Sổ tay bảo dưỡng vòng bi Skf

SKF bearing
maintenance
handbook
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® SKF, CARB, DURATEMP, HYDROCAM, INSOCOAT, KMT, KMTA,
LubriLean, RELIABILITY MAINTENANCE INSTITUTE,
SENSORMOUNT, SPEEDI-SLEEVE, SYSTEM 24, WAVE,
Vibracon, @ptitude are registered trademarks of the SKF Group.
™ SKF Explorer is a trademark of the SKF Group.
Epocast 36 is a registered trademark of H. A. Springer marine +
industrie service GmbH, an Illinois Tool Works company
© SKF Group 2010
The contents of this publication are the copyright of the publisher
and may not be reproduced (even extracts) unless prior written per-
mission is granted. Every care has been taken to ensure the accuracy
of the information contained in this publication but no liability can be
accepted for any loss or damage whether direct, indirect or conse-
quential arising out of the use of the information contained herein.
PUB SR/P7 10001 EN · July 2010
ISBN 978-91-978966-0-3
This publication supersedes publication 4100.
Printed in Sweden on environmentally friendly paper.
Certain image(s) used under license from Shutterstock.com.
1
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3
4
5
6
7
8

9
10
11
12
13
14
Basics1 8
Mounting rolling bearings2 . . . . . . . . . . . . . . . . . . . . . 44
Mounting bearing units3 . . . . . . . . . . . . . . . . . . . . . . . 92
Mounting bearing housings4 122
Mounting 5 seals 140
Alignment6 158
Lubrication7 178
Inspection8 216
Troubleshooting9 228
Dismounting10 252
Bearing damage and their causes11 288
Maintenance support12 324
Appendices13 332
Index14 438
1
The SKF brand now stands for more than
ever before, and means more to you as a
valued customer.
While SKF maintains its leadership as a
high-quality bearing manufacturer through-
out the world, new dimensions in technical
advances, product support and services have
evol ved SKF into a truly solutions-oriented
supplier, creating greater value for

customers.
These solutions enable customers to im-
prove productivity, not only with break-
through application-specific products, but
also through leading-edge design simulation
tools and consultancy services, plant asset
efficiency maintenance program mes, and
the industry’s most advanced supply man-
agement techniques.
The SKF brand still stands for the very best
in rolling bearings, but it now stands for
much more.
SKF – the knowledge engineering
company
2
Foreword
The SKF bearing maintenance handbook is a
comprehensive working guide for the main ten-
ance professional. With the recommendations in
this handbook, SKF aims to encourage safe and
skilful maintenance practices that can help ex-
tend bearing service life, reduce machine down-
time and minimize unplanned maintenance
activities.
This handbook is not intended as an applica-
tion design catalogue. For detailed information
about designing bearing arrangements, refer
to the SKF Interactive Engineering Catalogue
available online at www.skf.com.
Structure of the handbook

The handbook is divided into fourteen chapters,
marked with numbered blue tabs in the right
margin:
Chapter 1 covers the basics of bearings, re-•
lated products, and bearing arrangements.
Chapters 2 to 5 contain instructions for •
mounting rolling bearings, bearing housings,
bearing units, and seals.
Chapter 6 describes the maintenance • ac tiv-
ities associated with machine alignment.
Chapter 7 provides information and recom-•
mendations for important maintenance ac-
tivities in the bearing-related field of
lubrication.
Chapter 8 covers the maintenance activities •
of inspection and condition monitoring.
Chapter 9 is about troubleshooting, present-•
ing common trouble conditions and suggest-
ed solutions.
Chapter 10 contains instructions for dis-•
mounting rolling bearings, bearing units,
bearing housings and seals.
Chapter 11 is dedicated to bearing damage, •
including the ISO classification.
Chapter 12 provides an overview of SKF’s •
add ition al resources for maintenance
support.
Chapter 13
•
contains Appendices, with import-

