a90 part c - bsctraining.bsc.com.au/training/a9000/a9000/a90 set c.pdf · part c – ball bearings...

PART C – Ball Bearings Series 90 Training

A90 Series Correspondence Lessons

PART C

Ball Bearings

Lesson A9007 Single Row Deep Groove Ball Bearings Lesson A9008 Angular Contact Ball Bearings Lesson A9009 Other Standard Ball Bearings

PART C – Ball Bearings Series 90 Training

PART C Ball Bearings

Lessons A9007 to A9009

Correspondence Course LESSON A9007

Single Row Deep Groove Ball Bearings

LESSON A9007 Series 90 Training

Table of Contents 16000 Series Bearings 8 Medium Series, Imperial 16 6000 Series Bearings 6,17 Medium Series, Metric 6 600 Series Bearings 7,17 Metric Numbering System Chart 18 AFBMA Bearings 5,13 Normal Clearance 12 CONRAD Bearing 3 Narrow Series 8 CONRAD Assembly Method 4 Non-adjustable Clearance 3,12 Contact Seals 11 Outside Diameter 3 Corner RADII 3 Point Contact Rolling Motion 3 Deep Groove Ball Bearings 3 RADII 3 DU suffix 10 RLS (Light) Series 16 Extra Light Series 16 RMS (Medium) Series 16 Extra Wide Series 8 Seals 10 Felt Seal Ball Bearing Chart 21 Shields 10 Imperial Deep Groove Ball Brgs 15 Single Row Deep Groove Ball 3 Imperial Numbering System Chart 20 Snap Rings 11 Int’l Standards Organisation (ISO) 5 Standardization 4 Internal Clearance 12 V suffix 10 ISO Numbering Systems 5 Width 3 Light Series, Imperial 16 XLJ series 16 Light Series, Metric 6 Z suffix 10

Structured Training Plan

This lesson is the seventh of a series of Correspondence lessons in the BSC Structured Training Plan.

Objectives

The objective of this lesson is to elaborate on the information taught in Lesson 4 and to explain the numbering system used by BSC to identify single row deep groove ball bearings.

Pre-requisites

Completion of Correspondence Lessons A9001 - A9006.

Methods

Achievement of the objectives is by presentation of lessons in an 'On-Line' or Correspondence Course format. The lessons in a Correspondence Course style are conducted for internal students in a lecture situation.

Assessment

A formal test is provided with this lesson.

LESSON A9007 – Single Row Deep Groove Ball Bearings Series 90 Training page 2


Single Row Deep Groove Ball Bearings

In Lesson 4, you learnt the terminology used to identify the various parts of bearings and also some important dimensions. The most important of these dimensions are INSIDE DIAMETER (or BORE diameter), OUTSIDE DIAMETER and WIDTH and these are clearly identified in the diagram to the right.

It is important to learn the names of the parts of the bearing - Inner Ring, Outer Ring, Rolling Elements (in this case, Balls) and Cage (sometimes referred to as the retainer or separator).

Ball Bearing

Remember, Ball Bearings convert sliding friction into Point CONTACT rolling motion with spherical (round) balls. To enable the balls to roll, the ball bearing has a minute gap between the inner and outer rings and the balls. This is referred to as internal clearance and in ball bearings it is fixed by the bearing design and cannot be altered. The correct name for this fixed clearance is NON-ADJUSTABLE INTERNAL RUNNING Clearance.

The outer corners of the outer ring and the inner corners on the inner ring are rounded and this is called the bearing's corner RADII.

Most standard ball bearings use a stamped steel cage to properly space the balls around the bearing. Special precision made cages are used for applications involving extreme operating conditions, e.g. high loads, high speeds, shock loads or excessive vibration. Some are precision machined from steel or bronze. Others are stamped from brass and still others are now being made from high impact high strength plastics.

Although there are numerous types and sizes of ball bearings, the basic design from which all others may be considered variations, is called the CONRAD bearing (after the name of the inventor). The conrad bearing features a single row of precision ground spherical balls which roll radially around the bearing located between deep groove raceways in the inner and outer rings. Because of this feature, CONRAD bearings are commonly referred to as DEEP GROOVE BALL BEARINGS. The balls are evenly spaced within a cage.


DEEP GROOVE or CONRAD ball bearings basically support RADIAL LOADS but can take MODERATE THRUST LOADS in either direction, because of their deep raceways.

The load carrying capacity of deep groove ball bearings is limited by the number of balls that can be introduced between the rings. The balls are introduced as shown below:-

Conrad Assembly Method

A) The inner ring is

moved off centre from the outer ring.

B) The Balls are inserted in the gap between the rings.

C) The inner ring is moved back on

centre.

D) A cage is installed to maintain equal

spacing between the balls.

Remember, ball bearings are manufactured in both IMPERIAL and METRIC dimensions. It is important that you always check inner and outer ring dimensions rather than ball dimensions since. Whilst these measurements are standardized by international conventions, internal component sizes may vary between brands.

Standardization

Standard ball bearings of both Imperial and Metric dimensions are manufactured to international dimensions regardless of their country of origin.

In order to brand and identify each individual bearing, certain numbering systems were introduced. Some factories developed their own systems and others used a system which was common to many, whilst yet others used a combination of both. Despite the system used by an individual factory, there is always a key to be found somewhere to unravel what appears, at first sight, to be a series of confusing numbers, prefixes and suffixes.


METRIC DEEP GROOVE BALL BEARINGS - NUMBERS and CODES

In the main, we stock NSK and NBR brand metric deep groove ball bearings.

N.S.K manufacture to the Japanese equivalent of the I.S.O. (International Standards Organisation) standard. In fact most countries, except U.S.A. and Canada, manufacture to their equivalent of the I.S.O. standard. U.S.A. and Canada use the AFBMA (Anti-Friction Bearing Manufacturers Association) standard.

Bearings made to both I.S.O. AND AFBMA standards are so close that when one is replaced by the other, a similar performance in service will be given.

In 1993, AFBMA changed their name to ABMA (American Bearing Manufacturing Association). Their website includes an interesting summary of the history of bearings and the bearing industry.

I.S.O. Numbering Systems

Table A summarizes the I.S.O. numbering system and this covers all types of metric bearings. As we progress through these lessons we will explain the numbering systems in more detail for each individual bearing type.

In deep groove ball bearings, there are basically four series of bearings as below;

• Extra Light Series • Light Series • Medium Series • Heavy Series

The part numbers are made up of four digits which are sometimes followed by a suffix which we will explain later. The first digit is always a '6' which indicates that the bearing is a metric single row deep groove ball bearing. The second number indicates which series the bearing belongs to, thus:-

• Extra Light Series 60-- • Light Series 62-- • Medium Series 63-- • Heavy Series 64--

For bearings of 20mm inside diameter or more, the third and fourth numbers are arrived at by dividing the bore size by 5, thus a 20 mm bore bearing would have the number --04 and a 100mm bore would be --20.

Under the I.S.O. system, bearings of 20mm bore or more are manufactured in 5 mm increments but a smaller increment is required for bearings below 20mm. The following table shows bore sizes available and corresponding digits.


Digits - Bore Size

--00 10 mm --01 12 mm --02 15 mm --03 17 mm --04 20 mm

Between 20 mm and 110 mm, bearings are manufactured in 5 mm steps. From 110 mm to 200 mm the bore size increases in 10 mm steps while bore sizes of bearings over 200 mm increase in 20mm steps.

In recent years there has been a demand for additional sizes between 20 mm and 35 mm. These are now available and a hybrid numbering system has been utilized by using the first 2 digits from the 6000 series (60, 62, 63) and the actual bore size in millimetres, separated by a slash thus:

Bore Extra Light Series Light Series Medium Series

22 mm 60/22 62/22 63/22

28 mm 60/28 62/28 63/28

32 mm 60/32 62/32 63/32

These bore sizes are not manufactured in heavy series.

