mannual clutch plate (1)

8/10/2019 Mannual Clutch Plate (1)

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Clutch plate and pressure plate

To study single plate clutch and pressure plate assembly.

Objective of the experiment: to acquaint the students with the different types of clutches by actually

viewing the components and their construction, working and assembly.

Theory : clutch is a mechanism which enables the rotary motion of one shaft to be transmitted whendesired to a second shaft, the axis of which is coincident with that of first one.

The requirement of clutch of clutch is as follows:

1) Torque transmission

2) Gradual engagement

3) Heat dissipation.

4) Dynamic balancing

5) Vibration damping

6) Inertia

7) Clutch free pedal play

8) Easy to operate.

9) Size

Types of clutches:

The following are the main types of clutches:

1) Friction clutches

2) Fluid flywheel

The friction clutches work on the fact that friction is caused when two rotating disc come intocontact with each other. On the other hand ,the fluid flywheel works on the transfer of energy from

one rotor to another by means of some fluid.

Friction clutches works as dry or wet type. In an overwhelming majority of vehicles, the dry type ofclutches is used because of lower coefficient of friction in the wet type.However,the wet typeclutches have some definite advantage over dry type due to which they are being again increasingly

put into use in modern vehicles.

Dry friction clutches:


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1) Single plate clutch: as shown in the figure plate is held between the flywheel and thepressure plate. There are springs arranged circumferentially, which provides axial force tokeep the clutch in contact. The friction plate is mounted on a hub which is splined frominside and thus free to slide over a gear box shaft. Friction facing is attached to the friction

plate on both the sides to provide annular friction surface for transmission of power. A plateis provided to pull the pressure plate against the spring force whenever it is required to bedisengaged ordinarily it remains in engaged position. When the clutch pedal is pressedmoved it the right against the force of the springs .this is achieved by means of suitablelinkage and thrust bearings.

Advantages :With a single plate clutch gear changing is easier than with a cone clutch, because the pedal

movement is less in this case. It does not suffer from disadvantage of cone clutch, i.e.binding of cones etc. And hence it is more reliable.

Disadvantages:

As compared to cone clutch the springs have to stiffer and this means greater force isrequired to be applied by the driver while disengaging.There is an eye bolt nut which causes the strut to pull the pressure plate against the springs,

thus holding together the assembly. Anti rattle springs s serve to prevent the undesirablenoise due to release levers when clutch is in engaged position.

2) Diaphragm spring type single plate clutch:The construction of this clutch is similar to that of single plate clutch described above excepthere diaphragm springs are used instead of ordinary coil springs. In the free condition, thediaphragm spring flat condition because of which it exerts a load upon the pressure plate.

Advantage:

1) It is more compact means of storing energy. This compact design results in smallerclutch housing.

2) As the diaphragm spring is comparatively less affected by the centrifugal forces, it canwithstand higher rotational speeds.

3) In case of coil springs, they have less deflection due to which they would apply lessforce against the clutch plate, on the other hand in the case of diaphragm spring; the

load deflection curve is also not linear.

Multi-plate clutch:

The multi plate clutch is an extension of single plate type where the number of frictionalsurfaces and the metal plate is increased. The increase in the number of frictional surfacesincreases the capacity of the clutch to transmit torque, the size remaining fixed.Alternatively the overall diameter of the clutch is reduced for same torques transmission asa single plate clutch. This type of clutch is therefore used in heavy vehicles and racing carswhere high torque is to be transmitted. Besides, this finds application in case of scooters

motorcycles, where space available is limited.

The construction is similar to that of single plate clutch except that all friction plates in thiscare are two sets i.e. one set of plate slides in grooves on the flywheel and other one slide

on splines of pressure plate hub.


