Make sure the car starts smoothly
This is the primary function of the clutch. Before the car starts, it is natural to start the engine first. Whereas, when the car starts, the car accelerates gradually from a completely stationary state. If the drivetrain (which links the entire car) is rigidly connected to the engine, the car will suddenly rush forward as soon as the transmission is engaged, but it will not be able to start. This is because the car has a lot of inertia when it goes from stationary to forward, which causes a lot of drag torque to the engine. Under the action of this inertial drag torque, the engine speed drops sharply below the minimum stable speed (generally 300-500RPM) in an instantaneous time, and the engine stops and cannot work, and of course, the car cannot start.
That's why we need the help of the clutch. After the engine starts, before the car starts, the driver first presses the clutch pedal, disengages the clutch, disengages the engine and the drive train, and then puts the transmission into gear, and then gradually releases the clutch pedal to make the clutch gradually engaged. In the process of engagement, the drag torque of the engine gradually increases, so the accelerator pedal should be gradually pressed at the same time, that is, the fuel supply to the engine should be gradually increased, so that the engine speed is always maintained at the lowest stable speed without stalling. At the same time, as the engagement of the clutch gradually increases, the torque transmitted by the engine to the driving wheels through the drive train gradually increases, and when the traction force is sufficient to overcome the starting resistance, the car starts to move from a standstill and gradually accelerates.
Achieve smooth gear shifts
In the process of driving, in order to adapt to the changing driving conditions, the drive train often has to change different gears to work. To realize the gear shift of the gear transmission, it is generally to toggle the gear or other gear mechanism, so that a gear pair of the original gear is pushed out of the transmission, and then the gear pair of another gear is put into the work. Before shifting gears, the clutch pedal must be stepped on, and the power transmission is interrupted, so that the meshing pair of the original gear can be disengaged, and the speed of the meshing part of the new gear meshing pair is gradually synchronized, so that the impact when entering the meshing can be greatly reduced, so as to achieve smooth shifting. 3. Prevent overload of the drive train.
When the car is braking urgently, if there is no clutch, the engine will be rigidly connected with the drive train and reduce the speed sharply, so all the moving parts will produce a large moment of inertia (its value may greatly exceed the maximum torque emitted by the engine when it is working normally), causing a load to the drive train that exceeds its bearing capacity, and the parts are damaged. With a clutch, this danger can be eliminated by relying on the relative movement that may occur between the active and driven parts of the clutch. Therefore, we need a clutch to limit the maximum torque that the drivetrain can experience in order to be safe.