ant reference information needed for main-
ten ance work as well as an overview of SKF
maintenance products.
Chapter 14 is the Index.•
Every care has been taken to ensure the ac cur-
acy of the information and that the instructions
contained in this handbook are clear and reflect
sound practice, but no liability can be accepted
for any errors or omissions as well as from any
misuse of tools and other equipment supplied
by SKF.
A note about sustainability
Sustainability is about conducting activities in a
resource-efficient manner so that future gen-
erations will not be compromised. There are
many areas within bearing maintenance where
energy can be saved, from waste management
to reduction in lubricant usage to the proper use
of equipment and tools. SKF is committed to a
sustainable environment and encourages others
to contribute to energy and materials savings.
3
SKF – the knowledge
engineering company
From the company that invented the self-align-
ing ball bearing more than 100 years ago, SKF
has evol ved into a knowledge engin eering com-
pany that is able to draw on five technology
platforms to create unique solutions for its
custom ers. These platforms include bearings,

bearing units and seals, of course, but extend to
other areas including: lubricants and lubrication
sys tems, critical for long bearing life in many
appli cations; mecha tronics that combine mech-
anical and electron ics knowledge into systems
for more effective linear motion and sensorized
solutions; and a full range of ser vices, from de-
sign and logistics support to con dition monitor-
ing and reliability systems.
Though the scope has broadened, SKF con-
tinues to maintain the world’s leadership in the
design, manufacture and marketing of rolling
bearings, as well as complementary products
such as radial seals. SKF also holds an increas-
ingly important position in the market for linear
motion products, high-precision aerospace
bearings, machine tool spindles and plant main-
tenance services.
The SKF Group is globally certified to ISO
14001, the international standard for envi r o n-
mental management, as well as OHSAS 18001,
the health and safety manage ment standard.
Individual divisions have been ap proved for
quality certification in ac cord ance with ISO 9001
and other customer specific requirements.
With over 100 manufacturing sites worldwide
and sales companies in 70 countries, SKF is a
truly international corporation. In addition, our
15 000 distributors and dealers around the
world, an e-business marketplace, and a global

distribution system, put SKF closer to customers
to enhance their ability to quickly supply both
products and services. In essence, SKF solutions
are available wherever and whenever customers
need them. Over all, the SKF brand and the cor-
poration are stronger than ever. As the know-
ledge engin eering company, we stand ready to
serve you with world-class product competen-
cies, intellectual resources, and the vision to
help you succeed.
Seals
Bearings
and units
Lubrication
systems
Mechatronics Services
4
Evolving by-wire technology
SKF has a unique expertise in the fast-growing by-wire technology, from fly-by-wire,
to drive-by-wire, to work-by-wire. SKF pioneered practical fly-by-wire technology and
is a close working partner with all aerospace industry leaders. As an example, virtually
all aircraft of the Airbus design use SKF by-wire systems for cockpit flight control.
SKF is also a leader in automotive by-wire
technology, and has partnered with automotive
engin eers to develop two concept cars, which
employ SKF mecha tronics for steering and
braking. Further by-wire develop ment has led
SKF to produce an all-electric forklift truck,
which uses mecha tronics rather than
hydraulics for all controls.

© Airbus – photo: e
x
m company, H. Goussé
5
Harnessing wind power
The growing industry of wind-generated electric
power provides a source of clean, green electric-
ity. SKF is working closely with global industry
leaders to develop efficient and trouble-free tur-
bines, providing a wide range of large, highly
specialized bearings and condition monitoring
systems to extend equipment life of wind farms
located in even the most remote and inhospitable
environments.
Working in extreme environments
In frigid winters, especially in northern countries,
extreme sub-zero temperatures can cause bear-
ings in railway axleboxes to seize due to lubrica-
tion starvation. SKF created a new family of
synthetic lubricants formulated to retain their lu-
brication viscosity even at these extreme tem-
peratures. SKF knowledge enables manufactur-
ers and end user customers to overcome the
performance issues resulting from extreme tem-
peratures, whether hot or cold. For example, SKF
products are at work in diverse environments
such as baking ovens and instant freezing in food
processing plants.
Developing a cleaner cleaner
The electric motor and its bearings are the heart

