1. Ensure that the car starts smoothly: Before starting, the car is at a standstill. If the engine and the gearbox are rigidly connected, once the gear is engaged, the car will suddenly forward due to the sudden connection of power, which will not only cause damage to the mechanical parts, but also drive The force is not enough to overcome the huge inertial force generated by the forward rush of the car, causing the engine speed to drop sharply and stalling. If the clutch is used to temporarily separate the engine and the gearbox when starting, and then the clutch is gradually engaged, due to the phenomenon of slippage between the active part and the driven part of the clutch, the torque transmitted by the clutch can be gradually increased from zero. The driving force of the car has gradually increased, allowing the car to start smoothly.
2. Easy to change gears: During the driving process of the car, different gearbox positions are often used to adapt to changing driving conditions. If there is no clutch to temporarily separate the engine and the gearbox, the power transmission gears engaged in the gearbox will not be removed due to the load, and the pressure between the meshing tooth surfaces is very large and difficult to separate. The other gear to be meshed will be difficult to mesh due to the unequal peripheral speed of the two. Even if it is forced into the mesh, it will produce a great impact on the tooth end and easily damage the machine parts. When the clutch is used to temporarily separate the engine and the gearbox and then shift gears, the pair of gears that originally meshed will be removed due to load, and the pressure between the meshing surfaces will be greatly reduced, making it easy to separate. As for the other pair of gears to be meshed, since the driving gear is separated from the engine, the moment of inertia is small. Using a suitable shift action can make the peripheral speeds of the gears to be meshed equal or nearly equal, thereby avoiding or reducing the impact between the gears.
3. To prevent the drive train from overloading: When the car brakes in an emergency, the wheels suddenly slow down, and the drive train connected to the engine still maintains the original speed due to the rotating inertia, which often produces far greater than the engine torque in the drive system The moment of inertia makes the parts of the drive train easily damaged. Since the clutch transmits torque by friction force, when the load in the drive train exceeds the torque that can be transmitted by friction force, the driving and driven parts of the clutch will automatically slip, thus preventing the overload of the drive train. .