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Bearing terminology To better understand frequently used bearing terms, definitions are provided below and explained with the help of drawings. A detailed collection of bearing specific terms and definitions can be found in ISO 5593:1997: Rolling bearings - Vocabulary. Bearing arrangement ( fig) 1 Cylindrical roller bearing 2 Four-point contact ball bearing 3 Housing 4 Shaft 5 Shaft abutment shoulder 6 Shaft diameter 7 Locking plate 8 Radial shaft seal 9 Distance ring 10 Housing bore diameter 11 Housing bore 12 Housing cover 13 Snap ring Following terminology is used for the different parts of a rolling bearing.

1 2 3 4 5 6 7 8 9 10 11 12

Radial bearings ( fig / fig) Inner ring Outer ring Rolling element: ball, cylindrical roller, needle roller, tapered roller, spherical roller Cage Capping device Seal – made of elastomer, contact (shown in figure) or non-contact Shield – made of sheet steel, non-contact Outer ring outside diameter Inner ring bore Inner ring shoulder diameter Outer ring shoulder diameter Snap ring groove Snap ring Outer ring side face

13 14 15 16 17 18 19 20 21 22 23

Seal anchorage groove Outer ring raceway Inner ring raceway Sealing groove Inner ring side face Chamfer Mean bearing diameter Total bearing width Guiding flange Retaining flange Contact angle

Thrust bearings ( fig) 24 Shaft washer 25 Rolling element and cage assembly 26 Housing washer 27 Housing washer with sphered seat surface 28 Sphered seat washer

Bearing data - general Designations Designations of rolling bearings consist of combinations of figures and/or letters, the significance of which is not immediately apparent. Therefore, the SKF designation system for rolling bearings will be described and the significance of the more common supplementary designations explained. Very specific bearing types, such as fixed-section bearings, slewing bearings or linear bearings are not covered. These designations differ

sometimes considerably from the system described here. Bearing designations are divided into two main groups: designations for standard bearings and designations for special bearings. Standard bearings are bearings that normally have standardized dimensions, whereas special bearings have special dimensions dictated by customer demands. These customized bearings are also referred to as "drawing number" bearings and they will not be covered in detail in this section. The complete designation may consist of a basic designation with or without one or more supplementary designations (

fig).

The complete bearing designation, i.e. the basic designation with supplementary designations is always marked on the bearing package, whereas the designation marked on the bearing may sometimes be incomplete, e.g. for manufacturing reasons. Basic designations identify the – type – basic design – standard boundary dimensions of a bearing. Supplementary designations identify – bearing components and/or – variants having a design and/or feature(s) that differ in some respect from the basic design.

Supplementary designations may precede the basic designation (prefixes) or follow it (suffixes). Where several supplementary designations are used to identify a given bearing, they are always written in a given order (

fig).

The list of supplementary designations presented in the following is not exhaustive, but includes those most commonly used.

Designations - Basic designations All SKF standard bearings have a characteristic basic designation, which generally consists of 3, 4 or 5 figures, or a combination of letters and figures. The design of the system used for almost all standard ball and roller bearing types is shown schematically in diagram 1. The figures and combinations of letters and figures have the following meaning: – The first figure or the first letter or combination of letters identifies the bearing type; the

actual bearing type can be seen from the presentation ( diagram 1). – The following two figures identify the ISO Dimension Series; the first figure indicates the Width or Height Series (dimensions B, T or H respectively) and the second the Diameter Series (dimension D). – The last two figures of the basic designation give the size code of the bearing; when multiplied by 5, the bore diameter in millimetres is obtained. But there is no rule without some exceptions. The most important ones in the bearing designation system are listed below. 1. In a few cases the figure for the bearing type and/or the first figure of the Dimension 2.

3.

4.

5.

