SKF spherical roller thrust bearings for long lasting performance

SKF spherical roller thrust bearings for long lasting performance
SKF spherical roller
thrust bearings
For long lasting performance
Contents
The SKF brand now stands for more
than ever before, and means more
to you as a valued customer.
A Product information
3
Conquer misalignment and heavy axial
and radial loads
Where spherical roller thrust bearings
are superior
While SKF maintains its leadership as a
high-quality bearing manufacturer
throughout the world, new dimensions
in technical advances, product support
and services have evolved SKF into a
truly solutions-oriented supplier,
creating greater value for customers.
3
These solutions enable customers to
improve productivity, not only with
breakthrough application-specific products, but also through leading-edge
design simulation tools and consultancy
services, plant asset efficiency maintenance programmes, and the industry’s
most advanced
supply management techniques.
6
Unrivalled range
8
SKF Explorer spherical roller thrust
bearings – for premium performance
4
5
The strength of SKF spherical roller
thrust bearings
Setting new standards with SKF Explorer
bearings
30 Mounting and dismounting
30 Mounting
31 Dismounting
32 Service for a lasting partnership
C Product data
34 Bearing data – general
36 Product table
The SKF brand still stands for the very
best in rolling bearings, but it now
stands for much more.
SKF – the knowledge engineering
company
44 Related SKF products
10 Where heavy combined loads must be
accommodated
B Recommendations
12 Selection of bearing size
14 Design of bearing arrangements
14 Single direction thrust bearing
arrangements
14 Double direction thrust bearing
arrangements
16 Axial clearance and preload
18 High-speed bearing arrangements
18 Low-speed bearing arrangements
18 Stiffness
18 Design of associated components
19 Seals
20 Typical bearing arrangements
20 Single direction thrust bearing
arrangements
21 Double direction thrust bearing
arrangements
24
24
26
28
2
D Additional information
Lubrication and maintenance
Oil lubrication
Grease lubrication
Maintenance
46 SKF – the knowledge engineering
company
Conquer misalignment and heavy
axial and radial loads
Spherical roller thrust bearings are extremely
well suited for heavy-duty applications, with
axial loads or combined axial and radial loads.
They are self-aligning and can accommodate
low as well as high speeds. Due to their design,
various degrees of stiffness can be arranged.
Versatility is a characteristic of spherical
roller thrust bearings as they can contribute
to space saving and cost-effective designs.
The following pages provide more detailed
explan­ations about this bearing type and how
it can be used.
Self-aligning
Separable design
The spherical roller thrust bearing accom­
modates misalignment between the shaft
and housing. This gives smooth, friction-free
adjustment under virtually all operating
conditions.
The mounting procedure is facilitated, as the
bearing can be separated. The shaft washer
with the cage and roller assembly and the
housing washer can be mounted separately.
A
Combined load carrier
The bearing is designed to accommo­d­ate very
heavy axial loads in one direction or heavy
combined axial and radial loads.
Where spherical roller
thrust bearings are
superior
By design, spherical roller thrust bearings
are the only roller thrust bearings that can
accommodate radial loads in addition to axial
loads. This makes spherical roller thrust bearings an outstanding solution in applications
that have to accommodate very heavy axial
loads in combination with radial loads. This
ability to accommodate combined loads en­ables economical, space saving designs that
can also provide a high degree of stiffness
under heavy load conditions. In addition to
these unique benefits, spherical roller thrust
bearings are also the only roller thrust bear­
ings that can accom­mo­date misalignment
and shaft deflections.
Due to the contact angle in spherical roller
thrust bearings, they can successfully replace
tapered roller bearings in a number of
applications.
3
The strength of SKF spherical roller
thrust bearings
Superior bearing service life
Combined load carrier
Smooth running and long bearing service life
are a result of the internal design that gives
the raceways and rollers an optimized balance
between contact pressure and friction.
SKF spherical roller thrust bearings are well
proven in the field and are subject to continuous development to provide improved perform­
ance. SKF Explorer performance class bearings are a good example of what can be achieved
with purposeful development – in this case,
opening up new application horizons.
Spherical roller thrust bearings can accommodate radial loads up to 55 % of the simul­
taneously acting axial load. This means that
one spherical roller thrust bearing often can
be used instead of a combination of a radial
and a thrust bearing.
•Compact bearing arrangement
•Reduced arrangement weight
•Reduced arrangement cost
Wide speed range
Self-aligning excellence
Low internal friction permits the bearings
to operate from very low to very high speeds.
Speeds up to three times the reference speed
are possible by adding certain design features.
Basically, the speed performance depends on
the bearing arrangement, the application and
the operating conditions.
Depending on the operating conditions and
bearing series, SKF spherical roller thrust
bearings can accom­modate misalignment
of up to 3 degrees between the shaft and
housing without adversely affecting bearing
performance.
Robust design
SKF spherical roller thrust bearings are
designed for heavy-duty operating conditions
and are therefore highly reliable. Made from
the unique SKF Xbite heat treated steel, these
bearings exhibit excellent wear and fracture
toughness characteristics. SKF Xbite heat
treated steel also provides high dimensional
stability up to 200 °C (390 °F).
Benefits
Benefits
•Insensitive to some shaft misalignment
•Lower operating temperature
•Long bearing service life
•High reliability
up to
3°
4
Virtually eliminate edge stresses
High load carrying capability and minimized
risk of edge stresses is obtained by an optimal
relationship between the rollers and the
raceways.
Benefits
•Long bearing service life
•High reliability
Heavy-duty performance cages
SKF spherical roller thrust bearings are
designed for heavy-duty conditions. The
robust metallic cages have been designed
to take full advantage of the lubricant in the
sliding contacts even under poor lubrication
conditions.
Benefits
When stiffness counts
By design, spherical roller thrust bearings
provide a high degree of stiffness. In addition,
high moment stiffness can be achieved when
two spherical roller thrust bearings are
mounted in a back-to-back arrangement.
This is due to the long distance between the
pressure centres, where the loads are acting.
Benefits
•Minimal bearing arrangement deformation
under radial and axial loads
•Minimal bearing arrangement deflection
under moment loads
•Compact design
Cool running at high speeds ...
Specially designed spherical roller end/flange
contacts reduce stress levels and optimize
lubricant film formation. This reduces friction
enabling bearings to run cooler even in highspeed applications.
... and exceptionally low friction
at low speeds
The favourable roller end/flange contact
is also very beneficial for low speed
performance.
Benefits
•Suitable for high as well as low speed
applications
•Accommodate high temperatures
High operational reliability
High operational reliability is a prerequisite
for long and trouble-free service life. This is
why reliability is one of the cornerstones of
the SKF design philosophy. A recent example
of this is the SKF Explorer spherical roller
thrust bearing, which is stronger and more
reliable than any other spherical roller thrust
bearing on the market.
Benefits
•Longer service life
•Lower maintenance cost
•More machine uptime
Setting high standards
with SKF Explorer
bearings
A
SKF Explorer spherical roller thrust bear­ings
are the result of an intensive effort by an
international team of SKF scientists and
engin­eers. The result is a new performance
class for SKF spher­ical roller thrust bearings
that provides significantly longer service life
and smoother running.
Spherical roller thrust bearings belonging
to the SKF Explorer performance class have
their designation printed in blue in the product
table.
•Steel
Improved, ultra-clean steel provides lon­ger
bearing service life, even under heavier
loads.
•Heat treatment
A unique SKF heat treatment process
­significantly improves wear-resistance
and fracture toughness.
•Manufacturing
Refined precision manufacturing processes
allow the production of bearings that run
smoother and maximize the effects of the
lubricant between the contacting surfaces.
•Internal geometry
A fine-tuned micro-geometry of the rolling
contacts provides better load distribution
and reduced friction.
SKF Explorer spherical roller thrust bearings
provide higher performance for the same size
as explained in more detail starting on page 8.
•High machine output
•High reliability
•Minimized maintenance cost
•Reduced energy consumption
5
Unrivalled range
The standard range of SKF spherical roller
thrust bearings starts from a 60 mm bore
diameter and goes up to a 1 600 mm bore.
Larger sizes can be supplied on request.
Three bearing series
for a wide range of applications
The standard bearings cover an extensive
dimension range in the three ISO Dimension
Series 292, 293 and 294. They satisfy the
important selection criteria
When very high load carrying capacity is
required, bearings in the 293 and 294 series
are suitable. The small cross section of the
292 series bear­ings have favourable speed,
space and weight characteristics.
Smaller and more cost-effective equipment
can be designed for longer bearing service life
or higher output as a result of the high combined load carrying capacity of SKF spherical
roller thrust bearings.
These bearings can operate at high speeds
even under heavy load conditions.
•load carrying capacity
•rotational speed
•space in the application.
294
293
292
6
A
7
SKF Explorer spherical roller
thrust bearings – for premium
performance
Having invented the spherical roller thrust
bearing some sixty years ago, SKF has been
the leading manufacturer of these bearings
ever since.
Now, SKF specialists in different dis­cip­lines
have combined their experience and knowhow resulting in a large step forward in bearing technology.
We are proud of having made tomor­row’s
bear­ing technology available for our custom­
ers today. SKF Explorer bearings repre­sent
a significant breakthrough in performance.
By studying the interrelation­ship between
each bear­ing component, SKF scientists were
able to maximize the effects of internal load
distribution and lubrication and minimize the
effects of friction, wear, and contamination.
The SKF Explorer performance class is the
result of years of intensive re­search by an
international team of SKF scientists and
engin­eers. It incorporates a number of
improve­ments.
8
•Improved material
The improved steel used in SKF Explorer
bearings is extraordinarily clean and homogeneous. It forms an excellent structure
that contributes to an optimum stress
­distribution in the material.
•The unique SKF heat treatment process
To take advantage of the improved steel
used for SKF Explorer bearings, SKF has
developed a unique heat treatment process
to improve the bearing’s resistance to wear
while retaining the temperature resistance
and toughness of the bearing.
•New precision manufacturing processes
Improved manufacturing processes have
enabled SKF to provide closer tolerances for
all essential bearing parameters. In addition,
SKF Explorer bearings have an improved
surface texture to maintain an optimum
oil film between the contact surfaces.
•New bearing knowledge
Sophisticated in-house software has en­abled
SKF design engineers to study intern­al bear­
ing dynamics to an extent not pre­viously
possible. This has led the way to design
refinements that have been implemented
in SKF Explorer bearings, enabling further
optimization of the rolling elem­ent/raceway
contacts.
The result:
longer bearing service life
All these improvements contribute to a significant increase in bearing service life and
reliability. This can best be shown through
a calculation using the SKF rating life equation.
The properties of SKF Explorer spherical
roller thrust bearings are taken into con­
sideration by
Availability
Product designations
The popular small and medium size spherical
roller thrust bearings in the 293 and 294
series are available as SKF Explorer bearings.
In the product table, the SKF Explorer
bearing designations are printed in blue.
SKF Explorer bearings have retained the
­designations of the earlier stand­ard bearings,
e.g. 29330 E. However, each bearing and
its box are marked with the name “SKF
EXPLORER”.
•increased basic dynamic load ratings and
•better resistance to contamination, resulting
in an increased life modification factor aSKF.
The excellent performance of SKF Explorer spherical roller thrust bearings can be exploited in different ways depending on the application requirements
Increase service life of existing designs
Replace the existing bearing with
an SKF ­Explorer bearing of equal size to
Maintain power output of new designs
Use a smaller SKF Explorer bearing to
• reduce overall machine dimensions to save on
material costs and weight
• increase speeds
• achieve smoother, quieter operation
• reduce friction and energy consumption
• reduce lubricant usage.
• increase life
• increase machine uptime
• increase safety factor
• reduce maintenance costs.
RE
R
SK
F
EX
PL
EX
P
LO
ER
EX
P
F
R
LO
SK
PL
OR
ER
SK
F
EX
• increase power density (output)
• increase loads
• avoid costly redesign.