The above four series (60--, 62--, 63--, 64--) are collectively known as the '6000' series and they start at 10 mm bore.


600 Series

For bearings with a bore size smaller than 10 mm, there is a fifth series, collectively known as the '600' series. In this series, the first digit is always a 6 indicating deep groove ball bearing. The second digit is a 0, 2 or 3 indicating Extra Light, Light or Medium Series indicating Extra Light, Light or Medium Series respectively. The last digit is the actual bore size (not a code).

EXAMPLE: 627 -

• 6 = Deep Groove Ball Bearing • 2 = Light Series • 7 = 7 mm bore size

NSK also manufacture deep groove ball bearings in two further series - 6800 and 6900 series. These are smaller that the extra light series and are sometimes referred to as Extremely Light series. Here are some examples for comparison.

ID OD W

6004

20

42

12

6804 20 32 7

6904 20 37 9

6010

50

80

16

6810 50 65 7

6910 50 72 12


Narrow Series To add a bit of confusion, there are several 5 digit series of metric deep groove ball bearings. We will begin with the 16000 series. The inside diameter and outside diameter of these bearings is the same as the extra light series, but the width is reduced, hence, they are sometimes referred to as the NARROW series. The first digit is always a '1' whilst the rest of the part number is similar to the 6000 series.

EXAMPLE 16005 -

• 1 = 16000 series • 6 = Deep groove Ball Bearing • 0 = always a zero (extra light series) • 05 = 25 mm bore

Extra Wide Series

There is a limited range of bearings available in the extra wide series and these are used in special applications where a wider bearing size is required. The inside and outside dimensions of these bearings is identical to the standard ones but the width is greater. The extra digit occupies the second position and may be either a 2 or a 3.

The dynamic and static load ratings of these bearings are the same as the standard bearings they replace

The part numbers are 5 digit numbers and are always supplied in the 2 nitrile seal format which is indicated in this case by the suffix '2RS'. Less than 20 sizes are listed in our price list and in practice only a few of these are normally available from our stock. Some examples and comparisons are given below:

ID OD W

6001-2RS 12 28 8

63000-2RS 12 28 12

6201-2RS 12 32 10

62201-2RS 12 32 14

6301-2RS 12 37 12

62301-2RS 12 37 17

It is important to check the dimensions in a manufacturer’s catalogue before recommending a bearing from this series.


To recap, before we move on to the next section, the following series have been discussed so far:

• Extra light Series (68--, 69--) • Light Series (62-, 62--) • Narrow extra light Series (160--) • Medium Series (63-, 63--) • Extra Light Series (60-, 60--) • Heavy Series (64--) • Wide Series (620--, 622--, 623--, 630--)

Table A shows the complete range of bearings in the six series discussed above. Note that some series are not manufactured in all possible sizes.

Chart 1 summarises the Metric Bearing numbering system.


Shields, Seals, Rings and Ring Grooves

All of the '6000' series bearings are available with shields, seals, snap rings or a combination of all three. The '600' series are available with shields or seals but the '16000' series are only available as open bearings.

Shields, Seals and snap rings were discussed in detail in lesson 6. The information given below will help you to remember the main points and will also explain the part numbering system.

Shields

Shields are steel side plates attached to the outer ring that help prevent dirt from entering the bearing. When a shield is fitted, in most cases, the bearing number is stamped on the shield and not on the bearing.

A bearing with a single shield has the suffix 'Z' after the part number while two shields (one either side) are indicated by 'ZZ'. E.G. 6204Z, 6204ZZ.

Seals

Seals are similar to shields, except they are made from rubber. N.S.K. manufactures two types of seals - a non- contact type and a contact type.

A bearing with a single non-contact seal has the suffix 'V' while two non-contact seals (one either side) are indicated by 'VV'. For contact seals, the suffix is 'DU' (single contact seal) and 'DDU '(two contact seals).

BSC carries, in the main, non-contact ('V', 'VV') type sealed bearings.


Contact Seals

Contact seals are excellent in dust prevention and reasonable at waterproofing, and you will find from time to time, that this type of bearing is needed for a particular application.

Some 'DU' and 'DDU' type bearings may be in stock or alternatively you may have to order them in. Always check physical shelf stock for the equivalent 'VV' type first as we sometimes have to top up our stock with 'DDU's when 'VV's are in short supply. Also, some of the more popular contact seal type bearings are now stocked under their own stock number in addition to the non-contact type.

One point to note with contact seals, is that they limit high speed operation because the seal is actually touching the inner ring of the bearing.

Snap Rings

Snap Rings are metal rings which fit into a groove cut into the outside of the outer ring of a bearing. They are used to locate (hold in a fixed position) the bearing in a housing (see the diagram in lesson 6).

The suffix 'N' is used when a bearing has a snap ring groove cut into it. When the bearing is supplied with a ring the suffix becomes 'NR'.

You can, of course, have bearings which have a combination of shields or seals with a snap ring. The most common is to have a single shield with a snap ring and groove for which the suffix is 'ZNR' ('Z' for single shield, 'NR' for snap ring in groove). For this combination the snap ring is normally located on the opposite side to the shield.


Internal Clearance

Earlier in this lesson we talked about Non-adjustable Internal Running Clearance. This is factory set to a standard which is detailed in the manufacturers published tables and for convenience, is referred to as NORMAL clearance. Bearings are also available in other clearance levels and this is indicated by a C number which appears as a suffix in the part number, e.g. 6204 ZNR C3. Bearings with no suffix number showing are normal clearance.

NOTE - the clearance is not always marked on the bearing but will be marked on the box.

The suffixes for clearance are 'C1' to 'C5' with 'C1' having the smallest internal clearance and 'C5' the largest. The chart below might help to illustrate this point.

Internal Clearance Chart

SUFFIX CLEARANCE

C1 Clearance less than C2

C2 Clearance less than normal

(none) Normal Clearance

C3 Clearance greater than normal

C4 Clearance greater than C3

C5 Clearance greater than C4


AFBMA Bearings

Although these were once a popular series, it is unusual to find more that half a dozen sizes in stock, even in state warehouses. These Bearings have an alternative sealing arrangement with a combination of felt and steel shields. Most of these bearings are sourced from either NSK or Torrington-Fafnir but to distinguish them from the 6000 I.S.O. series we carry them under the old New Departure numbering system.

The series we carry are illustrated below:

8500 SERIES

Light series with a felt seal one side and an extended inner ring on the same side.

WC8500 SERIES

Same as 8500 series but the inner ring is slightly narrower that the outer ring.

87500 SERIES

Light series with a felt seal one side and a shield the other. Has an extended inner ring one side

WC87500 SERIES

Same as 87500 series but the inner ring is slightly narrower than the outer ring

8600 SERIES

Medium series with a felt seal one side and an extended inner ring one side.

WC8600 SERIES

Same as 8600 series but the inner ring is slightly narrower than the outer ring.


88500 SERIES Light series with a felt seal both sides and an extended inner ring both sides.

WC88500 Series

Same as 88500 series but the inner ring is only extended on one side.

88600 Series

Medium series with a felt seal both sides and an extended inner ring both sides.

WC88600 Series

Same as 88600 series but the inner ring is only extended on one side.

Bore Size

In all of the above series, the last two digits of the part number are a code for the bore size, and this code similar to the 6000 series bore code discussed previously. Thus, the bearings 8503, 87503, 88503, WC88603 0xc. all have a bore size of 17 mm.

For reference purposes, a full listing is available in Table 2 for the 87000 Series and Table 3 for the WC87000 Series.