of many household appliances. SKF works closely
with appliance manufacturers to improve their
products’ performance, cut costs, reduce weight,
and reduce energy consumption. A recent exam-
ple of this cooperation is a new generation of
vacuum cleaners with substantially more suction.
SKF knowledge in the area of small bearing tech-
nology is also applied to manufacturers of power
tools and office equipment.
6
Maintaining a 350 km/h R&D lab
In addition to SKF’s renowned research and de-
velopment facilities in Europe and the United
States, Formula One car racing provides a unique
environment for SKF to push the limits of bearing
technology. For over 60 years, SKF products, en-
gineering and knowledge have helped make Scu-
deria Ferrari a formid able force in F1 racing. (The
average racing Ferrari utilizes around 150 SKF
components.) Lessons learned here are applied
to the products we provide to automakers and
the aftermarket worldwide.
Delivering Asset Efficiency Optimization
Through SKF Reliability Systems, SKF provides a
comprehensive range of asset efficiency products
and services, from condition monitoring hard-
ware and software to maintenance strategies,
engineering assistance and machine reliability
programmes. To optimize efficiency and boost
productivity, some industrial facil ities opt for an

Integrated Maintenance Solution, in which SKF
delivers all ser vices under one fixed-fee, per-
formance-based contract.
Planning for sustainable growth
By their very nature, bearings make a positive
contribution to the natural environment, enab-
ling machinery to operate more efficiently, con-
sume less power, and require less lubrication. By
raising the performance bar for our own prod-
ucts, SKF is enabling a new generation of high-
efficiency products and equipment. With an eye
to the future and the world we will leave to our
children, the SKF Group policy on environment,
health and safety, as well as the manufacturing
techniques, are planned and implemented to
help protect and preserve the earth’s limited nat-
ural resources. We remain committed to sustain-
able, environmentally responsible growth.
7
1
Basics
Terminology . . . . . . . . . . . . . . . . . . . . . . . . 10
Rolling bearing types and designs . . . . . . 12
Radial bearings . . . . . . . . . . . . . . . . . . . 12
Thrust bearings . . . . . . . . . . . . . . . . . . . 18
Track runner bearings . . . . . . . . . . . . . . 19
Y-bearings 21
Designation system for rolling bearings . 22
Basic designations 22

Designation suffixes 24
Identifying SKF products 26
Bearing identification 26
Split housing and bearing unit
identification . . . . . . . . . . . . . . . . . . . . . 27
Replacement seals 27
Bearing life 27
Basic rating life 27
SKF rating life 27
Service life . . . . . . . . . . . . . . . . . . . . . . . . . 28
Bearing service life 28
Seal service life . . . . . . . . . . . . . . . . . . . 28
Lubricant service life . . . . . . . . . . . . . . . 28
Cleanliness 28
Bearing internal clearance . . . . . . . . . . . . 29
Bearing arrangements . . . . . . . . . . . . . . . 30
Types of bearing arrangements 30
Locating and non-locating bearing
arrangements 30
Adjusted bearing arrangements . . . . . 31
Methods of bearing location 31
Radial location of bearings 31
Selection of fit 32
Recommended fits and tolerances . . . 35
Dimensional, form and running
accuracy requirements . . . . . . . . . . . . 35
Surface roughness of bearing seats . . 36
Axial location of bearings 37
Abutment and fillet dimensions . . . . . 38
Sealing arrangements 39

External seals 39
Integral bearing sealing solutions . . . . . 40
Storage of bearings, seals and
lubricants 41
Storage of bearings, bearing units and
housings 41
Storage of elastomer seals 42
Storage of lubricants . . . . . . . . . . . . . . . 42
Lubricant disposal 43
9
Basics
Terminology
Bearings († fig. 1)
Inner ring1
Outer ring2
Rolling element: ball, cylindrical roller, 3
needle roller, tapered roller, spherical roller,
toroidal roller
Cage4
Sealing device5
Seal – made of elastomer, contact (shown in
figure) or non-contact
Shield – made of sheet steel, non-contact
Outer ring outside diameter6
Inner ring bore7
Inner ring shoulder diameter8
Outer ring shoulder diameter9
Snap ring groove10
Snap ring11
Outer ring side face12

