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  • Have you, ever wondered what is happening inside a car, when you press the clutch pedal

  • Or, why, do you need, to press the clutch pedal before you shift gears in a manual transmission car

  • This, video gives you, logical answers to these questions

  • At the end of the video we will, also understand the crucial role played, by the clutch in an uphill start

  • To, understand the need for a Clutch let's first understand the anatomy of an internal combustion engine car

  • Internal combustion engines have a very limited torque band

  • and

  • Due to this reason in order to efficiently vary the speed of the drive wheels

  • internal combustion engine cars need a transmission system

  • The use of this transmission makes sure that the engine is working within its optimum rpm range and by changing gear

  • According to the driving conditions the transmission helps to control the drive wheel speeds

  • In a manual transmission car making these gear changes is not an easy task to have a smooth gear change with a

  • Manual transmission the engine power flow to the transmission has to be discontinued

  • However it is not practical to turn off the engine just for this gear change

  • The clutch is used for this purpose

  • in short the clutch is a mechanism to disconnect the flow of power to the transmission without turning the engine off

  • Let's understand how it works

  • The main part of the clutch consists of a disc coated with high friction material on both sides a

  • simplified clutch disc is shown here this disc sits on the flywheel if

  • An external force presses against the clutch disc the clutch disc also will turn with the flywheel due to the frictional force

  • The input shaft of the transmission is connected to the disc

  • So that when an external force is applied to the disc the engine power will get transmitted to the transmission system

  • This external force is provided by a Pressure plate spring system

  • Cover of this system is attached firmly to the flywheel

  • So the pressure plate will firmly press onto the friction clutch disc and the engine power will be transmitted to the transmission system

  • But this is the case in normal driving so how is the power disengagement done with the clutch

  • For the disengagement purpose a special kind of spring is introduced in the pressure plate

  • Assembly, this spring is known as a diaphragm spring

  • To understand this diaphragm spring better, assume that the diaphragm spring motion is fixed around

  • This circle in this case if you press the center portion of the spring as shown

  • the outer portion should move in the opposite direction

  • The diaphragm spring sits between the pressure plate and the cover

  • To understand this configuration better let's take a cross-section of the assembly

  • the outer portion of the diaphragm spring is connected to the pressure disc

  • This means if you press the inner portion as shown the pressure disc will move away from the friction disk

  • thus the power flow will discontinue to the transmission

  • This is exactly what happens when you press the clutch pedal

  • A hydraulic system transfers the clutch motion to the center of the diaphragm spring

  • When the diaphragm spring is pressed the power flow is discontinued?

  • During this time you can make a gear change the clutch pedal is released after the gear change and the power flow continues again

  • This is how a clutch works

  • In an actual clutch you can see a few coil springs on the clutch disc what's the purpose of these springs

  • These are used to smooth out the fluctuations and vibrations from the engine power output

  • It is clear that the hub and disc are not directly connected

  • The engine power first reaches the disk then it transfers to the springs and finally to the output hub

  • This means that the springs will dampen out most of the power flow

  • Fluctuations from the engine and the motion transferred to the vehicle will be much smoother

  • Now, let's explore an extremely important and difficult task in driving cars with manual transmission starting from uphill

  • Even in a car without a handbrake you can use this clutch technique to start, while pointing uphill

  • In an uphill start initially both the brake and clutch pedal are pressed, while the engine is running

  • Now, release the clutch pedal partially until you feel the clutch bite

  • The clutch bite can be experienced at. Your foot it may feel like the engine is shivering at

  • This point even if you release the brake pedal you can see the vehicle will not roll the

  • Partially released clutch acts like a brake now You can press the gas pedal and the car will move forward

  • The big question here is how does the partially release clutch act like a break

  • This break phenomenon is nothing but a game of force balanced in a perfectly forced balanced condition the vehicle

  • Wheels will not be able to roll and the gravitational pull will be the same as static frictional force at the wheels

  • The vehicle wheels are prevented from rolling by another force balance

  • Force balance between the engine forward force and the same static frictional force

  • When you partially release the clutch and it balances for the clutch bite you are unknowingly doing all these force balances

  • When these forces are in perfect balance the wheels the transmission system and the clutch disk will not be able to spin

  • This is how the clutch bite acts as a brake but remember the frictional force between the rubbing surfaces

  • Produces the engine forward force in this case this will result in wear and tear of the friction material on the clutch disc

  • We hope this video will enable you to be a better engineer and a better driver

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  • thank you

Have you, ever wondered what is happening inside a car, when you press the clutch pedal

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    OolongCha posted on 2021/01/27
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