On all models with a manual transmission, a dry single-plate clutch is installed, which consists of a clutch driven and pressure plates, a diaphragm spring, a casing and a clutch release bearing. The pressure plate has an adjusting ring that provides self-adjustment of the clutch as it wears (see illustration 1.0). Such a clutch was designated SAC by the first letters of the English name «self-adjusting clutch».
The pressure plate is rigidly screwed to the flywheel, which, in turn, is flanged to the engine crankshaft. Between the pressure plate and the flywheel is the clutch disc, which is pressed against the flywheel by the pressure plate. The clutch disc is firmly connected to the input shaft of the gearbox with a splined hub.
The driven clutch disc moves freely on the splines of the input shaft of the gearbox and is pressed against the flywheel by the pressure plate with the force that its membrane spring creates. Friction linings are riveted on both sides of the driven disk. The clutch disc is firmly connected to the input shaft of the gearbox with a splined hub.
When you press the clutch pedal (clutch disengagement) hydraulic pressure is exerted on the clutch fork lever and the clutch release bearing is pressed against the diaphragm of the pressure plate. As a result of this, the pressure plate is released, and the clutch disc is no longer pressed against the flywheel. The power circuit between the engine and gearbox stops (see illustrations 1.0a, 1.0b and 1.0v).
The clutch release bearing is mounted on the front side of the gearbox and is mixed by the clutch release fork. When you press the clutch pedal, the piston in the master cylinder moves and squeezes out the brake fluid, which enters the clutch slave cylinder through the hose. Under the pressure of the fluid, the piston of the clutch slave cylinder moves and actuates the clutch release fork. The clutch release fork retracts the bearing, which acts on the pressure plate spring and presses the pressure plate away from the clutch disc.
Each time the clutch is engaged and disengaged, the friction lining of the clutch disc gradually wears out as a result of friction. Thus, the clutch disc is a wear part, but it lasts an average of more than 100,000 km. The degree of wear depends mainly on the load, for example, the operation of a vehicle with a trailer and on the driving style.
All engines are equipped with a so-called composite flywheel, which consists of two interconnected disks. Such a flywheel has a damping mechanism (depreciation) torsional vibrations that occur when the engine rotates, and helps to reduce the noise level when the engine is running at low speeds.
In addition, on cars with a demultiplier, to prevent the so-called peak loads caused by a sharp release of the clutch pedal, a special valve with the designation PTL is installed on its hydraulic actuator (abbreviation of the first letters of the English name of the valve, translated as «peak load limiter»). When the clutch pedal is released, the valve closes and brake fluid flows through the overflow hole on it. This slows down its flow and the driven disk connects more smoothly to the flywheel (see illustration 1.0g).
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