This ppt gives a gerenal view of hydrodynamic bearing ,then there is a discussion of failure chances and few variations.

1. MADAN MOHAN MALAVIYA
UNIVERSITY OF TECHNOLOGY
GORAKHPUR
HYDRODYNAMIC JOURNAL BEARINGS
Presented By:-
Shiv Prasad 1204240048
Shubham Shukla 1204240050
Suraj Gupta 1204240054
Swapnil Jain 1204240055
Swati Srivastava 1204240056
Swati Singh 1204240057
Vareesh Pratap 1204240058

2. CONTENTS
 Introduction
 Terminology
 Causes of failure
 Assumptions
 Problem statement
 Design procedure and calculation
 Graphs
 Applications
 Conclusion
 References

3. INTRODUCTION
 Bearings are machine elements that constrain
relative motion and reduce friction between
moving parts to only the desired motion.
 In sliding contact bearing, surface of the shaft
slides over surface of the bush.
 In order to reduce frictional resistance, wear
and to carry away the heat generated, a layer
of fluid i.e. lubricant is provided.

4. TERMINOLOGY
 D= diameter of bearing
 d= diameter of journal
 l= length of bearing
 c= radial clearance
 e= eccentricity
 h0 = minimum oil film
thickness.
 ε= eccentricity ratio= e-
c

5. CAUSES OF FAILURE
 Lubricant failure due to high operating
temperature.
 Corrosion
 Excessive loading
 Misalignment
 Improper mounting

6. Fig1: Failure chances in percentage of
a hydrodynamic bearing [2]

7. ASSUMPTIONS
 The bearing is subjected to static loads
only.
 Bearing is assumed to be made of babbitt
material.
 Lubricant carried away all the heat
generated during the operation.
 The lubricant obeys Newton's law of
viscous flow.
 The pressure is constant throughout the
film thickness.

8.  The flow is one dimensional, i.e. the side
leakage is neglected.
 The lubricant is incompressible.
 The viscosity is constant throughout the
film.
 There is continuous supply of lubricant.
 No dynamic forces acting on both shaft
and bearing.
 l=d
 c=0.001r
 h0 /c=0.6

9. PROBLEM STATEMENT
To design a full hydrodynamic journal bearing
with the following specification for high speed
machine tool application:[1]
• Journal diameter= 75mm
• Radial load=10kN
• Journal speed = 1440rpm
• Minimum oil film thickness=22.5microns
• Inlet temperature=400C
• Bearing material= Babbitt
Determine the length of the bearing and select a
suitable oil for this application.

10. DESIGN PROCEDURE
AND CALCULATION
Given: W=10kN, N=1440rpm, d=75mm,
h0= 22.5 microns, T= 40˚C
STEP 1: Length of bearing
For machine tool application , the
permissible bearing pressure, p=2N/mm²
l=W/(p*d) = 10000/(2*75) = 66.67mm
l/d= 66.67/75 =0.89 ≈1(standard value)
l=d=75mm

11.  STEP 2: Selection of lubricant
p=W/(l*d)
=10000/(75*75)
= 1.78N/mm²
c=0.001r
=0.001*37.5
=0.0375mm
l/d=1 and h0/c = 0.0225/0.0375=0.6( high
speed application)

12. From table[1], for the above values,
S=0.264,
(r/c)f=5.79,
Q/(r*c*n*l)=3.99,
n=1440/60
=24rps
S=(r/c)²(µn/p)
0.264=(1000)²(µ*24/1.78)
µ=19.58cP

13. ∆t={8.3p(CFV)}/(FV)
= (8.3*1.78*5.79)/3.99
= 21.44˚C
We know that,
Average temperature=Ti + (∆t/2)
= 40+(21.44/2)
=50.72˚C
RESULT :
1) Length of bearing= 75mm
2)The viscosity of SAE-10 oil is 22cP at 50˚C
.So we select SAE-10 oil for this application from
the graph.

14. Fig 2: Viscosity temperature

15. Fig 3: Variation between h0 and
frequency of rotation N [1],[6]
0
5
10
15
20
25
30
35
0 5 10 15 20 25 30 35 40 45 50
h0(micron)-->
Ns (Revolution per second) -->
µ= 12.9 cP µ = 18.9 cP µ = 27.52 cP

16. Fig 4: Variation between temperature
and frequency of rotation N[1]
0
20
40
60
80
100
120
0 10 20 30 40 50 60 70
Temperature(°C)-->
Ns (Revolution per second) -->
Ti Tmax Tavg

17. Fig 4:Variation between maximum load
with frequency of rotation[8]

18. APPLICATIONS
 Crankshaft bearings in petrol and diesel
engine
 Turbines
 Centrifugal pumps
 Rope conveyors
 Large electric motors

19. CONCLUSION
From the graph it can be concluded
that it is in agreement with a numerical
solution. Further it can be used to
select lubricating oil for a particular
speed and permissible limit of
temperature rise.

20. REFERENCES
1. Bhandari V B , “Design of machine element” McGraw-Hill
third edition 2014
2. Thakar Dutt “Bearing failure its causes and
countermeasures” 2014
3. Pickering Steve, “ Tribology of journal bearing subjected to
boundary and mixed lubrication” Department of mechanical
& industrial engineering Northeastern university 2011
4. “Bearing failure causes and curses” by Wilcoxon Research
5. Temiz Vedat “sliding contact bearing” 1995
6. http://www.viscopedia.com/viscosity-tables/substances/iso-
viscosity-classification/
7. http://www.engineeringtoolbox.com/iso-grade-oil-
d_1207.html
8. tribolab.mas.bg.ac.rs/radovi/2005_02.pdf
9. https://www.google.co.in/url?sa=t&rct=j&q=&esrc=s&sourc
e=web&cd=1&cad=rja&uact=8&ved=0CB4QFjAA&url=http
%3A%2F%2Ffaculty.ksu.edu.sa%2Fessam%2FDocuments
%2FME301chapter12.pdf&ei=G7IZVZeHDYKjuQTPyIDAD
g&usg=AFQjCNHG1H5YGbDUxgWliwf43TtosWRA1A