 38 16 43

6Table

ISO housing limits

Shaft Tolerancesdiameter h4 h3 js3 js4 js5Nominal Deviationsover incl. high low high low high low high low high low

mm m

6 10 0 4 0 2,5 +1,25 1,25 +2 2 +3 310 18 0 5 0 3 +1,5 1,5 +2,5 2,5 +4 418 30 0 6 0 4 +2 2 +3 3 +4,5 4,530 50 0 7 0 4 +2 2 +3,5 3,5 +5,5 5,550 80 0 8 0 5 +2,5 2,5 +4 4 +6,5 6,580 120 0 10 0 6 +3 3 +5 5 +7,5 7,5120 180 0 12 0 8 +4 4 +6 6 +9 9180 250 0 14 0 10 +5 5 +7 7 +10 10250 315 0 16 0 12 +6 6 +8 8 +11,5 11,5

Shaft Tolerancesdiameter js6 k4 k5 m5 n5Nominal Deviationsover incl. high low high low high low high low high low

mm m

6 10 +4,5 4,5 +5 +1 +7 +1 +12 +6 +16 +1010 18 +5,5 5,5 +6 +1 +9 +1 +15 +7 +20 +1218 30 +6,5 6,5 +8 +2 +11 +2 +17 +8 +24 +1530 50 +8 8 +9 +2 +13 +2 +20 +9 +28 +1750 80 +9,5 9,5 +10 +2 +15 +2 +24 +11 +33 +20

80 120 +11 11 +13 +3 +18 +3 +28 +13 +38 +23120 180 +12,5 12,5 +15 +3 +21 +3 +33 +15 +45 +27180 250 +14,5 14,5 +18 +4 +24 +4 +37 +17 +51 +31250 315 +16 16 +20 +4 +27 +4 +43 +20 +57 +34

5Table

ISO shaft limits



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Accuracy of formfor shafts1)

ABt3

A t4/300B t4/300

dB

B

dA

A

t

t

t1 Bt2

12

1) The shaft tolerances, symbols and reference surfaces are in accordance withISO 1101

A t4/300B t4/300

t3 ABA B

DBDA

t

t1

11

1) The housing form tolerances, symbols and reference surfaces are in accordance withISO 1101

Accuracy of formfor housings1)Accuracy of associated components

Maximum running accuracy, high speedsand low operating temperatures can onlybe achieved, even with precision bearings,if the mating parts and other associated

components are made with equal precision.Deviations from geometric form musttherefore be kept as small as possiblewhere the mating parts are concerned.

The rings of the bearings shown in thiscatalogue are relatively thin-walled, so theywill adapt themselves to the form of theshaft or housing bore.Any errors of form orother inaccuracies of the shaft and housingbore seating will thus be transmitted to theraceways of the bearing rings.Angular

misalignment of one bearing ring in relationto the other can cause high operatingtemperatures; the axial support surfacesfor the faces of the bearing rings musttherefore, be precisely machined.This is

particularly important where high-speedoperation is intended.Consequently, animportant prerequisite to achieving highlyaccurate bearing arrangements is that therecommendations, concerning accuracy ofform and position, as well as surface finish,are adhered to when machining the matingparts ( figs and ).

Limits for tolerance grades and roughnessclasses can be found in Tables andpage 50.

87

1211

Fig

Fig


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59

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58

Preventive stagesThe sealing system can be divided into thefollowing preventive stages ( fig ).

1 Direct access to the labyrinth of fluid

washing over the spindle housing isprevented.2 Splashguard, designed as a labyrinth,

together with the housing cover, throws

18

fluids outward. Both the splashguard andthe housing cover are provided with oneor several annular grooves to direct thefluid. When positioned on a rotating body,the grooves have little influence during

rotation.3 Gap with a height of 0,1 0,2 mm.4 Groove or grooves on the shaft to direct

the fluid under non-rotating conditions.

912

3

4

5

6

10

7 8 11 12

18

Labyrinth sealing system,example

prevent most of the fluid proceeding furtherin. The drainage chambers also serve toreduce the velocity of the fluid arising fromthe rotation of the shaft.

In order to avoid pumping effects inward,

the labyrinth components should progressivelydecrease in diameter inwards from theoutside. Machining spirals that can directthe fluid inwards should be avoided. If thespindle is designed to rotate in both directions clockwise and counter clockwise spiralshave to be avoided.Additional protection is

achieved by creating an overpressure insidethe spindle.This is the case when oil spotor oil mist lubrication systems are used.

Under severe conditions, an air barriercan be created by blowing air into the

labyrinth. It is important that the flow isbalanced, so that the dominant flow isoutwards. An air barrier can provide areasonably efficient sealing even witha fairly simple labyrinth design.Thefollowing is an example of an efficientsealing system.

