The principle of operation of the clutch is based on the transmission of torque from the flywheel and the leading part of the clutch to the driven disk, and therefore to the primary shaft of the gearbox, due to the friction forces that arise between the disks when the clutch is engaged. In this position, due to the elasticity of the pressure spring, the pressure disk clamps the driven disk between itself and the flywheel with a force that does not allow it to slip. In this case, the release bearing and the pressure spring do not touch.
When the clutch pedal is pressed, the release bearing, via the clutch cable and fork, presses the pressure spring of the clutch drive disc and pushes the drive disc away from the flywheel, as a result of which the driven disc is released and the transmission of torque between the engine and the gearbox stops.
On cars before 1996, the free play adjustment is automatic and occurs using a ratchet mechanism located near the clutch pedal.
Since each time the clutch is engaged and disengaged, there is minor wear of the clutch slave disk linings, free travel adjustment is required to maintain normal operation, which is performed by the automatic free travel selection mechanism installed in the upper part of the pedal. This mechanism ensures constant pedal free travel even with maximum wear of the clutch slave disk linings.
The free travel is adjusted automatically when the clutch pedal is pressed and released. The adjustment is performed by the toothed sector, rotating on the clutch pedal axis. The clutch cable is fixed to the toothed sector, bending around it, and when the pedal is released, the cable is tensioned only by the spring. When the clutch pedal is pressed, the ratchet locks the toothed sector, providing a rigid connection between the pedal and the sector, and the clutch cable is tensioned.
When releasing the clutch pedal to its original position, the clutch cable is tensioned only by the spring. In the event of wear of the driven disk linings, the spring rotates the toothed segment to a more distant position relative to the position occupied before disengaging the clutch. When the clutch pedal is pressed again, the toothed segment is locked by the ratchet with a shift of one tooth further, which compensates for wear of the linings.
The ratchet of the free travel adjustment mechanism allows the toothed sector to rotate only in the direction of the clutch cable tension, and ensures a constant travel of the clutch pedal.