General Data. Types of bearings 6. Standardization and interchangeability 12. Dimensions and part numbers 14. Bearing manufacturing precision 18

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1 General ata Types of bearings 6 efinitions 6 Vocabulary 8 Capabilities 9 Stanarization an interchangeability 12 The Stanars 12 Interchangeability 12 imensions an part numbers 14 General esignations 14 Complete reference 14 Basic reference 15 esignations of tapere roller bearing 16 esignation of special bearings 17 Bearing manufacturing precision 18 Stanarization 18 Tolerance efinition 19 Equivalence of bearing precision stanars 22 Bearing tolerances 22 Raial bearings - Normal tolerance classes 23 High-precision raial bearings - Tolerance class 6 24 High-precision raial bearings - Tolerance class 5 25 High-precision raial bearings - Tolerance class 4 26 High-precision raial bearings - Tolerance class 2 27 Tapere roller bearings - Normal tolerance class 28 High-precision tapere roller bearings - Tolerance class 6X 29 High-precision tapere roller bearings - Tolerance class 5 30 Ball thrust bearings - Normal tolerance class 31 Tapere bores: 1:12 an 1:30 taper 32 Bearings initial raial internal clearance 34 Raial clearance of raial contact bearings. efinition 34 Internal raial clearance groups 34 Axial clearance of angular contact bearings 35 Recoene axial clearance 35

2 efinitions General ata Types of bearings A bearing is a mechanical unit that provies a mobile link between two parts that rotate in relation to one another. Its function is to permit relative rotation of these parts, uner loa, with accuracy an minimum friction. A bearing consists of: two rings, one associate with a fixe element, the other with the moving element an featuring raceways rolling elements allowing relative isplacement of the two rings with minimum friction a cage separating the rolling elements There are two large bearing families: ball bearings, allowing high spees of rotation an where the ball-raceway interface is theoretically point contact roller bearings, where the ball-raceway interface is theoretically line contact. Roller bearings can withstan higher raial loas than ball bearings 6

3 Type Outer ring Inner ring Rolling elements Synthetic material Presse steel Integrally machine Ball bearing Cylinrical roller bearing Tapere roller bearing (cup) (cone) ouble-row spherical roller bearing Neele bearing Ball thrust bearing (housing ring) (shaft ring) Spherical roller thrust bearing (housing ring) (shaft ring) 7

4 General ata Types of bearings (continue) Vocabulary Stanar ISO 5593 has establishe a vocabulary of stanar terms applicable to bearings an bearing technology. The terms an efinitions are given in a multilingual glossary. cage rolling element pitch iameter shaft housing inner ring outer ring Ball bearing Angular-contact ball bearing Cylinrical roller bearing with outsie iameter corner raius raceway groove for seal or shiel face loa line shouler bevel shouler pitch iameter bore point of loa application α : contact angle Tapere roller bearing Ball thrust bearing Spherical roller thrust bearing outer ring (cup) shouler housing ring inner ring (cone) loa line shaft ring point of loa application α : contact angle point of loa application loa line 8

5 Capabilities General characteristics an capabilities Application examples Ball bearings Single- or ouble-row raial ball bearings Popular bearings ue to their cost/performance compromise. Numerous variants (shiele, seale etc.) an large selection of imensions. Electric motor Wheel of trailer Househol electrical appliances Wooworking machine spinles Small reucing gear Gear box Single-row angular-contact ball bearings Always mounte in opposition with another bearing of the same type. Give great assembly rigiity, especially when preloae Reuction gear box Machine-tool spinle ouble-row angular-contact ball bearings Withstan axial loas in both irections. Can be use alone as a ouble bearing. Reucing gear Automobile wheels Agricultural machinery 4-point angular contact ball bearings Withstan axial loas in both irections. Often associate with a raial contact bearing. Reucing gear ouble-row self-aligning ball or spherical roller bearings ouble-row self-aligning ball bearings The spherical raceway of the outer ring permits angular isplacement. A variant with a tapere bore simplifies fitting. For long shaft with eflection Spherical roller bearings The spherical raceway of the outer ring permits angular isplacement A variant with a tapere bore simplifies fitting. Roll stan Large reucing gear Large inustrial fan Printing machine roller Quarry machine 9

