A clutch is a well-known term in mechanical engineering which is used to provide the transmission of power from one component to another. Among the two members, one is a driving member and another is a driven, member.
These two members can be engaged or disengaged based on transmission requirements.
In an automobile, the clutch engages or disengages two parts, one is the engine and another one is the gearbox.
Here, the clutch helps to transmit the power from the engine to the gearbox which prides motion into the wheels of the vehicle.
Why do clutches require?
In automobiles, there are rotating shafts and which are necessary to connect by the clutch. One shaft is driven by the engine and it may run all the time. Whenever you want to stop your vehicle or again want to drive then you have to use a clutch.
The clutch connects the engine and another shaft which is to be driven so that the driven shaft will spin at the same speed or different speeds based on gear arrangements. When the vehicle needs to be stopped, the clutch will disconnect.
The clutch is essential because,
It transmits the maximum torque of the engine.
The clutch engage itself gradually and avoid sudden jerks.
It is able to dissipate heat generated during operation.
Dynamically balanced even also in high-speed engine applications.
It helps to damp vibrations
It eliminates noise produced during power transmission.
Small size to save space
Easy to operate
Trouble free operation
Easy to inspect
Easy operation, maintenance & repair
History of Clutch
A dry single-plate clutch was first developed by Duryea in 1893, however, it was further developed by Englishman Herbert Frood in 1921 which didn’t burn out in few hundred miles.
A clutch is defined as a device which is used to transmission of power from driving shaft to driven shaft by engaging or disengaging.
In this mechanism, the driving shaft is directly connected to an engine or motor and driven shaft get the power for the further utilization.
The clutches are used to control the motion between two components.
The clutch consists of various parts like friction surface, diaphragm spring, coil spring, pins, clutch paddle, hub, etc.
The most commonly used clutch is friction clutch in the automobile industries.
The clutch paddle is pressed for the change of gear based on the speed requirements.
Parts of Clutch
There are different types of clutches and their working principles are different. However, to understand the parts of clutch, basic parts are captured, to have a grip of the clutch system.
It consists of,
It has flywheel
The flywheel is mounted on the crankshaft.
There are few other components, pressure plate, spring & lever.
A cover is associated with all these members,
The cover is bolted to the flywheel.
If the flywheel rotates, the cover will rotate.
If the cover rotates, all the pressure plate, spring, etc. also will be rotated.
It has a plate or disc, which is known as a clutch plate.
There are splines on the clutch shaft.
The Clutch can easily slide on the shaft.
It has frictional surfaces.
Pedal which is pressed or release to engage or disengage.
How does a clutch work – Working Principle
Principle of Clutch
Take two-cylinder and keep them in contact. Now, if you rotate one cylinder, you will see another cylinder that will rotate at the same speed. Keep it in mind that both the surface will be frictional surface and pressure should be applied to avoid slip.
Explanation of Working Principle
Frictional surfaces or friction force and application of pressure help to unite both the cylinder or shafts and rotate at the same speed.
Flywheel – a driving member of a clutch &
Pressure plate – mounted is the driven member.
The flywheel is mounted on the engine crankshaft and it gets the same speed of the engine and the pressure plate is mounted on the transmission shaft are gets the same speed when engaged.
It can be controlled with gear arrangement and can be disengage whenever required.
Sometimes a different kind of plates, basically friction plates are kept between these two members. The plates are known as pressure plates.
This entire assembly is called a clutch.
Hence, the following factors are the main parameters for clutch:
Surface area: Frictional force between two surfaces depends on the surface area,
Pressure: Application of pressure is another important parameter
Frictional Force: Different materials provide different frictional forces, hence, it depends on type of materials.
Function of clutch
The main function of an Automobile Clutch is to Engage & Disengage.
In this case, the rotary motion of the engine is transmitted to the wheel.
The clutch transmits engine power to the machines based on the requirements.
In an ideal condition, there is no slipping between two components.
The clutch slips momentarily and provide very smooth engagement
Clutch lessens the shock on gears, shaft, and other parts of an automobile.
It allows the engine to take the load without any jerks
Controlling the clutch, vehicles are controlled.
The vehicle can be stopped easily by disengaging the clutch.
The engine will run without any impact or any transmission.
In disengage, the clutch permits the driver to shift transmission different gears based on requirements.
Gear shifting easy, without noise or damage
Types of clutch
There are various types of clutches used in the industry based on the applications. The selection of the right kinds of clutches for a specific industry totally depends on the beginning. Improper selection and application will incur less efficiency, hence, proper selection is a must to get maximum efficiency.
