Everything about the "Bearings". Read them, Learn them and ask your any question from me. If you find my fault, Please inform me. Good luck.

1. BEARINGS
•Kanan Sadigzada
•k.sadiqzade@stp.az
•Kheyrulla Amirov
•xeyrullamirov@gmail.com
19/07/2019

2. BEARINGS
• Introduction
• History
• Classification of Bearing
• Bearing Types
• Bearing Structure
• Bearing Mounting and Dismounting
• Bearing Lubrication
• Bearing Selection
• Bearing Failure
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3. Bearings
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Any machine or structure that has relative movement requires
the use of bearings. Bearings are the most common
component feature used in machines and structures The range
of bearing types and associated applications is huge and
without bearings the all motion would grind to a halt.
Bearings are used in everyday items ranging from the more
obvious applications such as washing machines, cars, the
watches on our wrists but also super structures such as
building supported on bearings to allow relative movements
during earthquakes

4. • Bearing provides relative rotational freedom and transmits a load between
two structures.
Inner Ring
Cage
Rolling Elements
Outer Ring
Wind Turbine Gearbox
Construction of a bearing
Bearings
Bearings inside
Gas Turbine Engine
Induction Motor
Bearing
4
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5. What is Friction ?
Friction is resistance to movement
 it opposes sliding
 it assists rotation
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6. WHAT IS FRICTION?
Plain bearings
sliding friction
Rolling bearings
rolling friction


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7. HISTORY
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8. How did a bearing evolve ?
Bearing history - a never-ending story
1100 B.C.
3500 B.C.
1995
1794
40 A.D.
1869
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9. How did a bearing evolve ?
* Invention of wheel
* Wheel rotates on axle
* Wear Plate + Rollers
* Inner ring + Outer ring
+ Rollers
* With introduction of
cage Rolling Bearing
was created
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10. • BASED ON NATURE OF CONTACT
• 1. Rolling Contact Bearings Balls or rollers introduced between moving and fixed elements
and it is also known as anti-friction bearings
• 2. Sliding Contact Bearing Sliding takes place between the fixed and moving element of
bearing and its also known as plain bearing
CLASIFICATION OF BEARING
1 19/07/2019

11. Rolling Element Bearings
They are also called antifriction bearings/rolling contact bearings/rolling bearings. Load is transferred through
elements in rolling contact. These bearings locate the shaft in axial and radial direction. Starting friction is
twice as the running friction. REB is an assembly rather than single element. There bearings are
manufactured to take loads:
- Pure radial
- Pure axial (thrust)
- Combined (radial and thrust)
They are designed taking into consideration below points:
- Space limitations
- Load characteristics
- Life fatigue
- Friction, heat
- Corrosion resistance
- Material properties
- Lubrication
- Tolerances
- Cost and etc 19/07/2019