Imperial Deep Groove Bearings

The introduction of the Metric system of measurement has meant that the old Imperial (Inch) system is becoming less important and the demand for imperial bearings is reducing. Whilst our normal source for these bearings is NSK-RHP and JAF, you are likely to find a variety of other brands on the shelf, We use either the I.S.O. numbering system or the RHP numbering code.

There are basically four series of bearings as below.

• Small R Series I.S.O. Numbering system • Extra Light XLJ Series RHP Numbering system • Light Series RLS Series I.S.O. Numbering system • Medium RMS Series I.S.O. Numbering system

R (Small) Series

In this series the letter "R" is followed by a code for the bore size that is the number of sixteenths of an inch that make up the bore size.

Shielded bearings have the suffix 'Z' or 'ZZ' and sealed bearings have the suffix 'RS' or '2RS'. The seals are contact type.

Note that when seals or shields are fitted to imperial bearings, the bearings are wider than the open type.

R Series SIZE TABLE

Bore size(inch) Open One Shield Two Shields One Seal Two Seals

1/8 R2 R2 Z R2 ZZ R2 RS R2 2RS

3/16 R3 R3 Z R3 ZZ R3 RS R3 2RS

1/4 R4A R4A Z R4A ZZ R4A RE R4A 2RS



and so on in 1/8" increases up to 1-1/2" Note - In the case of the 1/4 bore size, the 'A' after the bore code is to distinguish it from a R4 which has a different outside diameter.


XLJ (Extra Light) Series

This series runs from 1-1/2" bore to 6-1/2" bore. The numbering system is purely the bore size, expressed in fractions, following the letters XLJ. Shielded or sealed bearings are not available in this series.

A point to note is that from part number XLJ 4 on the letter 'E' (for English), is added after the part number for whole inch sizes only to show that the size is inches and not millimeters. Thus: XLJ 5E, XLJ 5-1/2, XLJ 6E.

XLS Series SIZE TABLE Bore Size (inch) Part Number (open)

1-1/2 XLJ 1-1/2 1-5/8 XLJ 1-5/8 1-3/4 XLJ 1-3/4 1-7/8 XLJ 1-7/8

and so on.

RLS (Light) Series

This series runs from 1/2" bore to 6" bore. The part number is made up of the letters 'RLS' followed by a code for the bore size that is the bore size expressed in eights of an inch.

Shielded bearings have the suffix 'Z' or 'ZZ' and sealed bearings have the suffix 'RS' or '2RS'

This series is also available with snap rings and this is indicated with the suffix 'NR'.

RLS Series SIZE TABLE

Bore size(inch) Open One Shield TwoShields One Seal Two Seals

1/2 RLS4 RLS4 Z RLS4 ZZ RLS4 RS RLS4 2RS

5/8 RLS5 RLS5 Z RLS5 ZZ RLS5 RS RLS5 2RS

3/4 RLS6 RLS6 Z RLS6 2Z RLS6 RS RLS6 2RS

7/8 RLS7 RLS7 Z RLS7 2Z RLS7 RS RLS7 2RS

and so on.

RMS (Medium) Series

This series runs from 3/8" bore to 5" bore. In all other respects, it is the same as the RLS numbering system.

For a comprehensive list of the Imperial numbering system, refer to Chart 2.

NOTE - RLS and RMS numbering systems are used by different manufacturers for completely different bearings. For instance, FAG manufacture imperial cylindrical Roller Bearings using the RLS and RMS numbering systems. The bearings are not interchangeable.


CHART 1. METRIC BEARING NUMBERING SYSTEM CHART Based on the I.S.O. numbering system (I.S.O. stands for International Standards Organisation), the main part of the numbering system may have either 3, 4 or 5 digits.

Three digits Four digits Five digits

1st digit - type 1st digit - type 1st digit -type

2nd digit - series 2nd digit - series 2nd & 3rd digit -series

3rd digit - inside diameter 3rd & 4th digit inside diameter

4th & 5th digit -inside diameter

1st digit - Type (dashes indicate number of digits)

1 - - - Self Aligning Ball Bearing

1 - - - -

Narrow Series Deep Groove Ball Bearing

2 - - - Self Aligning Ball Bearing

2 - - - -

Spherical Roller Bearing

3 - - - Double Row Angular Contact Ball Bearing

3 - - - -

I.S.O. Metric Tapered Roller Bearing

4 - - - Double Row Ball Bearing

5 - - - Double Row Angular Contact Ball Bearing

5 - - - -

Thrust Ball Bearing

6 - - Single Row Deep Grove Ball Bearing - bore less than 10mm

6 - - - Single Row Deep Grove Ball Bearing

7 - - - Angular Contact Ball Bearing

BL- - - Maximum Capacity Ball Bearing (always BL)

NU- - -

Cylindrical Roller Bearing (or N, NC, NF, NJ, NUP, RNU)

NU- - - -

Wide Series Cylindrical Roller Bearing (or NF, NJ, NUP)


CHART 1. METRIC BEARING NUMBERING SYSTEM CHART (cont.)

2nd digit (in 3 & 4 digit no's)

0 Extra light series

2 Light series

3 Medium series

4 Heavy series

2nd digit (in 5 digit no's) 3rd digit (in 5 digit no's)

(width series) (Diameter series)

1 Very Narrow series 0 Very Small series

2 Narrow series 1 Small series

3 Wide series 2 medium series

4 Extra Wide series

3 Large series

Bore Size

00 10 mm

01 12 mm

02 15 mm

03 17 mm

20 mm and over - bore size x 5


CHART 2. IMPERIAL BEARING NUMBERING SYSTEM CHART To use this chart look for the prefix in the Bearing type list, then read the explanation of how the remainder of the part number relates to the bore size.

Bearing Type List

LETTERS TYPE DESCRIPTION SIZE

FT Ball Extra light thrust (Flat raceways) I

LJT Ball Light journal thrust I

LLRJ Roller Light roller journal I

LRJ Roller Light roller journal I

LRJA Roller Light roller journal I

LT Ball Light Series thrust I

MJT Ball Medium Journal thrust I

MMRJ Roller Medium roller journal I

MMRJN Roller Medium roller journal I

MRJ Roller Medium roller journal I

MRJA Roller Medium roller journal I

MT Ball Medium series thrust I

NLJ Ball Self aligning light series I

NMJ Ball Self aligning medium series I

QJM Ball Duplex type single row angular contact I

R Ball Small series S

RLS Ball Rigid light series E

RMS Ball Rigid medium series E

XLJ Ball Extra light journal I

XLRJ Roller Extra light Journal I

XLT Ball Extra light thrust (grooved raceways) I

E - code derived from size expressed in eights of an inch I - size in inches (4 inch and larger carry the suffix "E") S - code derived from size expressed in sixteenths of an inch Note - the above numbering systems are a mixture of I.S.O. and RHP numbers. Always check the bearing type - Ball or Roller - against the above list as well as the letter prefix. An example of the danger here is the RLS series which we take to be rigid light series ball bearing but which is a roller bearing - light series under the FAG system.


