1. Selection of bearings

2. Function of bearings:
 Support the loads exerted on the
shaft
 Locate the shaft in position
– Radially
– Axially

3. Type of bearings:
•Sliding contact bearings
•Rolling contact bearings

4. Sliding contact bearings
W W
Hydraulic oil
Hydrodynamic Hydrostatic
bearings bearings

5. Rolling contact bearings:
• Ball bearings
Single row ball bearing
Double row ball bearing
Self alignment ball bearing
Angular contact ball bearing
Thrust ball bearing
• Roller contact bearings
Taper roller bearing
Straight roller bearing
Conical roller bearing
Concave roller bearing
Thrust roller bearing
Needle bearings

6. Ball bearing
Roller bearing
Spherical roller
thrust bearing
Radial tapered
roller bearing Ball
thrust Roller thrust
bearing bearing

7. Classification of bearing load
 The loading on bearings can be
classified into three groups:
 Solely radial loading
 Solely axial loading
 Combined radial and axial loading

8. The Bearing series
Extra Light Medium Heavy
light

9. Standardisation of ball bearings :
• Series Designation
6309
• Light : 200
• Medium: 300 Bearing type
Bore diameter
• Heavy : 400 Series number

10. Main parts of a typical ball bearing
Ball Ball retainer
Inner ring
Outer ring

11. Selection of ball bearings:
•The bearing must be of the series best suited
to the installation, in regard to both:
•capacity and
•dimensions.
•The type of bearing selected must be suitable
for the type of imposed load,
•radial,
•thrust or
•combined.
•The size of the bearing must be such as to give
the required length of service with sufficient
assurance.

12. Selection of ball bearing
 Bearings have to resist some combination of
radial and thrust loads.
 Combined load must be reduced to an equivalent
radial load
 In general the equivalent load Fe may be computed
by the equation:
 Fe XF r YF a
Type of bearing Y X
Deep groove 1
Angular contact
Self aligning

13. Selection of ball bearing
 Experiments have shown that the life of a
ball bearing is a function of the load it
carries.
Cd 3
. Ln = ( )
Fe
– Cd: dynamic specific capacity of bearing.
– Ln: Life of bearing in millions of revolution.
– Fe : Equivalent load
 The above equation can be rewritten as
1/3
C d = Fe L n

14. Bearing life
Life in working
Class of machine hours
Instruments and apparatus that are used only seldom. Demonstration apparatus,
1
mechanisms for operating sliding doors
2 Aircraft engines 1000 - 2000
Machines used for short periods or intermittently and whose brake down would not
have serious consequences; hand tools, lifting tackles in workshops, hand operated
3 4000 - 8000
machines, generally agricultural machines, cranes in erecting shops, domestic
machines
Machines working intermittently and where breakdown would have serious
4 consequences. Auxiliary machines in power stations, conveyor plant for flow 8000 - 12000
production, lifts cranes for piece goods; machine tools used infrequently
Machine for use 8 hours per day and fully utilized: stationary electric motors, general
5 12000 - 20000
purpose gear units.
Machine for use 8 hours per day and fully utilized: machines for engineering industry
6 20000 - 30000
generally: cranes for bulk goods, ventilating fans, countershafts
Machines for continuous use 24 hours per day: Separators, compressors, pumps, mine
7 hoist, stationary electric machines, machines in continuous operations on board naval 40000 - 60000
ships
Machines required to work with high degree of reliability 24 hours per day: pulp and
8 paper machinery; public power plants, mine pumps, pumps in water works, machinery 100000 - 200000
in continuous operation on board merchant ships

15. Factor of safety
Safety
factor, life
Safety factor, life of 5 to 10 years
Load of 10 to 20
conditions years
Intermittent 10 hours per day Continuous Continuous
Steady load 0.5 ----- 1 1.5 2 3
Light shock 1 ------- 2 2.5 3 4
Moderate 2 ------- 3 3.5 4 5
shock
Severe shock 3-------- 4 4.5 5 6

16. Over-all dimensions of radial ball bearings
SAE Bore of inner race (d) Outside diameter D mm Width B (mm)
Bearing 200 300 400 200 300 400
Number mm in
series series series series series series
…… ……
…… ……
…… ……

17. Installation of ball bearings:
 The shaft must be designed to take
the inner ring (race)., see fig. (6.7)
 A suitable mounting must be
designed for the outer ring (race).
 Lubrication must be provided for the
bearing
 Methods of sealing the lubricant and
preventing penetration of foreign
matter must be provided.

18. Fastening ball bearing to a shaft

19. Example2
 A shaft is supported by two bearings. One of the
bearings carries a radial load of 1200 lb and an axial
load of 600 lb with minor shocks. The shaft runs at
230 rpm and operates 10 hours per day for 5 days per
week. Select a suitable ball bearing with a service life
of 2 years if the diameter of the shaft can be varied
between 3 1 6 and 3 1 inch.
15
2
Fr = 1200 lb
Fa = 500 lb
Minor shock
Speed = 230 rpm
Operating hours =10/day
Working days = 5/week
Years = 2

20. SELECT FACTOR OF SAFETY
Factor of safety = 2.5
Fe = XFr+ Yfa Safety
factor, life
Load = 1.5 X 1200 +factor, life of 5 to 10 years
Safety 1 X 600
of 10 to 20
= 2100 lb
conditions years
Service lifeType of bearing hours per day Continuous Continuous
(Ln)
Intermittent 10 Y X
Steady load Deep----- 1
0.5 groove 1.5 1 2 3
Ln =
Light shock 1 ------- 2
Angular contact 2.5 3 4
Moderate 2 ------- 3
Self aligning 3.5 4 5
shock
Severe shock 3-------- 4 4.5 5 6

21.  3 15
16
<d< 3 1 inch
2
 101.01<d<88.9 mm
 From tables
 Select deep grove ball bearing
 SAE219 with dynamic capacity 17600
 Bore diameter = 95 mm

22. Dissassebly
Assembly
Manufacturing
Thank You