1. GANDHINAGAR INSTITUTE OF TECHNOLOGY THEORY OF MACHINES (2151902) Active Learning Assignment On MECHANICAL DEPARTMENT CLUTCHES PREPAIRED BY: KAUSHAL KAKADIYA (130120119079) HARSHIL KACHHA (13012019075) DEWAL JOSHI (130120119074) GUIDED BY: PROF. AMIT PATEL

2. PREPAIRED BY: KAUSHAL KAKADIYA (130120119079) HARSHIL KACHHA (13012019075) DEWAL JOSHI (130120119074) CLUTCHES

3. BASIC DIFFERENCE BETWEEN COUPLING,CLUTCHES, BRAKES A coupling such as a flange coupling, is a permanent connection. the driving and driven shafts are permanently attached by means of coupling and it is not possible to disconnect the shafts, unless the coupling dismantled. On the other hand, the clutch can connect or disconnect the driving and driven shafts, as and when required by the operator.  In the operation of clutch,the condition are follows: Initial condition: the driving member is rotating and the driven member is at rest. Final condition : both members rotate at the same speed and no relative motion.  In the operation of brake,the condition are follows: Initial condition : one member such as the brake drum is rotating and the braking member such as the brake shoe is at rest. Final condition : both members are at rest and have no relative motion.

4. WHAT IS CLUTCHES ? A clutch is a mechanical device that engages and disengages the power transmission, especially from driving shaft to driven shaft. In the simplest application, clutches connect and disconnect two rotating shafts (drive shafts or line shafts). In these devices, one shaft is typically attached to an engine or other power unit (the driving member) while the other shaft (the driven member) provides output power for work.

5. PRINCIPLE OF CLUTCH It operates on the principle of friction. When two surfaces are brought in contact and are held against each other due to friction between them, they can be used to transmit power. If one is rotated, then other also rotates. One surface is connected to engine and other to the transmission system of automobile. Thus, clutch is nothing but a combination of two friction surfaces.

6. MAIN PARTS OF A CLUTCH It consists of (a) a driving member, (b) a driven member, and (c) an operating member. Driving member has a flywheel which is mounted on the engine crankshaft. A disc is bolted to flywheel which is known as pressure plate or driving disc. The driven member is a disc called clutch plate. This plate can slide freely to and fro on the clutch shaft. The operating member consists of a pedal or lever which can be pressed to disengaged the driving and driven plate.

7. TYPES OF CLUTCHES 1)Mechanical clutches 2)Pneumatic clutches 3)Hydraulic clutches 4)Electromagnetic clutches  Mechanical clutches 1)Positive contact clutches i. jaw clutches ii.toothed clutches 2)Friction clutches i.Disc clutches ii.Cone clutches iii.centrifugal clutches

8. System Components Flywheel: Transfers engine power to the clutch Input shaft: Transfers power from clutch to the transmission Clutch Disk (clutch): Splined to input shaft; transfers power from engine to the input shaft Pressure Plate Assembly: Spring pressure tightly holds the clutch to the flywheel

9. Components cont: Release Bearing (throw-out bearing): Connected through linkage or hydraulics to the clutch pedal; Provides a way for the pressure plate to release pressure on the clutch Pilot Bearing (bushing) : Mounted in the tail of the crankshaft. Stabilizes the input shaft. Not always used for FWD. Clutch Fork (if applicable): Slides the release bearing into and away from the pressure plate assembly

11. Components cont: Clutch Linkage (or hydraulic plumbing): Allows the driver to operate the clutch fork Clutch (bell-housing) Housing: Encloses the clutch assembly – May be integral with the transmission or removable

12. Mounted on the rear of the crankshaft Acts as balancer for engine Adds inertia to the rotating crankshaft Provides a surface for the clutch to contact Usually surrounded by a ring gear for electric starter operation Clutch Components - Flywheel

13. Flywheel Construction Usually constructed of nodular cast iron which has a high graphite content The graphite helps lubricate engagement of the clutch May also be constructed from cold rolled steel

14. Clutch Disc Types Rigid - used primarily for industrial/racing applications. Flexible - most common, everything from grandma’s cruiser to street/strip racing.

15. Flexible Clutch Disc  Hub flange - in direct contact with the input shaft  Friction ring - in direct contact with the flywheel/pressure plate.