TABLE 2. SINGLE ROW BALL BEARINGS 87 and 88 SERIES

BORE - d

O. D. - D

WIDTH of OUTER RING

- Wo

WIDTH of INNER RING

- Wi

OVER ALL

Width

mm inch mm inch mm inch mm inch inch

Felt seal Ball

Bearing

19 0.748 8 0.3150 9.804 0.3860 0.406 87035 5 0.1969 19 0.748 8 0.3150 12.624 0.4970 88035

19 0.748 8 0.3150 9.804 0.3860 0.406 87306

24 0.9449 8 0.3150 9.804 0.3860 0.406 87006

19 0.748 8 0.3150 12.624 0.4970 88036 6 0.2362

24 0.9449 8 0.3150 12.624 0.4970 87006

22 0.8661 8 0.3150 9.804 0.3860 0.406 87037

24 0.9449 8 0.3150 9.804 0.3860 0.406 87007

22 0.8661 8 0.3150 12.624 0.4970 88037 7 0.2756

24 0.9449 8 0.3150 12.624 0.4970 88007

22 0.8661 8 0.3150 9.804 0.3860 0.406 87038

24 0.9449 8 0.3150 9.804 0.3860 0.406 87008

22 0.8661 8 0.3150 12.624 0.4970 88038 8 0.315

24 0.9449 8 0.3150 12.624 0.4970 88008

26 1.0236 8 0.3150 0.3860 0.406 87039

30 1.1811 9 0.3543 12.2 0.4800 0.500 87009

26 1.0236 8 0.3150 12.624 0.4970 88039 9 0.3543

30 0.1811 9 0.3543 16.401 0.6457 88009

30 1.1811 9 0.3543 12.2 0.4800 0.5 87500 10 0.3937 30 1.1811 9 0.3543 16.4 0.6457 88500

12.2 0.4800 0.5 87011 11 0.4331 32 1.2598 10 0.3937 15.4 0.6063 88011

12.2 0.4800 0.5 87501 12 0.4724 32 1.2598 10 0.3937 15.4 0.6063 88501

12.2 0.4800 0.5 87013 13 0.5118 32 1.2598 10 0.3937 15.4 0.6063 88013

12.2 0.4800 0.5 87014 14 0.5512 35 1.378 11 0.4331 14.4 0.5669 88014

12.2 0.4800 0.5 87502 35 1.378 11 0.4331 14.4 0.5669 88502 15 0.5906

42 1.6535 13 0.5118 17 0.6693 88602


TABLE 2. SINGLE ROW BALL BEARINGS 87 and 88 SERIES – cont.

BORE - d

O. D. - D

WIDTH of OUTER RING

- Wo

WIDTH of INNER RING

- Wi

OVER ALL

Width

mm inch mm inch mm inch mm inch inch

Felt seal Ball

Bearing

12.2 0.4800 0.5 87016 16 0.6299 35 1.378 11 0.4331 14.4 0.5669 88016

13.67 0.5380 0.563 87503 40 1.5748 12 0.4724 16.6 0.6536 88503 17 0.6693

47 14 0.5512 18 0.7087 88603

15.24 0.6000 0.625 87504 47 1.8504 14 0.5512 17.8 0.6988 88504 20 0.7874

52 2.0472 15 0.5906 23 0.9055 88604

15.24 0.6000 0.625 87505 52 2.0472 15 0.5906 16.8 0.6594 88505 25 0.9843

62 2.4409 17 0.6693 25 0.9843 88605

15.24 0.6000 0.625 87026 26 1.0236 52 2.0472 15 0.5906 16.8 0.6594 88026

19 0.7480 0.787 87506 62 2.4409 16 0.6299 24 0.9449 88506 30 1.1811

72 2.8346 19 0.748 27 1.0630 88606

20 0.7870 0.827 87507

88507 72 2.8346 17 0.6693 25 0.9843

88107 35 1.378

80 3.1496 21 0.8268 29 1.1417 88607

88128 38.98 1.5346 80 3.1496 21 0.8268 27.51 1.0831 1.0831

88128R

24 0.9450 0.945 87508 80 3.1496 21 0.8267 27 1.0630 88508 40 1.5748

90 3.5433 23 0.9055 31 1.2205 88608

24 0.9450 0.945 87509 85 3.3465 21 0.8267 27 1.0630 88509 45 1.7717

100 3.937 25 0.9843 35 1.3780 88609

26 1.0240 1.024 87510 50 1.9687 90 3.5433 22 0.8661 30 1.1811 88510


TABLE 3. SINGLE ROW BALL BEARINGS WC SERIES

BORE - d

O. D. - D

WIDTH OF OUTER RING -

Wo

WIDTH OF INNER RING –

Wi

mm inch mm inch mm inch mm inch

Felt seal Ball Bearing

12.192 0.48 WC 87500 10 0.3937 30 1.1811 12.7 0.5

16.4 0.6457 WC88500

12.192 0.48 WC87011 11 0.4331 32 1.2598 12.7 0.5

15.4 0.6063 WC88011

12.192 0.48 WC87501 12 0.4724 32 1.2598 12.7 0.5

15.4 0.6063 WC88501

12.192 0.48 WC87013 13 0.5118 32 1.2598 12.7 0.5

15.4 0.6063 WC88013

12.192 0.48 WC87014 14 0.5512 35 1.378 12.7 0.5

14.4 0.5669 WC88014

12.192 0.48 WC87502 15 0.5906 35 1.378 12.7 0.5

14.4 0.5669 WC88502

12.192 0.48 WC87016 16 0.6299 35 1.378 12.7 0.5

14.4 0.5669 WC88016

13.665 0.538 WC87503 17 0.6693 40 1.5748 14.3 0.563

16.6 0.6536 WC88503

15.24 0.6 WC87504 20 0.7874 47 1.8504 15.875 0.625

17.75 0.6988 WC88504

15.24 0.6 WC87505 25 0.9843 52 2.0472 15.875 0.625

16.8 0.6594 WC88505

15.24 0.6 WC87026 26 1.0236 52 2.0472 15.875 0.625

16.8 0.6594 WC88026

19 0.748 WC87506 30 1.1811 62 2.4409 20 0.787

24 0.9449 WC88506

20 0.787 WC87507 35 1.378 72 2.8346 21 0.827

25 0.9843 WC88507

24 0.945 WC87508 40 1.5748 80 3.1496 24 0.945

27 1.063 WC88508

24 0.945 WC87509 45 1.7717 85 3.3465 24 0.945

27 1.063 WC88509

26 1.024 WC87510 50 1.9687 90 3.5433 26 1.024

30 1.1811 WC88510


A9007 – Questionnaire

Name:

Branch (eg QAA)

Employee No (from Payslip):

Date:

Single row deep groove ball bearings

Questions Answers

Q1 What dimensions are usually specified when identifying Ball Bearings, and in what order?

A. Ball diameter, shaft diameter, Width

B. Inside diameter, outside diameter, Width

C. Outside diameter, Inside diameter, Width

D. Part number, dimensions, application

E. Width, outer diameter, inner diameter

Q2 The minute gap between the outer ring and the rolling elements is called the ...?

A. Internal clearance

B. External clearance

C. Running space

D. Raceway

Q3 Whilst most standard bearings are supplied with a pressed steel cage, cages made from precision machines bronze, steel and brass and high impact, high strength plastic are also available. Select three situations where one of these alternatives might be desirable:

A. High loads

B. High speeds

C. Shock loads

D. Excessive vibration

E. Dirty conditions

Q4 Ball bearings are sometimes referred to as Conrad bearings. To what does this refer

A. Application where the bearing is used.

B. The brand name of the bearing.

C. The method of assembly


A9007 – Questionnaire (cont.)

Name: Branch (eg QAA)


Date:


Q5 What are the four main series for metric bearings under the I.S.O. system?

A. Small series

B. Extra light series

C. Light series

D. Medium series

E. Heavy series

Q6 Tick the available bore sizes of a standard metric ball bearing, Light Series, from 10 mm to 25 mm and from 90 mm to 220 mm.