ER
SK
F
OR
Increase power output
of existing designs
Replace the existing bearing with
an SKF Explorer bearing of equal
size, maintaining machine uptime
to
Increase power density
of new designs
Use a lower cross section SKF
Explorer bearing with the same
­outside diameter to
• use a stronger or even hollow shaft
• achieve a stiffer and more costeffective design
• increase system life due to higher stiffness.
9
A
Where heavy combined loads
must be accommodated
Long service life, high reliability, re­duced main­
ten­ance and the ability to down-size are all
features of SKF Explorer spherical roller thrust
bearings.
In addition, the ability to accommodate very
heavy axial loads or heavy combined loads
make SKF spherical roller thrust bearings
indispens­able in many applications.
Industries
• Metalworking
• Plastics
• Marine
• Industrial gearboxes
• Pulp & paper
• Material handling
• Fluid machinery
• Mining & construction
10
SKF spherical roller thrust bearings are
f­requently used in the industries listed below.
Other applications include bridges, cranes,
wind turbines, hydraulic and electric motors,
and robots.
Requirements
• Reliability
• Long service life
• High load carrying capacity
• Insensitivity to misalignment
• Minimal maintenance
• Reduced operating costs
• Technical support
Solution
© Great Lakes Group, Cleveland, Ohio
A
11
Selection of bearing size
Bearing life
The aSKF factor
Equivalent dynamic bearing load
The life-extending improvements em­bo­died
in SKF Explorer spherical roller thrust bearings can best be understood using the SKF
rating life method. This method constitutes an
exten­sion of the fatigue life theory developed
by Lundberg and Palmgren and is better able
to predict bearing life. The SKF rating life
method was first presented in 1989. For roller
bearings
The aSKF factor represents a very complex
relationship between load, contamination and
lubrication. Values for aSKF can be obtained
from diagram 1 for differ­ent values of hc (Pu/P)
and k, where
Normally a spherical roller thrust bear­ing
is arranged so that runouts in the bearing
arrangement do not affect the load distribution
in the bearing. For dynamically loaded spherical
roller thrust bearings arranged under these
conditions, provided Fr ≤ 0,55 Fa
Lnm=a1 aSKF L10
or
q C w10/3
Lnm=a1 aSKF —
<Pz
If the speed is constant, it is often preferable
to calculate the life ex­pressed in operating
hours using
1 000 000 qCw 10/3
Lnmh= a1 aSKF ————— —
60 n <Pz
where
Lnm =SKF rating life (at 100 – n1) %
reliability), millions of revolutions
Lnmh=SKF rating life (at 100 – n1) %
reliability), operating hours
L10 =basic rating life (at 90 % reli­ability),
millions of revolutions
a1 =life adjustment factor for reliability
(† table 1)
aSKF =SKF life modification factor
(† diagram 1)
C =basic dynamic load rating, kN
P =equivalent dynamic bearing load, kN
n =rotational speed, r/min
1)
The factor n represents the failure probability, i.e. the
­difference between the ­requisite reliability and 100 %
12
hc=factor for contamination level
Pu=bearing fatigue load limit
P =equivalent dynamic bearing load
k =lubricant viscosity ratio
P = 0,88 (Fa + 1,2 Fr)
Diagram 1 is valid for lubricants with­out EP
additives. For non-SKF Explorer spherical
roller thrust bearings, the values in black
­colour on the x axis should be used. For SKF
Explorer bearings, the values in blue should
be used. For SKF Explorer spherical roller
thrust bearings it has been found appropriate
to multiply hc (Pu/P) by a factor of 1,4 as an
expression of the life extending refinements
of these bearings, and the blue values corres­
pond to this.
Detailed information is provided in the SKF
General Catalogue and the SKF Interactive
Engin­eering Catalogue online at www.skf.com.
When runouts in the bearing arrangement
affect the load distribution in the spherical
roller thrust bearing, provided Fr ≤ 0,55 Fa
P = Fa + 1,2 Fr
If Fr > 0,55 Fa, contact the SKF application
engineering service.
Equivalent static bearing load
For statically loaded spherical roller thrust
bearings, provided Fr ≤ 0,55 Fa,
P0= Fa + 2,7 Fr
If Fr > 0,55 Fa, contact the SKF application
engineering service.
Bearing arrangements with axial
loads acting in both directions
Table 1
Values for the life adjustment factor a1
Reliability
%
Failure
SKF
probability rating life
n
Lnm
%
Factor
a1
90
95
96
10
5
4
L10m
L5m
L4m
1
0,62
0,53
97
98
99
3
2
1
L3m
L2m
L1m
0,44
0,33
0,21
The information above is valid for sin­gle bearings but when the thrust load changes direction, it is necessary to use two bearings, most
often two spherical roller thrust bearings
mount­ed in a back-to-back or face-to-face
arrangement. In some cases the radial load
is accommodated by a separate radial bearing
and the spherical roller thrust bearings are
radially free and spring preloaded († fig. 4,
page 15) to provide that the bearing that is
axially unloaded is subjected to the minimum
requisite thrust load († section “Bearing data
– general”, starting on page 34).
In such cases the equivalent bear­ing load
is calculated for each bearing separately as for
single bearings. The life of the pair is then
­calculated as a system life.
Radial loads
Because the raceways are at an angle to the
bearing axis, an axial force is induced when
a spherical roller thrust bearing is subjected
to a radial load.
In cases where the bearings are radially
located and subjected to combined loads with
Fr > 0,55 Fa, this intern­al axial load must be
considered when the equivalent load is calculated for each of the bearings.
To calculate the equivalent load in such
cases, contact the SKF application engi­n­eering
service.
SKF Explorer bearings versus
earlier SKF bearings – a comparison
SKF Explorer bearing
For hc (Pu/P) = 0,4 (375/126) = 1,2 using
the blue values on the x axis in diagram 1
and k = 2.
aSKF=5,5
B
so that the life becomes
L10m=aSKF (C/P)10/3 = 5,5 (1 180/126)10/3
L10m=9 520 millions of revolutions
In this case, the life of the SKF Explorer bearing compared with that of the earlier standard
bearing is 9 520/3 090 = 3,08 or three times
longer.
The performance enhancements incorp­orated
in SKF Explorer spherical roller thrust bearings can best be demonstrated by a life calculation comparison.
The life of each bearing is then calculated.
Earlier standard bearing
For hc (Pu/P) = 0,4 (375/126) = 1,2 and using
the black values on the x axis in diagram 1
and k = 2
aSKF=3,0
so that the life becomes
20
1
10
5,5
0,8
5
3
0,6
2
1
0,5
0,3
0,2
0,2
0,15
0,1
0,1
a23
0,05
0,005 0,01 0,02
0,05
0,1
0,2
0,5
1,2
1
L10m=aSKF (C/P)10/3 = 3,0 (1 010/126)10/3
0,005 0,01 0,02
L10m=3 090 millions of revolutions
2
k=4
aSKF
0,5
Catalogue data:
•Earlier standard bearing
– a basic dynamic load rating
C = 1 010 kN
– a fatigue load limit
Pu = 375 kN
•SKF Explorer bearing
– a basic dynamic load rating
C = 1 180 kN
– a fatigue load limit
Pu = 375 kN
50
4
•equivalent dynamic bearing load P = 126 kN
•viscosity ratio k = 2
•contamination factor hc = 0,4.
Factor aSKF for spherical roller thrust bearings
0,
Example
The operating conditions for a 29332 E bearing in its earlier standard version and the new
SKF Explorer version are
Diagram 1
0,05
0,1
0,2
0,5
2
1,2
1
If k > 4, use curve for k = 4
As the value of hc (Pu/P) tends to zero, aSKF tends to 0,1 for all values of k
Other
5 SKF standard bearings
Pu
hc ––
P
SKF Explorer bearings
2
Pu
hc ––
P
13
Design of bearing arrangements
Single direction thrust
bearing arrangements
A single spherical roller thrust bearing can sup­
port a shaft together with a radial bearing when
•the thrust load is in one direction only, and
•the total axial load on the bearing is never
lower than the requisite min­imum axial load
(† page 35).
The spherical roller thrust bearing locates
the shaft radially and axially in one direction
(† fig. 1). A radial bear­ing provides radial
location at the other end.
In cases where the shaft is support­ed by
two radial bearings, the spher­ical roller thrust
bearing must be radial­ly free. If the axial load
can drop below the requisite minimum load,
the spherical roller thrust bearing should be
spring preloaded († fig. 2).
For very heavy axial loads, a tandem
arrangement can be used to distribute the
load over the bearings († fig. 7, page 22).
Double direction thrust
bearing arrangements
Spherical roller thrust bearings mounted in
pairs for thrust loads acting in both directions
can be mounted in a face-to-face or back-toback arrangement to eliminate the need for
a radial bearing. By eliminating the radial
bearing, any fretting and rubbing normally
associated with conflicts between the radial
bearing and thrust bearing are avoided.
Without spring preloading
SKF spherical roller thrust bearings operating
at moderate speeds can be mounted in pairs
to locate the shaft both axially and radially
without any axial spring preloading.
Like tapered roller bearings, SKF spherical
roller thrust bearings can be mounted with an
interference fit in the housing to avoid fretting
corrosion that otherwise would lead to wear.
Values for permissible axial clearance are
provided in the section “Axial clearance and
preload”, starting on page 16.
Double direction spherical roller thrust
bearing arrangements with axial clearance
should incorporate an internal design feature
indicated by the designation suffix VU029.
With spring preloading
SKF spherical roller thrust bearings operating
at high speeds should be spring preloaded to
secure the requisite minimum load and avoid
smearing († fig. 3).
Spring preloaded arrangements can be
either radially locating or radially free.
When the thrust bearing arrangement is
radially free, another bearing must be used
for radial location. The thrust bearing housing
washers must then be fitted with adequate
Face-to-face
arrangement
Back-to-back
arrangement
radial clearance so that radial load cannot act
on the thrust bearings († fig. 3).
For the permissible misalignment of a few
milliradians, the following rules can be applied
•radial clearance ∆h ≥ 0,5 mm
when D ≤ 250 mm
•radial clearance ∆h ≥ 0,002 D
when D > 250 mm.
If the maximum misalignment angle is known,
then the required minimum radial clearance
in the housing for each thrust bearing († fig. 4)
can be more precisely obtained from
∆h > 2 L1 sings + ∆oc
∆h > 2 L2 sings + ∆oc
Double direction spring preloaded thrust bearing
arrangement – the spherical roller thrust
bearings are radially free
Fig. 3
Single direction thrust bearing arrangement
for combined loads with a single spherical roller
thrust bearing
Single direction thrust arrangement with single
spring preloaded spherical roller thrust bearing
and two radial bearings
Fig. 1
Fig. 2
14
Fig. 4
Fig. 5
b
Dh
2
1
2
Fig. 6
a
L2
L1
Da
Dh
2
b
a
Fa
Fa
B
L
L
Dh
2
gs
Da
Dh
2
gs
Fa
gs
Fa
Fa
Fr
Double direction, spring preloaded spherical
roller thrust bearing arrangement, radially free
Double direction, spring preloaded spherical
roller thrust bearing arrangement with one
bearing radially free and the other carrying the
radial load
Double direction, spring preloaded spherical
roller thrust bearing arrangement where both
bearings can carry the radial load
where
∆h =minimum radial clearance be­tween
the bearing and housing, mm
L1 =distance between the centre of the
radial bearing and the pres­sure centre
of the thrust bearing 1, mm
L2 =distance between the centre of the
radial bearing and the pres­sure centre
of the thrust bearing 2, mm
gs =angular misalignment of shaft, rad
∆oc=the sum of the radial internal clear­­­ance
and the housing clearance fit of the
radial bearing, mm
so that the washer does not make contact
with the housing. If the axial clearance ∆a
in the housing is known, the permissible
­misalignment will be
is achieved because the axially loaded bearing
also accommodates the radial load († fig. 6).