6 General ata Types of bearings (continue) General characteristics an capabilities Application examples Roller bearings Cylinrical roller bearings Excellent resistance to instantaneous overloas an shocks. Simplification of installation thanks to their etachable elements. Certain types allow axial isplacement; others allow a low axial loa. Heavy-uty electric motor Wagon axle box Pressure roller Rolling machine roll Single-row tapere roller bearings Always mounte in opposition with another bearing of the same type. Give great assembly rigiity, especially when preloae. Reucing gear shaft Truck wheel Bevel gear transfer gearbox ouble-row tapere roller bearings (SNR TWINLINE) Accept axial loas in both irections. Often use alone as a ouble bearing. TGV high-spee train axle box Automobile wheel Neele bearings Accept relatively high raial loas with small space requirement an high raial rigiity. Thrust bearings Thrust bearings are often use with other types of bearing. Ball thrust bearings Withstan axial loas only. If raial loa is applie must be associate with a raial bearing. Spherical roller thrust bearings Can withstan a raial an axial loa while accepting misalignment. Vertical shaft Tailstock Plate pump Heavy-uty vertical shaft Turbo-generator Crane pivot Plastic injection screw 10

7 Loa capabilities raial axial Limiting spee of rotation Permissible misalignment between shaft an housing Types Cross-section low meium goo low meium goo low meium goo low goo Raial ball bearing ouble-row raial ball bearing Angular-contact ball bearing 4-point angular-contact ball bearing ouble-row angular contact ball bearing TWINLINE angular contact ball bearing ouble-row self-aligning ball bearing Cylinrical roller bearing (1) Tapere roller bearing TWINLINE tapere roller bearing ouble-row spherical roller bearing Single-irection ball thrust bearing Spherical roller thrust bearing (1) Types NJ an NUP accept low axial loas 11

8 General ata Stanarization an interchangeability The stanars The mission of the International Stanar Organisation (ISO) is to evelop an coorinate stanarization to facilitate the trae of proucts an services between nations. It encompasses the stanars coittees of 89 countries (AFNOR-France, IN-Germany, UNI-Italy, BS-Great Britain, ANSI-Unite States, etc.). Bearing stanarization is the responsibility of the ISO Technical Coittee "TC 4" in which SNR plays an active part. The main stanars use for bearings an thrust bearings are specifie in the appenix page 147. Interchangeability imensional interchangeability is guarantee by the values an tolerances on the bearing imensions:,, B, C, r an T. B C T r Bore iameter Outsie iameter With of bearing or with of inner ring (cone) With of bearing or with of outer ring (cup) With or total height Corner raius All types of bearings except tapere roller an thrust bearings B r Tapere roller bearings r T C r r B Strict application of the stanars in the manufacture of the bearing enables one to obtain full interchangeability between bearings of the same part number, whoever the manufacturer, place or ate of prouction. Stanarization of the bearing also allows imensional interchangeability between bearings of ifferent types, either total or partial. It is necessary to ensure the functional interchangeability. 12

9 Bearing series coes accoring to the ifferent outsie iameters an withs For a given bore the stanars provie for several iameter series (series 8, 9, 0, 1, 2, 3, 4 in ascening orer). For each iameter series there are several with series (series 0, 1, 2, 3, 4 in ascening orer). Interchangeability of etachable elements of cylinrical or tapere roller bearings Cylinrical or tapere roller bearings can be separate into two parts: a ring that is joine to the cage an rollers an a bare ring. Cylinrical roller bearings Interchangeability is ensure by the imensions below the rollers F an above the rollers E. ØF ØE Tapere roller bearings The interchangeability of the internal sub-assemblies (fitte cones) an outer rings (cups) is ensure by stanar ISO 355 which efines the contact angle α an the theoretical insie iameter of the cup E. One must check that the bearings are inee ientical (same suffix). ØE Caution : There is full interchangeability between SNR elements. ISO has stanarize the values of the above imensions without specifying their tolerances. Consequently, although the assembly of elements from ifferent manufacturers presents no risk, it oes not always give optimum performance an shoul therefore be avoie. 13

