In order to analyze the working process of car clutch plate, the following commonly used terms should be mastered first:
Free clearance: the clearance between the front end of the release bearing and the end of the release lever when the clutch is engaged.
Separation clearance: the clearance between the front and rear end faces of the driven plate and the surfaces of the flywheel and pressure plate after the clutch is separated.
Free travel of clutch pedal: the pedal travel corresponding to the elimination of free clearance from pressing down the clutch pedal.
Working travel of clutch pedal: the pedal travel corresponding to the generation of separation clearance after the free clearance is eliminated by further pressing down the clutch pedal.
In the separation process, when the clutch pedal is pressed, the free clearance of the clutch is first eliminated within the free travel, and then the separation clearance is generated within the working travel, resulting in clutch separation.
In the engagement process, the pressure plate gradually moves forward under the action of the pressure spring, first eliminating the separation clearance and exerting sufficient clamping force on the pressure plate, driven plate and flywheel working surfaces; then the release bearing moves backward under the action of the return spring, generating free clearance and clutch engagement.
In the use process, the driven plate will become thinner due to wear, causing the free clearance to decrease and ultimately affecting the normal engagement of the clutch. Therefore, the clutch needs to be adjusted after a period of use in order to ensure an appropriate free clearance. The location and method of clutch adjustment depend on the specific vehicle model.
The pressure plate is the active component of the clutch, always rotating with the flywheel. It can usually be driven to rotate with the flywheel through cam, key or pin, while the pressure plate can also move backward relative to the flywheel, causing the clutch to separate. The driven plate mainly consists of a driven plate body, friction plate and driven plate hub.
During the process of clutch separation and engagement, friction occurs between the friction plate and the surfaces of the flywheel and pressure plate, generating a large amount of heat. These heat needs to be dissipated in time to avoid damage to the friction plate due to high temperature, so there are windows on the clutch cover and some are also equipped with guide plates to strengthen internal ventilation and heat dissipation.
The most common clamping structures for friction clutches are spiral spring and diaphragm spring, and diaphragm spring clutches have two structural forms of push-type and pull-type. Spiral spring clutches are divided into peripheral spring and central spring types according to the way in which the spring is pressed on the pressure plate.
The operating mechanism of clutch plate is divided into mechanical operating mechanism and hydraulic operating mechanism. In order to reduce the required clutch pedal force without increasing the pedal travel due to the transmission ratio of the transmission device, power-assisted devices for the clutch pedal are used in some medium and heavy-duty trucks and certain cars. In addition, there is also a pneumatic power-assisted clutch operating mechanism that uses the engine to drive the air compressor as the main operating energy source, and the driver as the auxiliary or backup operating energy source. It is often used in conjunction with the compressed air source of the vehicle's pneumatic braking system or other pneumatic equipment.