If the axial and radial clearances are chosen
in accordance with the following rules, this
arrangement will accommodate misalignment
without increasing bearing loads.
In this case, the necessary radial movement
of the least loaded bearing can be accomplished
by the tilting of the housing washer rather than
radial movement in the housing.
The requisite axial clearance for a particular
shaft misalignment is calculated as follows
Spring preloading with a radially
locating and a radially free bearing
Arrangements where the axially load­ed bearing is radially located and the other is radially
free are frequently used († fig. 5).
A radially free opposing spherical roller thrust
bearing can accommodate a high de­gree of
misalignment, making it possible to utilize the
paired arrangement’s self-aligning features.
As the housing washer is supported by
springs, it will tilt but there will be no sliding
or rubbing motion between the washer and
housing. However, it is important that the
radial clearance in the housing is adequate
2 ∆a a
gs=––––––
LD
where
gs =angular misalignment of the shaft, rad
∆a=housing axial clearance, mm
a =distance between the pressure centre
and housing washer face of the unloaded
bearing, mm
L =distance between the pressure centres
of the bearings, mm
D =housing washer outside diameter, mm
The above equation is valid for both back-toback and face-to-face bearing arrangements. To
determine the necessary clearance, the above
formula for ∆h can be used when ­omitting ∆oc.
Spring preloading when both
bearings are radially located
gs L D
Da=———
2a
The corresponding requisite radial housing
clearance is
gs L qgs L D w
Dh=—— ———+b
a < 2 a z
where
b=width of radial support, mm
If both bearings are radially locating, then
a good conflict-free centring of the shaft
15
Axial clearance
and preload
Depending on the application, the spherical
roller thrust bearings in an arrangement can
have an operational axial clearance or
preload.
When a vertical application incorp­orates
a single spherical roller thrust bear­ing, the
load from the mass of the shaft acts as a
preload on the spherical roller thrust bearing
to locate the shaft radially and axially in one
direction († fig. 1, page 14).
The radial bearing at the other end of the
shaft must have a certain axial freedom to be
able to accommodate thermal expansion and
contraction of the shaft.
In applications where the shaft is supported
by two radial bearings, the spherical roller
thrust bearing must be mounted radially free.
If the thrust load can drop below the requisite
mini­mum load, the bearing should be spring
preloaded († fig. 2, page 14).
Table 1
Series
292
293
294
∆a/H1)
Horizontal shaft
0,0012
0,0010
0,0026
Vertical shaft
Unloaded housing washer2)
– face down
Unloaded housing washer
– face up
0,0022
0,0026
0,0038
0
0,0001
0,0004
1)
∆a=residual axial clearance after mounting, mm
H =height of one bearing, mm
If Fr > 0,64 Fa, the rules for unloaded housing washer face up apply, if the shaft is vertical. However, the listed
­values are to be multiplied by a factor of two since, under radial loading, the clearance is shared equally by the
bearings. With an arrangement design described in the section “Bearing arrangement with a spherical roller thrust
bearing combined with a thrust ball bearing” († fig. 9, page 23), the listed values under Vertical shaft – face down
are valid.
2)
Recommendations for maximum axial clearance in relation to the bearing height for double direction
thrust bearing arrangements without spring preloading – two spherical roller thrust bearings on
a horizontal or a vertical shaft
Axial clearance
Axial preload
Since a spherical roller thrust bearing is separ­
able, the axial clearance can only be obtained
after mounting and is determined by adjusting the bearing against a second bearing that
provides location in the other direction.
In some applications, an axial preload is
used to enhance the stiffness of the bearing
arrange­ment, improve the accuracy of the
shaft guidance or increase the service life
of the bearings. In other applications, the
preload is used to safeguard the minimum
load prerequisite to avoid bearing damage
caused by sliding of the rollers on the
raceways.
Double direction thrust bearing
arrangements with two spherical
roller thrust bearings on a horizontal
or vertical shaft
For bearing arrangements without spring
loading and operating under moderate
speeds, recommendations for the maximum
axial internal clearance in relation to bearing
height after mounting are shown in table 1.
Clearance changes due
to temperature differences
Generally, the shaft and shaft washers have a
higher operating temperature than the housing and housing washers. This temperature
difference influences the bearing operating
clearance.
For a face-to-face arrangement, the radial
as well as the axial expansion will reduce
bearing clearance.
For a back-to-back arrangement, radial
expansion will reduce the clearance while
­axial expansion will increase the clearance
in the bearing. By choosing a specific bearing
distance, the radial and axial thermal expansion can cancel each other out so that the
clearance will not be affected significantly.
16
Determining preload
Preload is expressed either as a force or as
a displacement.
Empirical values for the optimum preload
force can be obtained from proven designs
and can be applied to similar designs. For new
designs, however, SKF recommends calculating the preload force and, when possible, verifying the calculations by testing. The reliability
of the calculation depends on how well the
assumptions made about the temperature
conditions in operation and the elastic behaviour of the associated components, especially
the housing, coincide with the actual
conditions.
When determining the mounting preload,
the operational preload force required for an
optimum combination of stiffness, bearing
service life and reliability must be calculated
first. Then the cold mounting preload can be
calculated. The appropriate preload at operating temperature depends on the bearing load.
For a spherical roller thrust bear­ing exposed
to a radial load, a force acting in the axial
direction will be induced in the bearing. This
force must be accommodated by another
bearing facing in the opposite direction. This
load must be considered when the preload
force is calculated († section “Radial loads”
on page 13).
For spring preloaded spherical roller thrust
bearings, the total spring force and any loads
from the mass of a vertical shaft need to be
identified so that the load on the bear­ing is
always equal to or larger than the requisite
minimum axial load. Four springs can be used
for smaller bearings but the number must
be increased for larger bearings to provide
proper support and prevent deformation
of the housing washer.
To determine the appropriate value of the
preload force and the num­ber of springs for
spring preloading, contact the SKF application
engi­neering service.
Setting clearance and preload
In face-to-face arrangements, the clearance
and preload is set by adjusting the housing
washers, which in most cases have a clearance fit and are therefore easy to move. The
required position is obtained by placing shims
between the housing and cover.
For back-to-back arrangements, the shaft
washer, which generally has an inter­ference
fit, can be difficult to move into position. Here,
use of the SKF oil injection method can facilitate the adjustment.
In case of preload, the oil injection method,
in combination with an HMV .. E type SKF
hydraulic nut, can be used († fig. 7). When
the washer has been heat mounted close to
its correct position, the preload force is applied
to the shaft washer by means of a specific oil
pressure in the hydraulic nut, while oil is
injected between the washer and shaft. This
pushes the washer into the correct position.
The preload from the hydraulic nut must be
maintained until the oil injection pressure has
been released and the washer has obtained
a full interference fit with the shaft.
However, to use the oil injection method, the
shaft needs to be pre­pared with the necessary
ducts and grooves († section “Dismounting”,
starting on page 30).
Fig. 7
B
Setting the required preload using the oil injection method and
an SKF hydraulic nut
17
High-speed bearing
arrangements
Low-speed bearing
arrangements
SKF spherical roller thrust bearings have
a built-in capacity for high speed. With certain
modifications to the intern­al design and with
special precautions related to lubrication,
cooling and preload, it is possible to operate
the bear­ings at speeds up to three times
greater than the catalogue refer­ence speed
(approximately one and a half times the limiting speed).
A bearing arrangement in a disc refiner
for very high speed is shown in fig. 8.
In this application, a very heavy axial load
is shared equally by two spherical roller thrust
bearings mounted in tandem and preload
applied by two hydraulic pistons. Prior to
designing or operating any machine at speeds
higher than the thermal reference speed,
consult the SKF application engineering
service.
In applications such as vertical air preheaters
and extruders, speeds can be as low as 0,5
to 5 r/min while loads can be as heavy as
P = 0,1 C0. High viscosity oils with addi­t­ives
have proven to be effective for these types
of applications. For additional information,
contact the SKF application engineering
service.
Low speed applications such as bridge and
crane pivots are consid­e­r­ed to be static applications and the bear­ings should be calculated
with a static safety factor of s0 ≈ 4 or greater.
SKF spherical roller thrust bearing arrangement
in a high-speed disc refiner, lubricated with
circulating oil
Fig. 8
18
Design of associated
components
Stiffness
Some machines require stiffer bearing
arrange­ments than others. To meet those
varied requirements, SKF spher­i­cal roller
thrust bearings can be ar­ranged for different
levels of stiffness.
In back-to-back arrangements, the pressure centres of the bearings will be far apart
to provide a very stiff arrangement that
accommodates bend­ing moments as well as
axial and radial loads († fig. 9).
The face-to-face arrangement is not
so stiff due to the shorter distance be­tween
the pressure centres. How­ever, it is equally
stiff for axial load and radial load respectively
(† fig. 10).
In face-to-face arrangements, the bearings
can be placed so that their pressure centres
coincide and the whole arrangement will be
self-aligning, but with equal stiffness in both
the axial and radial direction.
Back-to-back arrangements provide very high
stiffness
Fig. 9
Support of bearing washers
To optimize bearing performance under heavy
axial loads, it is vital that the bear­ing has supports strong enough to prevent deformation
of the bearing washers.
The abutment dimensions da min and Da max
quoted in the product table, starting on page 36,
apply for axial bearing loads Fa ≤ 0,1 C0.
If the bearings are subjected to heavier
loads, it may be necessary for the bearing
washers to be supported across their entire
width (da = d1 and Da = D1). At heavy loads,
P > 0,1 C0, the shaft washer bore must be
fully supported by the shaft, preferably by
an interfer­ence fit. Even the housing washer
should be radially supported († fig. 11).
For further information about dimensioning
of washer supports, contact the SKF application
engineering service.
Face-to-face arrangements provide high stiffness
Fig. 10
Seals
The service life of a bearing depends to a
large extent on the effectiveness of the seals.
Seals prevent the entry of contaminants while
retaining the lubricant.
The selection of a seal type depends on the
operating conditions and environmental considerations such as
•the type of lubricant
•the sliding velocity of the sealing surfaces
•a vertical or horizontal shaft
•the degree of misalignment
•the type of contamination
•thermal conditions.
Detailed information about selecting the seal
type can be found in the SKF catalogue
“Industrial shaft seals”.
Seals for oil lubrication
Contaminant exclusion
Lubricating oils are generally more difficult to
retain in a bearing arrangement than greases.
Therefore, spring loaded radial seals are used
almost exclus­ively, e.g. SKF seals of the CRW1,
CRWH1, HMS4 or HDS3 designs.
Normally, CRW1 radial seals with a hydrodynamically formed seal lip, called SKF WAVE,
are adequate († fig. 12). The SKF WAVE seal
lip has a sinusoid­ally formed edge which induces
a pumping action to the inside as well as the
outside, irrespective of the shaft’s direction
of rotation.
Due to their internal design, spher­ical roller
thrust bearings create a pumping action
which should be considered when selecting
seals († section “Lubrication and mainten­
ance”, starting on page 24).
V-ring seals are very suitable to prevent
ingress of contaminants. They rotate with the
shaft, act as flingers and seal against a surface,
which is at a right angle to the shaft († fig. 13).
Radial seals, i.e. CRW1 design, which are
primarily intended to prevent ingress of con­ta­minants, should be mounted with the lip
pointing away from the bearing.
Spring loaded CRW1 radial seal for oil lubricated
arrangements
V-ring seals are suitable to prevent ingress
of contaminants
Seals for grease lubrication
Lubricating greases are relatively easy to
retain in the bear­ing arrangement. As a result,
the demands on seals are generally moderate.
SKF radial seals without a garter spring,
HM and HMA types, are suit­able for low sliding
speeds. The seals should be arranged so the
lip faces the bearing. V-rings or spring loaded
radial seals, e.g. CRW1 design, are equally
suitable for retaining grease.
If frequent relubrication is required, the lip
of at least one of the seals should be arranged
away from the grease so that excess grease
can escape via this lip.
More information about sealing arrangements can be found in the section “Grease
lubrication”, starting on page 26.