10 General ata imensions an part numbers General esignations ISO has establishe stanars in the form of a general plan of imensions corresponing to stanars ISO 15, ISO 355 an ISO 104. These stanars allow universal use of the ifferent types of bearings. The general esignation system taken from stanars ISO 15 an ISO 104 applies to all types of stanarize bearings Tapere roller bearings have specific esignations taken from stanar ISO 355 The special bearings have a specific numbering system. Complete part number Each bearing part number is comprise of the following components: ZZ Prefix Series coe Bore coe Suffix (optional) (optional) Basic part number Complete part number Examples: No prefix ZZ Suffix ZZ ouble shieling Series 62 coe Bore coe 04 x 5 = 20 bore Series NU3 : cylinrical roller bearings NU x 5 = 70 bore Series 302 tapere roller bearings 08 x 5 = 40 bore The table on the following page specifies the ifferent possibilities for the series coes an bore coes. The main suffixes an prefixes are specifie in the chapter corresponing to each family. 14

11 Basic part number 60 XX Part number 60 X 62 X 63 XX 64 XX 160 XX 618 XX 619 XX 622 XX 623 XX 2 XX 3 XX 42 XX 43 XX 302 XX 303 XX 313 XX 320 XX 322 XX 323 XX 330 XX 331 XX 332 XX N..2 XX N..3 XX N..4 XX N..10 XX N..22 XX N..23 XX Type of bearing Raial ball bearing With 1 row of balls With a filling slot With 2 rows of balls Tapere roller bearing Cylinrical roller bearing NU N NJ NUP Part number 72 XX 73 XX 718 XX QJ2 XX QJ3 XX 32 XX 33 XX 52 XX 53 XX 213 XX 222 XX 223 XX 230 XX 231 XX 232 XX 240 XX 241 XX 511 XX 512 XX 513 XX 514 XX Type of bearing Angular-contact ball bearing With 1 row of balls With 4 points of contact With 2 rows of balls With 2 rows of balls ZZ or EE ouble-row spherical roller bearing Ball thrust bearing Bore coe 3 / /6 7 /7 8 / /22 /28 / Bore iameter x5 = 20 05x5 = 25 06x5 = 30 07x5 = 35 08x5 = XX 13 XX 22 XX 23 XX ouble-row self-aligning ball bearing 293 XX 294 XX Spherical roller thrust bearing 112 XX 113 XX Wie inner ring 15

12 General ata imensions an part numbers (continue) esignations of tapere roller bearings Stanar ISO 355 efines the series of imensions of tapere roller bearings. The ol part numbering system has been maintaine in this catalog. The new esignation is however mentione for the bearings of the new series. T 4 C 075 Letter T for tapere roller bearings Bearing bore Range of contact angles Angle series Contact angle 2 10 < α < α < α < α < α < α 30 iameter series B C E F G With series B C E With an iameter series G iameter series F E C B BCE BCE BCE BCE B C E B C E With series 16

13 esignation of special bearings The part numbers of special bearings is not stanar an is specific to each manufacturer. The esignation system efine by SNR is given below. Y53 GB S01 Material moification or heat treatment (optional) Sequence number in the following number ranges: 9000 to to Variant suffix Type of bearing Examples AB BB GB TGB HGB B AP QJ TJ N.. GNU EC FC TFC QR X... CH Single-row raial contact ball bearing Single-row angular contact ball bearing Two-part ouble-row angular contact ball bearing Single-flange ouble-row angular contact ball bearing Two-flange ouble-row angular contact ball bearing ouble-row raial contact ball bearing Ball thrust bearing 4-point angular contact bearings 3-point angular contact bearings Cylinrical roller bearing: N, NU, NUP Cylinrical roller bearing Single-row tapere roller bearing ouble-row tapere roller bearing Single-flange ouble-row tapere roller bearing Crosse roller bearing Sensor bearings XGB, XTGB, XHGB, XFC, XTFC Ceramic Rolling Elements 17

14 General ata Bearing manufacturing precision Stanarization Stanar ISO 492 specifies the tolerances applicable to the imensions an precision of rotation of metric series raial bearings. The imensional tolerances efine by this stanar bear the following symbols: r B B r T C Internal master gauge subassembly T2 External master gauge subassembly T1 r r B Tolerance classes efine by stanar ISO 492: The Normal class, which is that of all the stanar bearings, an is not usually inicate in the bearing esignation The High precision classes which are, in ascening orer of precision: ISO 6, ISO 5, ISO 4, ISO 2 These classes are inicate in the suffix ae to the bearing reference. Example: C3 P5 Clearance category 3 ISO precision class 5 Stanar ISO 199 sets the tolerances on thrust bearing imensions. Stanar ISO 582 sets the tolerances on bearing corner raii. The imensions applicable to fillets an shoulers are inicate in the table of bearing characteristics. Stanar ISO 5753 efines the tolerances on the raial clearance of the bearings. 18

