Clutch operation: When the clutch pedal is pressed, the release clutch in the gearbox moves the clutch pusher (6) to the left, in the direction of the crankshaft (2). Due to this, the thrust disk is pressed against the disc spring (1). This spring, located in the pressure plate (3), bends, releasing the leading disk (5) of the clutch, as a result of which the disk can rotate freely together with the gearbox shaft. There is now no connection between the flywheel (4), connected to the crankshaft and the pressure plate, fixed to the gearbox shaft. When the clutch pedal is released, the disengaging disk returns back together with the working rod. The disc spring in the pressure plate again presses the leading disk against the flywheel. Now the crankshaft and the gearbox shaft are again connected
Power is transferred from the engine to the gearbox using friction. The rubbing parts in this case are:
- flywheel as a friction surface:
- clutch pressure plate, which is the second friction surface; the pressure plate presses on the flywheel;
- the clutch drive disc, it also participates in friction and is located on the drive shaft of the gearbox;
- clutch release sleeve.
When the clutch pedal is pressed, force is transmitted through the clutch rod and the release lever rotates on the shaft. The pusher transmits this movement through the release clutch, which is located in the gearbox. The pusher moves in the hole in the drive shaft and presses the spring of the pressure plate through the thrust disk. The release clutch takes the force of the spring, the pressure plate is unloaded and moves back when the pedal is fully depressed. Now the drive clutch disk can rotate freely together with the gearbox shaft. The clutch is disengaged.
When the clutch is engaged, the disc spring of the pressure plate presses the drive disc again towards the engine flywheel. This must happen slowly to ensure smooth transmission of force. The friction surfaces therefore slide against each other for a certain time before the friction becomes so great again that the engine power is fully transmitted to the gearbox.
This generates heat. At low speeds and short-term clutch engagement, less heat is generated than at high speeds and slow clutch pedal pressing. The duration of contact and heat generation determine the service life of the linings on the clutch master disc.
Clutch life
There are drivers who replace the old clutch assembly with a new one after 15,000 km. Others replace it after 100,000 km. The clutch has a greater durability if the car mainly travels long distances and the clutch is treated with care. If the driver is forced to drive his car mainly in the city (and the clutch pedal is pressed more often than usual), it is unlikely that he will be able to maintain first grip for long.
As mentioned in the previous section, each time the clutch engages, the linings of the drive disc contact the surface of the opposite part. As a result, the parts heat up. Wear is particularly promoted by starting off at high engine speeds, starting off in 2nd gear, driving at intersections in 2nd or 3rd gear with the clutch pedal partially depressed, and "balancing" on a slope using the clutch pedal and the accelerator pedal.
Is it necessary to disengage the clutch at an intersection when stopping?
A very common bad habit is to wait for a traffic light with 1st gear engaged and the clutch pedal depressed. Some drivers are afraid that they will not be able to quickly engage a particular gear when the green light comes on. Even if there is no immediate, noticeable damage, disengaging the clutch still puts a load on the disengaging clutch and causes wear. The more often and for longer this mistake is made in front of many traffic lights, the sooner the clutch wears out.
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