Shaft and housing dimensions for support
of bearing washers
Fig. 11
Fig. 12
Fig. 13
d1
da
Fa
D1
Da
19
B
Typical bearing arrangements
To fully utilize the features of spherical roller
thrust bearings, they must be properly applied.
One of the advantages of spherical roller
thrust bearings is that they can accommodate
radial as well as axial loads. This is why a single spherical roller thrust bearing is fre­quently
used in some applications to accommodate
combined loads.
Correctly applied, the bearing will then
work smoothly as long as Fr ≤ 0,55 Fa. If the
bearing must accommodate a heavy radial
load, Fr > 0,55 Fa, the bearing should be combined with another bearing. This second
bearing can be a spherical roller thrust bearing, but other bearing types can be used. In
applications where a spherical roller thrust
bearing is mounted radially free and axial
loads may not meet requisite minimums,
springs must be used to preload the bearing.
Some typical bearing arrangements incorp­
orating spherical roller thrust bear­ings are
shown below.
Bearing arrangement with a single
spherical roller thrust bearing,
radially free on a horizon­tal or
vertical shaft
This ar­range­ment is suitable when the axial
load in one direction is predominant. Typical
applications are pinions, pumps and fans.
In this example, the spherical roller thrust
bearing is spring preloaded and carries the
predominant axial load. The shaft is supported by two radial bearings of which one is
locating in the opposite direction († fig. 2).
Bearing arrangement with a single spherical roller thrust bearing,
radially located on a vertical shaft
Fig. 1
Single direction thrust
bearing arrangements
Bearing arrangement with a single
spherical roller thrust bearing,
radially located on a vertical shaft
When a spherical roller thrust bearing is
axial­ly loaded with at least the min­imum
­requisite bearing load, it can be used as a
­single bearing to accommodate both the radial
and axial loads. († fig. 1). The bearing at the
other end of the shaft, however, should be
a radial bearing.
This arrangement is suitable when the axial
load always acts in one direction. Typical app­li­
cations are electric motors, crane pivots and
bridges.
20
Bearing arrangement with a single spherical roller thrust bearing,
radially free on a horizontal or vertical shaft
Fig. 2
Double direction thrust
bearing arrangements
Fig. 3
Bearing arrangement
with two spherical
roller thrust bearings,
radially free in a backto-back arrangement
Bearing arrangement with two
spherical roller thrust bearings,
radially free in a back-to-back
or face-to-face arrangement
B
Bearings in either of these arrangements can
carry axial loads in both directions. The min­
imum axial load is provided by spring preloading the housing wash­ers. The radial loads are
accommod­ated by a separate radial bearing
(† fig. 3). The non-locating bearing at the
other end of the shaft is a radial bearing.
This bearing arrangement is suitable for
axial loads acting in both directions in combin­
ation with heavy radial loads and for relatively
high speed applications. Typical applications
are industrial gearboxes and rolling mills.
Bearing arrangement with two
spherical roller thrust bearings,
radially located in a back-to-back
or face-to-face arrangement
The housing washers of both bearings can be
mounted with a loose fit or an inter­ference fit
in the housing. The bear­ings accommodate
axial loads in both directions in combination
with simul­taneously acting radial loads. They
are mounted with a certain internal axial
clearance († fig. 4).
The non-locating bearing at the other end
of the shaft is a radial roller bearing.
This arrangement offers a compact solution
for applications where there are axial loads in
both directions and simultan­eously acting
radial loads. It is especially suitable for moderate speed applications. Typical applications are
marine thrusters and large electric motors.
Bearing arrangement
with two spherical
roller thrust bearings,
radially located in
a back-to-back (a)
or face-to-face (b)
arrangement
Fig. 4
a
b
Fig. 5
Bearing arrangement with two
spherical roller thrust bearings,
one providing radial support and
one radially free
Bearings in this arrangement can be mount­ed
in a back-to-back († fig. 5) or face-to-face
arrangement. The radially guided bear­ing
carries both axial and radial loads while the
other spring loaded bearing is radially free in
the housing. The non-locat­ing bearing at the
other end of the shaft is a radial bear­ing.
The bearing arrangement is suitable for
radial loads and for heavy axial loads acting
in one direction and an occasional light load in
the opposite direction. The ar­rangement can
also be used for relatively high speed applica-
Bearing arrangement
with two spherical
roller thrust bearings,
one providing radial
support and one
radially free
21
Fig. 6
tions. Typical arrangements are disc refiners
and small horizontal water turbines.
Bearing arrangement with
a spherical roller thrust bearing
combined with a spherical roller
bearing – common pressure centre
The bearings in this arrangement are mounted to achieve a common pres­sure centre,
which makes the arrangement self-aligning.
The spher­ical roller thrust bearing is radially
free and accommodates axial loads only.
Radial loads are accommodated by the spherical roller bearing. The minimum axial load on
the spherical roller thrust bearing is achieved
by spring loading the hous­ing washer
(† fig. 6). The non-locating bearing at the
other end of the shaft is a radial roller
bearing.
This bearing arrangement is suitable for
radial loads and heavy axial loads acting in
one direction and an occasional light axial load
in the opposite direction. This applies for low
as well as high speed applications. Typical
arrangements are propeller thrust bearing
arrangements, waterjets and pumps.
Bearing arrangement
with a spherical roller
thrust bearing
combined with
a spherical roller
bearing – common
pressure centre
Fig. 7
Bearing arrangement with two
spherical roller thrust bearings
in tandem arrangement
For very heavy axial loads, two spherical roller
thrust bearings mounted in tandem can be
used to carry the predominant axial load. The
load is equally shared by the two bearings by
means of two hydraulic pistons. The spherical
roller thrust bearings are radially free and the
shaft is radially supported by two radial
bearings.
Alternatively, one of the bearings in the
tandem arrangement can be used for radial
support as well, together with a third spher­ical
roller thrust bearing that provides shaft location
in the other direction († fig. 7).
The arrangement is suitable when the axial
load is very heavy in one direction. Typical
ar­range­ments are spindle units and disc
refiners.
22
Bearing arrangement
with two spherical
roller thrust bearings
in tandem
arrangement
Bearing arrangement with
a spherical roller thrust bearing
combined with a tapered roller
bear­ing
Fig. 8
Bearing arrangement
with a spherical roller
thrust bearing combined
with a tapered roller
bear­ing
Fig. 9
Both bearings in this arrangement are radially
guided, not preloaded, and mounted in a
face-to-face arrangement. Each bearing can
take axial load in one direction only. The bearing that is axially loaded carries the simultan­
eously acting radial load as well († fig. 8).
If a non-locating bearing is required at the
other end of the shaft, a radial bearing needs
to be used.
The bearing arrangement is suitable for
axial loads in both directions in combination
with radial loads. The predominant axial load
is accom­mo­d­ated by the spherical roller thrust
bearing.
Typical arrangements are hyd­raul­ic motors
and injection moulding machines.
Bearing arrangement with
a spherical roller thrust bearing
combined with a thrust ball bearing
Bearing arrangement
with a spherical
roller thrust bearing
combined with a thrust
ball bearing
The spherical roller thrust bearing in this
arrangement is radially guided and can
ac­commodate axial and radial loads. To provide the requisite minimum axial load, a
thrust ball bear­ing is adjusted against the
spherical roller thrust bearing by means of
springs († fig. 9). The non-locating bearing
at the other end of the shaft is a radial
bearing.
The bearing arrangement is suitable for
predominant axial loads acting in one direction. Examples of this arrange­ment include
water turbines and pulp boilers.
23
B
Lubrication and maintenance
Lubricants
Generally, lubrication with oil or grease containing EP additives is recommend­ed for
spherical roller thrust bear­ings.
Pumping effect
Because of their internal design, spher­ical
roller thrust bearings have a pumping action
that can be taken advantage of to provide
circulation of the lubricating oil. The pump­ing
action must be considered when selecting
the type of lubricant and seals († diagram 1).
Oil viscosity
The selection of an oil or grease is primarily
based on the viscosity required to adequately
lubricate the bearing. The viscosity of a lubri-
cant is tem­perature dependent and decreases
as temperature increases. In order to form
a sufficient film thickness in the contact area
between the rolling elements and raceways,
the oil must retain a minimum viscosity at
normal operating temperature.
To determine the suitable lubricant viscosity
at a certain operating temperature, use the
information provided in the SKF General
­Cata­logue or the SKF Interactive Engineering
Cata­logue online at www.skf.com.
Cleanliness
Cleanliness is very important for the performance of rolling bearings. This is reflected in the
SKF rating life equation († section “Selection
of bearing size”, starting on page 12).
Diagram 1
Oil flow, l/min
80
60
40
20
500
1000
1500
2000
2500
3000
Speed, r/min
24
Oil is the preferred lubrication method for
spherical roller thrust bearings, particularly
in applications with static load conditions, e.g.
bridge pivots, to avoid bearing damage from
vibration when not rotat­ing.
Oil bath lubrication should be chosen when
the need for cooling of the bearing is moderate.
Circulating oil lubrication should be chosen
when the operating temperature is high.
Irrespective of the oil lubrication method,
there must always be a com­mun­i­cating duct
between the oil reservoirs on both sides of the
bearing († fig. 1).
For information about suitable sizes for oil
ducts, contact the SKF application engineering
service.
A communication duct provides equal oil level
on both sides of the bearings
Pumping effect in spherical roller thrust bearings (example of a 29420 E bearing)
0
Oil lubrication
Fig. 1
Oil bath lubrication
Circulating oil lubrication
Cooling
For vertical shafts, oil bath lubrication is an
appropriate choice. The pumping effect of the
bearing can be used to force oil through the
bearing.
In many cases, the pumping action of a spher­
ical roller thrust bearing is suffi­cient to provide
effective oil circulation to cool the bearing.
If the pumping action does not suffice, it
might be necessary to circulate oil by means
of a pump. The direction of the oil circulation
should coincide with the pumping action of
the spherical roller thrust bear­ing.
The higher the operating temperature, the
more rapidly the lubricating oil will oxidize. An
increase in bearing temperature also means
that the oil viscosity is reduced and the lubricant film is thinner.
Lubricating with circulating oil ex­tends the
oil change interval.
To improve cleanliness, the oil should be
cleaned by a filter before it is pumped back
to the bearing († fig. 4).
At moderate speeds, a simple cooling system
can be arranged by including a coil of cooling
tubes in the oil tank. In high-speed applications and in the case of high ambient tem­
peratures, the oil flow rate required to maintain a suitable running temperature must
be estimated.
Effective cooling is important if spher­ical
roller thrust bearings are to operate at very
high speeds.
Cooling can be accomplished via an oil
­cooler in a circulating oil system († fig. 4).
To define necessary oil flow rates, contact
the SKF application engineering service.
Oil levels
The recommended oil level for a ver­tical shaft
is shown in fig. 2.
For bearings on a horizontal shaft, the oil
level should be at distance “a” from the centre
of the bearing († fig. 3).
a = 0,5 dm ± 2 mm for d < 200 mm
a = 0,5 dm + 0 to + 5 mm for d ≥ 200 mm
where
dm=bearing mean diameter
=0,5 (d + D), mm
d =bearing bore diameter, mm
D =bearing outside diameter, mm
Heating
When the ambient temperature is low, e.g.
for bridge and crane pivot applications, it
might be necessary to heat the oil to achieve
suitable viscosity for pumping lubricant to the
bearing.
However, for low and medium speed applications, the bearing can be totally immersed
in oil.
Recommended oil level for vertical shaft
applications
Recommended oil level for horizontal shaft
applications
Fig. 2
Fig. 3
Circulating oil system with cooler and filter
Fig. 4
a
C
0,6–0,8 C
25
B
Grease lubrication
Fig. 5
Fig. 6
When lubricating with grease, the roller end/
flange contacts must be adequate­ly supplied
with lubricant. Depending on the application,
this can best be done by completely filling the
bearing and housing with grease before the
initial start-up and then following up with
a regular relubrication schedule.