Seal anchorage groove13
Outer ring raceway14
Inner ring raceway15
Seal16 groove
Inner ring side face17
Chamfer18
Bearing mean diameter19
Total bearing width20
Guiding flange21
Retaining flange22
Contact angle23
Shaft washer24
Rolling element and cage assembly25
Housing washer26
Housing washer with sphered seat surface27
Seat washer28
Fig. 1
Tapered roller bearing
Double direction thrust ball bearing
Spherical roller thrust bearing
10 11
18
12
13
14
15
16
17
18
19

9
7
5
6
8
1
2
3
4
14
21
15
17
23
20
6
2
12
3
4
22
1
7
a
a
27
24
28
24
25

26
25
27
24
28
24
25
26
25
Deep groove ball bearing
10
1
Terminology
Bearing arrangements († fig. 2)
Cylindrical roller bearing1
Four-point contact ball bearing2
Housing3
Shaft4
Shaft abutment shoulder5
Shaft diameter6
Locking plate7
Radial shaft seal8
Distance ring9
Housing bore10
Housing cover11
Snap ring12
Fig. 2
1
3
4

5
8
9
10
13
12
14
7
11
6
2
Fig. 3
SNL plummer (pillow) block housing
6
7
8
1
4
2
3
5
Housings († fig. 3)
Housing cap1
Housing base2
Housing foot3
Attachment bolt4
Cap bolt5
Dimple6
Grease fitting7
Hole for eye bolt8

Seals († fig. 4)
Rubber shell1
Sheet steel reinforcement2
Seal lip3
Auxiliary seal lip4
Garter spring5
Seal counterface6
Fig. 4
Radial shaft seal
1
2
5
3
6
4
11
Basics
Deep groove ball bearings
single row, with or without filling slots
open basic design (1)
with shields
with contact seals (2)
with a snap ring groove, with or without
a snap ring
single row with a fixed section
open basic design (3)
with contact seals
double row (4)
Angular contact ball bearings
single row

basic design for single mounting
design for universal matching (5)
single row high- and super-precision
open basic design
with contact seals
open high-speed design
with contact seals (6)
open high-capacity design
with contact seals
double row
with a one-piece inner ring (7)
open basic design
with shields
with contact seals
with a two-piece inner ring
1 2
3 4
5
7
Rolling bearing types and designs
This section gives a summary of the different
standard bearing types and designs. Most are
illustrated.
6
Radial bearings
12
1
Rolling bearing types and designs
Four-point contact ball bearings (8)
8

9
10
11
12 13
14 15
Self-aligning ball bearings
with a cylindrical or tapered bore
open basic design (9)
with contact seals (10)
with an extended inner ring (11)
Cylindrical roller bearings
single row
NU design (12)
with angle ring
N design (13)
single row
NJ design (14)
with angle ring
NUP design (15)
Radial bearings
13
Basics
double row
with a cylindrical or tapered bore
NNU design (17)
NN design (18)
NNUP design
17 18
19
20 21

22 23
four-row
with a cylindrical or tapered bore
open design (19)
with contact seals
Full complement cylindrical roller bearings
single row
NCF design (20)
NJG design (21)
double row
with integral flanges on the inner ring (22)
with integral flanges on the inner and
outer rings
with contact seals (23)
16
Cylindrical roller bearings
single row
high-capacity NCF design (16)
Radial bearings
14
1
24 25
26 27
Needle roller and cage assemblies
single row (24)
double row (25)
Drawn cup needle roller bearings, open ends
single and double row
open basic design (26)
with contact seals (27)