The working principle is different for clutches and each type has some advantages and disadvantages.
The different types of the clutch are
Friction Type Clutch
Single Plate Type Clutch
Multi-Plate Type Clutch
Cone Type Clutch
Centrifugal Type Clutch
Semi-centrifugal Type Clutch
Diaphragm Type Clutch
Dog and Spline Type Clutch
Electromagnetic Type Clutch
Vacuum Type Clutches
Hydraulic Type clutch
Flywheel Type Clutch
Let’s discuss all types of clutches in detail.
Friction clutches are widely used in cars. This clutch is operated through a mechanical or hydraulic cable and consists
a clutch plate,
a pressure plate, and
a release bearing.
These are further classified into two types,
Single Plate Clutch
Single plate clutch means as the name implies, has only single clutch plate. It is widely used mainly in lightweight modern vehicles. It transmits the torque from an engine to the transmission input shaft.
The components of the single plate clutch,
Advantages of Single Plate Clutch
There are few advantages of the single-plate clutch,
It produces less heat
No coolant is required for cooling
Very smooth engagement & disengagement
Operation is smooth
The loss of power is very less due to low torque
Very easy to change the gears
Excellent load withstanding capacity
It helps to safeguard other rotating parts.
Disadvantages of Single Plate Clutch
The disadvantages are as follows,
Size is big compared to other types.
It is a dry type clutch, no cooling medium & high maintenance.
It is used only for low torque applications.
Multiple clutches are widely used in the industry. There are multiple plates and due to it, this clutch is known as a multi-plate clutch.
It mainly transmits the power from the driver shaft (engine shaft) to the driven shaft (transmission) shaft to produce high torque. Friction takes place between these two and high torque is developed.
It is used in F1 level racing cars, racing motorcycles, in many diesel locomotives, etc., in the case of high torque requirements.
It is also used in many electronically controlled all-wheel drive systems now. Multiple plate clutch is further divided into two categories,
wet clutch and
A wet clutch is operated within the cooling lubricating fluid and gives longer life with smoother performance.
Wet clutches tend to lose some energy to the liquid. However, due to multiple numbers of discs, it can compensate the frictional losses and eliminate slippage.
The Hele-Shaw is one type of wet clutch which works on viscous effects, other than on friction.
A dry clutch, as the name implies, is operated without oil.
Advantages of Multi-Plate Clutch
The advantages of the Multi-Plate clutch,
torque is quite high due to multiple plates, as well as the more frictional area available.
Compact and small in size, the application is in more area
Used in racing cars etc.
It has more frictional surfaces.
The transmission of torque depends on the area of frictional surfaces.
A multi-plate clutch produces more torque than a single-plate clutch.
Acceleration is better.
Disadvantages of Multi-Plate Clutch
The disadvantages are, as follows:
The weight is heavy so it is not suitable for all-time use.
The cost of the multi-plate clutch is very expensive.
More friction, additional cooling arrangement required, incurs more maintenance.
High powered car.
Working Principle of Friction Clutch
In the friction clutch, Single plate and multiple plates, friction is created between the engine shaft and the transmission shaft to provide the force required to move the vehicle. The working principle of friction clutch shall be, as follows:
Firstly, driver needs to press the clutch paddle
Spring will be compressed, due to this pressure,
Pressure plate move backside
Clutch becomes disengaged
The shifting of the gears will be very
It will rotate the flywheel until the engine shaft does not stop rotation.
When the clutch is engaged, the friction plate will be sandwiched between the engine flywheel and a pressure plate
There is a pressure between the pressure plate and flywheel
If the pressure is sufficient, the friction plate will not be slipped and the vehicle performs well.
If the pressure is not sufficient, the friction plate will be slipped and the vehicle will not perform properly.
In the cone clutch, there are two mating members of cone-shaped, one is a male member and another is a female member. When these two members are engaged, the frictional force is generated and transmission happens.
The main components of cone clutch are,
Male cone or internal or inner cone
Female cone or external or outer cone
In the cone clutch, engagement & disengagement of the male cone and female cone member has happened.
The female cone is mounted on the engine crankshaft
The male cone is mounted on a spline clutch shaft
Male cone easily slides on spline shaft
Both the cones have conical shaped frictional surface
Spring brings the male cone back after using clutch control
Clutch control separates both the cones by pressing the paddle
It uses these surfaces to transmit the torque.
High torque is transferred since both the cones are fastened compactly with the larger surface area
Advantages of Cone Clutch
There are few advantages of Cone Clutch
Higher torque generated
Noise level is less with respect to plate clutch
Low wear & tear in comparison with displacement clutch
The normal force acting on the frictional contact surface is greater than the axial force.