It is important that excess grease can leave
the bearing († figs. 5 and 6).
Vertical shaft
To retain the grease in the bearing arrangement of a vertical shaft, a radial seal is applied
underneath the bearing. The grease supply
duct is positioned on the housing washer side
(† fig. 5).
Horizontal shaft
Sealing arrangement for a vertical shaft –
the grease inlet is positioned just underneath
the bearing
Sealing arrangement for a horizontal shaft –
the grease inlet is positioned on the housing
washer side
The sealing arrangement for horizontal shafts
should be designed so that the fresh grease
passes through the bear­ing and used grease
is purged on the shaft washer side († fig. 6).
Diagram 2
Recommended relubrication intervals for spherical roller thrust bearings
Suitable greases
The most suitable SKF greases for lubrication
of spherical roller thrust bearings are listed
in table 1. Their technical specifications can
be found in table 2.
Relubrication interval at 70 °C (160 °F)
100 000
50 000
Regreasing interval
•an operating temperature of 70 °C (160 °F),
using a good quality mineral oil based
grease with a lithium soap
•a rotating shaft washer
•a horizontal shaft.
10 000
5 000
1 000
tf, operating hours
Proper lubrication requires regreasing at
regular intervals. Be careful not to overgrease
the bearing, as this can lead to increased
operating temperature.
The relubrication interval tf for normal
operating conditions is provided in diagram 2.
The diagram is valid for bearings on horizontal
shafts oper­ating under clean conditions.
The value on the x axis is obtained from
4 n dm (4 ¥ operational speed ¥ bear­ing mean
diameter).
The tf value is then derived considering the
load magnitude given by the load ratio C/P.
The relubrication interval tf is an estimated
value and valid for
500
C/P = 15
C/P = 8
100
C/P = 4
0
100 000 200 000 300 000 400 000 500 000 600 000 700 000 800 000
4 n dm, mm
min
n dm limits* for grease life graph
C/P ≈ 15
200 000
C/P ≈ 8 C/P ≈ 4
120 000 60 000
*If these values are exceeded contact the SKF application engineering service
26
Table 1
SKF standard bearing greases for spherical roller thrust bearings
Grease
desig-
nation
Bearing operating conditions
Very high
Very low speed
Low torque
Severe
Heavy
speed
and/or oscillating
and friction
vibration
load
movements
Rust
inhibiting
properties
Water
resistance
LGEP 2
o
o
–
+
+
+
+
LGHB 2
o
+
–
+
+
+
+
LGEM 2
–
+
–
+
+
+
+
LGEV 2
–
+
–
+
+
+
+
LGWM 1
o
o
o
–
+
+
+
B
+ = Very suitable o = Suitable – = Unsuitable
For additional information, contact the SKF application engineering service
Table 2
Technical specifications
Grease Description
NLGI
Thickener
Base oil
desig-
class
type
nation
Base oil viscosity
(mm2/s)
40 °C
100 °C
Temperature range1)
(°C)
LTL
HTPL
LGEP 2
Heavy load
LGHB 2
2
Lithium
Mineral
200
16
–20
+110
EP high viscosity
2
high temperature Complex calcium
sulphonate
Mineral
400–450
26,5
–20
+150
LGEM 2
High viscosity with
solid lubricants
2
Lithium
Mineral
500
32
–20
+120
LGEV 2
Extra high viscosity
with solid lubricants
2
Lithium-calcium
Mineral
1 020
58
–10
+120
LGWM 1
EP – low temperature
1
Lithium
Mineral
200
16
–30
+110
LTL
Low Temperature Limit
HTPL High Temperature Performance Limit
1)
For safe bearing operating temperatures where the grease will function reliably, † the SKF General Catalogue 6000,
section “Temperature range – the SKF traffic light concept”, starting on page 232
To account for the accelerated ageing of
the grease with increasing temperature, SKF
­recommends halving the relubrication interval
obtained from the diagram for every 15 °C
increase in bearing temperature between 70 °C
and the operating temperature limit for the
grease. For spherical roller thrust bearings,
do not extend the relubrication interval for
operating temperatures below 70 °C.
•For bearings on vertical shafts with the shaft
washer at the top, the intervals obtained
from the diagram should be halved.
•For a rotating housing washer, oil lubrication
is recommended.
•For bearings on vertical shafts with the
shaft washer at the bottom, contact the SKF
application engineering service.
If the determined tf value from the diagram
proves to be insufficient for a particular
application
•check the grease for water content and contamination
•check the bearing operating temperature
•consider another grease
•check the bearing application conditions
such as load, misalignment etc.
To establish a proper relubrication interval for
spherical roller thrust bearings used in critical
positions in process industries, an interactive
procedure is recommended. In these cases it
is advisable to relubricate more frequently
and adhere strictly to the regreasing quantity
(† “Relubrication procedures” below).
Before regreasing, the appearance of the
grease and the degree of contamination due
to particles and water should be checked. SKF
also recom­mends a complete check of the
27
seals for wear, damage, and leakage. When
the condition of the grease and associated
components are satisfactory, the relubrication
interval can be gradually increased.
Relubrication procedures
The most common relubrication procedures
for spherical roller thrust bearings are replenishment and continuous lubrication. The choice
depends on the operat­ing conditions.
•Replenishment is a convenient and preferred procedure in many applications: it
enables uninterrupted operation and provides, when compared to continuous relubrication, a lower steady state temperature.
•Continuous relubrication is used when the
calculated relubrication intervals are short
or due to the adverse effects of con­ta­min­
ation.
When using different bearing types on the
same shaft, it is common practice to apply the
lowest individual calcu­lated relubrication
interval for all bear­ings. The guidelines and
grease quantities for the relubrication pro­ced­
ures are provided below.
Replenishment
Suitable quantities for replenishment can
be obtained from
Gp=0,005 D H
where
Gp=grease quantity to be added when
replenishing, g
D =bearing outside diameter, mm
H =bearing height, mm
To facilitate the supply of grease using a
grease gun, a grease nipple must be provided
on the housing († figs. 5 and 6, page 26).
To be effective in replacing old grease, it is
important to replenish while the machine is in
operation. In cases where the machine is not
in operation, the bearing should be ro­tated
during replenishment.
Where centralized lubrication equipment is
used, provision must be made to adequately
pump the grease at the lowest expected
ambient temperature.
SKF recommends replacing complete
grease fill after approximately 5 replenish­
ments.
28
Continuous relubrication
Feel the temperature
Due to possible churning of the grease that
can lead to increased temperatures, continuous relubrication is only recommended when
operating speeds are low, n dm values below
75 000. The quantity for relubrication per
time unit is derived from the equation for Gp
(see above) by spreading this quantity over
the relubrication interval.
Continually check the temperature around the
bearing. Any change in temperature can be an
indication of a malfunction if the running conditions have not been altered. Temperature
checks can be performed with an SKF therm­
ometer.
After relubrication, a natural temper­a­ture
rise lasting one or two days can occur.
Maintenance
Proper bearing maintenance is a key factor
to keep equipment running on schedule.
Foresighted planning, use of professional
main­tenance techniques and tools combined
with the appropriate bearing accessories are
vital.
Further information about spherical roller
thrust bearing maintenance can be found
in the SKF Bearing Mainten­ance Handbook
or online at www.aptitudexchange.com.
What to look for during operation
Checking the machine condition during operation and planning for maintenance is import­
ant. Bearings are vital components in most
machines and monitoring their condition represents an increasingly important activity in
the field of pre­ventive maintenance. A variety
of systems and equipment are available to
moni­tor bear­ings.
However, for practical reasons, not all
machine functions are monitored using
advanced instru­mentation. By remaining alert
for “trouble signs”, such as noise, increases in
temperature and vibration etc., problems can
be detected.
Listen
Bearings in good operating condition produce
a soft purring noise. Grinding, squeaking and
other irregular sounds usually point to bearings in poor condition.
Damaged bearings produce irregular and
loud noises. Instruments such as the SKF
electronic stetho­scope make “listening” more
accurate and help to detect damage at an
earlier stage.
Look
Check the condition of the seals near the
bearing to be sure that they are operating
satisfactorily and have not allowed contaminants to penetrate. Oil leaks are usually signs
of worn seals, seal defects or loose plugs.
Check the bearing arrangement and replace
worn seals immediately.
Discoloration or darkening are usually signs
that the lubricant contains impurities.
Relubrication
Relubrication is best performed when the
bearing is running. Relubricate with small
quantities each time.
Periodically, clean out used grease or purge
out through drain plugs. When lubricating,
always keep con­taminants away from the
grease.
Checking the oil
Check the oil level and when neces­sary fill
up or replace with the same type of oil. Take
a sample of the used oil and compare it with
fresh oil. If the sample looks cloudy, it may be
mixed with water and should be replaced.
Dark oil is a sign of dirt, or indicates that
the oil has started to carbonize. Clean the
bearing and change the oil with a similar type
of oil.
Condition monitoring of bearings
in operation
It is advisable to systematically check the
bearing condition. A lack of lubricant, excessive loads, high operating temperatures and
mounting errors can all contribute to premature bearing failure. By methodical condition
monitoring, bearing damage can be detect­ed
at an early stage († fig. 7). It is then easy
to plan for bearing replacement.
SKF can help you select the right monitoring system, train your personnel and install
the system († pages 32 and 33).
Prepared for vibration analysis
Fig. 7
Bearing damage can be identified by its defect
frequency. To simplify vibration analysis, the
packaging of SKF spherical roller thrust bearings is marked with individual bearing data
required for damage analysis († fig. 8).
B
SKF offers a range of different instruments for condition monitoring. An example is the range
of portable MARLIN machine inspection systems for fast and reliable vibration analysis
The packaging of SKF spherical roller thrust bearings is marked with vibration analysis data
Fig. 8
29
Mounting and dismounting
Mounting
Mounting bearings with an
interference fit
SKF spherical roller thrust bearings are
separ­able so that the housing washer and
the shaft washer with rollers and cage are
mounted independently († fig. 1).
One or both of the washers can have
an interference fit.
Depending on whether the interfer­ence
fit is between a shaft washer and shaft or
housing washer and housing, the shaft washer or the housing should be heated before
mounting.
To mount a washer with an interfer­ence fit
on a shaft, heat the washer to about 80 to 90 °C
(175 to 195 °F) above the temperature of the
shaft. This can be done by means of an SKF
induction heater († fig. 2), a heating cabinet
or an oil bath.
Double direction thrust bearing
arrangements – paired spherical
roller thrust bearings
Replacing bearings where axial
forces are transmitted via the inside
face of the shaft washer
Spherical roller thrust bearings mount­ed in
pairs must be adjusted to a certain axial clearance, or preloaded during assembly († section
“Axial clear­ance and preload”, starting on
page 16).
In some cases, the correct position of the
bearings must be determined from measurements of the bearing heights and the adjacent
components before mounting.
New, unique detailed mounting and dismounting instructions for SKF spherical roller
thrust bearings are available online at
www.skf.com/mount.
Generally, when replacing a spherical roller
thrust bearing of one design with a corres­
ponding bearing of another design, it is
important to consider the need of introducing
a distance sleeve or modifying the available
sleeve.
When an SKF spherical roller thrust bearing with a machined cage is to be re­placed by
an E design bearing with a pressed steel cage,
and axial forces are transmitted via the cage
guiding sleeve, it is necessary to insert a
spacer sleeve between the shaft abutment
and the shaft washer († fig. 3).
If an SKF bearing of the earlier B design
mounted with a spacer sleeve is to be replaced,
the spacer sleeve generally needs to be modified († fig. 4).
For SKF spherical roller thrust bearings,
appropriate dimensions for the sleeves can be
found in the product table starting on page 36.
Fig. 3
Spherical roller thrust bearings are separable,
which facilitates mounting
Fig. 1
SKF offers a wide range of induction heaters
to facilitate mounting a bearing with an
interference fit on a shaft
Fig. 2
Old design
E design
Fig. 4
B design
30
E design
Dismounting
If the shaft washer has to be moved over
a long distance on the shaft, more than
one groove and duct might be required.