16. Flexible Clutch Disc  Clutch facing - friction material  marcel springs - facing dampener  Torsional springs - further dampening for clutch application  Stop pins - limits the torsional spring’s travel  Rivets -fastens the facing material to marcel (springs)

17. Belleville/diaphragm Spring:

18. Spring-type Pressure Plate

19. Benefits and Disadvantages: Belleville/diaphragm type: cost effective uniform engagement limited spring pressure Spring: unlimited pressure capabilities as springs wear, pressure may become inconsistent

20. Clutch Components Release (throw-out) bearing  Operated by the clutch linkage  Presses against the pressure plate to release the clutch

22. Clutch Components Pilot Bearing (bushing) Installed (pressed) into a machined bore in the end of the crankshaft or flywheel May be a bushing, ball-bearing or roller-bearing

23. Clutch linkage – Mechanical Linkage-type

24. Clutch linkage – Mechanical Cable-type

25. SINGLE PLATE CLUTCH A single plate is commonly used in cars and light vehicles. It has only one clutch plate which is mounted on the splines of the clutch shaft. A flywheel is mounted on the crankshaft of the engine. A pressure plate is connected to the flywheel through the bolts and clutch springs. It is free to slide on the clutch shaft with the movement of clutch pedal. When clutch is in engaged position, the clutch plate remains gripped between flywheel and pressure plate. Friction linings are provided on both the sides of clutch plate.

26. On one side clutch plate is in touch with flywheel and on other side with pressure plate. Due to friction on both sides, the clutch plate revolves with engine flywheel. Transmission Therefore, clutch transmits engine power to clutch shaft. Clutch shaft is connected to transmission (or gear box) of automobile. Thus, clutch transmits power from engine to transmission system which inturn rotates wheels of engine. When the clutch plate is to be disengaged, the clutch pedal is pressed. Because of this pressure plate moves back and clutch plate is disengaged from flywheel. Thus, clutch shaft stops rotating even if engine flywheel is rotating. In this position, power does not reach the wheels and vehicle also stops running. Single plate clutch is show n fig.

27. Design of clutch plate

28. Single Plate Clutch W=total axial load R1=External radius of clutch plate R2=internal radius of the clutch plate P=intensity of pressure between contacting surfaces. µ=coefficient of friction between contacting surfaces

29. Single Plate Clutch Consider a elemental ring of radius ‘r’ and thickness δr on the contacting surface. therefore, Area of the ring on contacting surface is, Axial load on the ring is, δW=pressure×Area of the ring

30. Single Plate Clutch Frictional resistance offered by ring is, Frictional torque acting on the ring is,

31. Single Plate Clutch Torque transmitted by single plate clutch is obtained by considering following two assumptions (a)uniform pressure theory (b)uniform wear theory

32. Single Plate Clutch (a)uniform pressure theory: Assuming that the intensity of pressure over the entire contacting surface area is constant, Total torque transmitted by single plate clutch can be obtain by integrating Equation Then, p=constant

33. Single Plate Clutch (1)within limit R2 to R1 we [ ∵ p=Constant]

34. …….(A) Equation (A) gives the torque transmitted by single plate clutch due to friction considering uniform pressure theory.

35. Single Plate Clutch (b) 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 P.r=C P=C/r …...(3)

36. Single Plate Clutch Axial load acting on the ring is δW=p 2π r δr δW=2 π C δ r …(4) Integrating above Equation(4) within limit we get,

37. Single Plate Clutch We know that frictional torque acting on ring is, ……….(5) …….(6)

38. Single Plate Clutch Torque transmitted by single plate clutch can be obtain by integrating the Equation (4 ) within the limit R2 to R1 we get,

39. Single Plate Clutch This is the torque transmitted by single plate due to friction considering uniform wear theory.

40. Single Plate Clutch Power transmitted by single plate clutch is given by,

41. MULTIPLATE CLUTCH Multi-plate clutch consists of more than one clutch plates contrary to single plate clutch which consists of only one plate. Friction surfaces are made in case of multi- plate clutch. Due to increased number of friction surfaces, a multi-plate clutch can transmit large torque. Therefore, it is used in racing cars and heavy motor vehicles witch have high engine power. The clutch plates are alternatively fitted with engine shaft and the shaft of gear box. He plates are firmly held by the force of coil springs and they assembled in a drum.

42. One plate slides in the grooves on the flywheel and the next plate slides on spines provided on pressure plate. Thus, each alternate plate slides in grooves on the flywheel and the other on splines of pressure plate. If we take two consecutive plates, then one has inner and other has outer splines. When the clutch pedal is pressed, the pressure plate moves back against the force of coil spring, hence the clutch plates are disengaged and engine flywheel and gear box are decoupled. However, when clutch pedal is not pressed the clutch remain in engaged position and the power can be transmitted from engine flywheel to the gear box. This type of clutch has been shown in Figure.