Rolling bearing types and designs
Drawn cup needle roller bearings, closed end
single and double row
open basic design (28)
with a contact seal (29)
28 29
30 31
32 33
Needle roller bearings with flanges
single and double row
without an inner ring (30)
with an inner ring
open basic design
with contact seals (31)
Needle roller bearings without flanges
single and double row
with an inner ring (32)
without an inner ring (33)
Radial bearings
15
Basics
Needle roller / cylindrical roller thrust bearings
without a cover (39)
with a cover (40)
39 40
41 42
Tapered roller bearings
single row
single bearings (41)
matched bearing sets

face-to-face (42)
back-to-back
tandem
34
35 36
37 38
Alignment needle roller bearings
without an inner ring
with an inner ring (34)
Combined needle roller bearings
Needle roller / angular contact ball bearings
single direction (35)
double direction (36)
Needle roller / thrust ball bearings
with a full complement thrust ball bearing (37)
with a cage-guided ball set
with or without (38) a cover
Radial bearings
16
1
43 44
45
46 47
48 49
double row
TDO configuration (back-to-back) (43)
TDI configuration (face-to-face) (44)
four-row
open design
with contact seals

TQO configuration (45)
TQI configuration
Spherical roller bearings
with a cylindrical or tapered bore
open basic designs (46)
with contact seals (47)
CARB toroidal roller bearings
with a cylindrical or tapered bore
open basic designs
with a cage-guided roller set (48)
with a full complement roller set
with contact seals (49)
Rolling bearing types and designs
Radial bearings
17
Basics
51
50
53
52
55
54
57
56
59
58
double direction
with flat housing washers (52)
with sphered housing washers
with (53) or without seat washers

Angular contact thrust ball bearings
high- and super-precision bearings
single direction
basic design for single mounting (54)
design for universal matching
matched bearing sets (55)
double direction
basic design (56)
high-speed design (57)
Cylindrical roller thrust bearings
single direction
single row (58)
double row (59)
components
cylindrical roller and cage thrust assemblies
shaft and housing washers
Thrust ball bearings
single direction
with a flat housing washer (50)
with a sphered housing washer
with (51) or without a seat washer
Thrust bearings
18
1
61
63
62
Spherical roller thrust bearings
single direction (61)
Tapered roller thrust bearings

single direction
with or without (62) a cover
screw down bearings
double direction (63)
Rolling bearing types and designs
60
Needle roller thrust bearings
single direction
needle roller and cage thrust assemblies (60)
raceway washers
thrust washers
Thrust bearings
65
64
Cam rollers
single row ball bearing cam roller (64)
double row ball bearing cam roller (65)
Track runner bearings
19
Basics
66
69
68
67
70
Support rollers
with a needle roller and cage assembly,
without axial guidance
with or without contact seals
without an inner ring

with an inner ring (66)
with needle rollers, with thrust washers for
axial guidance
with or without contact seals
with a needle roller and cage assembly (67)
with a full complement of needle rollers
with a full complement of cylindrical rollers,
axially guided by flanges
with labyrinth seals (68)
with contact seals (69)
with lamellar seals
Cam followers
with needle rollers, axially guided by the stud,
thrust plate and roller flanges
with or without contact seals
with a concentric seat (70)
with an eccentric seat collar
with a needle roller and cage assembly (70)
with a full complement of needle rollers
with a full complement of cylindrical rollers,
axially guided by the stud, flange ring and roller
flanges
with labyrinth seals (71)
with contact seals
with a concentric seat (71)
with an eccentric seat collar
71
Track runner bearings
20
1