15 Tolerance efinition The tolerance classes fix several types of tolerances an characteristics given for a temperature of 20 C ± 1 C (68 F ±1.8). imensional tolerances Stanar ISO 492 sets the tolerances for the three main imensions of a bearing: the bore iameter the outsie iameter the with of each ring B an C with, in aition, for tapere bearings, the total with T Functional tolerances The stanar also efines the precision of rotation of the bearings: the raceway raial runout of each ring. It is measure on the moving ring with respect to the fixe ring sie face runout with reference to the bore of the inner ring outer ring sie face runout with respect to the outer iameter sie face runout with respect to the track 19

16 General ata Bearing manufacturing precision (continue) imensional tolerances : nominal bore iameter eviations mp eviation of a mean bore iameter in an isolate plane (tolerance on the mean iameter) Vp Variation in the bore iameter in an isolate raial plane (ovality) Vmp Variation in the mean bore iameter (applies only to a supposely cylinrical bore) in ifferent planes : nominal outsie iameter mp eviation of a mean outsie iameter in an isolate plane (tolerance on the mean iameter) Vp Variation in the outsie iameter in an isolate raial plane (ovality) Vmp Variation in the mean outsie iameter in ifferent planes B: nominal with of ring Bs VBs eviation of an isolate with of the inner ring (with tolerance) Variation in the with of the inner ring (face parallelism) C: nominal with of ring Cs VCs eviation of an isolate with of the outer ring (with tolerance) Variation in the with of the outer ring (face parallelism) T : nominal with of tapere bearing T1: effective nominal with of the internal sub-assembly T2: effective nominal with of the external sub-assembly Ts T1s T2s eviation in the actual with of the bearing eviation in the effective actual with of the internal sub-assembly eviation in the effective actual with of the external sub-assembly 20

17 Functional tolerances raial run-out Kia Kea eviations Raial run-out of the inner ring on the assemble bearing Raial run-out of the outer ring on the assemble bearing run-out of the reference face S S Axial run-out of the reference face (or large face if applicable) of the inner ring with respect to the bore (run-out of the face of the inner ring) Perpenicularity error of the external surface with respect to the reference face (or large face) of the outer ring (external surface run-out) bearing raceway run-out Sea Sia Axial run-out of the reference face (or large face) of the outer ring with respect to the bearing raceway, on the assemble bearing (run-out of outer ring raceway) Axial run-out of the reference face (or large face) of the inner ring with respect to the bearing raceway on the assemble bearing (run-out of the inner ring raceway) Consult SNR for the metho of measurement. 21

18 General ata Bearing manufacturing precision (continue) Equivalence of bearing precision stanars Stanar Precision High Precision ISO AFNOR ABEC IN tolerance tolerance tolerance tolerance class class class class Normal Normal 1 P P P P P2 The values given by the various stanars for certain characteristics are not rigorously ientical. The tolerance class, when inicate on the bearing, imposes compliance with all the tolerances in the sai class. Nevertheless, certain bearing applications require special tolerances on certain imensions or characteristics. To avoi using an excessively expensive high-precision bearing, SNR can supply bearings with reuce tolerances on certain imensions or characteristics. For example, run-out of inner ring of high-spee bearings for woo-working machine spinles. Consult SNR. Bearing tolerances Raial bearings Stanar ISO 492 Normal tolerance class page 23 Tolerance class 6 page 24 Tolerance class 5 page 25 Tolerance class 4 page 26 Tolerance class 2 page 27 Tapere roller bearings Stanar ISO 492 Normal tolerance class page 28 Tolerance class 6X page 29 Tolerance class 5 page 30 Thrust bearings Stanar ISO 199 Normal tolerance class, 6 an 5 page 31 Tapere bores Stanar ISO 492 Bore with 1:12 an 1:30 taper page 32 22