12. BEARING TYPES:
Can be classified according to shape of element and load type. According to the type of
element:
- Ball bearings
- Roller Bearings
According to the type of the load Some bearings can carry both
axial and radial loads
- Radial bearings (ring bearings radial loads)
- Thrust bearings (axial loads
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13. The components of a bearing
Seal Rolling elements Inner ring
Outer ring SealCage
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14. Pg. 7
Bearing Installation and Maintenance Guide
Bearing Basics
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15. BALL
POINT
CONTACT
SPHERICAL
LINE CONTACT
TAPERED
LINE CONTACT
Bearing Basics
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16. Characteristics
Deep groove Angular
ball bearing contact
ball bearing
Self-aligning
ball bearing
Ball bearings Point Contact :
Cylindrical
roller
bearing
Taper Needle
roller roller
bearing bearing
Spherical
roller
bearing
* Less area of contact
* Less friction
* More speed
* Less load
Roller bearings
Line Contact :
* More area of contact
* More friction
* Less speed
* More load
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17. Rolling elements name the bearing
Spherical roller
(symmetrical)
Ball Spherical roller
(asymmetrical)
Needle roller
Cylindrical roller Taper roller
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18. Bearing loads
Radial load
Fr
Axial load
Fa
C o m b in e d
load
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19. Radial rolling bearings
Deep groove
ball bearing
Angular
contact
ball bearing
Self-aligning
ball bearing
Cylindrical
roller
bearing
Taper
roller
Needle
roller
bearing bearing
Spherical
roller
bearing
Ball bearings Roller bearings
Radial rolling bearings
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20. Thrust
ball bearing
Ball bearings Roller bearings
Thrust bearings
Angular
Contact
Ball Thrust
bearing
Taper
Roller
Thrust
bearing
Spherical
Roller
Thrust
bearing
Cylindrical
/ Needle
Roller
Thrust
bearing
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21. Bearings with shields and seals
Shields Low-friction
seals
Seals
-Z and -2Z -RZ and -2RZ -RS1 and -2RS1
Contaminant
exclusion
Silent
running
Grease
retention
Speed
capability
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22. BALL BEARINGS
Rolling elements are balls and are used in simple bearing applications. They have
smaller load carrying capacity when compared to similar size roller bearings.
Radial bearings:
1) Deep Groove Ball bearings (rigid, non-separable, both axial and radial loads,
highest speed limits). Both rings contain grooves and due to this they can
support high radial loads as well as some axial loads. Most widely used ball
bearings. They are not self- aligning therefore accurate alignment between
shaft and housing is required. There is a cage to position the rolling elements
Single row deep groove ball bearings Have
continuous deep raceways. Designed for radial
loads. Can take some axial thrust as well
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23. STANDARDIZATION OF
BEARINGS
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24. Ball bearing properties
Deep groove
ball bearing
Angular contact Self-aligning ball bearing
ball bearing
radial load
carrying capacity
axial load
carrying capacity
speed
capability
can accommodate
misalignment
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25. Self-aligning bearings
They have 2 rows of balls with common raceway in the
outer ring. This enables relative positioning
of inner ring with respect to the outer ring and gives the
bearing its self-aligning property. Accommodate
misalignment due to mounting and shaft deflection.
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26. Angular contact ball bearings:
Can support thrust loads combined with moderate
radial loads.
The axial difference between inner
and outer rings provides the contact
angles. There are:
- Single row angular contact ball bearings (1
directional thrust)
- Double row angular contact ball bearings (2
directional thrust)
- Four-point (duplex) ball bearings (2 directional
thrust)
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27. Thrust ball bearing
a) Single direction thrust ball bearings:
Carry thrust loads in one direction. They can locate shaft in 1 direction.
b) Double direction thrust ball bearing
Separable, only thrust capacity, not suitable for high speeds. Can carry
thrust loads in both directions and can locate shaft in both directions.
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28. Angular Contact Thrust Ball Bearing
Uses same principle as its radial counterpart in terms of
raceway geometry. Capable of operating at higher speeds