A. 10mm B. 11mm C. 12mm D. 15mm

E. 16mm F. 17mm G. 20mm H. 22mm

I. 25mm J. 90mm K. 95mm L. 100mm

M. 105mm N. 110mm O. 115mm P. 120mm

Q. 130mm R. 140mm S. 150mm T. 160mm

U. 170mm V. 180mm W.

190mm X. 200mm

Y. 210mm Z. 220mm





Date:


A. 16001 Series

A. Narrow

B. Small

C. Medium

B. 6004

Bore size

A. 4 mm

B. 10mm

C. 20mm

C. 60/22

Outside diameter

A. 40 mm

B. 42 mm

C. 44 mm

D. 623

Bore size

A. 3 mm

B. 15 mm

C. 23 mm

E. 6206ZZ

Sealing type

A. 2 Metal Shields

B. 2 Non Contact Rubber

C. 2 Contact Rubber

F. 623ZNR

Explain ZNR

A. 2 Metal Shields, Groove

B. 1 Metal Shield, Snap ring and groove

C. Oil Groove

Q7 For each of the following bearings, give the attribute selected.

G. 87502

Sealing type

A. Felt one side, Shield Other side

B. Unsealed Bearing

C. Felt both sided





Date:


H. 6210VVC3

Explain C3

A. Standard Clearance

B. Greater than standard clearance

C. Less then standard clearance

I. WC88501

Describe inner ring

A. Extended on outer ring

B. Flush with outer ring

C. Extended on inner ring

J. R4A ZZ Series

A. Narrow series

B. Small series imperial

C. Small series metric

K. XLJ1-5/8 Bore size

A. 5/8 inches

B. 1-5/8 inches

C. 3/4 inch

Q7 For each of the following bearings, give the attribute selected. (cont.)

L. RMS5 2RS (JAF brand)

Sealing type

A. 2 Metal shields

B. 2 Non contact rubber

C. 2 Contact rubber

Q8 List the 4 series of bearing available in imperial size. A. Small series

B. Extra light series

C. Light series

D. Medium series

E. Heavy series




Angular Contact Ball Bearings


Table of Contents 3000 series 9 Face to Face 4 5000 series 10 Flush face ground 6 7000 series 5 Four Point Bearings 8 ABEC 7 super precision 6 G suffix 6 Angel Suffix 5 Imperial angular contact 7 Angular Contact Ball Bearings 3 Inch Numbering System 7 Back to Back Bearings 4 Light series (LJT) 7 Cage Suffix Description 5 LOC suffix 8 Combining Angular Contact 4 Magneto bearings 11 Contact angles 3 Matched Pairs 4 DA suffix 9 Medium series (MJT) 7 DB (back to back) 4 Metric Numbering System 5 DF (Face to Face) 4 MRC Bearings 10 DT (tandem) 4 Precision Angular Contact 6 DU suffix 7 QJ 200 Series (Metric Light) 8 Double row angular contact 9 QJ 300 Series (Metric Med) 8 Duplex 8 QJL Series (Imp Light) 8 EN Series 11 QJM Series (Imp Medium) 8 E Series 11 Tandem 4


This lesson is the Eighth of a series of Correspondence lessons in the BSC Structured Training Plan.

Objectives

The objective of this lesson is to teach students about the various types on Angular Contact Ball Bearings.

Pre-requisites


Methods


Assessment


LESSON A9008 – Angular Contact Ball Bearings Series 90 Training page 2



Angular contact ball bearings are made in many different designs and types and are designed to take Angular Contact Loads which was discussed in Lesson 6. An angular contact load is a combination of a radial load and a thrust load.

These bearings are sourced in the main from NSK (for metric bearings) and RHP (for imperial bearings). The range in bore is 10mm to 200mm for metric A/C bearings and 3/8" to 6-1/2" for imperial angular contact bearings.

The outer ring of angular contact bearings have a deep shoulder on one side of the ball and a small shoulder the other side, making the outer ring inseparable from the rest of the bearing.

On single row angular contact bearings, thrust can only be applied from the side that ensures that the balls remain in contact with the larger shoulder in the outer ring.

The bearings are manufactured to various contact angles ranging from 12 degrees off perpendicular (the right angle to the centre line of the shaft) to 40 degrees as illustrated in the diagram below. The larger the contact angle, the higher the thrust load capability.

The metric bearings that we stock in NSK brand have an angle of 40 degrees whereas the imperial bearings that we stock in RHP brand have an angle of 20 degrees off perpendicular.


Combining Angular Contact Bearings

Very often bearings are mounted together 'side by side'. To help describe the mounting of a pair of bearings, we refer to the thrust face of the outer ring as being the 'BACK' of the bearing.

When the "back" of a pair of bearings faces each other, or the "backs" are together, this is called "BACK TO BACK" mounting. The other side of the outer ring is called the "FACE" and therefore when two bearings are mounted with their "FACES" together, it is called "FACE TO FACE" mounting. The bearings can also be mounted in "TANDEM", in other words, both facing the same way.

When the bearings are to be mounted together, in any of the three ways above, they have to have precision ground faces.

FACE TO FACE (DF) - Takes radial load in either direction

- less rigidity, must be located in housing.

BACK TO BACK (DB) - Takes radial Load and thrust load in either

direction - high rigidity.

TANDEM (DT) - Takes radial load in one direction only.

Capacity to take thrust loads is increased to just over one and a half times that of a single bearing

Matched Pairs

In the past, if angular contact bearings were to be mounted side by side they had to be supplied "factory matched" in pairs to specifically suit one of the three types of mounting. Whilst there may still be some of these sets on our shelves, the improvement in manufacturing technology combined with the practice of "flush face" grinding of both sides of the bearings has made this practice unnecessary.

NSK use the suffix "G" (ground face) to denote this and RHP uses the suffix "U" (Universal facing). A detailed explanation is given later in this lesson.


Metric Numbering System

As mentioned above, we stock NSK metric angular contact ball bearings. The ISO code for metric ac ball bearings is "7000". The "7" identifies the series and the rest of the part number is then the same as used for deep groove ball bearings.

There are four series of metric angular contact bearings:

• Extra Light Series - 7000 series - e.g. part number 7003(17mm bore). • Light Series - 7200 series - e.g. part number 7204 (20mm bore). • Medium Series - 7300 series - e.g. part number 7305 (25mm bore). • Heavy Series - 7400 series - e.g. part number 7406 (30mm bore).

The heavy (7400) series is not really in demand these days and most manufacturers, including NSK, have ceased making them.

Angle Suffix

To identify the angle off perpendicular, a suffix is added after the part number. NSK make three different angles as below:-

• 30 degrees A • 40 degrees B • 15 degrees C

We stock those manufactured to an angle of 40 degrees off perpendicular, thus a bearing with a 20mm bore in the light series has the part number 7204B.

Cage Type

The type of cage is important in angular contact bearings as it affects the limiting speed of the bearings.

NSK manufacture these bearings with three different cages as below:

Cage Suffix Description

W Pressed Steel Cage - lowest grade

M Machined Brass Cage

T Phenolic Resin Cage - highest speed usually only in precision class 5 or better.

BSC stock the A/C bearings with pressed steel cages. Thus the full part number for a normal precision, 20mm bore light series, 40 degree off perpendicular, pressed steel cage angular contact bearing is 7204BW.

If the bearings are to be mounted together then they must be either factory matched or "flush face" ground on both sides of the bearings as explained above. Factory matched means the bearings are marked with one of three suffixes, DB (back to back), DF ( face


to face), or DT (tandem). These bearings can only be mounted in the way that is indicated by the suffix.

"Flush face" ground bearings can be supplied individually and the ground sides enable any two of these bearings to be used back to back, face to face, or in tandem. These bearings are often referred to as "universal" and many manufacturers use the suffix "U" to show that the bearing concerned has "flush face" ground sides.

However, NSK, and some other manufacturers use the suffix "G". Thus our standard 7204BW part number now becomes 7204BWG if it is "flush face" ground.