19 Raial bearings - Normal tolerance classes With the exception of tapere roller bearings an thrust bearings. Stanar ISO 492. Inner ring Vp (1) mp iameter series Vmp Kia VBs 9 0,1 2,3,4 all normal moifie (1) upper lower max max max upper lower max 0,6 2, ,5 < < < < < < < < < < < < < < (1) Relates to the rings of isolate bearings for installation in pairs or per unit. Bs Outer ring Vp (1) Shiele Open bearings Cs VCs bearings mp Vmp iameter series (1) Kea C1s (2) VC1s (2) 9 0,1 2,3,4 2,3,4 upper lower max max max upper lower max 2, < < < < < < < < < < < Ientical to Bs an VBs of the inner ring of the same bearing 500 < < < Note: The tolerances on the outsie iameter, 1, of the flange on the outer ring are given in stanar ISO 492. (1) Taken before fitting an after removal of the inner or outer snap ring. (2) Only applies to ball an groove bearings. 23

20 General ata Bearing manufacturing precision (continue) High-precision raial bearings Tolerance class 6 With the exception of tapere roller bearings an thrust bearings. Stanar ISO 492. Inner ring Vp mp iameter series Vmp Kia VBs 9 0,1 2,3,4 all normal moifie (1) upper lower max max max upper lower max 0,6 2, ,5 < < < < < < < < < < < < (1) Relates to the rings of isolate bearings for installation in pairs or per unit. Bs Outer ring Vp (1) Shiele Open bearings bearings Cs VCs mp Vmp iameter series (1) Kea C1s (2) VC1s (2) 9 0,1 2,3,4 0,1,2,3,4 upper lower max max max upper lower max 2, < < < < < < < < < < < < < < Note: The tolerances on the outsie iameter, 1, of the flange on the outer ring are given in stanar ISO 492. (1) Taken before fitting an after removal of the inner or outer snap ring. (2) Only applies to ball an groove bearings. Ientical to Bs an VBs of the inner ring of the same bearing 24

21 High-precision raial bearings Tolerance class 5 With the exception of tapere roller bearings an thrust bearings. Stanar ISO 492. Inner ring Vp Bs mp iameter series Vmp Kia S Sia (1) VBs 9 0,1,2,3,4 all normal moifie (2) upper lower max max max max max upper lower max 0,6 2, ,5 < < < < < < < < < < (1) Only applies to ball an groove bearings (2) Relates to the rings of isolate bearings for installation in pairs or per unit. Outer ring mp Vp iameter series 9 0,1,2,3,4 Vmp Cs C1s (2) upper lower max max max max max max max lower max 2, < < < < < Ientical 8 to Bs 120 < < of the inner ring < of the same 10 bearing 250 < < < < < Kea S (1) S1 (2) Sea (1)(2) Sea1 (2) Note: The tolerances on the outsie iameter, 1, of the flange on the outer ring are given in stanar ISO 492. (1) oes not apply to bearings with a flange-type outer ring. (2) Only applies to ball an groove bearings. VCs VC1s (2) 25

22 General ata Bearing manufacturing precision (continue) High-precision raial bearings Tolerance class 4 With the exception of tapere roller bearings an thrust bearings. Stanar ISO 492. Inner ring Vp Bs mp s (1) Ø series Vmp Kia S Sia (2) VBs 9 0,1,2,3,4 all normal moifie (2) upper lower upper lower max max max max max upper lower max 0,6 2, , ,5 2,5 < , ,5 10 < , ,5 18 < , ,5 30 < < , < < < (1) These ifferences apply to iameter series 0, 1, 2, 3 an 4 only. (2) Only applies to ball an groove bearings (3) Relates to the rings of isolate bearings for installation in pairs or per unit. Outer ring Vp mp s S Cs (1) Ø series Vmp Kea (2) VCs Sea S1 (2)(3) Sea1 (3) (3) C1s (3) VC1s (3) 9 0,1,2,3,4 upper lower upper lower max max max max max max upper lower max 2, ,5 6 < ,5 18 < , ,5 30 < Ientical 2,5 50 < , to Bs 3 80 < of the inner 4 ring of the 120 < < same bearing < < < Note: The tolerances on the outsie iameter, 1, of the flange on the outer ring are given in stanar ISO 492. (1) These ifferences apply to iameter series 0, 1, 2, 3 an 4 only. (2) Only applies to ball an groove bearings (3) Relates to the rings of isolate bearings for installation in pairs or per unit. 26