due to ability to support centrifugal loads on the balls by
virtue of the inclined contact angle. Reasonable axial load
capacity and offers high precision, typically assembled with
pre-load or as preloaded pair
Some features of ball bearings:
- shields provide partial protection against dirt
- seals provide better protection against dirt
- if the bearing has seals on both sides’ leakage is
prevented and the bearing may be
factory oiled for life
- single row bearings can withstand small amount of
shaft misalignment and deflection
- if there is severe misalignment or deflection, self-
aligning bearings should be used.
- Double row bearings can carry higher radial and
thrust loads. They are better than two single row
bearings because they require fewer parts and less
space
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29. Roller Bearings
In general, these bearings have greater load carrying capacity due to
increased contact surface. They require closer tolerance on raceways
and rollers. Heavier retainers are used. Some straight roller bearings
can carry NO thrust load, some can carry thrust to a limited extend and
some can carry great amount.
Radial Roller Bearings
1. Cylindrical roller bearings:
Separable, higher load carrying capacity, relatively high rotational
speeds, those with lips on inner and outer rings can carry some
thrust. Can accommodate LESS misalignment and deflection (very
sensitive to misalignment).
Construction differs for different types where locating lips are either
present on one of the races or both. If both rings have location lips,
then axial loads can be taken. When used with only location lips on
one race relative axial movements possible
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30. Cylindrical roller bearings
More and larger
rollers
Logarithmic contact
profile plus optimised
surface finish
Improved roller
end/flange contact
geometry
3 cage variants: steel,
polyamide, brass
NU NUPNJ
N NJ+HJNU+HJ
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31. 2. Needle roller bearings
Takes less radial space, they are long and thin
(diameter to length ratio 2.5-10),
high load carrying capacity.
Should not be used where misalignment exist.
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32. 3. Spherical roller bearings
Have two rows of rollers with a common raceway
in the outer ring. The two inner raceways are inclined
to an angle to the bearing axis. Insensitive to
misalignment. They can carry thrust loads in
both directions in addition to radial loads.
Allowable angular misalignment is between
1.50-30
Radial load capacity is high and high axial loads can be accommodated
with appropriate ratio of radial load, axial load only capacity is poor
and not recommended
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33. Spherical roller bearings
Symmetrical rollers
for maximum life under
any conditions
Floating guide ring
gives minimum friction
and ensures reliable
operation
Window-type steel cages
strong and tolerant to
high temperatures
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34. 4. Taper roller bearings
Have tapered inner and outer
raceways Suitable for combined
radial and axial loading
They can carry axial loads in 1 direction only
(single tapered) They should be used in pairs.
Can support high loads.
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35. Spherical roller bearings
Symmetrical rollers
for maximum life under
any conditions
Floating guide ring
gives minimum friction
and ensures reliable
operation
Window-type steel cages
strong and tolerant to
high temperatures
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36. Thrust Roller Bearings
1. Cylindrical roller thrust bearing Carry only thrust
loads in 1 direction Locate shaft in 1 direction
Used mainly if capacity of thrust ball bearing is inadequate. No
radial loads, speed is limited
Sensitive to misalignment
2. Needle roller thrust bearing
Suitable for axial space limited application
3. Spherical roller thrust bearings
Carry radial loads in addition to thrust loads. Locate
shaft in 1 direction
Self-aligning can accommodate misalignment very high
loads and moderate radial loads
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37. ROLLER BEARINGS
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38. 4. Tapered roller thrust bearings
Suitable for extremely high axial loads- no radial loads. Sensitive to
face misalignment but can compensate for radial misalignment.
Limited operating speeds, help to reduce sliding
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39. Single row and paired single row
taper roller bearings
Single row Face-to-face
arrangement
suffix DF
Back-to-back
arrangement
suffix DB
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40. 19/07/2019