17

16

Non-contacting seals, examples

Fig

Fig

Fig


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67

curves refer to single bearings, so data formatched sets should be reduced dependingon the arrangement as per Table .

For hybrid bearings the estimated greaseservice life can be obtained by multiplying

the calculated value for the all-steel bearingby the factor given in Table .4

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66

Grease service lifeSeveral methods are used to calculate therelubrication interval for grease lubricatedbearings. However there are severalimportant factors influencing the grease life,

many of which are difficult to estimate. It isextremely complex to calculate preciselyhow long the grease can survive in a given

application depending on the actualconditions. It is better to talk of grease lifeestimation, and the following data assistsin making the best estimate.The graph( Diagram and Tables and )

shows the theoretical relubrication intervaltf for high-precision bearings in variousexecutions.The angular contact ball bearing

431

Relubrication interval (hours)

100 000

10 000

1 000

100

Speed factor, n dm(millions)

0,1 0,15 0,2 0,3 0,5 0,7 1 1,5

A15

A25

CN 10

T& B

CNN 30

1

Bearing Preload classdesign Light Medium Heavy

ASet of 2 0,8 0,7 0,55Set of 3 0,7 0,55 0,35Set of 4 0,65 0,45 0,25More Contact SKF

T,BTM series 1 0,5B As A As A

3

n dm A T C

millions

0,5 3 3 3

0,7 3,5 3

1 3 3

1,5 2,8 2,5

4

Factors to calculate grease relubrication intervaldepending on bearing arrangement

Grease relubrication intervals guidelines

Ceramic material effect

Codes:

A = Angular Contact Ball Bearings;C = Cylindrical Roller Bearings;T = Angular Contact Thrust Ball Bearings;B = Ball Screw Support Bearings.

Shaft position Vertical Horizontal

correction factor C1 0,5 1

Bearing load C/P > 20 C/P > 10 C/P > 8 C/P > 5 C/P > 2 C/P >1correction factor C2 1 0,7 0,5 0,3 0,2 0,1

Reliability L1 L50correction factor C3 0,37 2

Air flow-through Low Moderate Strongcorrection factor C4 1 0,3 0,1

Damp & dust Low Moderate High Very highcorrection factor C5 1 0,5 0,3 0,1

Temperature 40 C 55 C 70 C 85 C 100 Ccorrection factor C6 > 1 > 1 1 0,5 0,25

5

Guidelines on correction factorsfor relubrication interval estimation

Diagram

Table Table

Table


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Withdrawal of the shaft from housing 5Fig7020 ACD/P4ATBTB having an outside Use a puller to withdraw the shaft


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Withdrawal of the shaft from housing.The spindle is equipped with a reinforcedlabyrinth seal at the work side. Removethe external component (7) ( fig ).Normally some force is necessary towithdraw the shaft from the cartr idge,as in most cases the work side bearingshave a certain interference fit.The requiredwithdrawal force expressed in N for a set ofthree bearings can be estimated at 20 timesthe outside diameter of the bearingexpressed in mm. Example: Bearing set

5

6

4

7

5Fig

Removing the drive side bearing:inject the oil until the inner ring is released

Withdrawal of the shaft from housing:removal of the external cover

SKF pump 729124 for pressure up to 100 MPa

7020 ACD/P4ATBTB having an outsidediameter of 150 mm will require awithdrawal force of approximately20 150 = 3 000 N.

If the bearings are to be used again,e.g. after being relubricated, great caremust be taken to avoid damaging themduring disassembly of the spindle. Blowsto the shaft as a method of withdrawal mustbe avoided as this can easily create seriousindentations on the raceways, making thebearings unfit for further use.

Use a puller to withdraw the shaft,rotating the shaft during withdrawal tominimise the risk of damage. If no suitablepuller is available, one can be madeaccording to the illustration ( fig ).The bar through the shaft is threaded atboth ends. Turn the nut at the work sideof the spindle to withdraw the shaft andbearings.While doing this, rotate the shaftto avoid damage to the bearings if the fitis tight. If there is no bore through the shaft,arrange a suitable attachment of the barto the spindle nose.

6

6Fig

Removal of the shaft using a puller

Fig


Removing drive side bearings Removing the locating device 8Fig


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85

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84

Removing drive side bearingsIf the drive side bearing has not alreadybeen removed by the oil injection methodthis should now be done.

A puller to grip the side face of the spacer(6) is used. Do not pull over the roller setas this could make the puller lose its grip,damaging the bearing and making it unfitfor further use. The required pulling forceexpressed in N is about 300 times the borediameter expressed in mm. As the seatingis tapered the pulling force acts only torelease the bearing ( fig ).