Precision Angular Contact Bearings

All of the bearings discussed so far in this series have been manufactured to standard precision or "normal" precision. Angular Contact bearings can be obtained in "higher" or better precisions with closer tolerances for the bearing dimensions.

The ISO code and the AFBMA code for the degree of precision vary only slightly from one another and they are considered similar. The codes are as follows:

ISO Code AFBMA Code (none) ABEC 1 standard precision (normal)

P6 ABEC 3 special precision P5 ABEC 5 special, seldom found now P4 ABEC 7 super precision

ABEC 9 ultra precision

Bearings in higher than standard precision are used for applications that require:

• 1) high speeds • 2) extreme running accuracy • 3) exceptional axial and radial rigidity

We are currently purchasing many of our requirements of precision angular contact bearings from NSK-RHP. An explanation of a typical part number, 7217TDUEP7 is:

• 7217 - Angular contact, Light series, 17mm bore • T - Laminated Fabric (Phenolic) cage • DU - Paired unit, universal facing • EP7 - Extra Precision to ABEC 7 (ISO 4)


Inch Numbering System

We stock RHP brand imperial angular contact bearings and as such use their numbering system.

There are two series:

• Light series LJT • Medium series MJT

The part number simply consists of the above letters followed by the bore size.

e.g., 1-1/8" bore Light series - part number LJT 1-1/8

1-1/2" bore Medium series - part number MJT 1/2

The angle off perpendicular is 20 degrees for standard (non precision) bearings. Bearings with 40 degrees off perpendicular can be obtained and bear the suffix "X6".

Bearing "flush face" ground also can be obtained and bear the suffix "U". Again, if they are supplied as factory matched pairs, they will bear one of the suffixes DF, DB, or DT and cannot be used any other way, except if they bear the suffix "DU"(meaning the pair can be mounted in any of the three ways).


DUPLEX (FOUR POINT) SINGLE ROW ANGULAR CONTACT BALL BEARINGS The term "duplex" has different meanings according to different manufacturers.

American manufacturers use the term "duplex" to mean that a pair of angular contact bearings is factory matched for mounting side by side. FAG and SKF also use the term "duplex" to indicate mounting.

English manufacturers, however, use the term "duplex" to mean a single row ball bearing with either a split inner or split outer ring used for thrust loads in either direction. FAG calls this bearing a "four point" bearing.

We source our "duplex (four-point)" bearings from NSK-RHP and therefore use their numbering systems. The bearings are made to both imperial and metric dimensions.

In the metric series, there is a light series and a medium series as below:

• Metric Light Series QJ 200 • Metric Medium Series QJ 300

The bore size code is exactly the same as that used for deep groove ball bearings. Thus 17mm bore light series has the part number QJ203.

In the imperial series, there are also two series:

• Imperial Light Series QJL • Imperial Medium Series QJM

These letters are then followed by the bore size in whole numbers and fractions. Thus 1-1/4" bore light series has the part number QJL 1-1/4.

For bearings greater than 4" bore, an "E" is added after whole numbers to mean imperial, e.g. QJL 4E, QJL 4-1/2, QJL 5E etc.

The suffix "loc" is used when the bearings have reduced outside diameters so that when mounted adjacent to cylindrical roller bearings of the same size the housings can be bored straight through to suit the roller bearings. The duplex "loc" bearings will take axial loading only.


DOUBLE ROW ANGULAR CONTACT BALL BEARINGS

There are basically three types of double row angular contact ball bearings:

1) With the load lines externally converging.

2) With the load lines externally diverging.

3) With a split inner ring and the load lines externally converging.

Normal Externally

Converging Externally Diverging Externally Converging

Split Inner Ring.

The bearings follow the same bore and outside diameter size as the deep groove conrad type bearings in the light, medium and heavy series. However, the width dimension is in inches and two single row A/C bearings together have a larger width dimension than one double row angular contact bearing.

Externally Converging

For externally converging double row A/C bearings, we use the ISO numbering systems:

• light series - 3200 • medium series - 3300 • heavy series - 3400

The code for the bore size is the same as deep groove ball bearings.

Seals and shields have the following suffixes:

• One Shield - Z • Two Shield - ZZ • One Seal - RS • Two Seals - 2RS • Snap Ring & Groove - NR

These bearings have a filling slot on one side of the bearing to allow more balls to be inserted into the bearing and can therefore carry a greater radial load. The slot can clearly be seen in this photograph. Care must be taken to ensure that thrust load is only applied to the side opposite that with filling slot.

For externally converging split inner ring double row A/C bearings we use the same numbering systems above but add the suffix "DA" immediately after the part number.


Externally Diverging

For externally diverging double row A/C bearings we use a "5000" numbering systems. thus:-

• Light Series - 5200 • Medium Series - 5300 • Heavy Series - 5400

Bore codes and sealing suffixes etc. are the same as for the "3000" series.

The standard "externally converging" and the reverse angle "externally diverging" A/C bearings have about equal radial load capacity, in the same size and series, but the standard has slightly more thrust load capacity than the reverse angle.

These series do not have filling slots and can take thrust load from either direction, but with lesser balls, the radial capacity is reduced. However, beware - some manufacturers do make them with filling slots. Fafnir use "W" suffix on their bearings with filling slot.

MRC bearings have a hole on the outer ring. This is for assembling the cage during manufacture and not for lubrication as many people think. The hole can be used for lubrication, but any standard bearing by any other manufacturer is suitable as a replacement.

When seals or shields are added some manufacturers also increase the width of the bearing. Take care. Note - Whilst the 3000 series are dimensionally interchangeable with the 5000 series, in almost all cases they do have different capacities and different costs.

If you offer a customer a 5200 series bearing in place of a 3200 series bearing you must advise him that the radial capacity is less. Also when offering a customer a 3200 series bearing in place of a 5200 series bearing you must point out that the bearing has limited thrust capacity in one direction, so care will need to be exercised to ensure that it is fitted the right way.

TAKE CARE WITH INA BRAND BEARINGS AS THEY ONLY MAKE THE 5200 AND 5300 SERIES BUT NUMBER THEM AS 3200 AND 3300 SERIES.


MAGNETO BEARINGS

Magneto bearings are not truly angular contact since they do not have the shoulder on the inner ring. Instead, they have a deep groove type inner ring although the raceway is shallower than the standard deep groove ball bearing. The outer ring has a shoulder on one side only, enabling the removal of the outer ring for ease of fitting. Inner rings and outer rings are interchangeable with ones of the same dimensions.

Compare this diagram with the one on page 3 of this lesson.

These bearings are capable of taking both radial and thrust load at the same time. They range in bore size from 4mm to 30mm and are usually sourced from NSK.

Thrust can only be applied to one side of the inner ring so that the ball is held against the shoulder of the outer ring.

Magneto Bearing Numbering Systems

There are two series of magneto bearings:

The "E" series has a "+" (positive) tolerance on the outside diameter of the bearing. By this we mean that the finished size of the outer ring is equal to or greater than the nominal size shown in the manufacturer’s catalogue.

The "EN" series is the same dimensionally as the "E" series except it has a "-" (negative) tolerance on the outside diameter of the bearing. Whilst the finished size may be only microns larger or smaller, this may be of importance to the equipment designers who wishes to achieve as near perfection as possible in their products.

The rest of the part number is simply the actual bore size in millimeters.

Thus, part number E12 tells us that it is a magneto bearing that has a plus tolerance on the outside diameter with a bore of 12mm.


A9008 - Questionnaire

Name:

Branch (eg QAA)


Date:


Questions Answers

Q1. Angular Contact type ball bearings are designed to carry a greater/lesser angular load than deep groove ball bearings.