41. Compact Aligning Roller Bearings
CARB
TM
Safer, more optimized design
Increased service life
Lower running temperature
Lower vibration and noise level
Extended maintenance interval
Higher axial clearence
No internal Friction force
Longer life
Higher speed
Downsizing possibility
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42. CARBTM
- Bearing
Compact Aligning Roller Bearing
 Self-aligning as spherical roller bearing
 Permits axial displacements like a cylindrical roller bearing
 Compact as a needle roller bearing
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43. Advantages and disadvantages of rolling bearings compared to
journal bearings:
Advantages:
- Low starting friction/torque
- Ease of lubrication
- Less axial space
- Thrust and radial load support
- Early warning against failure
- Standard close tolerances
- Preloading is possible
- Freedom of shaft positioning
- Special housing is available
Disadvantages:
- Greater radial space
- Higher initial cost
- More noise
- Possibility of early failure
- Finite life
- Lower shock resistance
Failure types of Rolling Element bearings:
Failure is happening due to inadequate shaft guidance, excessive
noise and vibration
1. Fatigue due to high fluctuating stresses (indications are pitting,
spalling)
2. Failure due to misalignment, unsuitable loading, lack of
lubrication, dirt/contamination
3. Outer raceway breakage due to overload
4. Cage (separator, retainer) failure- due to high centrifugal forces
at high speeds
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44. Bearings are precision products
Example:
Tolerances for
bore diameter
75 mm
Precision High precision
bearing bearing
Normal
Tolerance
classes
Standard P6 P5
SP
P4A
UP
PA9A
PA9B
0/-7 m
0/-2,5 m
0/-15 m 0/-12 m 0/-9 m
How much is a m
1
0,06 mm
A
human
hair
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45. Materials for rolling bearings
Bearing rings and rolling elements
1. Through-hardening steels
Carbon chromium steel containing approximately
1 %carbon and 1,5 % chromium
2. Case-hardening steels
– Chromium-nickel alloyed steel
– Manganese-chromium alloyed steel
appr. 0,20 % carbon
bearing steels have very high cleanliness
– the content of macroand microinclusions is
extremely low.
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46. Cages keep the rolling elements separated
Prevent immediate contact
between rolling elements to
minimise friction and heat
generation
Guide the rolling elements
Provide space for lubricant
Serve to retain the rolling
elements when bearings of
separable design are mounted
or dismounted
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47. Cage variants
Polyamide cage
+ lightweight
+ high elasticity
+ good sliding properties
+ good marginal lubrication
properties
- operating temperature
limit +120°C
Window-type steel cage
+ lightweight
+ high strength
+ no operating temperature
limit
+ high vibration and
acceleration resistance
- sensitive to poor
lubrication
Window-type brass cage
+ very high strength
+ very high vibration and
acceleration resistance
+ suitable for very high
speeds in connection with
circulating oil lubrication
- relatively expensive
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48. • Based on Nature ofContact
1. Sliding Contact Bearing
Sliding takes place between the fixed and moving element of
bearing and its also known as plain bearing
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49. SLIDING CONTACT BEARING
• 1. Based on type of load carried
• 2. Based on type of lubrication
• 3. Based on lubrication mechanism
Sliding contact bearings are classified in three ways.
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50. SLIDING CONTACT BEARING • Working surfaces separated by some medium or force
• Working medium can be solids, fluids, gas or magnetic forces (or
combination)
• Reduced local friction but can have high drag losses
• Life can become theoretically infinite due to lack of fatigue loads and
wear
• Often dependent on presence of other equipment to provide working
media
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51. BASED ON TYPE OF LOAD CARRIED
a. Radial bearings
(These bearings carry only radial loads.)
b. Thrust bearings or axial bearings
( These bearings carry only axial loads)
c. Radial – thrust bearings
(These bearings carry both radial and thrust loads. )
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52. BASED ON TYPE OF LUBRICATION
• The type of lubrication means the extent to which the contacting surfaces are separated in a shaft
bearing combination. This classification includes
(a) Thick film lubrication
(b) Thin film lubrication
(c) Boundary lubrication
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53. 19/07/2019