23 High-precision raial bearings Tolerance class 2 With the exception of tapere roller bearings an thrust bearings. Stanar ISO 492. Inner ring mp s Vp (1) Bs Vmp Kia S Sia (2) all normal moifie (2) VBs upper lower upper lower max max max max max upper lower max 0,6 2,5 0-2,5 0-2,5 2,5 1,5 1,5 1,5 1, ,5 2,5 < ,5 0-2,5 2,5 1,5 1,5 1,5 1, ,5 10 < ,5 0-2,5 2,5 1,5 1,5 1,5 1, ,5 18 < ,5 0-2,5 2,5 1,5 2,5 1,5 2, ,5 30 < ,5 0-2,5 2,5 1,5 2,5 1,5 2, ,5 50 < ,5 1,5 2, ,5 80 < ,5 2,5 2,5 2, ,5 120 < ,5 2,5 2,5 2, ,5 150 < , < (1) These ifferences apply to iameter series 0, 1, 2, 3 an 4 only. (2) Only applies to ball an groove bearings (3) Relates to the rings of isolate bearings for installation in pairs or per unit. Outer ring Cs VCs mp s Vp (1) Vp Kea Sia S1 (2)(3) Sia1 (3) (3) C1s (3) VC1s (3) upper lower upper lower max max max max max max upper lower max 2, ,5 0-2,5 2,5 1,5 1,5 1,5 1,5 3 1,5 6 < ,5 0-2,5 2,5 1,5 1,5 1,5 1,5 3 1,5 18 < ,5 1,5 2,5 4 1,5 30 < ,5 1,5 2,5 4 Ientical 1,5 50 < ,5 4 6 to Bs 1,5 80 < ,5 5 2,5 5 7 of the inner 2,5 ring of the 120 < ,5 5 2, ,5 150 < ,5 5 2,5 5 7 same bearing 2,5 180 < < < Note: The tolerances on the outsie iameter, 1, of the flange on the outer ring are given in stanar ISO 492. (1) These ifferences apply to iameter series 0, 1, 2, 3 an 4 only. (2) Only applies to ball an groove bearings (3) Relates to the rings of isolate bearings for installation in pairs or per unit. S (2) 27

24 General ata Bearing manufacturing precision (continue) Tapere roller bearings - Normal tolerance class iameter an raial run-out - Inner ring mp Vp Vmp Kia upper lower max max max < < < < < < < < iameter an raial run-out - Outer ring mp Vp Vmp Kea upper lower max max max < < < < < < < < < < Note: The tolerances on the outsie iameter, 1, of the flange on the outer ring are given in stanar ISO

25 With - Inner an outer rings, single-row bearings an single-row sub-assemblies Bs Cs Ts T1s T2s upper lower upper lower upper lower upper lower upper lower < < < < < < < < High-precision tapere roller bearings Tolerance class 6X The iameter an raial run-out tolerances of inner rings (cones) an outer rings (cups ) in this tolerance class are the same as those given in page 28 for the normal class. The with tolerances are given below. With - Inner an outer rings, single-row bearings an single-row sub-assemblies Bs Cs Ts T1s T2s upper lower upper lower upper lower upper lower upper lower < < < < < < < <

26 General ata Bearing manufacturing precision (continue) High-precision tapere roller bearings - Tolerance class 5 Inner ring (cone) an with of single-row bearing mp Vp Vmp Kia S Bs Ts upper lower max max max max upper lower upper lower < < < < < < Outer ring (cup) mp Vp Vmp Kea S (1), S1 Ts upper lower max max max max upper lower 18 < < < < < < < < < Ientical to Bs of the inner ring of the same bearing Note: The tolerances on the outsie iameter, 1, of the flange on the outer ring are given in stanar ISO 492. (1) oes not apply to bearings with a flange outer ring. 30