To prevent the washer from getting
stuck, the shaft should, where possible,
be designed for a clearance fit.
Removing the shaft washer
A considerable amount of force is required
to remove a washer mounted with an interference fit. Washers of small and medium size
bearings can usually be removed using a
mechanical or hydraulic withdrawal tool.
B
Applying the SKF oil injection
method for dismounting spherical
roller thrust bear­ings
The use of the SKF oil injection method
(† fig. 5), in combination with a suit­able
mechanical withdrawal tool, simplifies
the removal of larger shaft washers.
This method involves injecting oil under
high pressure between the washer bore and
the shaft seat surface until the two surfaces
are separated. The resulting oil film consider­
ably reduces the requisite dismounting force.
However, this requires that the shaft has oil
ducts and grooves which are necessary for
this type of dismounting. Dimensions can
be found in table 1.
Due to the irregular shape and sectional
height of the shaft washer, the groove must
be placed where the shaft washer cross section is the largest. This is approximately a
­distance of one third of the washer height
measured from the outside face († table 1).
Table 1
Recommended dimensions for oil supply ducts, grooves and threaded holes for connecting
the oil supply
ba
Shaft
diameter
over
incl.
Dimensions
ba
ha
mm
mm
100
150
100
150
200
3
4
4
0,5
0,8
0,8
2,5
3
3
2,5
3
3
200
250
300
250
300
400
5
5
6
1
1
1,25
4
4
4,5
4
4
5
400
500
650
500
650
800
7
8
10
1,5
1,5
2
5
6
7
5
6
7
800
1 000
12
2,5
8
8
ra
ra
N
ha
N
L/3
L
The use of the SKF oil injection method simplifies
dismounting of a shaft washer having a tight fit
on the shaft
Fig. 5
Thread Design Dimensions
Ga
Gb
Gc1)
max
Gb
Gc
Na
–
–
mm
M 6
A
10
8
3
G 1/8
A
12
10
3
G 1/4
A
15
12
5
G 3/8
B
15
12
8
G 1/2
B
18
14
8
G 3/4
B
20
16
8
Ga
Na
60°
Design A
Gb
Gc
Na
Ga
Design B
1)
Effective threaded length
31
Service for a lasting partnership
Integrated platform for asset efficiency optimization
SKF @ptitude Decision Support System
SKF Machine Suite or SKF @ptitude Observer
data management and analysis software
Operator
tools
Single
point
monitors
Operator Driven
Reliability (ODR)
Vibration
analysis
Transient
analysis
Proactive Reliability Maintenance (PRM)
SKF Reliability Systems offers data acquisition
hard­ware, condition monitoring software, decision
support systems, and reliability and logistics services.
32
Online
monitoring
Protection
systems
Alignment
Lubrication
Balancing
Mechanical maintenance
Based on more than 100 years of experience
with rotating equipment, SKF’s expertise
begins at the component level and extends
to a deep under­standing of the technologies
required to improve manufacturing processes.
Using this knowledge, SKF can work with
you to design more efficiency into your
machines and then provide maintenance
solutions to keep those machines in peak
operating condition.
B
SKF concepts for creating
customer value
ERP/CMMS1)
Process
control
Consulting
services
Reliability
services
Maintenance
services
Maintenance
tools
Technology
bearing
System
installation
and
management
services
Technology
upgrades
1)
Enterprise Resource Planning/Computerized
Maintenance Management System.
With experience in virtually every industrial
sector, SKF can provide solutions that go beyond
simple maintenance to improve machine performance and productivity. With our Total
Shaft Solutions concept, customers can take
full advantage of our in-depth competence
including, but not limited to
For more information about SKF competencies and services contact your local SKF
representative.
• root cause failure analysis
• maintenance assessments
• predictive and preventive maintenance
• lubrication and filtration management
• equipment maintenance and monitoring
– fans, pumps, gearboxes and spindles
• precision balancing
• precision alignment
• applications-specific training
• component and technology upgrades
• installation and repair services.
Another SKF concept that embraces a broader
view of improving machine reliability is called
Asset Efficiency Optimization (AEO). As the
name implies, AEO recognizes the importance
of treating machinery and equipment as plant
assets. SKF programmes that take a systems
approach to managing these assets include
• Operator Driven Reliability (ODR)
• Proactive Reliability Maintenance (PRM)
• Integrated Maintenance Solutions, which
include all-inclusive contractual programmes.
SKF uses its own product, service and
knowledge capabilities, in combination
with other providers, to implement a
complete reliability programme based
on specific business goals.
33
Bearing data – general
Dimensions
Cages
Speeds
The boundary dimensions of SKF spherical
roller thrust bearings are in accordance with
ISO 104:2002.
Bearings identified with the suffix E up to and
including size 68 have a stamped steel windowtype cage. All other bearings have a machined
brass or steel cage guided by a sleeve that is
fixed in the shaft washer bore. In all bearings,
the cage (and sleeve) forms a non-separ­able
assembly with the rollers and shaft washer.
There is a speed limit for the operation of
spherical roller thrust bearings. Generally, it
is the permitted operating temperature of the
lubricant that sets the limit. In cases where
cooling facili­ties are used and the lubricant is
properly utilized, the limit is set by the cage
properties.
Tolerances
SKF spherical roller thrust bearings are produced as standard to Normal tolerances in
accordance with ISO 199:2005.
However, the SKF standard toler­ance for
the height H is considerably tighter than
speci­fied by ISO († table 1). For SKF Explorer
bearings it is even tighter.
Table 1
Bearing bore
diameter d
over
incl.
SKF height (H)
tolerance
high low
mm
µm
50
80
120
80
120
180
0
0
0
–125/–1001)
–150/–1001)
–175/–1251)
180
250
315
250
315
400
0
0
0
–200/–1251)
–225/–1501)
–300/–2001)
400
500
630
500
630
800
0
0
0
–400
–500
–630
0
0
0
–800
–1 000
–1 200
800
1 000
1 000 1 250
1 250 1 600
1)
Valid for SKF Explorer bearings
34
Reference speeds
Misalignment
By virtue of their design, spherical roller
thrust bearings are self-aligning, i.e. they can
accommodate misalignment of the shaft relative to the housing and shaft deflections during
operation.
The permissible misalignment is reduced
as the load increases. The values indicated in
table 2 can be applied provided there is constant misalignment relative to the housing
washer.
In practice, this means no problem for the
vast majority of applications.
Whether the permissible misalignment can
be fully exploited depends on the design of
the bearing arrangement, the type of seal etc.
When designing bearing arrangements
where the housing washer is to rotate, or
where there is a risk that the shaft washer
will wobble, it is advis­able to contact the SKF
application engineering service.
Table 2
Permissible angular misalignment
Bearing Permissible misalignment
series
when bearing load P01)
< 0,05 C0 > 0,15 C0 > 0,3 C0
–
degrees
292 (E)
293 (E)
294 (E)
2
2,5
3
1)
P0 = Fa + 2,7 Fr
1,5
1,5
1,5
1
0,3
0,3
The reference speed for a bearing represents
the speed at which, under specified operating
conditions and heat flow from the bearing, an
equi­librium is reached between the heat generated by the friction in the bear­ing and the
heat removed from the bearing via the shaft,
housing and, if applicable, the lubricant. The
refer­ence conditions for obtaining this balance
are according to ISO 15312:2003.
It is possible to operate spherical roller
thrust bearings above the refer­ence speed if
proper lubrication can be achieved (minimized
friction) and cool­ing facilities are used.
Limiting speeds
The limiting speed is based on the demand of
high-speed operating applications and takes
into account criteria such as cage strength,
running accuracy, form stability and gyratory
forces acting on the rollers.
It is possible to run spherical roller thrust
bearings at higher speeds than the limiting
speeds shown in the bear­ing tables. However,
bearings with special features, such as those
with increased running accuracy, may need
to be used. In such cases, contact the SKF
application engineering service.
Influence of operating temperature
on the bearing materials
All SKF spherical roller thrust bearings are
subjected to a special heat treatment so they
can be used at tempera­t­ures up to +200 °C
(390 °F).
Minimum load
In order to provide satisfactory oper­ation,
spherical roller thrust bearings, like all ball
and roller bear­ings, must always be subjected
to a given min­imum load, particularly if they
are to operate at high speeds or are subject­ed
to high accelerations or rapid changes in the
direction of load. Under such conditions, the
inertia forces of the rollers and cage, and the
friction in the lubricant, can have a detrimental
influence on the rolling conditions in the bearing and may cause damaging sliding movements to occur between the rollers and
raceways.
The requisite minimum axial load to be
applied to spherical roller thrust bearings
can be estimated using
q n w2
Fam =1,8 Fr + A———
<1 000z
Supplementary designations
The designation suffixes often used to identify
certain features of SKF spher­ical roller thrust
bearings are explain­ed in the following.
E
Optimized internal design, windowtype steel cage
EF
Optimized internal design,
machined steel cage
EM
Optimized internal design,
machined brass cage
N1
One locating slot in the housing
washer
N2
Two locating slots slots, 180° apart,
in the housing washer
VE447 Shaft washer with three equally
spaced threaded holes in one side
face to take hoisting tackle
VE447E As VE447, but with three appropriate
eye bolts
VE632 Housing washer with three equally
spaced threaded holes in one side
face to take hoisting tackle
VU029 Internal design feature for bearings
operating under combined loads
without any spring loading and
adjusted to a specific axial clearance
C
where
Fam =minimum axial load, kN
Fr =radial component of load for bearings
subjected to combined load, kN
C0 =basic static load rating, kN
A =minimum load factor († product table)
n =rotational speed, r/min
If 1,8 Fr < 0,0005 C0 then 0,0005 C0 should
be used in the above equation instead of
1,8 Fr.
At speeds higher than the reference speed
or when starting up at low temperatures, or
when the lubricant is highly viscous, even
greater minimum loads may be required.
The weight of the components supported
by the bear­ing, together with external forces,
generally exceed the requisite min­imum load.
If this is not the case, the spherical roller
thrust bearing must be preloaded, e.g. by
use of springs.
However, when a spherical roller thrust
bearing is radially guided and mounted with
clearance, the axial minimum load can be
reduced under certain conditions. Contact
the SKF application engineering service for
advice.
