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1
Rolling Bearing Fundamentals
2
How to select a bearing
Outer ring
Key components
Inner ring
Rolling element
cage
By changing these and their combination a rolling
bearing can be optimized for almost every
application
3
How to select a bearing
Ball cylindrical roller
tapered roller
symmetrical Barrel roller
asymmetrical Barrel roller
Needle roller
4
How to select a bearing
Main stress factors that require spezialized
bearings for different applications

• Radial load
• Axial load
• speed
• Misalignment
• Temperature

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Radial load
6
Radial load
a raceway b lip
The radial load bearing capacity of a rolling
bearing depends on the length of the contact line
between rolling element and ring
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Axial load
8
Axial load
The axial load bearing capacity of a rolling
bearing can be judged from its contact angle
9
Inclined load
An inclined load may be split into two components
Radial load FR and Axial load FA
10
Speed
The larger the rolling elements and the higher
the speed of the bearing the higher is the
centrifugal force pressing the rolling elements
against the outer ring raceway. This means an
extra load on the oil film and on the raceways.
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Static misalignment
Static misalignment can arise from the processing
of the bearing seatings from a shaft or a
housing, especially if the seatings are
manufactured not in one setting
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Dynamic misalignment
Dynamic misalignment is caused by shaft
deflection as a result of operating loads.
13
Dynamic-Static misalignment
14
Temperature
Suitability for higher temperatures is a matter
of the material of the rings, rolling elements
and cages. Therefore it cannot be judged simply
from the design of a bearing.
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Temperature
Permissible operating temperatures for Rolling
bearings and their components
Bearing steel 150C Cages Brass/Steel 300C C
ages Polyamide 120C Cages
Phenolic 110C Seals NBR (RSR) 110C Shields
(ZR) 300C
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Bearing types
Radial- Ball Bearings
Ancular contact ball bearing Single row
douple row
Deep groove ball bearing
Four point ball bearing
Self aligning ball bearing
Radial- Roller Bearings
Cylindrical roller bearing
Tapered roller bearing
Barrel roller bearing
Spherical roller bearing
Thrust ancular contact ball bearing
Thrust cylindrical roller bearing
Thrust ball bearing
Thrust spherical roller bearing
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Cage design
- it keeps the rolling elements apart to prevent
mutual contact - it keeps the rolling elements
evenly spaced to ensure a more even load
distribution - it guides the rolling elements in
the unloaded bearing zones - it prevents the
rolling elements from falling out of separable
and slewable bearings, thereby facilitating
bearing mounting.
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Cage design
Pressed cages are usually made from sheet steel,
but sometimes also from brass sheet. They offer
the advantages of a light weight and low material
cost. If manufactured in large numbers, they are
economic in spite of the expensive manufacturing
tools. Solid cages are made from brass, steel,
light metal or textile-laminated phenolic resin.
They are manufactured either by machining, by
injection moulding of plastic materials or by
sintering metals.
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Cage design
Pressed cage J
Pressed cage JN
Machined cage M
Machined cage MP
Machined cage M
Machined cage M1
Machined cage TV
Machined cage TVP
Machined cage TVP
Pressed cage JPA
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Cage design
21
Cage design
Temperatures for polyamid cages -40C lower
limit 120C upper limit 150C some hours
(approx. 5h) 180C short peak temperature
(approx. 5min.) 255C Melting point
Continous operating temperature
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Cage design
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Rolling Bearing Clearance
The clearance defines the way which a bearing
ring can move in radial or in axial direction
against to the other ring.
Gr
Ga
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Rolling Bearing Clearance
We distinguish the clearance between a
non-mounted bearing and a mounted bearing. The
clearance of a mounted bearing should be small as
possible that the shaft is guided well. The
clearance of a non mounted bearing will reduce
during mounting because of the tight fits. It
also reduce during operation if the inner ring is
warmer than the outer ring. For this the
clearance of a non mounted bearing should be
bigger.
25
Rolling Bearing Clearance
Radial Clearance influences the Bearing load zone
(Radial clearance optimized for high load zone)
26
Rolling Bearing Clearance
Radial Clearance influences the Bearing load zone
(to high radial clearance - small load zone)
27
Designing of Rolling Bearing arrangements
28
Rolling Bearing arrangements
In order to guide and support a rotating shaft,
at least two bearings are required which are
arranged at a certain distance from each other.
Depending on the application, a bearing
arrangement with locating and floating bearing,
with adjusted bearings or with floating bearings
can be selected.
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Locating-floating arrangement
Due to machining tolerances the centre distances
between the shaft seats and the housing seats are
often not exactly the same with a shaft which is
supported by two radial bearings. Warming- up
during operation also causes the distances to
change. These differences in distance are
compensated for in the floating bearing. The
locating bearing guides the shaft axially and
transmit external axial forces.
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Locating-floating arrangement
31
Locating-floating arrangement
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Locating-floating arrangement
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Locating-floating arrangement
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Adjusted bearing arrangement
As a rule, an adjusted bearing arrangement
consists of two symmetrically arranged angular
contact ball bearings or tapered roller
bearings. During mounting, the required bearing
clearance or the preload is set. This arrangement
is suitable for those cases in which close axial
guidance is required.
35
Adjusted bearing arrangement
In the O- Arrangement, the apexes of the cone
formed by the contact lines point outward (back
to back).
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Adjusted bearing arrangement
In the X-Arrangement the apexes of the cone
formed by the contact lines point inward (face to
face).
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Adjusted bearing arrangement
Thermal expansion must be taken into
consideration when setting the axial clearance.
38
Adjusted bearing arrangement
39
Adjusted bearing arrangement
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Floating bearing arrangement
The floating bearing arrangement is an economical
solution where close axial guidance of the shaft
is not required. The shaft can shift by the axial
clearance s relative to the housing. The value s
is determined depending on the guiding accuracy
in such a way that detrimental axial preloading
of the bearings is prevented even under
unfavourable thermal conditions.
41
Floating bearing arrangement
With NJ cylindrical roller bearings, length is
compensated in the bearings. Inner and outer
rings can be fitted tightly.
42
Floating bearing arrangement
In non - seperable bearings one ring is fitted
loosely to allow displacement.
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Floating bearing arrangement
Elastic adjustment of deep-groove ball bearings