1. Coupling
It is the mechanical element used to connect two shaft of a transmission system and transmit the torque from one shaft to another
Coupling

2. COUPLING Functions of coupling:
It is the mechanical element used to connect two shafts of a transmission system and transmit the torque from one shaft to another.
Functions of coupling:
It connects the shafts of two different units such as an electric motor and machine.
It introduces mechanical flexibility between two connected units and tolerates small misalignment between the connecting shafts.
It reduces the transmission of vibrations and shocks between two
connected units.

3. Requirements of good coupling
It should transmit the full power from one shaft to another.
It should keep the shafts in perfect alignment.
It should absorb the slight misalignment that may be present between the driver and drive shaft.
It should be easy to connect and disconnect.
It should have no projecting parts.

4. Types of Coupling Rigid couplings Flexible Couplings
Muff and sleeve coupling
Split muff or compression coupling
Flanged coupling
Flexible Couplings
Bushed-pin type flexible coupling
Oldham coupling
Universal coupling

5. Rigid Couplings
Rigid couplings are used to connect two shafts which are perfectly aligned.
These couplings are not capable of tolerating any misalignment between two shafts.
These couplings are not capable of absorbing shocks and vibrations.
These are simple and inexpensive. .

6. Rigid Flanged coupling

8. Rigid couplings
Rigid couplings do not allow any misalignment of connecting members.
Not of absorbing shocks and vibration.
Muff and sleeve coupling
Split muff or compression coupling
Flanged coupling
Use to connect two line shafts
Muff and sleeve coupling

9. A protected type rigid flange coupling
It consists of two flanges :
one keyed to the driving shaft and other to the driven shaft. One of the flange has projected portion and other has a corresponding recess. This helps to bring two shafts in line and maintain the alignment.
The two flanges are coupled together by means of bolts and nuts. The number of bolts used are generally three, four or six. The two keys are staggered at right angles along the circumference of the shafts.
• The flanges are made of cast iron, cast steel, or steel.
The torque is transmitted from the driving shaft to the left side flange through the key. It is then transmitted from the left side flange to the right side flange through the bolts. Finally, it is transmitted from the right side flange to the driven shaft through the key.
Advantages
The flange coupling is easy to assemble and disassemble.
It has high torque transmitting capacity.
Disadvantages
The flange coupling cannot tolerate misalignment between driving and driven shafts.
It requires more radial space.
Applications
The flange coupling is used for connecting electric motor to pump or compressor.

10. Split muff or compression coupling

11. Flexible couplings
It is used to connect shafts having small amount of lateral or/and angular misalignment.
These coupling are capable of absorbing shocks and vibration.
Bushed-pin type flexible coupling
Oldham coupling
Universal coupling

12. Bushed-pin type flexible coupling
Used to connect diesel engine to generator

13. Use to connect Two eccentric shafts
Oldham coupling
Use to connect Two eccentric shafts

14. Universal coupling

15. Sr. No.
Comparison Parameters
Rigid Coupling
Flexible Coupling 1
Purpose
To connect two shafts which are perfectly aligned
To connect two shafts having small misalignment 2
Alignment
Cannot tolerate any misalignment
Can tolerate any misalignment 3
Shock and vibration
Cannot absorb Shock and vibration
Can absorb Shock and vibration 4
Deflection
Deflection is less
Deflection is more 5
Cost
Less expensive
More expensive

17. Bearings Introduction
Bearing is a mechanical element, which supports the rotating element. Thus it permits the relative rotating motion between two parts.
Due to relative motion, a moving part comes in contact causing friction with the stationary part, resulting wear of mating surface. To reduce the frictional resistance and wear, a lubricant is provided between the mating surface.
A lubricant is a substance placed between the two surfaces which reduces friction, wear and takes away heat is known as lubricant.
Generally mineral oil, vegetable oil or grease are used as lubricant in bearings.

18. Types of Bearings
Sliding Contact Bearings
Rolling Contact Bearings

20. Sliding Contact Bearings
In sliding contact bearings, the motion between the shaft and the bearing is purely sliding. Because of the surface contact, the friction between the rotating shaft and bearing surface is high and hence lubrication is necessary.
They are used for crankshaft in I.C. engine, ball mills, centrifugal machines in sugar industry, turbo-generators centrifugal pumps. etc.

21. Rolling Contact Bearing
Rolling motion takes place along the surfaces of contact between the parts. Steel balls or rollers are interposed between the moving and fixed elements, which offer rolling friction. They are also known as antifriction bearings. They have point or line contact with moving element.

22. Ball bearing
Double Row
Single Row

23. The Ball Bearing It is as shown in Fig.
It also consists of four major parts.
(i) Outer race
(ii) Inner race
(iii) Balls and
(iv) Cage
• It consist of number of balls placed between the races. The balls are placed properly by the cage, which acts like a separator. All balls are free to rotate within the cage and are able to roll inside the outer race and inner race. • A position clearance is kept between the races to accomplish slight misalignment of balls due to load. • Ball bearings are able to take only radial loads. It is used in high speed applications like grinders, cutters etc. • Deep groove ball bearings are able to sustain radial load as well as axial (thrust) load.

24. Deep Groove Ball Bearing

25. Cylindrical Roller Bearing

26. Angular Contact Bearing

27. Taper Roller Bearing

28. Self-Aligning Bearing

29. Thrust Ball Bearing

30. Sr. No.
Comparison parameter
Ball bearing
Roller Bearing 1
Rolling bearing
Spherical ball
Cylindrical roller 2
Nature of contact
Point contact
Surface contact 3
Load carrying capacity
low
High 4
Radial dimensions
More
Less, use for compactness 5
Axial dimensions
less
more

31. Sr. No.
Comparison parameter
Sliding contact bearing
Rolling contact bearing 1
Nature of relative motion
sliding
rolling 2
Starting friction
high
low 3
Running friction
High 4
Load carrying capacity
More
Less, use for compactness 5
Nature of load
Can take shock load
Poor in taking shock load 6
Type of load
Either radial or axial
Can take combine radial & axial 7
speed
Suitable for high speed application
Not suitable for high speed 8
Life
Less 9
Positional accuracy
Poor
Good 10
Lubrication
Required continuous supply
Not Required continuous supply 11
Noise
Noise less
More noise 12
Initial cost
Low 13
Maintenance
less 14
Application
Steam and gas engine, crankshaft bearing, marine, conveyors, centrifugal pumps
Automotive gear box, m/c spindle, automobile