Define Clutch and Brake| What are the Types of Clutch

CLUTCH

A Clutch is an engaging & disengaging mechanical device which helps in transmitting torque/power produced by the engine. They are commonly used in every car, bike, trucks, locomotive engines & machines Etc. Each type has it’s own advantages & own field of application based on their torque/power transmitting capacity, their compactness & other design constraints

TYPES OF CLUTCHES

There are many types of clutches some of them are following:

1. PLATE CLUTCHES.
2. CONE CLUTCHES.
3. CENTRIFUGAL CLUTCHES.

          Etc.

A.  PLATE CLUTCHES

  Plate clutches are of two types.

1. Single plate clutches.
2. Multi-plate clutches.

SINGLE PLATE CLUTCHES

The single plate clutches have fewer parts comparatively & are very easy to understand. The device contains only 2 friction discs.

Torque transmission takes place when both of them come in contact with each other. One is bolted to the flywheel(gearbox, input shaft) while another is bolted to pressure plate & could be slide on a splined shaft. The pressure plate is connected to a pre-compressed spring(here diaphragm spring) which applies axial force on the other disc.

More the force, more the friction, more the torque transmitting capacity of the clutch.

These clutches had many limitations and hence it is highly unlikely to find them in any of the todays’ applications. Thus there was an immediate requirement to design new types of clutches since they couldn’t provide adequate torque

MATERILAS

Steel and a friction material, which is usually "organic", aka fiberglass, silicon dioxide, and some metal.

Sometimes, kevlar, ceramics, and metallic compounds are used as a friction material instead.

APPLICATIONS

1. Trucks, buses, cars.
2. Machines and early vehicles where torque requirement is moderate 

          Etc.

MULTI-PLATE CLUTCHES

Multi-plate clutches as the name suggests, consists of multiple plates or friction discs and work similarly as single plate. Multiple disc offer more area to be in contact with each other. More the number of plates more the torque transmitting capacity. Thus for same radius of friction disc used in single plate ones, multi-plate clutches transmit significantly high power.

They heat up quickly and this is one of their biggest disadvantage. Hence the whole clutch assembly containing plates is filled with oil to dissipate the heat faster.

MATERIALS

The inside discs are usually made of steel and outside discs are usually made of bronze. The materials used for lining of friction surfaces are Asbestos, Cork, Rubber, Cast iron, Powder metal

APPLICATIONS

They have a wide variety of applications in cars, trucks, locomotive engines & machines.

ETC.

B.   CONE CLUTCHES

Cone clutch consists of two drums- a male & a female. The male drum is attached with engine crankshaft and has inner friction lining while the female drum is mounted on a splined shaft and has outer friction lining.

When the clutch is engaged, the female cone gets inside the male one & they both start rotating together. The female cone is attached to a pre-compressed spring and has a similar apparatus as of single plate clutches.

The cone clutch can transmit higher torque than single plate clutches of same size because of relative more frictional area and wedging action.

The cone angle/semi-cone angle also plays an important role in providing the axial force. Generally, the semi cone angle is between 12º to 15º.

 

MATERIALS

Cone clutches typically use compound organic resin with copper wire facing or a ceramic material. Ceramic materials are typically used in heavy applications such as racing or heavy-duty hauling, though the harder ceramic materials increase flywheel and pressure plate wear.

APPLICATIONS

      Cone clutches are are only found in racing cars and extreme off-road vehicles but more common in powerboats.

      Small cone clutches are used as synchronisers in transmission system & in limited slip differentials.

Etc.

C.   CENTRIFUGAL CLUTCHES

Centrifugal clutches are also called as automatic clutches since you don’t need a clutch pedal and they automatically engage.

The name itself says that the working of this clutch is based on centrifugal force. The construction and working both are simple.

There is a hub at the center which is keyed with engine crankshaft. Multiple shoes are connected to this hub via springs and each shoe has its outer surface covered with friction material.

When the hub starts rotating, the shoes along with it also starts rotating. Any body performing rotational motion generates centrifugal force. The shoes are thrown outwards because of this force. As soon as the shoes touch the friction lining of the drum, the engine starts transmitting power to the drum i.e wheels.

MATERIALS

Typically use compound organic resin with copper wire facing or a ceramic material.

APPLICATIONS

Mopeds & scooters like Honda , Vespa etc.

BAND BRAKES

A band brake is a primary or secondary brake, consisting of a band of friction material that tightens concentrically around a cylindrical piece of equipment to either prevent it from rotating (a static or "holding" brake), or to slow it .

CONSTRUCTION

• Band brake is made of rope or belt band which is lined with a friction material.
• Band is wrapped partially around a drum with its free ends to a lever.
• An external force can be applied to the free ends of this lever for breaking.
• Due to addition of a external force there is a friction between the bands.
• Due to this friction force, the band is tighten and a tangential force acts on the drum.
• The tightening of the bands creates a tension in the band.
• It stop the wheel connected.

                                                                          

MATERIALS

They can be made of cast iron, ductile iron, rolled steel. A common brake band is made of steel with an inner surface of friction material

APPLICATIONS

• Band brakes have commonly been used as parking brakes in motor vehicles.
• Band brakes have also been used as clutches in automatic transmissions. 

          Etc.