44. For multiplate clutch For uniform pressure theory, For uniform wear theory,

45. Multiplate Clutch Notes: In case of new clutch,the intensity of pressure is uniform along the surface of clutch but in case of old clutch uniform theory is more correct. For single plate clutch normally both sides of the plate are effective.there for single plate clutch has two pairs of contacting surface i.e. n=2. In actual practice, usually the theory of uniform wear is used in analysis of clutch.

46. Intensity of pressure is maximum at the inner radius R2 of the friction or contact surface, Intensity of pressure is minimum at the inner radius R1 of the friction or contact surface,

47. In mutilate disc clutch no of disc on driving shaft no of disc on driven shaft So no. of pairs in contact,

48. Clutch plate

49. DIFFERENCE BETWEEN SINGLE AND MULTI-PLATE CLUTCHES :-  The number of pairs of contacting surfaces in the single plate clutch is one or at the most, two. These are more number of contacting surfaces in the multi-disk clutch.  As the number of contacting surfaces is increased, the torque transmitting capacity is also increased, other conditions being equal. In other words, for a given torque capacity, the size of the multi-plate clutch is smaller than that of the single plate clutch, resulting in compact construction.

50.  The work done by friction force during engagement is converted into heat. More heat is generated in the multi-plate clutch due to increased number of contacting surface. Heat dissipation is a serious problem in the multi-plate clutch. Therefore, multi-plate clutches are wet clutches, while single plate clutches are dry.  The coefficient of friction decreases due to cooling oil, thereby reducing the torque transmitting capacity of the multi-plate clutch. The coefficient of friction is high in dry single plate clutches.  Single plate clutches are used in applications where large radial space is a available, such as trucks and cars. Multi-disk clutches are used in applications where compact construction is desirable, e.g., scooter and motorcycle.

51. Cone clutch α = semi-apex angle of the cone Only one pair of driving surfaces is possible, n =1 The maximum torque transmitted = T = μ Wr m cosec α

53. Centrifugal clutch Driving shaft Driven shaft Friction lining Total friction torque, T = nµR(F-P) F=mrω 2 ω ω

55. Objectives Diagnose clutch problems before disassembly Adjust a clutch Install a replacement clutch Inspect worn or damaged clutch parts and determine the cause of the problem

56. Introduction Early automobiles – Produced with manual shift transmissions Required clutch Some new model cars and light trucks have manual transmissions – Utilize a clutch as well Common to have at least one new clutch installed Clutch work is not difficult to learn Diagnose problems before and after disassembly

57. Transmission Noise Sometimes noise occurs only when engine is idling in neutral with clutch engaged – Front transmission bearing on input shaft and mainshaft pilot are only bearings rotating One of these bearings is probably the noise source

58. Pedal Problems and Slipping Clutch Diagnosis on basis of pedal feel – Pulsating pedal: something internal in clutch – Pedal is hard to depress: binding linkage or cable Slipping clutch – Tested by putting it in the highest gear range Several possible reasons clutch slip – Partial engagement – Partial disengagement

59. Dragging Clutch Clutch drags: does not release properly – Disc stays attached to the flywheel Test for a dragging clutch – Start engine and run it to normal operating temperature – Engine at idle and transmission in neutral: depress clutch to floor – Wait ten seconds – Shift transmission into reverse

60. Oily Clutch Facings Oil leaking onto clutch disc: – Causes clutch slipping Disc may overheat and burn its friction surface During repair: – Disc and pressure plate are replaced Rest of the parts are thoroughly cleaned – Determine and repair oil leak source Oil on front side of flywheel: crankshaft rear seal or external engine leak Oil on rear side of flywheel: bad front transmission seal or overfilled transmission

61. Damaged Friction Surfaces Damage to friction surfaces of clutch cover or flywheel can cause clutch to slip – Clutch slips: heat is generated Flywheel or pressure plate can be warped Flywheel, pressure plate, or disc can all become glazed Flywheel is commonly resurfaced

62. Chattering or Grabbing Clutch Chattering clutch – Occurs when pedal shakes as clutch is engaged Grabbing clutch – Occurs when friction disc does not slip normally but grabs all at once Causes of clutch chatter or grabbing – Oil on friction lining – Worn or broken motor mounts – Worn or bent clutch fork