Rolling bearing types and designs
73
72
75
76
77
74
Y-bearings (insert bearings)
with grub (set) screws
inner ring extended on one side (72)
inner ring extended on both sides (73)
with an eccentric locking collar
inner ring extended on one side (74)
inner ring extended on both sides (75)
with a tapered bore
inner ring extended on both sides (76)
for adapter sleeve mounting
with a standard inner ring
located on the shaft with an interference
fit (77)
with a hexagonal bore (78)
78
Y-bearings
21
Basics
Designation system for rolling
bearings
Basic designations
All SKF standard bearings have a characteristic
basic designation, which generally consists of

three, four or five 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 and
eventually a basic variant.
The following two figures identify the ISO •
dimension series; the first figure indicates the
width or height series (dimensions B, T or H)
and the second the diameter series
(dimension D).
The last two figures of the basic designation •
give the size code of the bearing; when multi-
plied by 5, the bore diameter in millimetres is
obtained.
The most important exceptions to the basic
bearing designation system are listed here.
In a few cases1 , the figure for the bearing type
or the first figure of the dimension series
identification is omitted. These figures are
shown in brackets in diagram 1.
Bearings with bore diameters of 10, 12, 15 or 2
17 mm have the following size code
identifications:

00 = 10 mm
01 = 12 mm
02 = 15 mm
03 = 17 mm
For bearings having a bore diameter smaller 3
than 10 mm, or 500 mm and larger, the bore
diameter is generally given in millimetres and
is not coded. The size identi fication is sep ar-
ated 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 in accordance with ISO
15:1998 that have bore diameters of 22, 28
or 32 mm, e.g. 62/22 (d = 22 mm).
For some 4 small bearings having a bore
diameter smaller than 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, 129 or 709 (d = 9 mm).
Bore diameters that deviate from standard 5
bore diameters are uncoded and given in
milli metres 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 (6202 bearing with a special
bore 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 com bin-
ation of these letters, e.g. CA. These are used to
identify differences in internal design, e.g. con-
tact angle.
The most common bearing series designa-
tions are shown in diagram 1, above the bear-
ing sketches. The figures in brackets are omitted
in the series designation.
22
1
Designation system for rolling bearings
Diagram 2
Designation system for SKF standard metric ball and roller bearings
139
130
(1)23
1(0)3
(1)22
1(0)2
1(1)0
223
213
232
222
241

231
240
230
249
239
248
238
294
293
292
323
313
303
332
322
302
331
330
320
329
4(2)3
4(2)2
544
524
543
523
542
522
534
514

533
513
532
512
511
510
591
590
6(0)4
623
6(0)3
622
6(0)2
630
6(1)0
16(0)0
639
619
609
638
628
618
608
637
627
617
7(0)4
7(0)3
7(0)2
7(1)0

719
718
708
814
894
874
813
893
812
811
(0)4
33
23
(0)3
22
12
(0)2
31
30
20
10
39
29
19
38
28
18
23
32
22

41
31
60
50
40
30
69
59
49
39
29
41
31
60
50
40
30
69
49
39
48
23
(0)3
12
(0)2
10
19
(0)
1 2
3

4
5
6
7
8 C
N
NN
QJ
H
T
B
D
8
7
9
0
1
2
3
4
NC, NCF
NF, NFP
NJ, NJP
NP, NPF
NU
NUP, NUPJ
NNF
NNC
NNCF
NNCL

NNU
7
9
1
2
XXXXX
1 5 6 708 2 3 4
(0)33
(0)32
Bearing type
Radial bearings
Width (B, T)
Dimen sion
series
Bearing series Size
d/5
Thrust bearings
Height (H)
Diameter series
Bearing series
Code Bearing type
0 Double row angular contact ball
bearing
1 Self-aligning ball bearing
2 Spherical roller bearings, spherical
roller thrust bearing
3 Tapered roller bearing
4 Double row deep groove ball bearing
5 Thrust ball bearing
6 Single row deep groove ball bearing

Code Bearing type
7 Single row angular contact ball
bearing
8 Cylindrical roller thrust bearing
C CARB toroidal roller bearing
N Cylindrical roller bearing. Two or more
letters are used to identify the
number of the rows or the
configuration of the flanges, e.g. NJ,
NU, NUP, NN, NNU, NNCF etc.
Code Bearing type
QJ Four-point contact ball bearing
T Tapered roller bearing in accordance
with ISO 355-2007
23