Classification of clutches, torque transmission capacity, considerations for uniform wear and uniform pressure theory

it is Classification of clutches, torque transmission capacity, considerations for uniform wear and uniform pressure theory under theory of machine

1. THEORY OF MACHINE Classification of clutches, torque transmission capacity, considerations for uniform wear and uniform pressure theory

2. What is clutch The Clutch is a mechanical device used to connect or disconnect the driven shaft from the driving shaft at the will of the operator while power is transmitted from driving to driven shaft. Clutch is mounted between driving and driven shaft and power is transmitted from one shaft to the another shaft which is required to be started and stopped frequently.

3. Location of clutch

4. Different clutch positions

5. C lassification

6. Positive Clutch In this type of clutch, the engaging clutch surfaces interlock to produce rigid joint they are suitable for situations requiring simple & rapid disconnection, although they must be connected while shaft are stationary & unloaded. The jaw may be square jaw type or spiral jaw type. They are designed empirically by considering compressive strength of the material used.

7. Positive Clutch

8. Friction Clutch Friction Clutches work on the basis of the frictional forces developed between the two or more surfaces in contact. Friction clutches are usually over the jaw clutches due to their better performance. There is a slip in friction clutch. The major types of friction clutches are Single Plate Clutch Multi Plate Clutch Cone Clutch Centrifugal Clutch

9. Single Plate Friction Clutch A single plate friction clutch consisting of two flanges. One flange is rigidly keyed in to the driving shaft, while the other if free to move along the driven shaft due to spliced connection. The actuating force is provided by a spring.

10. Multi Plate Friction Clutch

11. CONE CLUTCH Cone clutches are friction clutches. They are simple in construction and are easy to disengage. However, the driving and driven shafts must be perfectly coaxial for efficient functioning of the clutch. This requirement is more critical for cone clutch compared to single plate friction clutch. A cone clutch consists of two working surfaces, viz., inner and outer cones

12. Centrifugal Clutch The centrifugal clutch permits the drive motor to start, warm up and accelerate to the operating speed without load. Then the clutch is automatically engaged and the driven equipment is smoothly brought up to the operating speed.

13. Torque transmitted by single plate clutch is obtained as follows R1 = External radius of clutch plate R2 = Internal radius of clutch plate r = Small elemental ring of radius

14. Area of the ring on contacting surface is, Axial load on the ring is, Frictional resistance offered by ring is, Frictional torque acting on ring is,

15. Uniform pressure theory Torque transmitted by single plate clutch is obtained by considering following two assumptions: Uniform pressure theory Uniform wear theory Assuming that the intensity of pressure over the entire contacting surfaces area is constant, then, p = Constant Pressure is uniformly distributed over the contacting surfaces area,

16. Total torque transmitted by single plate clutch can be obtained by integrating the Equation (1) within limits R2 to R1 Equation (2) gives the torque transmitted single plate clutch due to friction considering uniform pressure theory.

17. Uniform wear theory In this theory, we are considering that wear which take place is uniform over the entire contacting surface i.e. p.r = Constant So, p = C/r We know that axial loading acting on the ring is, Integrating above equation within limits we get,

18. We know that, frictional torque acting on the ring is, Torque transmitted by single plate clutch can be obtained by integrating the equation within the limits R2 to R1 we get,

19. This is the torque transmitted by single plate clutch due to friction considering uniform wear theory. Power transmitted by single plate clutch is given by, Where, N = Speed of driving shaft

20. Thank you