A. Greater

B. Lesser

The angle of contact of NSK angular contact bearing is normally __________ degrees.

A. 40 Degrees

B. 30 Degrees

C. 25 Degrees

Q2.

This is shown by suffix _______. A. A

B. B

C. C

Q3. NSK also manufactures angular contact bearings with 30 degree angle off perpendicular (suffix ________) and a 15 degree angle (suffix_____).

30 Degree suffix

A. A

B. B

C. C

15 Degree suffix

A. A

B. B

C. C

Q4. When mounting angular contact bearings in pairs to take radial and thrust loads in one direction only the mounting method is known as __________.

A. Externally converging

B. Externally diverging

C. Tandem

Q5. NSK manufacture angular contact bearings with pressed steel, machined brass or __________ Cages.


A9008 – Questionnaire (cont.) Name: Branch (eg

QAA) Employee No (from Payslip):

Date:


Q6. The suffix BWG on an NSK angular contact bearing indicates: (tick all applicable)

A. 25 degree contact angle

B. 40 Degree Contact Angle

C. Phenolic resin cage

D. Pressed steel cage.

E. Ground faces

F. Magneto bearing

Q7. Single row metric angular contact bearings part numbers carry the first digit no ___________to indicate the type.

A. 3

B. 5

C. 7

Q8. A 1/2 bore medium series A/C. bearing would be a part no. _________. (using the NSK-RHP. numbering system)

A. MJT 1/2

B. LJT 1/2

C. QLM 1/2

Q9. R.H.P's standard angle of contact for A/C. bearing is _______ degrees.

A. 20 Degrees

B. 30 Degrees

B. 40 Degrees

Q10.

A _________or 4 (four) point bearing can carry thrust loads in either direction.

A. Angular contact

B. Simplex

C. Duplex

Q11.

The letter prefix used to indicate this type of bearing is _________ (metric) or __________imperial light series or imperial medium series_______.

Metric

Imperial light series Imperial medium series



Name:

Branch (eg QAA)


Date:


Q12.

Double row angular contact bearings are available in the following 3 types:

3000 Externally converging

Externally diverging Split inner ring

5000 Externally converging


3000DA

Externally converging


Q13.

The radial capacity of a 5200 series is _______ than that of A 3200 series.

A. Greater than

B. Equal to

C. Less than

Q14.

An INA brand 3206 is similar to a JAF _________.

A. 3206

B. 5206

C. QLM 6

Q15.

An E12 is a type of __________ bearing (please pick the most specific answer).

A. Magneto bearing

B. Angular contact bearing

C. Ball bearing

Magneto bearings are designed to take ... A. Thrust loads

B. Radial Loads

C. Combined Loads

Q16.

The inner ring raceway is ________than that of a standard deep groove ball bearing.

A. Deeper than

B. The same depth as

C. Shallower than




Other Standard Ball Bearings


Table of Contents 100 Series 6 Filling Slot 3,4 1200 Series 6 ISO Metric Numbering System 11 1300 Series 6 K suffix 6 2200 Series 6 Maximum Capacity Ball 3 2300 Series 6 Misalignment 4,5 4200 Series 4 NLJ Series 6 4300 Series 4 NMJ Series 6 BL200 Series 3 Spherical Raceways 5 BL300 Series 3 Supplement 1 9 Common Suffixes Chart 9 Supplement 2 11 Double Row Deep Groove Ball 4 Tapered Bore Bearings 6,10 Double Row Self Aligning Ball 5


This lesson is the ninth of a series of Correspondence lessons in the BSC Structured Training Plan.

Objectives

The objective of this lesson is to acquaint students with the other types of ball bearing not covered in lessons A2007 and A2008. Bearing types to be covered are:

• Maximum Capacity Ball Bearings • Double Row Deep Groove Ball Bearings • Double Row Self Aligning Ball Bearings

Pre-requisites


Methods


Assessment


LESSON A9009 – Other Standard Ball Bearings Series 90 Training page 2


Besides single row deep groove ball bearings, there are many other types of ball bearings that we shall discuss in this lesson.

MAXIMUM CAPACITY BALL BEARINGS

These bearings are sourced, in the main, from NSK and range in bore size from 25mm to 110mm.

They are metric ball bearings and use the same coding, for bore size, as the deep groove "6000" series. In fact they are dimensionally the same, in the same series, as the “6000” series.

Maximum capacity ball bearings have greater number of balls than a similar deep groove bearing, and thus can take a greater radial load.

The greater number of balls, in the bearing, is achieved by means of a filling slot through which the balls are inserted between the outer and inner rings. The slot can be clearly seen in the photograph.

The precision ground slot is accurately located, so there is no possibility of interference with the normal path of the balls when the bearing is under radial load. Thrust load should not be applied to these bearings.

NUMBERING SYSTEM

The part number, used by NSK, is made up of the letters "BL" and then three figures. The first figure is for the series, either 2 or 3 (light or medium series); the second and third figures are the code for the bore size which is exactly the same as the "6000" series. Thus, part number BL206 tells us that it is a maximum capacity ball bearing, light series with a 30mm bore. Maximum capacity ball bearings can be either open, with one shield (suffix "Z") or with the two shields (suffix "ZZ"). They can also be supplied with a snap ring and groove (suffix "NR").

Part Number Example - BL208ZNR

• BL - Maximum Capacity (think of 'Big Load') • 2 - Light Series • 08 - 40 mm Bore (08 x 5) • Z - one steel shield • NR - snap ring and groove


DOUBLE ROW DEEP GROOVE BALL BEARINGS

These bearings are sourced from NSK and we use the ISO numbering system.

The bearings have two rows of balls. Some brands have filling slots either in just one side or in both sides of the bearing but these are achieved to make the assembly easier rather than to allow extra balls to be inserted. Thus, they should not be confused with Maximum Capacity bearings.

They are able to take a higher radial load than single row types but their rigidity makes them less tolerant of misalignment.

Although they will take a small amount of thrust load they are not designed for this, whereas an angular contact bearing is.

In practice, these bearings are rarely used in modern equipment as the 3000 and 5000 series can fulfill the same function. We stock a limited range so that we can supply them for older equipment.

Numbering system

There are two series available in double row deep groove ball bearings:-

• Light series 4200 • Medium series 4300

The bore code is identical to deep groove ball bearings. Thus a bearing in the light series with a bore size of 17mm has the part number 4203. No shields or seals are available with this series.

Typical Part Number: 4206

• 4 - Double Row Deep Groove Ball Bearing • 2 - Light Series • 06 - 30mm Bore (06 x 5)


DOUBLE ROW SELF ALIGNING BALL BEARINGS

All the ball bearings that we have covered so far are known as "rigid" ball bearings. By "rigid" we mean that they can only take a very small amount of misalignment.

Misalignment is when the shaft is not at a "right angle" to the bearing or, an off-square mounting condition due to the position of the shaft or housing. If a bearing is misaligned the rolling elements do not track correctly but veer from side to side in the raceways, causing overloading, overheating and usually breaks the cage.

To the right is an illustration of a misaligned bearing.

Self aligning ball bearings are more expensive than deep groove ball bearings and only have approximately 60% to 70% of the capacity of deep groove ball bearings. A diagram is shown to the left.

However, if it is difficult to accurately hold alignment or it is an expensive engineering operation, then self-aligning bearings are an obvious choice.

Double row self-aligning ball bearings are "internally aligning" bearings.

They are similar to double row ball bearings except that the outer ring has a spherical ground raceway which permits the two rows of balls to pick up a true running position, even if the rings are twisted out of alignment.

Double row self-aligning ball bearings do not have a filling slot.


