Rolling bearing and slide bearing

1. Govt.
College of
Engineering
and
Technology
Safapora,
Ganderbal
Presented by :
Shahnawaz Hassan
Roll No. : 190543
Topic : Sliding Contact
Bearing

2. Topic: Design and selection of Sliding and
Roller Bearing
• BEARING:A bearing is a machine element
which support another moving machine
element(known as journal).It permits a relative
motion between the contact surfaces of the
members, while carrying load.

3. CLASSIFICATION OF BEARINGS
1)Depending upon the direction of Load to be supported.
A) Radial Bearings
B) Axial/Thrust Bearings

4. • 2) Depending upon the nature of contact
A) Sliding contact Bearings
the Sliding contact bearings takes place along the surfaces of contact between the moving element
and fixed element.The Sliding contact Bearings are also known as plain Bearings.

6. • B) Rolling contact Bearings
The steel balls or Rollers are interposed between the moving and fixed and fixed elements.
• The balls offer friction at two points for each balls or Roller.

7. Types of sliding contact Bearings
• A) Full Journal Bearing
When the angle of contact of the bearing with the journal is 360 degree
B) Partial journal Bearing
when the angle of contact is 120 degree b/w journal and bearing
C) Fitted journal Bearing
same like partial journal bearing but the dia. Of the journal and bearing are same.

8. According to thickness of layer of lubricant
b/w bearing and journal
• 1) Thick film bearings
2) Thin film bearings
3)Zero film bearings
4)Hydrostatic or externally lubricated bearings
the hydrostatic bearings are those which can support steady loads without
any relative motion b/w the journal and bearing.

9. Materials used
• 1)Babbit metal:Tin based and lead based babbits are widely used as a bearing materials,maximum bearing pressure is from 7
to 14 N/mm2.it is used in automobiles.
Tin based babbit metals : tin 90%; copper 4.5%; antimony 5%; lead 0.5%
Lead based babbits : lead84% ; tin 6% ;antimony9.5% ;copper 0.5
• 2) Bronze: the bronze(alloys of copper ,tin ,zinc) is used to form brushes pressed into the shell.
• The brush may be in one or two pieces.
• The bronzes commonly used for bearing material are gun metal and phosphor bronzes.
• The gun metal(copper88%;tin10%;zinc2%) is used for high grade bearings subjected to high pressure and high speeds.
• The phosphor bronze(copper80%;tin10%;lead9%;phosphorous 1%) is used for bearings subjected to very high pressure and
speeds.
• 3) Cast iron: the cast iron bearings are usually used with steel journals. It can bear pressure upto 3.5 N/mm2.

10. • Non-metallic bearings
the various non-metallic bearings are made of carbon-graphite,rubber,wood, and
plastics

11. Design procedure for Journal Bearing
Let,
W=load on bearing
U(mu)=coefficient of friction
N=speed of journal
p=bearing pressure on the projected bearing area
R=radius of the bearing
r=radius of journal
l=length of bearing
c=diametric clearance=D-d

12. • Diametric clearance.Itis the difference between the diameters of the bearing and journal .
• Radial clearance.It is the difference b/w the radii of the bearing and the
journal.Mathematically,radial clearance ,
C1 = R-r = D-d/2 = c/2
.Diametral clearance ratio. It is the ratio of diametral clearance to diameter of the
journal.Mathwmatically,
Clearance ratio=c/d = D-d/d
Eccentricity.It is the radial distance between the center(O) of bearing and the displaced center
(O^) of bearing under load.it is denoted by e.
Minimum oil film thickness.It is the minimum distance b/w bearing and journal,under
complete lubrication condition.It is denoted by h0 and occurs at the line of centers.its value may be
assumed as c/4.
Short and long bearing.if the ratio of the length to the dia. Of journal (i.el/d) is less than 1 .it is
known as short bearing.and if l/d is greater than 1 ,it is known as long bearing.

13. Advantages and Dis-advantages
• A simple bearing and housing design.
• They are more compact and takes up less radial area.
• They are less expensive.
• They can with stand a lot of shocks.
• They are more silent in operation.
• They are well suited to operations at medium at high speeds

14. • DISADVANTAGES
• Frictional power loss is greater.
• They necessitated careful lubrication.
• They are usually made to carry solely radial or axial loads.

15. Applications
• Sliding contact bearings are used in the following
applications
• Centrifugal pumps,
• large size of electric motors,
• steam and gas turbines