Clutch System

Why is CLUTCH Required?

IC engines develop low torque at starting speed and as the speed increases, develop enough torque to pick up the load.

Clutch components and clutch linkages

According to Clutch linkages clutches are classified as,

I.      Mechanically Actuated Clutch: 

II.      Hydraulically Operated Clutch:

         III.      Electromagnetically Operated Clutch:                IV.      Pneumatically Operated Clutch:

         V.      Vacuum Operated Clutch:

Mechanically Linkages and Operation:

Clutch linkage transfers the clutch pedal movement to the release bearing. Mechanical clutch linkage uses shafts, levers, or a cable.

Clutch Pedal Play: It means free movement of the pedal without causing any motion to the linkages.

Clutch fee play is provided in four wheeler= 5 to 25 mm; For two wheeler= 2 to 5mm.

Hydraulically actuated clutch:

It is basically a subassembly which contains:

1.   Central steel plate with splined hub.

2.   Friction Facings or linings mounted on outer rings.

3.   Rivets for attaching friction linings on both sides of steel plates.

4.   Cushioning springs: These springs are segmental in shape and wavy in profile. It is attached to steel plate at equal intervals on its periphery.

It is provided for smoother engagement of a clutch. Thus uniform heat generation over entire friction surface and increase friction surface life.

5.   Torsional springs: While transmitting torque produced at engine shaft to gearbox, undesirable torsional vibrations are introduced in the clutch plates.

The torsional springs are helically coiled springs which absorb torsional vibration by compressing themselves. They 3, 4, 6 or 8 in numbers depending upon the size of clutch.

•   Clutch Facing or Friction Facing:

Suitable Selection of clutch facing is an important aspect because torque transmission is

depends upon the frictional surface.

Basic requirement of Friction Facing:

1.   Good wear resistance

2.   High coefficient of friction

3.   High heat resistance

4.   Light in weight

5.   Longer life

6.   Homogeneous binding

Clutch Facing materials:

1.   Asbestos  2. Reybestos          3. Fabric         4.Leather        5. Cork

6. Organic fiber composites         7.Sintered Metals       8.Ceramic

Pressure Plate Assembly

–  Squeezes clutch disc onto flywheel.

–  Can be engaged or disengaged.

–  Acts like a spring-loaded clamp.

–  Two common types, the coil spring and diaphragm (Belleville) spring design.

Release Levers:

They are used to push release bearing for clutch engagements when driver’s effort is

applied on them through clutch pedal. They are manufactured from alloy steel by forging. They are also called fork lever.

Release bearings

Acted on by clutch fork - acting on pressure plate.

•    Moves toward flywheel when pedal pushed.

•    Slides on front portion of transmission called bearing retainer.

•    Normally not in contact with pressure plate until pedal pushed.

Pivot Bearing:

-The  purpose  of  the  pilot  bushing  or  bearing  is  to  support  the  outer  end  of  the

transmission’s input shaft.

-Allows the input shaft to rotate in the crankshaft.

What is the advantage of diaphragm clutch over spring clutch?

diaphragm clutch is small in size as compare to spring clutch
and it transmits more torque as diaphragm exerts more force as compare to springs......therefore it is advantageous to use diaphragm clutch instead of spring clutch...

more compact means of storing energy. thus compact design results in smaller clutch housing......... less affected by centrifugal force..can withstand higher rotational speeds...

diaphragm acts as both clamping spring and release levers..therefore many extra parts like struts, eye bolts, levers etc can be eliminated....

Advantages of a disc clutch over the Cone clutch?

I assume that we are talking about marine transmissions in which case both types of clutches will be operated "wet". The chief problem with the cone clutch is that when it fails the parts are going to be "captive" and very costly. Disc clutches however can have the friction plates reconditioned by having new material bonded on just like motorcycle clutches. Some Italian fishing boat engines in the 7 to 20 HP range had engines with a dry car type clutch between the engine and gearbox. This avoided wear on the gearbox clutches. For some reason this design has left the marketplace.

What are 3 advantages of a diaphragm spring type clutch compared to a multi coil spring clutch?

diaphragm clutch is small in size as compare to spring clutch and it transmits more torque as diaphragm exerts more force as compare to springs...... therefore it is advantageous to use diaphragm...

Why single plate clutch is used in trucks & Cars  while multi-plate clutch is used in bikes?

In Trucks & Cars use a single plate clutch as there is enough space to use the correct diameter plate to create the right amount of torque while motorbikes use multi-plate clutches as they have  limited room and need to create more friction surfaces to produce the required torque.