Series identification is omitted. These figures are given in brackets in diagram 1. For bearings having a bore diameter smaller than 10 mm or equal to or greater than 500 mm, the bore diameter is generally given in millimetres and is not coded. The size identification is separated from the rest of the bearing designation by an oblique stroke, e.g. 618/8 (d = 8 mm) or 511/530 (d = 530 mm). This is also true of standard bearings according to ISO 15:1998 that have bore diameters of 22, 28 or 32 mm, e.g. 62/22 (d = 22 mm). Bearings with bore diameters of 10, 12, 15 and 17 mm have the following size code identifications: 00 = 10 mm 01 = 12 mm 02 = 15 mm 03 = 17 mm For some smaller bearings having a bore diameter below 10 mm, such as deep groove, self-aligning and angular contact ball bearings, the bore diameter is also given in millimetres (uncoded) but is not separated from the series designation by an oblique stroke, e.g. 629 or 129 (d = 9 mm). Bore diameters that deviate from the standard bore diameter of a bearing have always been given uncoded, in millimetres with up to three decimal places. This bore diameter identification is part of the basic designation and is separated from the basic designation by an oblique stroke, e.g. 6202/15.875 (d = 15,875 mm = 5/8 in).

Series designations Each standard bearing belongs to a given bearing series, which is identified by the basic designation without the size identification. Series designations often include a suffix A, B, C, D or E or a combination of these letters e.g. CA. These are used to identify differences in internal design, e.g. contact angle. The most common series designations are shown in diagram 1 above the bearing sketches. The figures in brackets are not included in the series designation.

Diagram 1 Designations - Basic designations - Special bearings The basic designation of special bearings is usually the number of the drawing of the bearing. These Drawing Numbers are usually 6 or 7-figure numbers and do not generally give any indication of the bearing type, size or design. Bearings, the design of which has been modified from the original design, often have a suffix A to E or a combination of these letters, e.g. AB, added to the original Drawing No. The meaning of these suffixes is specific to the actual bearing and reference must be made to the actual drawing. More recently, Drawing Numbers have been prefixed by Bxxx, where B stands for bearing and the other three positions identify the bearing type. In some cases the fourth

letter is omitted. Even more recently four figure numbers preceded by a prefix identifying the bearing type and separated from it by a hyphen, e.g. BB1-3001 have been introduced instead of the 6 or 7-figure Drawing Numbers.

Designations - Identification of bearing type 0 Double row angular contact ball bearings 1 Self-aligning ball bearings 2 Spherical roller bearings, spherical roller thrust bearings 3 Tapered roller bearings 4 Double row deep groove ball bearings 5 Thrust ball bearings 6 Single row deep groove ball bearings 7 Single row angular contact ball bearings 8 Cylindrical roller thrust bearings BK C HK K N

Drawn cup needle roller bearings with closed end CARB toroidal roller bearings Drawn cup needle roller bearings with open ends Needle roller and cage thrust assemblies Cylindrical roller bearings A second and sometimes a third letter are used to identify the configuration of the flanges, e.g. NJ, NU, NUP; double or multi-row cylindrical roller bearing designations always start with NN. NA Needle roller bearings with boundary dimensions to ISO 15 NK Needle roller bearings QJ Four-point contact ball bearings T Tapered roller bearings, a few metric sizes to ISO 355-1977 Inch tapered roller bearings with dimensions to an ABMA series are designated according to a different system to ANSI-ABMA Standard 19 (see also under prefix K-) Designations - Supplementary designations - Prefixes Prefixes are used to identify components of a bearing and are usually then followed by the designation of the complete bearing, or to avoid confusion with other bearing designations. For example they are used in front of designations for tapered roller bearings according to a system described in ANSI/ABMA Standard 19 for (predominantly) inch bearings. AR- Ball or roller and cage assembly

E2. GS IRK K-

SKF Energy Efficient bearings Housing washer of a cylindrical roller thrust bearing Inner ring of radial bearing Cylindrical roller and cage thrust assembly Inner ring with roller and cage assembly (cone) or outer ring (cup) of inch tapered roller bearing belonging to an ABMA standard series L Separate inner or outer ring of a separable bearing OR- Outer ring of radial bearing R Inner or outer ring with roller (and cage) assembly of a separable bearing W Stainless steel deep groove ball bearing WF Deep groove ball bearing of stainless steel with external flange on outer ring WS Shaft washer of a cylindrical roller thrust bearing ZE Bearing with SensorMount® feature