The outer ring of the cylindrical rollerbearing is still seated in the housing.Remove it using a puller, gripping the innerside-face of the ring.Do not put tools onthe raceways if the bearings are to be usedagain. If you do not need to check thebearings, these may be left on site. Oftenthe housing is provided with two diametricallyopposed slots for gaining access with pullerto the bearing inner side face ( fig ).9

7

Removing the locating devicefor the work side bearingsThe locating device for the work sidebearings in this example is a so-calledstepped sleeve. It is kept on the shaft bya rather heavy interference fit and ensuresvery good accuracy of the spindle.

This method eliminates the need forthreaded components and the inaccuracythat the threads can create.The steppedsleeve is fastened on the spindle by aninterference fit that must be heavy enoughto withstand the axial forces. The sleeve ismounted and dismounted by the oil injectionmethod, thus ensuring careful handlingof the components.The step that acts asa pressure surface during the mounting anddismounting operation can be sealed intwo different ways; by the sleeve having twobore diameters, each with an interferencefit on the shaft, or by using an O-ring.Thelatter system is somewhat easier from amanufacturing point of view.

Connecting nipples

Location device stepped sleeve

8


9 Removal of the outer ringof the cylindrical roller bearing

Removal of the locating devicefor the work side bearing

6

7

Removal of the drive side bearing using a puller

Fig Fig

g


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Mounting the grease.The properties of the greaseSpindle with cylindrical roller bearing Otherwise a puller is used. It should grip


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Mounting

Mounting a spindle with bearingsarrangement 70 CD/TBT at the workside and NN 30 K at the drive sideBefore mounting the bearings, a greaseof appropriate quality and quantity shouldbe applied. For best performance of thespindle, a grease with synthetic base oilshould be used.See section Greaselubrication under Lubrication page 62for details.

The NN 30 K bearing at the drive sideof the spindle should be adjusted to its finalposition by means of the spacer at the largeend of the taper.This bearing shouldtherefore be lubricated only when it is finallyto be mounted.

For bearings that will be used at relativelyhigh speeds, it is recommended that therust-inhibiting compound is washed awayand the bearings are dried before applying

g p p gare then better utilised. Special care mustbe taken to ensure that the bearings arenot contaminated during washing.

Using a syringe to apply the grease isa convenient way to get the proper quantity,and makes it easy for feeding inside thebearing. Distribute the grease evenlyaround the rolling element set.

Mounting the work side bearings1 Check that the distance between the

housing seating abutment and housingcover side face LH, is smaller than thetotal width of the bearing package LB,measured over the outer rings. If notthere will be an axial play in the spindle.It may be recommended to have LH10 15 m smaller for a diameter around100 mm. Too large a difference mayinduce deformations when tighteningthe screws ( fig ).13

p y gand angular contact thrust ball bearingat work sideA cylindrical roller bearing at the work sideof the spindle is dismounted in the sameway as described for the drive side bearing.For removing this bearing, together with theangular contact thrust ball bearing generallypresent in this position, the system withscrew should preferably be used if provided.

p g pover the inner ring of the cylindrical bearingor over the shaft sealing-washer. Dependingon the design, access may be difficult andit might be necessary to pull over thehousing cover and the outer rings. Angularcontact thrust ball bearings normally haveonly a light fit and the withdrawal force isminimal ( fig ).12


12

LH

LB

13

Spindle with cylindrical roller bearing and angularcontact thrust ball bearing at work side Mounting the work side bearings

Fig Fig


Mounting the stepped sleeve ( fig )15 3 The sleeve should be allowed to cool2 Particularly when large bearings are 6 Align the rings so that the marking for the


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91

1

90

g pp g1 Heat the stepped sleeve to about 150 C

above ambient for smaller sizes (borediameter 60 mm) and about 110 C forlarger sizes, preferably with an inductionheater.

2 When heated up, the sleeve can be easilyhandled by using the connecting nippleas a handle. Put the sleeve quickly on tothe shaft so that the shaft does not heatup before the sleeve comes into contactwith the bearings.

down to room temperature beforeproceeding.

4 For final adjustment of the sleeve the oilinjection method should be used.

5 Connect the nipples and the oil injectorto the sleeve.

6 Provide for an arrangement that will applyan axial load over the sleeve-bearingsystem to withstand the force createdby the oil injected to the sleeve, and toovercome the bearing fits and preload.

y g gused, the spindle should preferably bekept in a vertical position during themounting procedure ( fig ).

3 Position the shaft labyrinth (9); it mayhave to be warmed slightly, and thehousing cover (10). Be sure not to forgetthe housing cover!

4 Warm the bearings on a hot plate orinduction heater; 20 30 C aboveambient is normally sufficient to allow thebearings to pass freely over the shaft.

5 Ensure that the bearings are facing in thecorrect direction. If using a matched setlook for the markings on the outsidediameter of the outer r ings.