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Wet clutch:

The construction of this type of clutch is similar to that of the dry type except here clutchplates are always wetted by dry circulation .many types of wet clutches are used in trucks.The simplest type out of these is the spry type. Its construction is similar to that of a dry

clutch, except that different types of friction materials are used and the construction ofclutch plate is also different. The oil is sprayed through the holes of the clutch plate by anozzle. This type of clutch is suitable only for small trucks where sufficient torque can beobtained with a single plate unit. Thermal limitation because of poor oil distribution to the

more remote friction surfaces makes this type unsuitable for higher number of clutch plates.

Another type of wet clutch is there, which is suitable for heavy duty trucks. It differs fromthe spray clutch in that a disc pack and a different method of oil supply are employed. An oil

collector is provided with the hub if the disk pack and is supplied by the oil passing betweenthe transmission input shafts and the clutch throughout bearing support tube. With this

arrangement t5he oil is not diverted due to rotation of the clutch oil lever and even oildistribution to all the friction surfaces is provided, thus making it suitable for heavy duty

three or four plate design.

In the multi plate clutches the clutch brakes has to be provided to overcome viscous drag

and permit shifting from neutral into first or reverse when the vehicle is standing still.

The oil flow requirement for the wet clutches varies considerably depending upon theapplication and efficiency of the grooving pattern on the clutch palte, but generally falls

within a range of one gallon per minutes for each 109-20hp rating of the engine.

Comparison with dry type:

1) Wet clutch has a longer life that the dry type.

2) Wet clutches as applied to trucks have lower torque peaks in the drive train.

3) Due to lower coefficient of friction the wet clutches has lower torque capacity compared

to the dry type.

4) Wet clutch heat transfer is very efficient as compared to (metal or air) dry clutch.

Clutch components:

1) Clutch plate: The clutch plate consist of steel plate with a splined control hub. Annularfriction facing are attached to the steel plate by rivets. Special resins are also being used to

bind the friction facings.

With the solid clutch plate, described above it becomes difficult to control the engagement

of the clutch. A commonly used solution fir this is the provisions of axial cushioning interposed between the clutch plates and the friction facings the curved cushioning springsegments are attached rigidly to the centre and the friction facings to these springs.

2) Clutch facing : requirements of good clutch facing are :


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1) Good wearing properties.

2) Presence of binder in it.

3) Cheap and easy to manufacture.

4) High coefficient of friction.

5) High resistance to heat.

Various facing materials: Leather, cork, fabric, asbestos, reybestos and ferrodo,non-abestos

clutch facing such as SWS-AFR, HWK-200.

3) Pressure plate: High tensile grey iron is the most commonly used material for pressureplate, which must be sufficiently rigid so as to not to distort under the pressure of clutch

springs. Adequate rigidity is also needed to provide uniform pressure to clutch plate. The

pressure plate should also have sufficient mass and thermal conductivity to absorb andconduct away the heat generated during engagement.

4) Springs: Normal duty clutch springs are made from oil tempered spring steel wire.However,for reverse conditions they are made from silicon chrome steel to prevent heat set.Insulating washers are also sometimes used under extreme conditions to reduce heatconduction from the plate to the springs the stiffness of the clutch springs should be

maximum possible so that sufficient axial load applied by them .

Fluid flywheel or couplings:

It consists of two members, driving and driven. Driving members is attached to flywheel and

driven to transmission shaft. Two members do not have direct contact with each other.Driver is free to slide on splines on transmission shaft. Two rotors are always filled with fluid

of suitable viscosity.

Torque transmission:

At start X is rotated with N rpm and Y tube is stationary. With the movement of fluid in X andY also starts rotating with lower speeds. Speed increases and become equal to X coupling tofully engage.

Advantages:

1) No wear on moving parts.2) No adjustment to be made.3) No skill required for operating.4) No maintenance except oil level.5) Simple in design.

Disadvantages:

1) Drag of gear box shaft.

2) Chances of crashing of gear box are more.


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List of equipments with specifications:

1) Single plate friction type with diaphragm pressure plate make-MARUTI CAR ANDVAN.

2) Single plate friction type with helical coil spring pressure plate make-WILLEYS JEEP.

3) Release bearing make-MARUTI VAN.

mannual clutch plate (1)

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