Numbering system

In the main metric SADR ball bearings are sourced from NSK and we use the ISO numbering system. There are five series as follows:

• Small Series 100 • Light Series 1200 • Light Wide Series 2200 • Medium Series 1300 • Medium Wide Series 2300

In the small series there are only five part numbers as below:

Code Number (sizes in mm)

• ID OD W • 135 5 x 19 x 6 • 126 6 x 19 x 6 • 127 7 x 22 x 7 • 108 8 x 22 x 7 • 129 9 x 26 x 8

In each case the bore diameter is the last figure in the part number.

All the other metric series have the same bore coding as used with the deep groove ball bearing.

They can also be supplied with a tapered bore so the bearings can be mounted on a shaft with an adaptor or withdrawal sleeve (see lesson titled "transmission"). If they have a tapered bore, the suffix "K" is added.

Imperial Double Row Self Aligning Ball Bearings

Our imperial SADR ball bearings are sourced from RHP and therefore we use their numbering system.

There are two series:

• Light series NLJ • Medium series NMJ

For both these series, the bore size in whole numbers and fractions is added to the above to make the part number, eg. NJL 2-1/4. An "E" is added to whole numbers from "4" upwards.

Common Suffixes

Suffixes, which indicate variations to the basic bearing type, are standardised by most manufacturers across their bearing range. Supplement 1 contains a list of common suffixes used by major bearing manufacturers.


Recap

Supplement 2 is a summary of the Metric Ball Bearing range covered in the lessons so far. Study this carefully and go back over the notes if there are any points you do not understand.

As we progress through other types of bearings, we will build on this chart so that you will be able to see how far you have progressed with your studies.

We have now covered all the standard ball bearings types except Thrust Ball Bearings which are included in lesson 13, and Wide Inner Ring ball bearings which will be covered in lesson 14.

Easy wasn't it!


Supplement 1

Common Suffixes

Feature SKF NSK FAG RHP SNR NTN NACHII

Contact Angle (Angular Contact Bearings)

15o C C C X2 C C C(13o) 20o None

25o AC A5 E H

30o A A A X4 A 35o 40o B B B B B B B

Ground Face G G G G G G G

Internal Design CA/CAC CA A/B MB B UA E

Spherical Roller CC CD E H-L V B E

- M - - - - -

H ETVBP E VG25 Cage Material

Steel J J W J J J J Bronze/Brass M M M M M M/L1 MY Textile Phenolic TH T T TH TH TI G

Polyamide 66 TN H TVBP N TG25 T2 -

Full Compliment V V V V V V V

Shields/Seals

Metal Z/ZZ Z/ZZ Z/ZZ Z/ZZ Z/ZZ Z/ZZ Z/ZZ Rubber RS/2RS V/VV RS/2RS RS/2RS E/EE LB/LLB NK/2NK Contact Rubber RSR/2RSR DU/DDU

RSR/ 2RSR RSR/2RSR

E10/ EE10 LU/LLU NSL/2NSL

Oil Entry in Outer Ring W33 E4 S W33 B33 D1 W33


Heat Treatment

150o S0 X26 S0 S0 S0 TS2 S26 200o S1 X28/S11 S1 S1 S01 TS3 S28 250o S2 X29 S2 S2 S02 TS4 -

300o S3 X30 S3 S3 S03 TS5 - Precision Class

Normal (P7) None None None None None None None Better than normal P6 P6 P6 EP5 P6 P6 P6/A5

High Precision P5 P5 P5 EP7 P5 P5 P5/A7

Super Precision P4 P4 P4 EP9 P4 P4 P4

Tapered Bore

1:12 Taper K K K K K K K 1:30 Taper K30 K30 K30 K30 K30 K30 K30

Table - Common Suffixes


Supplement 2

I.S.O. Metric Bearing Numbering System

TYPE Basic Metric Numbering System

Double Row Self Aligning Ball Bearings

1 - - Small Sizes under 10mm bore

12 - - Light Series 22 - - Light Wide Series

13 - - Medium Series

23 - - Medium Wide Series

Sizes from 10mm bore

14 - - Heavy Series

Double Row Angular Contact Ball Bearings

32 - -

33 - - Externally converging

52 - -

53 - - Externally Diverging

32 - - DA

33 - - DA Externally Converging - Split inner ring

Note - INA use 32 - - and 32 - - for externally converging

Double Row Ball Bearings

42 - - Light Series


Maximum Capacity Ball Bearings

2 - - or BL2 - -

Light Series

2 - - or BL3 - -

Medium Series

Magneto Type ball Bearings

E -

E - - Most Common Positive tolerance

EN - L - -

EN - - BO - - Negative Tolerance


Angular Contact Single Row Ball Bearings

70 - - Extra Light Series

72 - - Light Series


74 - - Heavy Series

Suffix that follows the number designates, designates contact Angle. I.E. A. B. C. E. AC. (B at 400 is most common)

Four Point Bearing (Split inner ring)

QJ 2 - - Light Series

QJ 3 - - Medium Series

Deep Groove Ball Bearings

60 -

62 -

63 -

618/-

Small Series up to 10mm bore

160 - -

161 - -

618 - -

Narrow Series extra light over 10mm bore

60 - - Extra Light Series

62 - - Light Series


64 - - Heavy Series

From 10mm bore

620 - -

622 - -

623 - -

Light Series but with increased width

630 - -

632 - -

633 - -

Medium series but with increased width

68 - -

69 - - Extremely Light Series

Table - Numbering System


A9009 - Questionnaire

Name:

Branch (eg QAA)


Date:


Questions Answers

Q1. Which type of ball bearings are designed to carry a greater radial load than deep grove ball bearings?

A. Angular contact

B. Double row spherical

C. Maximum capacity

Q2. Maximum capacity ball bearing should not be used for applications where a high to medium _______ load is present.

A. Thrust load

B. Radial load

C. Combined

Q3. The suffix BL on an NSK ball bearing indicates …

A. Basic load only

B. Maximum capacity

C. Angular contact

Metric bearings designed for higher radial loads, with 2 rows of balls running in grooves and a filling slot are called ...

A. Double row angular contact bearings

B. Double row deep groove ball bearings

C. Double row self aligning ball bearings

Q4.

and have a numbering system commencing with the number ... A. 3

B. 4

C. 5

Q5. An alternative ball bearing type designed to cope with the problem of misalignment is called a ...

A. Double row angular contact bearings

B. Double row deep groove ball bearings

C. Double row self aligning ball bearings



Name:

Branch (eg QAA)


Date:


Q6. Double row self-aligning ball bearings have a _______________raceway on the outer ring.

A. Spherical

B. Parallel

C. Deep groove

Q7. The part number for a Medium Wide Series Double Row Self Aligning Ball Bearing with a bore size (inside diameter) of 25 mm is ____________________

A. 2325

B. 2305

C. 1305

Q8. The dimensions of a 126 bearing are _____ I.D. x _____O.D. x _____ Width

A. 5 x 19 x 6

B. 9 x 26 x 8

C. 6 x 19 x 6

Q9. In the part number 1210K What does the 'K' indicates? A. Tapered bore

B. Tapered roller bearing

C. High temperature bearing

Q10. The part number for an imperial medium series self-aligning ball bearing with Bore Size 1¾ is __________________

A. QJM 1-3/4

B. NLJ 1-3/4

C. NMJ 1-3/4

Q11. Which letter do most suppliers use to indicate a ground face bearing?

A. K

B. G

C. F

Q12. From Supplement 2, What type of bearing is a QJ206?

A. Angular contact ball bearing.

B. Self aligning ball bearing.

C. most suppliers use to indicate a ground face bearing

a90 part c - bsctraining.bsc.com.au/training/a9000/a9000/a90 set c.pdf · part c – ball bearings...

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