A very less axial force is required to engage the clutch
Disadvantages of Cone Clutch
Although there are some disadvantages of cone clutch, and here are those:
Inefficient sometimes to disengage the clutch.
If the cone angle is less than 20°, then the male cone tends to couple with the female cone makes it difficult to disengage.
Small wear can make the large axial movement of the inner cone
This leads to high maintenance.
A centrifugal clutch, as the name suggests, uses centrifugal force for operation. By using this type of clutch, the speed of the driven shaft can be controlled.
It is operated based on the speed of an engine.
No clutch paddle is required.
The speed of the driver can be adjusted without changing the gear.
flyweights (clutch shoes),
friction linings and
spider or guide
Working Principle of Centrifugal Clutch
The centrifugal clutch has a weight, called flyweight, is pivoted in a specific location.
The engine creates a centrifugal force by the revolutions on the crankshaft
This force is transmitted to the flyweights
The shaft of the clutch rotates at the same speed as the crankshaft
The shoes are forced to rotate by the hub
This process is going on unless shoes come into contact with the drum.
In this way, torque is transmitted from the flyweights to the drum
And drive will be then connected.
Advantages of Centrifugal Clutch
These are the advantages of Centrifugal Clutch
This clutch is engaged and disengaged automatically.
No shock waves
Loss due to wear and tear is very less
Easy to control the speed
No separate control mechanism is required.
Disadvantages of Centrifugal Clutch
Here are some disadvantages of Centrifugal Clutch
Power loss due to friction
Power loss due to slippage at a lower speed
It is not suitable for high torque application
High load condition, shoe slips.
In the case of the high-speed engine, centrifugal clutches are not suitable.
The maximum speed depends on the size of the clutch.
We have already learned a centrifugal clutch. Now, if spring forced is used along with centrifugal force to engage the clutch, then it is called a semi centrifugal clutch.
Weights with levers
Working Principle of Semi-Centrifugal Clutch
In this type of clutch, levers and clutch springs fix upon the pressure plate equally. When levers or springs are fixed, power transmission happens.
There are two options,
At low engine speed: Spring fix itself to the clutch plate & transmit the power,
At normal engine speed: Here, also, same as low speed. Spring is fixed.
In this case, no pressure is exerted on the clutch plate from the levers.
At normal speed, there is no pressure on the pressure plate and it remains engaged.
At a high engine speed: weights fly off and due to this, levers give pressure on the pressure plate and the clutch is engaged.
It helps to transmit high torque.
In this case, springs are not required to be stiffer to keep the clutch engaged.
Weighted levers with centrifugal force help to select the less stiff springs.
When the speed of the engine decreases, the centrifugal force of weight reduces and it falls.
It loses contact and no pressure force exerted on the clutch plate.
But spring force exerted on the plate and clutch got engaged.
Advantages of Semi-Centrifugal Clutch
The stiffness of the spring of this clutch is less & it operates at low speed only.
Shifting of the gear is very smooth & no stain in operation.
Disadvantages of Semi-Centrifugal Clutch
Springs transmit the torque only at a lower speed.
Only at high speed, centrifugal forces work to transmit the torque.
High powered engines
Racing car etc.
We have seen, coil or helical springs are used in the clutches. But in the case, spring is diaphragm type and that is why this clutch is known as a diaphragm clutch.
Clutch has not required any levers
The diaphragm spring acts like a series of levers
Diaphragm springs don’t have any constant rate characteristics like coil or helical springs
The diaphragm spring exerts pressures unless it becomes flat.
This type of clutch generates pressure on the pressure plate to engage the clutch.
The diaphragm clutch consists of
Working Principle of Diaphragm Clutch
In a diaphragm clutch, the diaphragm is used as a spring. It is a thin sheet of metal. When pressure is applied on the diaphragm, it yields and when pressure is removed, the diaphragm will come in the original shape.
Friction lining consists of the flywheel.
The flywheel is connected to this clutch.
The Clutch is having a diaphragm spring.
This spring is supported on a fulcrum.
Spring and fulcrum act as a simple lever system.
Behind the pressure plate, the clutch plate is placed.
The pressure plate is in a radial position with respect to the cover and moves axially.
Engine power is transferred to the flywheel from the crankshaft.
When the clutch pedal is pressed.
The spring load is relieved
The Clutch is disconnected.
Advantages of Diaphragm Clutch
The advantages of Diaphragm Clutch, are as follows
It requires very less effort when the clutch needs to be disengaged.
Less moving parts
Springs act as livers, hence, no additional release lever is required.