54. JOURNAL
BEARING
Hydrodynamic Bearing Hydrostatic Bearing
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55. 19/07/2019

56. Journal (Sleeve) Bearings
Load is transferred through a lubricant in sliding contact
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57. JOURNAL (SLEEVE)
BEARINGSThick-film lubrication (hydrodynamic), pressure distribution, and
film thickness.
hmin = minimum film thickness, c = radial clearance,
e = eccentricity
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58. 19/07/2019

59. PREVENTION OF ROTATION OF BRASSES
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60. DESIGNATION OF BEARINGS:
Rolling contact bearings and necessary parts used for mounting and sealing of them have been all standardized by ISO.
Bearings are designated by numbers and letters.
1. Bearing type
2. Dimension series
3. Borenumber
4. Specialshape
5. Special accuracy and clearance
Bearing type:
Numeric or alphanumeric designations areused 6- single row deep
groove ball bearings
2- spherical roller bearings 3- taper roller bearings
N-cylindrical roller bearings
….. etc
Dimension series
For each bearings size, there are standard series of outside diameter and width designations.
- The first number in the dimension series indicates the shape of the cross section of the bearings, which is the
ratio of the width to the outside diameter and called as width number.
- The second number indicates the ratio of the outside diameter to the bore diameter and called as diameter
number
Width number- 0, 1, 2, 3, 4, 5, 6
Diameter number- 8, 9, 0, 1, 2, 3, 4
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61. EXAMPLE:
6314-ZN-C2
6- deep groove ball bearing
3- dimension series (03, 0 width is not written)
14- bore number 14x5=70mm
Z- shield (non-rubbing seal) at one side
N- snap ring groove at the surface of the outer ring
C2- internal clearance is less than standard
6305-ZNR-P62 P6+C2 closer tolerance
Bore Number
Indicates the bore diameter of
the bearing
Bore number Bore diameter (mm)
00 10
01 12
02 15
03 17
n (n≥4) 5n
Special Shape
Numeric or alphanumeric designations are used
Z : shield (non-rubbing seal) at one side of
bearing 2Z: Z shields at both sides
N : snap ring groove in outside cylindrical surface of
outer ring NR: N with snap ring
F : machined cage made of steel or iron
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62. PREPARATION FOR MOUNTING AND DIMOUNTING.
Before mounting, all the necessary parts, tool, equipment and data need to be at hand. It is also
recommended that any drawings or instruction be studied to determine the correct order in
which to assemble the various components.
Housing, shafts, seals and other components of the bearing arrangement need to be checked to
see that they are clean, particularly any threaded holes, leads or grooves where remnants of
previous machining operation might have collected.
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63. MOUNTING METHOD
Depending on the bearing type, and size, mechanical, thermal and hydraulic
methods are used for mounting.
1. Cold Mounting Method.
2. Hot Mounting Method
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64. COLD MOUNTING
If the fit is not too tight, small bearings may be
driven into position by applying light hammer
blows to a sleeve placed against the bearing
ring face.
The blows should be evenly distributed around
the ring to prevent the bearing from tilting or
skewing.
The use of the mounting dolly instead of a sleeve
allows the mounting force to be applied
centrally.
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65. HOT MOUNTING
It is generally not possible to mount larger bearing in the cold
state, as the force required to mount a bearing increases very
considerably with increasing bearing size .
The inner rings or the housings are there fore heated prior to
mounting.
Bearing should not be heated to more than 125c as otherwise
dimensional changes caused by alterations in the structure of
the bearing material may occur.
Bearing fitted with shields or seals should not be heated above
80c because of their grease fill or seal material.
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66. POSITIONS OF BEARING
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67. DISMOUNTING METHOD
If the bearings are to be used again after removal, the force used to dismount them must never be
applied through the rolling elements.
With separable bearings, the ring with the rolling element and cage assembly can be removed
independently of the other ring.
To dismount a bearing having an interference fit, the tools described in the following section may be
used, the choice of tools will depend on bearing type, size and fit.
1. Cold dismounting.
2. Hot dismounting.
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68. COLD DISMOUNTING
Small bearing maybe removed from their settings by
applying light hammer blows via a suitable drift to
the ring face, or preferably by using a puller
The claws of the puller should be placed around the
side face of the ring to be removed or an adjacent
component.
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69. HOT DISMOUNTING
Special induction heaters have been
developed to dismount the inner
ring of cylindrical roller bearing
having no flanges or only one
flange.
They heat the inner ring rapidly
without heating the shaft to any
degree, so that the expanded ring
can easily be removed.
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70. BEARING CLEARANCE
Radial
clearance
Axial
clearance
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71. Clearance
Normal clearance Increased clearance
because of temperature
Reduced clearance
because of tight fit
Example:
6210/C3 = Deep groove ball bearing with
clearance greater than Normal
CN does not normally appear in the
bearing designation
Suffix clearance
/C1 less than C2
/C2 less than Normal
/CN Normal
/C3 greater than Normal
/C4 greater than C3
/C5 greater than C4
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72. SPECIALIZED BEARINGS:
There are, of course, several kinds of bearings that are
manufactured for specific applications, such as magnetic
bearings and giant roller bearings.
 Magnetic Bearings:
Magnetic bearings are found in high-speed devices because it has
no moving parts this stability enables it to support devices that
move unconscionably fast.
 Giant Roller Bearings:
Giant roller bearings are used to move extremely large and heavy
loads, such as buildings and large structural components.
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73. BEARING LUBRICATION
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Lubrication reduces friction. It also
prevents wear and corrosion, and
guards against solid and liquid
contamination. Theoretically, a
properly lubricated bearing
operating under ideal conditions will
last forever. This is not possible in
reality, of course. But a properly
lubricated bearing has the best
chance of achieving its maximum
service life.

