1. Bearings
Nizwa College of Technology

2. BEARINGS- INTRODUCTION
Bearings are machine elements which are used to support a rotating member called as shaft.
They transmit the load from a rotating member to a stationary member known as frame or housing.

3. Bearing Motions Axial rotation e.g. shaft rotation
Common motions permitted by bearings are:
Axial rotation e.g. shaft rotation
Linear motion e.g. Carriage over the bed, drawer in the table
spherical rotation e.g. ball and socket joint
Hinge motion e.g. door

4. Bearing Loads Radial Load ThrustLoad Combination of both. Fr
Radial &Thrust load

5. Bearing Loads-Radial load
The bearings that support the shafts of motors and pulleys are subject to a radial load.

6. Bearing Loads-Thrust load
The bearings in this stool
are subject to a thrust load

7. Bearing Loads-Combination of Radial &Thrust load
The bearings in a car wheel are subject
to both thrust and radial loads.

8. Bearing Classification
On the basis of contact they have between the rotating and the stationary member
Plain bearings
(Sliding contact)
Rolling bearings
(Rolling contact)

9. Plain bearings-Sleeve Bearing
Advantages :
It takes up less space.
It has a rigid construction
It will carry loads more effectively
It is suitable for larger diameter shafts
It is cheap to manufacture and cost less.
They operate more silently.
They have good shock load capacity.
Disadvantages:
It has higher frictional resistance
It is more difficult to lubricate
There are limited choice of designs available

10. Sliding contact- Sleeve Bearing
Split Sleeve
Suitable for large diameters shafts
Solid Sleeve
Suitable to radial load only
Slit Sleeve
Adjustable to compensate wear

11. Rolling Bearings Things roll better than they slide
The concept behind a ball bearing is very simple:
Things roll better than they slide
Two surfaces can roll over each other, the friction is greatly reduced.
Bearings reduce friction by providing smooth metal balls or rollers, and a smooth inner and outer metal surface for the balls to roll against.
These balls or rollers "bear" the load, allowing the device to spin smoothly.

12. Rolling Bearings Advantages
The rolling bearings have a lower frictional resistance than plain bearings
The Lubrication of rolling bearings is easier because they can be "grease packed'
A greater choice of roller bearing designs are available than for plain bearings
Disadvantages
It takes up more space than plain bearings
The rolling bearings are not as rigid as plain bearings
More nosier in operation than plain bearings

13. Types of rolling Bearings
Ball bearings,
Roller bearings,
Tapered roller bearings.
Ball thrust bearings,
Roller thrust bearings and

14. Ball bearings
Cutaway view of a ball bearing

15. Ball bearings
In a ball bearing, the load is transmitted from the outer race to the ball and from the ball to the inner race
Since the ball is a sphere, it only contacts the inner and outer race at a very small point, which helps it spin very smoothly
But it also means that there is not very much contact area holding that load, so if the bearing is overloaded, the balls can deform and spoil the bearing
Less expensive and suitable for lighter loads and applications

16. Rolling Element Bearing Parts
Outer Race
Inner Race
Ball
Cage or Separator
Bore

17. Roller bearing
Common roller bearings use cylinders of slightly greater length
than diameter.
Roller bearings typically have higher radial load capacity than
ball bearings, but a low axial capacity and higher friction under
axial loads.
If the inner and outer races are misaligned, the bearing capacity
often drops quickly compared to either a ball bearing

18. Roller bearing Advantages They can carry greater radial loads
The geometric shape of the rolling element can be varied
They are having greater area of contact with the race ways
Disadvantages
Not suitable to take much thrust load
Expensive

19. Taper Roller Bearings
Tapered roller bearings use conical rollers that run on conical races.
Tapered roller bearings support both radial and axial loads, and
generally
can carry higher loads than ball bearings due to greater contact area.
Taper roller bearings are extensively used in Machine spindles and
gear boxes using helical gears
The disadvantage of this bearing is that due to manufacturing
complexities, tapered roller bearings are usually more expensive than
ball bearings

20. Needle Bearing
A variation of the roller type of bearing is called a needle bearing, uses cylinders with a very small diameter.
This allows the bearing to fit into tight places.
Advantages
Smaller diameter rollers (Needles) enable larger area of contact and greater
load carrying capacity.
Less space is occupied
Disadvantages
More area of contact resulted in more frictional resistance to motion.

21. Ball Thrust Bearing
Ball thrust bearings like the one shown are mostly used for
low-speed applications and cannot handle much
radial load.
Lead screws and feed rods use this type of bearing at its end.

22. Roller Thrust Bearing
Roller thrust bearings like the one illustrated can support large thrust loads.
They are often found in gear sets like machine transmissions between gears, and between the housing and the rotating shafts.
The helical gears used in most transmissions have angled teeth
and this causes a thrust load that must be supported by this type of bearing