Small in size comparatively.
Disadvantages of Diaphragm Clutch
Size is more, to get the coefficient of friction.
Spring may become stiff after a certain extent.
Difficult to use in heavy vehicles
Light vehicles, etc.
In this type of clutch, two parts of the clutch are engaged or disengaged. These two parts may be shafts or maybe shaft and gear.
One part of the dog clutch is having external teeth (shaft or gear – male part)
Another part (shaft – female part) is having internal teeth.
When both this male and female part engaged
Rotate at the same speed.
Due to these teeth, no slippage.
When the male part is taken out from the female part, the clutch got disengaged.
Advantages of Dog Clutch
Attachment with teeth, hence, no slippage between two parts.
Produce high toque.
Very efficient for power transmission.
Disadvantages of Dog Clutch
It is not possible to engage the clutch at high speed
Relative motion is required, during engagement & disengagement.
Marine propeller drives, etc.
In this kind of clutch, there will also be two mating parts. There will be spline on the driven shaft and grooves will be in the driving shaft.
The driven shaft is having a spline
The driveshaft is having grooves
During the engagement, spline and grooves are attached.
Both are rotating at the same speed.
No slippage as the same as a dog clutch.
When the spline is taken out from grooves, the clutch got disengaged.
Advantages of Spline Clutch
Clutches engaged very strongly, and no chance of slippage.
High torque is produced like a dog clutch.
Disadvantages of Spline Clutch
Difficult to engage at high speed.
Additional relative motion is required.
Electromagnetic clutches or sometimes called electromechanical clutches, or EM clutch works electrically but remember transmission of torque is by mechanical means.
Torque is transmitted from the rotor to the armature.
If the power supply is stopped, the clutch will be disengaged.
The Clutch is disengaged once required by changing the gear.
Advantages of Electromagnetic Clutch:
Widely used in the electrical system.
The remote application is suitable.
No linkage is required.
Disadvantages of Electromagnetic Clutch:
Capital cost is high.
Limitation on high temperature.
Clutch Plate Material
There are various materials used to construct a clutch. Clutch plates are the main component in the clutch
Earlier asbestos is widely used, however, in the recent era, there are different kinds of materials used for clutches.
Ceramic materials, organic, semi organics, etc. are widely used based on the applications.
Widely used materials.
Phenolic resins, compounded rubber, or metallic powders may be used.
Durability and longevity are very good.
Heavy-duty organic materials are also available now a day, which can withstand very high temperature.
This is made in a combination with copper, bronze, silicon, and graphite etc.
Widely used in trucks, racing cars, etc.
It can withstand large friction and heat.
It is used the combination of copper, steel & iron.
High grade of ceramic discs.
Combination of silicon, graphite & steel.
What are Common Problems
There are a few common problems associated with clutches:
Wear is the main problem that is the clutch. Constant friction between two friction materials will cause to wear out.
While driving, if the clutch is not released properly, it will create a problem on grinding, or shifting the gears.
The stretched clutch cable can be broken if there is a problem of tension to push and pull.
If there is a leakage in the cylinder to create necessary pressure.
If there is a problem of air in the hydraulic line which builds the pressure.
The wrong amount of force applied in the pedal will transmit an imbalanced force.
Mismatched clutch components
Sticking or binding can happen if there is a problem in the linkage, cabling, pivot, etc.
Worn seals in the hydraulic system can make a hard clutch.
Worn throw-out bearing or clutch release bearing may create problems and a rumbling sound comes when the clutch engages.
How to check clutch health?
It is required to check the health of the clutch often since it is having a vital role in vehicle performance as well as our safety. This health can be checked by us only. Check out the below tables:
Start your car, keep your hand break up & keep it in neutral mode. Now, without pushing the clutch, listen for a growling noise.
No noise coming
No issue on clutch
It is a problem associated with transmission.
In the same neutral conditions, start to push the clutch
No abnormal noise
No problem in clutch
Push the clutch up to maximum
No different noise
No problem here
pilot bearing or bushing problem
Clutch Slipping Symptoms
The clutch performance will diminish over time, and clutch slippage should be relatively apparent to a competent, clued-up driver. There are a number of signs you can look out for that would push you towards a diagnosis.
The squeaking sound may come.
The problem in changing gears
The clutch pedal sticks vibrate or feel spongey
Acceleration is a struggle, experience momentary losses
A burning smell under the hood, this may also mean bad wiring or an oil leak
Clutch disengages very quickly
Revs are very high
Clutch pedal height
We have learned the basics of the clutch, along with different types of clutch and descriptions, working principles, advantages, disadvantages.