74. LUBRICANT SUPLLY SYSTEM
Oil and grease require different types of supply
systems.
Several oil and grease supply systems exist that
meet the needs of various bearing
applications.
Oil supply systems include: oil baths, circulating
oil systems, spray or mist systems, and the
wick feed method.
Grease supply systems include: housings (with or
without grease fittings), grease chamber
lubrication, and the grease quantity regulator.
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75. WHYLUBRICATION??
• Formation of protective film to







Reduce friction
Prevent corrosion
Remove wear particles and debris
Provide efficient cooling
Reduce wear
Shock absorption
Overall life improvement

76. LUBRICATION THEORY
• Full film
●
● Static
Hydrodynamic
• Elastohydrodynamic
●
● Application of pressure / load
Depends upon speeds, loads, lubricant viscosity
• Boundary layer
●
● Layer separation not complete
Results from insufficient lube, incorrect lube

77. GREASE Vs OILWhen greases?
 Normal speed and temp conditions
 Simpler / cheaper installation
 Better adhesion
 Protection against impurities
 Less frequent application required
When Oils?
 High Speed and temp
 Excellent cleaning and flushing characteristics
 Can be used in recirculative systems
 Can serve better in excessive dirt environment
 More stable than greases

78. Bearing Life
Failure mode - Spalling
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79. BEARING LIFE
Bearing life is defined as the
Number of revolutions
that a bearing undergoes
under a constant load
( Equivalent Dynamic Bearing Load )
before
the first sign of fatigue failure occurs.

80. Calculating Dynamic Bearing Load
G
Kr
Ka
G1
Kr1
I
II
l
a1
FrII
FrI
l
a1
a2
Kr
Ka
III
FrI FrII
Kr1
Stationary Electrical Machine
a2
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81. Bearing Selection
Bearings are selected based on:
 Load
 Speed
 Temperature
 Environment
 Life expectancy
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82. Selection of bearings
Some aspects to be considered
Available space Misalignment
Speed Life
Load/Direction Operating conditions
L10
P
= (C)p
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83. Load carrying capacity
is expressed as the basic
dynamic load rating
Load carrying capacity
of different bearing types having the same bore and outside
diameters
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84. 0 r/min
Oil lubrication
speed rating
Grease lubrication
speed rating
Bearingspeed
limit
Speed ratings = speed
limit
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85. Factors influencing speed capability
Increases speed
 Low loads
 High accuracy
 Good sliding properties
of cage guiding surface
 Correct clearance
 Optimised lubrication
 Effective cooling
Reduces speed
 High loads
 Poor accuracy
 Excess of lubricant
 Lack of lubricant
 Excessive lubricant
viscosity
 Poor cooling
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86. Basic Terminologies :
1. Static Load
1. Dynamic Load
1. Life Requirement
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87. BASIC DYNAMIC LOAD
RATING
ISO dynamicload rating
C= Load that gives a basic rating
life of 1 000 000 revolutions
C
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88. BEARING LIFE CONSIDERATIONS
VARY DEPENDING ON :
Type of Rolling Element
1. Ball
2. Roller
a. Cylindrical
b. Needle
c. Tapered
d. Spherical
I. Symmetrical
II. Asymmetrical
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89. Load carrying capacity
L10 = basic rating life, millions of
revolutions
C = basic dynamic load rating, N
P = equivalent dynamic bearing load, N
p = exponent of the life equation
With the load P = C
the L10 life will be 1 million revolutions
0Basic dynamic load rating C Basic static load rating C
P P0
P P0
The ISO life equation
s0
P0
C0
= static safety factor
= equivalent static bearing load, N
= basic static load rating, N
With the load P = C0
the static safety factor s0 will be 1
The static safety factor
s =0
C0
P0
( )L =10
C
P
p
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90. Basic rating life equation:
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91. Adjusted Rating Life Equations:
In the basic life equation effect of bearing load on the life is
considered. However, by using adjusted bearing life equation
effects of other factors can be considered.
Index i (sometimes n) above represents difference between 100% and
the required reliability (probability of a bearing to achieve a specified
life). For instance, for 95% reliability, adjusted bearing rating life is
denoted as L5a.
If bearing is operating at constant speed, it may more convenient to
express the rated life in terms of hours.
The factors a2 and a3 are independent from each other and can be
combined as a23. It is life adjustment factor for material and
operating conditions.
Lna=a1a23L10 Lna=a1a23(C/P)p
Reliability factor a1 – This factor modifies the calculated life down to
account for the extra level of reliability required above 90% and is
based the fatigue probability principles already applied.
Material adjustment factor a2 – For standard bearings the factor is
equal to 1. The factor addresses the potential performance gains
that can be achieved by material processing and principally
cleanliness control. For specialist steel factors of 6 or more are
quoted.
Operating condition factor a3 – This factor takes into consideration the
impact of operating conditions within the bearing. In particular is
considers the effects of the lubrication conditions and material
lubricant/environment cleanliness
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92. 19/07/2019

