Bearings are machine elements designed to reduce friction, carry loads, and guide moving parts. They come in many types including ball bearings, roller bearings, and thrust bearings which use either rolling or sliding friction. Over time, bearings have evolved from early wheels to modern designs with inner and outer rings and cages to separate rolling elements. Proper bearing selection, installation, and maintenance are important to maximize bearing life.
7. 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
8. The components of a bearing
Seal Rolling elements Inner ring
Outer ring SealCage
11. Characteristics
Deep groove
ball bearing
Angular
contact
ball bearing
Self-aligning
ball bearing
Ball bearings Point Contact :
* Less area of contact
* Less friction
* More speed
* Less load
Cylindrical
roller
bearing
Taper
roller
bearing
Needle
roller
bearing
Spherical
roller
bearing
Roller bearings
Line Contact :
* More area of contact
* More friction
* Less speed
* More load
12. Rolling elements name the bearing
Spherical roller
(symmetrical)
Ball Spherical roller
(asymmetrical)
Needle roller
Cylindrical roller Taper roller
17. 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
20. Misalignments
produce additional stresses
shorten bearing life
increase seal wear
increase vibration
increase noise
increase energy consumption
which will be avoided by proper
shaft alignment or the use of a
self-aligning bearing
Misalignment
Parallel or offset misalignment Angular misalignment
21. The industrial revolution has depended
on a seldom recognized
component, the rolling bearing. So
important is the rolling bearing that
without it today's modern industry would
literally grind to a halt. From the
beginning, SKF has led the world in
reducing friction with innovative rolling
bearing solutions that have moved
industry forward.
SKF was founded in Sweden in 1907
and grew out of Sven
Wingquist's solution to a misaligned
drive shaft problem he faced in a textile
mill. His invention of a double row self-
aligning ball bearing was only the first of
many innovations SKF has provided
industry. From the first spherical rolling
bearing to the current bearing life
calculation methods used worldwide,
SKF has pioneered the way with over
2,200 patents.
30. Paired mounting increases load carrying capacity
and stiffness of the bearing arrangement
Face-to-face
arrangement
e.g. 71906/DF
Back-to-back
arrangement
e.g. 71906/DB
Tandem
arrangement
e.g. 71906/DT
Bearing stiffness (N/mm) =
Force acting on bearing or set
Elastic deformation due to load
47. 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
51. Taper rollers
for perfect rolling contact
Specially designed flange
gives minimum friction and
ensures reliable operation
Window-type steel cages
strong and tolerant to high
temperatures
Logarithmic profiled rollers
for protection from edge loading
Taper roller bearings
52. Single row and paired single row
taper roller bearings
Single row Face-to-face
arrangement
suffix DF
Back-to-back
arrangement
suffix DB
53. 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
54. CARB - BearingTM
Compact Aligning Roller Bearing
Self-aligning as spherical roller bearing
Permits axial displacements like a cylindrical roller bearing
Compact as a needle roller bearing
55. Thrust bearings
Thrust ball bearing
single direction
Thrust ball bearing
single direction with
sphered housing washer
Thrust ball bearing
double direction
Thrust ball bearing
double direction with
sphered housing washers
Cylindrical roller
thrust bearing
single direction
Spherical roller
thrust bearing
56. Combined load carrying capacity
Can take 55% of thrust load as
radial load
Specially designed flange
gives minimum friction and
ensures reliable operation
Window-type steel cages
strong and tolerant to high
temperatures
Logarithmic profiled rollers
for protection from edge loading
Spherical roller thrust bearings
57. 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
58. Bearings are precision products
Example:
Tolerances for
bore diameter
75 mm
Precision
bearing
High precision
bearing
Normal
Tolerance
classes
Standard P6 P5
SP
P4A
UP
PA9A
PA9B
0/-15 µm 0/-12 µm 0/-9 µm 0/-7 µm
0/-2,5 µm
How much is a µm
1µ
0,06 mm
A
human
hair
59. 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
SKF bearing steels have very high cleanliness
– the content of macro and microinclusions is
extremely low.
60. 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
63. 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
Cage variants
+
+
+
+
-
+
+
+
+
-
+
+
+
-
67. 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
clearance
less than C2
less than Normal
Normal
greater than Normal
greater than C3
greater than C4
Suffix
/C1
/C2
/CN
/C3
/C4
/C5