35
Spherical roller thrust bearings
d 60 – 190 mm
r1
C
r2
d1
d
r2
B
s
B1
H
r1
D1
D
Principal dimensions
Basic load ratings
Fatigue Minimum
Speed ratings
Mass
dynamic static
load load
Reference Limiting limit
factor
speed
speed
d
D
H
C
C0
Pu
A
Designation
mm
–
kN
kN
–
r/min
kg
60
130
42
390
915
114
0,080
2 800
5 000
2,20
65
140
45
455
1 080
137
0,11
2 600
4 800
3,20
70
150
48
520
1 250
153
0,15
2 400
4 300
3,90
75
160
51
600
1 430
173
0,19
2 400
4 000
4,70
80
170
54
670
1 630
193
0,25
2 200
3 800
5,60
85
150
39
380
1 060
129
0,11
2 400
4 000
2,75
180
58
735
1 800
212
0,31
2 000
3 600
6,75
90
155
39
400
1 080
132
0,11
2 400
4 000
2,85
190
60
815
2 000
232
0,38
1 900
3 400
7,75
100
170
42
465
1 290
156
0,16
2 200
3 600
3,65
210
67
980
2 500
275
0,59
1 700
3 000
10,5
110
190
48
610
1 730
204
0,28
1 900
3 200
5,30
230
73
1 180
3 000
325
0,86
1 600
2 800
13,5
120
210
54
765
2 120
245
0,43
1 700
2 800
7,35
250
78
1 370
3 450
375
1,1
1 500
2 600
17,5
130
225
58
865
2 500
280
0,59
1 600
2 600
9,00
270
85
1 560
4 050
430
1,6
1 300
2 400
22,0
140
240
60
980
2 850
315
0,77
1 500
2 600
10,5
280
85
1 630
4 300
455
1,8
1 300
2 400
23,0
150
215
39
408
1 600
180
0,24
1 800
2 800
4,30
250
60
1 000
2 850
315
0,77
1 500
2 400
11,0
300
90
1 860
5 100
520
2,5
1 200
2 200
28,0
160
270
67
1 180
3 450
375
1,1
1 300
2 200
14,5
320
95
2 080
5 600
570
3
1 100
2 000
33,5
170
280
67
1 200
3 550
365
1,2
1 300
2 200
15,0
340
103
2 360
6 550
640
4,1
1 100
1 900
44,5
180
250
42
495
2 040
212
0,40
1 600
2 600
5,80
300
73
1 430
4 300
440
1,8
1 200
2 000
19,5
360
109
2 600
7 350
710
5,1
1 000
1 800
52,5
190
320
78
1 630
4 750
490
2,1
1 100
1 900
23,5
380
115
2 850
8 000
765
6,1
950
1 700
60,5
The designations of SKF Explorer bearings are printed in blue
36
29412 E
29413 E
29414 E
29415 E
29416 E
29317 E
29417 E
29318 E
29418 E
29320 E
29420 E
29322 E
29422 E
29324 E
29424 E
29326 E
29426 E
29328 E
29428 E
29230 E
29330 E
29430 E
29332 E
29432 E
29334 E
29434 E
29236 E
29336 E
29436 E
29338 E
29438 E
da
db1
db2
db1
30°
ra
30˚
Ha
ra
db2
Da
30˚
Dimensions
Abutment and fillet dimensions
d
da
min
d1
~
D1
B
B1
C
~
C
db2
r1,2
s
min
mm
db1
max
db2 max
Ha
min
Da
max
ra
max
107
1,5
117
2
125
2
133
2
141
2
129
151
1,5
2
134
158
1,5
2
147
175
1,5
2,5
164
193
2
2,5
181
209
2
3
194
227
2
3
208
236
2
3
193
219
253
1,5
2
3
235
270
2,5
4
245
286
2,5
4
226
262
304
1,5
2,5
4
280
321
3
4
mm
60
112,2
85,5
27
36,7
21
1,5
38
90
67
67
–
65
120,6
91,5
29,5
39,8
22
2
42
100
72
72
–
70
129,7
99
31
41
23,8
2
44,8
105
77,5
77,5
–
75
138,3
105,5
33,5
45,7
24,5
2
47
115
82,5
82,5
–
80
147,2
112,5
35
48,1
26,5
2,1
50
120
88
88
–
85
134,8
109,5
24,5
33,8
20
1,5
50
115
90
90
–
155,8
121
37
51,1
28
2,1
54
130
94
94
–
90
138,6
115
24,5
34,5
19,5
1,5
53
120
95
95
–
164,6
127,5
39
54
28,5
2,1
56
135
99
99
–
100
152,3
127,5
26,2
36,3
20,5
1,5
58
130
107
107
–
182,2
141,5
43
57,3
32
3
62
150
110
110
–
110
171,1
140
30,3
41,7
24,8
2
63,8
145
117
117
–
199,4
155,5
47
64,7
34,7
3
69
165
120,5
129
–
120
188,1
154
34
48,2
27
2,1
70
160
128
128
–
216,8
171
50,5
70,3
36,5
4
74
180
132
142
–
130
203,4
165,5
36,7
50,6
30,1
2,1
75,6
175
138
143
–
234,4
184,5
54
76
40,9
4
81
195
142,5
153
–
140
216,1
177
38,5
54
30
2,1
82
185
148
154
–
245,4
194,5
54
75,6
41
4
86
205
153
162
–
150
200,4
176
24
34,3
20,5
1,5
82
180
154
154
14
223,9
190
38
54,9
28
2,1
87
195
158
163
–
262,9
207,5
58
80,8
43,4
4
92
220
163
175
–
160
243,5
203
42
60
33
3
92
210
169
176
–
279,3
223,5
60,5
84,3
45,5
5
99
235
175
189
–
170
251,2
215
42,2
61
30,5
3
96
220
178
188
–
297,7
236
65,5
91,2
50
5
104
250
185
199
–
180
234,4
208
26
36,9
22
1,5
97
210
187
187
14
270
227
46
66,2
35,5
3
103
235
189
195
–
315,9
250
69,5
96,4
53
5
110
265
196
210
–
190
285,6
243,5
49
71,3
36
4
110
250
200
211
–
332,9
264,5
73
101
55,5
5
117
280
207
223
–
37
Spherical roller thrust bearings
d 200 – 420 mm
r1
C
r2
d1
d
r2
B
s
B1
B
H
B1
r1
D1
D
Principal dimensions
Basic load ratings
dynamic
static
d
D
H
C
C0
Fatigue
load
limit
Pu
Minimum
load
factor
A
Speed ratings
Reference
Limiting
speed
speed
Mass
Designation
mm
kN
–
r/min
kg
–
kN
200
280
48
656
2 650
285
0,67
1 400
2 200
9,30
340
85
1 860
5 500
550
2,9
1 000
1 700
29,5
400
122
3 200
9 000
850
7,7
850
1 600
72,0
220
300
48
690
3 000
310
0,86
1 300
2 200
10,0
360
85
2 000
6 300
610
3,8
1 000
1 700
33,5
420
122
3 350
9 650
900
8,8
850
1 500
75,0
240
340
60
799
3 450
335
1,1
1 100
1 800
16,5
380
85
2 040
6 550
630
4,1
1 000
1 600
35,5
440
122
3 400
10 200
930
9,9
850
1 500
80,0
260
360
60
817
3 650
345
1,3
1 100
1 700
18,5
420
95
2 550
8 300
780
6,5
850
1 400
49,0
480
132
4 050
12 900
1 080
16
750
1 300
105
280
380
60
863
4 000
375
1,5
1 000
1 700
19,5
440
95
2 550
8 650
800
7,1
850
1 400
53,0
520
145
4 900
15 300
1 320
22
670
1 200
135
300
420
73
1 070
4 800
465
2,2
900
1 400
30,5
480
109
3 100
10 600
930
11
750
1 200
75,0
540
145
4 310
16 600
1 340
26
600
1 200
140
320
440
73
1 110
5 100
465
2,5
850
1 400
33,0
500
109
3 350
11 200
1 000
12
750
1 200
78,0
580
155
4 950
19 000
1 530
34
560
1 100
175
340
460
73
1 130
5 400
480
2,8
850
1 300
33,5
540
122
2 710
11 000
950
11
600
1 100
105
620
170
5 750
22 400
1 760
48
500
1 000
220
360
500
85
1 460
6 800
585
4,4
750
1 200
52,0
560
122
2 760
11 600
980
13
600
1 100
110
640
170
5 350
21 200
1 630
43
500
950
230
29240 E
29340 E
29440 E
380
520
85
1 580
7 650
655
5,6
700
1 100
53,0
600
132
3 340
14 000
1 160
19
530
1 000
140
670
175
5 870
24 000
1 860
55
480
900
260
400
540
85
1 610
8 000
695
6,1
700
1 100
55,5
620
132
3 450
14 600
1 200
20
530
950
150
710
185
6 560
26 500
1 960
67
450
850
310
420
580
95
1 990
9 800
815
9,1
630
1 000
75,5
650
140
3 740
16 000
1 290
24
500
900
170
730
185
6 730
27 500
2 080
72
430
850
325
29276
29376
29476 EM
The designations of SKF Explorer bearings are printed in blue
38
29244 E
29344 E
29444 E
29248
29348 E
29448 E
29252
29352 E
29452 E
29256
29356 E
29456 E
29260
29360 E
29460 E
29264
29364 E
29464 E
29268
29368
29468 E
29272
29372
29472 EM
29280
29380
29480 EM
29284
29384
29484 EM
da
db1
30°
ra
db2
db1
30˚
Ha
ra
db2
Da
30˚
C
db2
Dimensions
Abutment and fillet dimensions
d
da
min
d1
~
D1
B
B1
C
~
r1,2
s
min
mm
db1
max
db2 max
Ha
min
Da
max
ra
max
253
297
337
2
3
4
271
316
358
2
3
5
308
336
378
2
3
5
326
370
412
2
4
5
347
390
446
2
4
5
380
423
465
2,5
4
5
400
442
500
2,5
4
6
422
479
530
2,5
4
6
453
500
550
3
4
6
473
535
580
3
5
6
493
550
615
3
5
6
525
580
635
4
5
6
mm
200
260,5
232,5
30
43,4
24
2
108
235
206
207
17
304,3
257
53,5
76,7
40
4
116
265
211
224
–
350,7
277,5
77
107,1
59,4
5
122
295
217,5
234
–
220
280,5
251,5
30
43,4
24,5
2
117
255
224,5
227
17
326,3
273,5
55
77,7
41
4
125
285
229
240
–
371,6
300
77
107,4
58,5
6
132
315
238
254
–
240
330
283
19
57
30
2,1
130
290
–
–
–
345,1
295,5
54
77,8
40,5
4
135
305
249
259
–
391,6
322
76
107,1
59
6
142
335
258
276
–
260
350
302
19
57
30
2,1
139
310
–
–
–
382,2
324
61
86,6
46
5
148
335
273
286
–
427,9
346
86
119
63
6
154
365
278
296
–
280
370
323
19
57
30,5
2,1
150
325
–
–
–
401
343
62
86,7
45,5
5
158
355
293
305
–
464,3
372
95
129,9
70
6
166
395
300
320
–
300
405
353
21
69
38
3
162
360
–
–
–
434,1
372
70
98,9
51
5
168
385
313
329
–
485
392
95
130,3
70,5
6
175
415
319
340
–
320
430
372
21
69
38
3
172
380
–
–
–
454,5
391
68
97,8
53
5
180
405
332
347
–
520,3
422
102
139,4
74,5
7,5
191
450
344
367
–
340
445
395
21
69
37,5
3
183
400
–
–
–
520
428
40,6
117
59,5
5
192
440
–
–
–
557,9
445
112
151,4
84
7,5
201
475
363
386
–
360
485
423
25
81
44
4
194,5
430
–
–
–
540
448
40,5
117
59,5
5
202
460
–
–
–
580
474
63
164
83,5
7,5
210
495
–
–
–
380
505
441
27
81
42
4
202
450
–
–
–
580
477
45
127
63,5
6
216
495
–
–
–
610
494
67
168
87,5
7,5
222
525
–
–
–
400
526
460
27
81
42,2
4
212
470
–
–
–
596
494
43
127
64
6
225
510
–
–
–
645
525
69
178
89,5
7,5
234
550
–
–
–
420
564
489
30
91
46
5
225
500
–
–
–
626
520
49
135
67,5
6
235
535
–
–
–
665
545
70
178
90,5
7,5
244
575
–
–
–
39
Spherical roller thrust bearings
d 440 – 900 mm
r1
C
r2
d1
d
r2
s
B
H
B1
r1
D1
D
Principal dimensions
Basic load ratings
dynamic
static
d
D
H
C
C0
Fatigue
load
limit
Pu
Minimum
load
factor
A
Speed ratings
Reference
Limiting
speed
speed
Mass
Designation
mm
kN
–
r/min
kg
–
kN
440
600
95
2 070
10 400
850
10
630
1 000
78,0
680
145
4 490
19 300
1 560
35
480
850
180
780
206
7 820
32 000
2 320
87
380
750
410
460
620
95
2 070
10 600
865
11
600
950
81,0
710
150
4 310
19 000
1 500
34
450
800
215
800
206
7 990
33 500
2 450
110
380
750
425
480
650
103
2 350
11 800
950
13
560
900
98,0
730
150
4 370
19 600
1 530
36
450
800
220
850
224
9 550
39 000
2 800
140
340
670
550
500
670
103
2 390
12 500
1 000
15
560
900
100
750
150
4 490
20 400
1 560
40
430
800
235
870
224
9 370
40 000
2 850
150
340
670
560
530
710
109
3 110
15 300
1 220
22
530
850
115
800
160
5 230
23 600
1 800
53
400
750
270
920
236
10 500
44 000
3 100
180
320
630
650
560
750
115
2 990
16 000
1 220
24
480
800
140
980
250
12 000
51 000
3 550
250
300
560
810
600
800
122
3 740
18 600
1 460
33
450
700
170
900
180
7 530
34 500
2 600
110
340
630
405
1 030 258
13 100
56 000
4 000
300
280
530
845
630
850
132
4 770
23 600
1 800
53
400
670
210
950
190
8 450
38 000
2 900
140
320
600
485
1 090 280
14 400
62 000
4 150
370
260
500
1 040
29288
29388 EM
29488 EM
670
900
140
4 200
22 800
1 660
49
380
630
255
1 150 290
15 400
68 000
4 500
440
240
450
1 210
710
1 060 212
9 950
45 500
3 400
200
280
500
660
1 220 308
17 600
76 500
5 000
560
220
430
1 500
750
1 000 150
6 100
31 000
2 320
91
340
560
325
1 120 224
9 370
45 000
3 050
190
260
480
770
1 280 315
18 700
85 000
5 500
690
200
400
1 650
800
1 060 155
6 560
34 500
2 550
110
320
530
380
1 180 230
9 950
49 000
3 250
230
240
450
865
1 360 335
20 200
93 000
5 850
820
190
360
2 025
850
1 120 160
6 730
36 000
2 550
120
300
500
425
1 440 354
23 900
108 000
7 100
1 100
170
340
2 390
900
1 520 372
26 700
122 000
7 200
1 400
160
300
2 650
292/670
294/670 EM
40
29292
29392
29492 EM
29296
29396
29496 EM
292/500
293/500
294/500 EM
292/530 EM
293/530
294/530 EM
292/560
294/560 EM
292/600 EM
293/600
294/600 EM
292/630 EM