93. 19/07/2019

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95. Example:
Solutions;
a1=1
(80+40)/2=60=dm
From fig.2 (with n=1500rpm) V1=15mm2/s
From fig.3 (with T=60C, v40=220) V=60 mm2/s
X=V/V1=60/15=4
a23=3 (from fig.4)
L=a1*a23*(C/P)^p=1*3*(32.5/24)^3=1058=
=8 million revolutions
Lh=8*10^6/(1500*60)=89 hours
6208 DEEP Groove Ball bearing is to
be used in application T=60 deg C,
n=1500 rpm,
ν40=220mm2/s. P=24000N. What is
the adjusted rating life?
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96. Equivalent bearing load (Fe or P)
Equivalent dynamic bearing load
 Used for combination of radial and axial load.
It is stationary radial load or axial if thrust
bearing, if applied to a bearing, it will give
same life as actual loading and rotating
conditions.
 A fictitious radial load is calculated to be
compared with basic static and/or dynamic
load rating.
 P is supposed to have the same effect on
bearing life as the actual loading consisting of
Fa and Fr.
 Thrust ball bearings Pa=Fa No radial load
carrying capacity
 Radial bearings P=Fr
 Combined loading P=VXFr+YFa
o P: equivalent dynamic load N
o Fr: actual bearing radial load
o Fa: actual bearing axial load
o X: radial load factor
o Y: axial load factor
o The damaged bearing fit on the shaft
o V: rotation factor
 V=1 for rotating inner ring
 V=1.2 for rotating outer ring (V=1 for
self-aligning bearings)
X and Y depends on the bearing type and its
geometry. Plotting
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97. Basic static load rating
ISO basic load rating Co
corresponds to a stress that
gives permanent deformation
of 0,0001 of the rolling
element diameter
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100. BEARING
LIFE
P10
L = (C )
p
Lnaa= a1 a SKF P
(C)p
ISO
Load P
Finite life
Life
The SKF New Life Theory
Service life:
This is the actual life achieved by the bearing before it fails.
Load P
Infinite life
PU
Life
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101. Friction Under certain conditions the frictional
moment can be calculated with sufficient
accuracy
M = 0,5 . µ . F . d
M = frictional moment (Nmm)
µ = coefficient of friction
F = bearing load (N)
d = bearing bore diameter (mm)
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