adhesive elementused in journal jourbearing.ppt

bearing is design element used in automobiles

1. •Design of Bearing

2. Design of Bearing
•A bearing is a mechanical element that
permits relative motion between two parts
such as shaft & housing, with minimum
friction

3. Function of Bearing
•The bearing ensures free rotation of shaft or
axle with minimum friction
•The bearing supports the shaft or the axle &
holds it in correct position
•The bearing takes up the forces that act on the
shaft or the axle & transmits them to the
frame or the foundation

4. Classification of Bearing
A) Depending upon direction of force that acts
on them
•1.Radial Bearing:-Load is perpendicular to the
axis of shaft
•2. Thrust Bearing :-It supports load which acts
along the axis of the shaft

5. Radial & Thrust Bearing

6. Classification of Bearing
B) Depending upon nature of contact
•1.Sliding contact bearings( Journal or plain or
sleeve):-Sliding takes place along surfaces of
contact between moving element (shaft) &
fixed element (bush)
•2.Rolling contact bearings(Antifriction
bearing):-Steel balls or Rollers are introduced
between moving & fixed elements

7. Sliding & Rolling contact bearing

8. Sliding contact bearing

9. Rolling contact bearing
•Roller bearing

12. Ball bearings

13. Applications of Sliding contact bearings (Journal
bearing)
•1. Crankshaft bearings in petrol & diesel
engines
•2. Centrifugal pumps
•3. Large size electric motors
•4. Steam & gas turbines
•5. Concrete mixer
•6. Rope conveyor & marine installations

14. Applications of Rolling contact bearings
(Antifriction bearing)
•1. Machine tool spindles
•2. Automobile front & rear axles
•3. Gear boxes
•4. Small size electric motors
•5. rope sheave, crane hook & hoisting drum

15. SLIDING CONTACT BEARING

16. Types of Sliding contact bearing (Journal
Bearing)
On basis of sliding action
•1.Full journal Bearing:-Angle of contact
bearing with journal is 360
0
•2.Partial journal bearing:-Angle of contact of
bearing with journal is 120
0
•3.Fitted bearing:-when partial bearing has no
clearance i.e. the diameters of journal &
bearing are equal

17. •Types of Sliding contact bearing (Journal
Bearing

18. Types of Sliding contact bearing (Journal
Bearing)
•On basis of thickness of layer of lubricant
•1. Thick film bearings:-In this, two surfaces of bearing in
relative motion are completely separated by a film of fluid
(lubricant)
•2. Thin film bearing (Boundary lubrication):-In this, lubricant
film is relatively thin & there is partial metal to metal contact.
•3. Zero film bearings:-These bearings operate without any
lubricant present

19. Types of thick film bearings
•1. Hydrodynamic lubrication
•2. Hydrostatic lubrication

20. Types of thick film bearings
•1. Hydrodynamic lubrication:-
It is a system of lubrication in which load
supporting fluid film is created by the shape &
relative motion of sliding surfaces. In this case,
bearing is supplied with sufficient lubricant, a
pressure is build up in the clearance space
when journal is rotating

21. Types of thick film bearings
•2. Hydrostatic lubrication:-It is a system of
lubrication in which the load supporting fluid
film, separating the two surfaces is created by
an external source, like a pump, supplying
sufficient fluid under pressure. Since the
lubricant is supplied with under pressure
hence it is also called externally pressurized
bearing

22. Advantages of hydrodynamic
•1 Simple in construction
•2. Easy to maintain
•3.Lower in initial as well as maintenance cost

23. Advantages of hydrostatic
•1. High load carrying capacity even at low
speed
•2. No starting friction
Applications:-Vertical turbo generators,
Centrifuges
Ball mills

24. Material (sliding contact bearing)
•1.Babbit metal:-Recommended pressure range:-7-14 MPa
Tin base babbit:
Tin 90%; Cu 4.5%; Antimony 5%; Lead 0.5%
Lead base babbit:
Lead 84%; Tin 6%; Antimony 9.5%; Cu 0.5%
•2.Bronzes
•3 Copper-lead
•4.Aluminimun alloys
•5.Plastics, Nylon & Teflon
•6. Cast iron

25. Lubricants
•Function
1. To reduce friction between rubbing surfaces
2. To carry away heat generated by friction
3.TO Protect against corrision
4. To reduce wear

26. Classification of lubricants
•1. Liquid:-Mineral or vegetable oil
•2. Semi-liquid lubricant:-Greases
Recommended for slow speed &
high pressure
•3.Solid lubricant:-Graphite or molybdenum
disulphide
Recommended where oil film can not be
maintained because of pressures or temp.

27. Terminology

31. •Design of Bearing

36. Coefficient of Friction

39. Design Procedure of Journal Bearing

40. Table 26.3 (Design values)

44. Ex 2:-The load on the journal bearing is 150 kN due to turbine shaft of 300 mm
diameter running at 1800 r.p.m. Determine the following :
1. Length of the bearing if the allowable bearing pressure is 1.6 N/mm
2
, and
2. Amount of heat to be removed by the lubricant per minute if the bearing
temperature is 60°C and viscosity of the oil at 60°C is 0.02 kg/m-s and the bearing
clearance is 0.25 mm.