Clutches

Clutch Definition,classification of clutch, Cone Clutch

1. THEORY OF MACHINE (2151902) CLUTCHES Prepared by:- Chintan Charola(130990119005) Mayurrajsinh Chauhan (130990119006) Krishna Chaudhary (130990119008) Delin Davy (130990119009) Mechanical Engg. ( 5 th SEM)

2. CONTENTS What is Clutch? Classification of Clutch Cone clutch

3. 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.

4. Location of Clutch

5. Bolted to Crank (friction disk) splined to transmission Input shaft (throw-out bearing T/O bearing ) allows to push on rotating clutch fingers Bolted to flywheel - Applies the spring force to clamp the friction disk to the flywheel (clutch fork) pushes T/O bearing to release rotating clutch Pilot bushing or bearing in center of flywheel or crankshaft, supports the end of input shaft

6. Different Clutch Position

7. Classification of clutch

8. 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.

9. Positive Clutch

10. Positive Clutch Advantages Simple No heat generated No slip Compact Low cost Disadvantages Must be connected when shaft is unloaded

11. 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

12. 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.

13. Torque transmitted by single plate clutch is obtained as follows : R 1 = External radius of clutch plate R 2 = 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, …….(1)

15. Torque transmitted by single plate clutch is obtained by considering following two assumptions: Uniform pressure theory Uniform wear theory

16. Uniform pressure 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, p = = Total torque transmitted by single plate clutch can be obtained by integrating the Equation (1) within limits R 2 to R 1 we get,

17. Equation (2) gives the torque transmitted single plate clutch due to friction considering uniform pressure theory.

18. 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 a xial loading acting on the ring is, Integrating above equation within limits we get,

19. 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 R 2 to R 1 we get,

20. 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

21. APPLICATION

22. Multi Plate Friction Clutch

23. Exploded view of multi-plate clutch

24. APPLICATION

25. 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 CONE CLUTCH

26. Cone Clutch

27. The outer cone is fastened to the driving shaft and the inner cone is free to slide axially on the driven (output) shaft due to splines. A spring provides the necessary axial force to the inner cone to press against the outer cone, thus engaging the clutch. A contact lever is used to disengage the clutch.

28. The inner cone surface is lined with friction material. Due to wedging action between the conical working surfaces, there is considerable normal pressure and friction force with a small engaging force. The semi cone angle  a  is kept greater than a certain value to avoid self-engagement; otherwise disengagement of clutch would be difficult. This is kept around 12.5 .

29. CONE CLUTCH 1. Cones: female cone (green), male cone(blue) 2. Shaft: male cone is sliding on splines 3. Friction material 4. Spring: brings the male cone back after using the clutch control 5. Clutch control: separating both cones by pressing 6. Rotating direction: both direction of the axis are possible

30. Torque transmitted by single plate clutch is obtained as follows : R 1 & R 2 = Outer & Inner radius of the cone 2 = Cone angle = Semi – cone angle p = Intensity of pressure normal to the cone

31. Consider a elemental ring of radius ‘r’ & thickness on cone, let is the length of ring along the cone such that, Area of the ring , Normal load acting on the ring is, Horizontal load acting on ring is, Friction resistance offered by ring is,

32. Friction torque on the ring is, Torque transmitted by Cone clutch is obtained by considering following two assumptions: Uniform pressure theory Uniform wear theory

33. Uniform pressure 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, p = = Total torque transmitted by cone clutch can be obtained by integrating the Equation (1) within limits R 2 to R 1 we get,

34. Equation (2) gives the torque transmitted cone clutch due to friction considering uniform pressure theory.

35. 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 a xial loading acting on the ring is, Integrating above equation within limits we get,

36. We know that, frictional torque acting on the ring is, Torque transmitted by cone clutch can be obtained by integrating the equation within the limits R 2 to R 1 we get,

37. This is the torque transmitted by cone clutch due to friction considering uniform wear theory.

38. Sr. No. Type of clutch Uniform pressure theory Uniform wear theory 1. Single plate clutch 2. Multi- plate clutch 3. Cone clutch

39. 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.