63. Clutch Service Includes: – Checking and adjusting free play and travel – Hydraulic component service – Clutch replacement Some clutches require adjustment – As the disc wears, it becomes thinner Results in release levers moving closer to the release bearing which means less clearance

64. Servicing Hydraulic Components Internal hydraulic system problems – Usually the result of dirty or aging internal rubber sealing parts Master cylinder and slave cylinder – Either can develop leaks Different methods can be used to bleed air from a clutch hydraulic system – Gravity bleeding

65. Clutch Replacement Includes replacement of several parts – Disc – Release bearing – Clutch cover – Pilot bearing or bushing – Sometimes a flywheel and/or front transmission seal Often come in a clutch parts kit

66. Design and Analysis of Clutch Using Sintered Iron as a Friction Material RESEARCH PAPER

67. ABSTRACT Clutch system is among the main systems inside a vehicle. Clutch is a mechanical device located between a vehicle engine and its transmission and provides mechanical coupling between the engine and transmission input shaft. Clutch system comprise of flywheel, clutch disc plate and friction material, pressure plate, clutch cover, diaphragm spring and the linkage necessary to operate the clutch. The clutch engages the transmission gradually by allowing a certain amount of slippage between the flywheel and the transmission input shaft. However, the slipping mechanism of the clutch generates heat energy due to friction between the clutch disc and the flywheel. At high sliding velocity, excessive frictional heat is generated which lead to high temperature rise at the clutch disc surface, and this causes thermo-mechanical problems such as thermal deformations and thermo-elastic instability which can lead to thermal cracking, wear and other mode of failure of the clutch disc component.

68. AUTOMOTIVE CLUTCH SYSTEM Automotive clutches are located between the engine and the transmission. It provides mechanical coupling between the engine and transmission input shaft. Manual transmission cars need a clutch to enable engaging and disengaging the transmission. The clutch engages the transmission gradually by allowing a certain amount of slippage between the flywheel and the transmission input shaft (Erjavec 2005).Clutch basically consists of six major parts: flywheel, clutch disc, pressure plate, diaphragm spring, clutch cover and the linkage necessary to operate the clutch (Lee and Cho 2006) as shown in Figure 1.

70. CLUTCH MATERIALS The clutch disc is generally made from grey cast iron (Afferante et al. 2003; Poser et al. 2005). This is because grey cast iron has a good wear resistance with high thermal conductivity and the production cost is low compare to other clutch disc materials such as A1-MMC (aluminum-metal matrix composite), carbon composites and ceramic based composites (Terhech et al. 1995; Jang et al. 2003). High thermal conductivity of diffusivity of the material is considered advantageous because heat is then allowed to dissipate at higher rate (Bostwick and Szadkowski 1998). In this project, BS200 or ASTM G2500 grade grey cast iron is selected as the material for the commercial clutch disc. Some properties of the material (BS Grade 200lASTM G2500) are shown in Table below (Heo et al. 2002; CES EduPack 2005).

71. SINTERED FRICITON MATERIL Friction pads are manufactured by sintering blend of powders consisting of heat absorption material along with friction generating & lubricating materials. The powders are blended in optimized proportions & compacted to form a solid flat button of predetermined shape. They are highly durable with harsher engagement characteristics compared to organic linings. The quality of materials used along with the sintering parameter play an important role in providing the required performance (Aleksandrova et al 1972).Particulate reinforcement gives the necessary WEAR resistant for the sintered matrix (Mustafa Boz & AdemKurtt2007 )

72. Method Of Analysis The torque that can be transmitted by a clutch is a function of its geometry & the magnitude of the actuating force applied as well the condition of contact prevailing between the members. The applied force can keep the members together with a uniform pressure all over its contact area & the consequent analysis is based on uniform pressure condition. However as the time progresses some wear takes place between the contacting members & this may alter or vary the contact pressure appropriately and uniform pressure condition may no longer prevail. Hence the analysis here is based on uniform wear condition.

74. Single plate clutch

81. CONCLUSION

82. CONCLUSION CONT..

83. REFERENCES [1] Machine Design II, by Prof. K.Gopinath & Prof. M. M. Mayuram [2] K Tripathi, “Design Optimization of Friction Clutch “ [3] United States Patent Office On - “Auxiliary drive clutch mechanism “ [4] Arvind vadiraj “Engagement characteristic of friction pad for the commercial vehicle clutch system “

84. Any quetion