27 Ball thrust bearings - Normal tolerance class Stanar ISO 199 References mp Vp mp Vp Si Se Ts Nominal bore iameter of the shaft ring of a singleirection thrust bearing eviation in the mean bore iameter of the shaft ring of a single-irection thrust bearing, in an isolate plane Variation in the bore iameter of the shaft ring of a single-irection thrust bearing, in an isolate raial plane Nominal outsie iameter of the housing ring eviation in the mean outsie iameter of the housing ring in an isolate plane Variation in the outsie iameter of the housing ring in an isolate raial plane Variation in thickness between the bearing raceway an the contact face of the shaft ring Variation in thickness between the bearing raceway an the contact face of the housing ring Variation in total height T Shaft ring an height of thrust bearing mp > upper lower max max upper lower Vp Si Ts 31

28 General ata Bearing manufacturing precision (continue) Housing ring mp Vp Se > upper lower max max Ientical to Si of the shaft ring of the same type Tapere bores: 1:12 an 1:30 taper Stanar ISO 492 Nominal half-angle at apex of cone: 1/12 : α = = = ra 1/30 : α = = = ra ' Nominal iameter at the largest theoretical with of the bore: 1/12 : = + B / 12 1/30 : = + B / 30 B Theoretical tapere bore 'mp - mp 2 The tolerances on a tapere bore comprise: a tolerance on the mean iameter, given by the limits of the actual eviation of the mean iameter at the smallest theoretical with of the bore mp, a taper tolerance, given by the limits of the eviation between the mean iameter eviations at each en of the bore mp - mp, a tolerance on the iameter variation Vp given by a maximum value applicable in any raial plane of the bore + mp B ' + 'mp Tapere bore with mean iameters an eviations 32

29 Tapere bore, 1:12 taper mp mp - mp Vp (1)(2) upper lower upper lower max < < < < < < < < < < < < < (1) Applies to any isolate raial plane of the bore. (2) oes not apply to iameter series 7 an 8. Tapere bore, 1:30 taper mp mp - mp Vp (1)(2) upper lower upper lower max 50 < < < < < < < < (1) Applies to any isolate raial plane of the bore. (2) oes not apply to iameter series 7 an 8. 33

30 General ata Bearings initial raial internal clearance Raial clearance of raial contact bearings. efinition The internal raial clearance is the loa-free isplacement of one ring with respect to the other in the raial irection. Raial contact bearings to run correctly must have a slight raial clearance. Raial contact bearings have a built in internal clearance. When the bearing is fitte, a resiual clearance must remain. This raial clearance leas to an axial clearance (except in the case of cylinrical roller bearings). Internal raial clearance groups The clearance tolerances of groups are stanar (ISO 5753 stanar). The internal clearance group is chosen accoring to the application specifications an the resiual clearance calculation. Raial Bearing clearance esignation Other manufacturers Type Group SNR suffix Normal clearance N Suitable for low or moerate loas, normal interference fit of only one of the two rings, normal temperatures. Increase clearance C3 C4 C5 Clearance frequently use in the following cases: - tight interference fit of one ring or slight on both rings - possible misalignment, bening of shaft - to increase the contact angle of highly-loae raial contact ball bearings - high temperatures Clearance groups 4 an 5 are use in the above cases when group 3 is insufficient. Reuce clearance 2 C2 This clearance group is use (rarely) when very goo guiance with reuce clearance is require, an in applications with alternating loas an high impact levels. The use of this clearance group is highly particular because its aim is usually to cancel the bearing operating clearance. The stuy of the assembly (alignment), fits an operating conitions (temperature, spee) must be carrie out with particular care. Consult SNR. 34

31 Axial clearance of angular contact bearings Recoene axial clearance By construction, single-row angular contact ball bearings or tapere roller bearings have no internal clearance. The bearing clearance is zero when its inner ring, rolling elements an outer ring are in contact without any loa applie. Reference loa line with no clearance Reference loa line with no clearance When the bearing is mounte it can be given a clearance or a preloa with respect to this reference position. The figure opposite shows the positions of the components when there is an axial clearance. Axial clearance Reference Axial clearance Reference loa line with clearance Reference Magnitue of the axial clearance of an assembly in operation The value of the initial clearance on fitting must take into account the operating conitions. The relation between the axial clearance an raial clearance of a two-bearing assembly is inicate for each type of bearing in chapter corresponing to each family. = bearing bore Ja = axial clearance < 20 Ja = 0.03 up to < 80 Ja = 0.05 up to < 120 Ja = 0.05 up to 0.25 > 120 Ja = 0.10 up to