14

g g gthickest part is at the same position forthe inner rings as for the outer rings.This will ensure the best possible divisionof load between the bearings.

7 Smear the bearing seatings lightly witha thin oil.

8 Position the bearings on to the shaft,not forgetting the two spacers (11)and (12) between the second and thirdbearing. The shaft spacer may haveto be warmed.

12

11

10

9

14Fig



10 MPa

60100 MPa

15Fig

Do not forget to grease the bearingsbefore mounting.

Mounting the work side bearings with the spindlein vertical position

Mounting the stepped sleeve


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adjustment screw and the gaugel d i iti th ll t Th

again shows zero. The gauge needs to bed d i th dj t t 1


bath. The heated housing with outer ringh ld th b ll d t l d t

the instructions supplied with each GB 30( fi 96)22


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95

placed in position over the roller set. Theadjustment screw needs then to beturned in the opposite direction until thegauge, by virtue of its inherent resilience,is in contact with the roller set.

6 The inner ring is driven further up on toits seating until the indicator on the gauge

expanded using the adjustment screwand removed.The required drive-up forcein N is 200 400 times the bearing borediameter in mm.

7 The distance between the mounted inner

ring and the shoulder on the spindle needsto be measured using gauge blocks. Make

1

94

should then be allowed to cool down toambient temperature. All components aswell as the gauges must have the samestable temperature during the measuringprocedure ( fig ).

2 The bore gauge need to be introducedinto the outer ring raceway, and theindicator set to zero.The raceway diametermeasured in this way is transferred tothe GB 30 gauge ( fig ).

3 The bore gauge is applied to the centreof the gauging zone of the GB 30 gauge.The screw of the latter gauge is thenadjusted until the indicator of the boregauge shows zero minus a correctionfactor. The correction factor is given in

20

19

gauge ( fig page 96).4 The internal diameter of the envelope

diameter gauge needs to be reduced bythe value of the desired clearance, orincreased by the value of the desired

preload using the adjustment screw. Theindicator on the envelope diameter gaugeneeds to be set to zero. The setting of theindicator should be left undisturbed fromnow on ( fig page 97).

5 The tapered bearing seating on thespindle needs to be lightly oiled with thinoil. The inner ring with roller and cageassembly needs be lightly driven up on thetapered seating.The envelope diametergauge needs to be expanded using the

25

22

Fig 18

Fig 19 Fig 20

Drive-up distance


21Fig

Pushing the inner ring up on the shaftuntil it firmly abuts the spacer ring


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Mounting other bearingsarrangements

Spindle with cylindrical roller bearingand angular contact thrust ball bearing 1


Inserting spindle shaft in the housing( fig )26

Mount the sealing components and thepulley and tighten the nut.


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101

arrangements

Spindle with tandem set of angularcontact ball bearings at both sides( fig )

The drive side bearings for this spindlemust be mounted after the shaft with thework side bearings has been insertedin the housing.This type of arrangementmust have a clearance between drive sidebearing outer rings and housing seating asthe bearings should be axially displaceable.Therefore the bearings can be mountedwithout heating the housing. However it maybe preferred to heat the bearings somewhatto get them on to the shaft more easily.

The outer rings are then also expandedand to avoid forcing the bearings into thehousing it should also be somewhat heated.

27

and angular contact thrust ball bearingat work side ( fig )A cylindrical roller bearing mountedtogether with an angular contact thrust ballbearing has to be inserted into the housing

complete with the outer ring.The housingshould then be heated to about 20 30 Cover ambient for easy introduction of theouter ring.The outside diameter of theangular contact thrust ball bearing hassuch tolerances that it will have a radialclearance in the housing even when thehousing is not heated.The radial clearancebetween this bearing and the housing isnecessary to ensure that only the cylindricalbearing is supporting the radial load.

281

100

( fig )The spindle with the work side bearingsand the inner ring assembly of the driveside bearing can now be inserted in thehousing. Heat the housing to 10 to 30 C

above ambient temperature to easily getthe bearings into position.The spindleneeds to be turned slowly as the inner ringand roller and cage assembly are insertedin the outer ring, to prevent the racewaysand rollers from becoming damaged.

Alternatively the spindle with only thework side bearings can be inserted, andafter securing the housing cover, the innerring assembly of the drive side bearingis driven up on the seating.

6 pulley and tighten the nut.Do not overtighten the screws for the

housing covers at the work side and atthe drive side as this may deform thehousing seatings if the distance between

the threads and the seatings is short.

26 27 28

Inserting spindle shaft in the housingSpindle with tandem set of angular contact ballbearings at both sides

Spindle with cylindrical roller bearing and angularcontact thrust ball bearing at work side

Fig Fig Fig


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Skf Bearing Selection

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