293/630 EM
294/630 EM
293/710 EM
294/710 EF
292/750 EM
293/750
294/750 EF
292/800 EM
293/800
294/800 EF
292/850 EM
294/850 EF
294/900 EF
da
ra
ra
Da
C
Dimensions
Abutment and fillet dimensions
d
da
min
d1
~
D1
B
B1
C
~
r1,2
s
min
mm
Da
max
ra
max
mm
440
585
508
30
91
46,5
5
235
520
545
626
540
49
140
70,5
6
249
560
605
710
577
77
199
101
9,5
257
605
675
460
605
530
30
91
46
5
245
540
565
685
567
50
144
72,5
6
257
585
630
730
596
77
199
101,5 9,5
268
630
695
480
635
556
33
99
53,5
5
259
570
595
705
591
50
144
73,5
6
270
610
655
770
625
88
216
108
9,5
280
660
735
500
654
574
33
99
53,5
5
268
585
615
725
611
50
144
74
6
280
630
675
795
648
86
216
110
9,5
290
685
755
530
675
608
32
105
56
5
285
620
655
772
648
53
154
76
7,5
295
670
715
840
686
89
228
116
9,5
308
725
800
560
732
644
37
111
61
5
302
655
685
890
727
99
241
122
12
328
770
850
600
760
688
39
117
60
5
321
700
735
840
720
65
174
89
7,5
340
755
810
940
769
99
249
128
12
349
815
900
4
6
10
630
810
880
995
723
761
815
50
68
107
127
183
270
62
92
137
6
9,5
12
338
359
365
740
795
860
780
860
950
5
8
10
670
880
1 045
773
864
45
110
135
280
73
141
6
15
361
387
790
905
825
1 000
5
12
710
985
1 110
855
917
74
117
205
298
103
149
9,5
15
404
415
890
965
960
1 070
8
12
750
950
1 086
1 170
858
910
964
50
76
121
144
216
305
74
109
153
6
9,5
15
409
415
436
880
935
1 015
925
1 000
1 120
5
8
12
800
1 010
1 146
1 250
911
965
1 034
52
77
123
149
222
324
77
111
165
7,5
9,5
15
434
440
462
935
995
1 080
980
1 060
1 185
6
8
12
850
1 060
1 315
967
1 077
47
142
154
342
82
172
7,5
15
455
507
980
1 160
1 030
1 270
6
12
900
1 394
1 137
147
360
186
15
518
1 215
1 320
12
4
5
8
4
5
8
4
5
8
4
5
8
4
6
8
4
10
41
Spherical roller thrust bearings
d 950 – 1 600 mm
r1
C
r2
d1
d
r2
s
B
H
B1
r1
D1
D
Principal dimensions
Basic load ratings
dynamic
static
d
D
H
C
C0
Fatigue
load
limit
Pu
Minimum
load
factor
A
Speed ratings
Reference
Limiting
speed
speed
Mass
Designation
mm
kN
–
r/min
kg
–
kN
950
1 250 180
8 280
45 500
3 100
200
260
430
600
1 600 390
28 200
132 000
7 800
1 700
140
280
3 065
1 000 1 670 402
31 100
140 000
8 650
1 900
130
260
3 380
1 060 1 400 206
10 500
58 500
3 750
330
220
360
860
1 770 426
33 400
156 000
8 500
2 300
120
240
4 280
1 180 1 520 206
10 900
64 000
3 750
390
220
340
950
1 250 1 800 330
24 800
129 000
7 500
1 600
130
240
2 770
1 600 2 280 408
36 800
200 000
11 800
3 800
90
160
5 375
42
292/950 EM
294/950 EF
294/1000 EF
292/1060 EF
294/1060 EF
292/1180 EF
293/1250 EF
293/1600 EF
da
ra
ra
Da
C
Dimensions
Abutment and fillet dimensions
d
da
min
d1
~
D1
B
B1
C
~
r1,2
s
min
Da
max
ra
max
mm
mm
950
1 185
1 470
1 081
1 209
58
153
174
377
88
191
7,5
15
507
546
1 095
1 275
1 155
1 400
6
12
1 000
1 531
1 270
155
389
190
15
599
1 350
1 490
12
1 060
1 325
1 615
1 211
1 349
66
192
199
412
100
207
9,5
15
566
610
1 225
1 410
1 290
1 555
8
12
1 180
1 450
1 331
83
199
101
9,5
625
1 345
1 410
8
1 250
1 685
1 474
148
319
161
12
698
1 540
1 640
10
1 600
2 130
1 885
166
395
195
19
894
1 955
2 090
15
43
Related SKF products
The right equipment
Lubrication grease
To achieve maximum bearing service life and
optimum performance from SKF spherical
roller thrust bearings, they must be mounted
correctly.
SKF offers a comprehensive line of tools
and equipment for mounting, dismounting
and maintenance of bear­ings, e.g. a range of
induction heaters, hydraulic pumps and nuts
etc.
High quality bearings need high qual­ity
grease. Extensive research, testing and field
experience are behind the formulation of all
SKF greases. And they have the same high
quality wher­ever you are in the world.
The most commonly used SKF greases for
spherical roller thrust bearings are listed in
tables 1 and 2 on page 27.
SKF has a wide range of bearing lubrication greases
in different packagings to suit different needs
44
Special housing for ship propeller
shafts
SKF offers a range of special housings for ship
propeller-shaft supports. They are designed
to accommodate a spher­ical roller bearing in
combination with a spherical roller thrust
bearing.
Condition monitoring equipment
Properly dimensioned and mounted bearings
are reliable components. For a number of
applications, however, it is recommended to
monitor the bear­ing condition, as to avoid
unexpected breakdowns. These could happen,
for example, when operating under adverse
conditions.
Condition monitoring enables early detection of bearing damage, which means that
bearing replacement can be scheduled when
the machine is not in operation.
SKF supplies equipment for both periodic
and continuous condition monitoring.
D
SKF’s handy general purpose electronic thermometer, ThermoPen TMTP 200
SKF’s easy-to-use electronic stethoscope TMST 3 is an instrument to detect
damaged bearings. The set includes a demonstration tape
SKF offers a large assortment of hydraulic tools to facilitate mounting
and dismounting of rolling bearings
45
SKF – the knowledge
engineering company
From the company that invented the selfaligning ball bearing more than 100 years
ago, SKF has evolved into a knowledge engineering company that is able to draw on five
technology platforms to create unique solutions for its customers. These platforms
include bearings, bearing units and seals, of
course, but extend to other areas including:
lubricants and lubrication systems, critical for
long bearing life in many applications; mechatronics that combine mechanical and electronics knowledge into systems for more effective
linear motion and sensorized solutions; and
a full range of services, from design and logistics support to condition monitoring and reliability systems.
Though the scope has broadened, SKF
continues 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 increasingly important position in the market for linear motion products, high-precision
aerospace bearings, machine tool spindles
and plant maintenance services.
The SKF Group is globally certified to ISO
14001, the international standard for environmental management, as well as OHSAS
18001, the health and safety management
standard. Individual divisions have been
approved for quality certification in accordance
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 distributors and dealers in
some 15 000 locations around the world,
an e-business marketplace and a global distribution system put SKF close to customers for
the supply of both products and services. In
essence, SKF solutions are available wherever
and whenever customers need them. Overall, the SKF brand and the corporation are
stronger than ever. As the knowledge engineering company, we stand ready to serve
you with world-class product competencies,
intellectual resources, and the vision to help
you succeed.
© Airbus – photo: exm company, H. Goussé
Evolving by-wire technology
SKF has a unique expertise in the fast-growing bywire technology, from fly-by-wire, to drive-by-wire,
to work-by-wire. SKF pioneered practical fly-bywire 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 engineers to
develop two concept cars, which employ SKF mechatronics for steering and braking. Further by-wire
development has led SKF to produce an all-electric
forklift truck, which uses mechatronics rather than
hydraulics for all controls.
Seals
Bearings
and units
Mechatronics
46
Lubrication
systems
Services
Harnessing wind power
The growing industry of wind-generated electric power provides a source of
clean, green electricity. SKF is working closely with global industry leaders to
develop efficient and trouble-free turbines, 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 bearings in railway axleboxes to seize due to lubrication starvation. SKF created a new family of synthetic lubricants formulated to retain their
lubrication viscosity even at these extreme temperatures. SKF knowledge enables
manufacturers and end user customers to overcome the performance issues
resulting from extreme temperatures, 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.
D
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
example of this cooperation is a new generation of vacuum cleaners with substantially more suction. SKF knowledge in the area of small bearing technology
is also applied to manufacturers of power tools and office equipment.
Maintaining a 350 km/h R&D lab
In addition to SKF’s renowned research and development 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,
engineering and knowledge have helped make Scuderia Ferrari a formidable
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 hardware and software to maintenance strategies, engineering assistance and machine reliability
programmes. To optimize efficiency and boost productivity, some industrial facilities opt for an Integrated Maintenance Solution, in which SKF delivers all services under one fixed-fee, performance-based contract.
Planning for sustainable growth
By their very nature, bearings make a positive contribution to the natural environment, enabling machinery to operate more efficiently, consume less power,
and require less lubrication. By raising the performance bar for our own products, 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 natural resources. We remain committed to sustainable, environmentally responsible growth.
47
®SKF, @PTITUDE, WAVE and MARLIN are registered
trademarks of the SKF Group.
™ SKF EXPLORER and TOTAL SHAFT SOLUTION are
trademarks of the SKF Group.
©SKF Group 2010
The contents of this publication are the copyright of the
publisher and may not be reproduced (even extracts) unless
prior written permission 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 consequential
arising out of the use of the information contained herein.
PUB BU/P2 06104/1 EN · June 2010
Printed in Sweden on environmentally friendly paper.
skf.com
Was this manual useful for you? yes no
Thank you for your participation!

* Your assessment is very important for improving the work of artificial intelligence, which forms the content of this project

Download PDF

advertisement