Clutch - Overview

Clutch Components

The clutch consists of:

• Flywheel
• Clutch disc
• Clutch pressure plate assembly

The clutch transmits the engine torque to the transmission.

The clutch is a single plate, dry friction disc with a diaphragm spring clutch pressure plate. The clutch disc has a hub splined to the transmission input shaft. The clutch disc has friction material where it contacts the flywheel and the clutch pressure plate. The clutch pressure plate applies pressure to the clutch disc, holding it tightly against the surface of the flywheel. In the engaged position, the diaphragm spring holds the clutch pressure plate against the clutch disc so that engine torque is transmitted to the input shaft.

When the clutch pedal is applied, the release bearing pushes the diaphragm spring center of the clutch pressure plate toward the flywheel. The diaphragm spring pivots at the fulcrum, relieving the load on the clutch pressure plate. The clutch slave cylinder assists in the effort it takes to relieve the load on the clutch pressure plate. Steel spring straps riveted to the clutch pressure plate cover pull the clutch pressure plate from the clutch disc, disengaging the engine torque from the transmission.

Clutch Disc

The clutch disc has a splined hub (with integral torsional dampening springs) which attaches the clutch disc to the input shaft. Engine output is coupled to the input shaft by the friction existing between the clutch disc facings and the flywheel/clutch pressure plate assembly.

Clutch Pressure Plate Assembly

The clutch pressure plate applies pressure to the clutch disc holding it tightly against the surface of the flywheel. In the engaged position, the diaphragm spring holds the clutch pressure plate against the clutch disc so that engine torque is transmitted to the input shaft.

Clutch Release Hub and Bearing

The clutch system is disengaged when the clutch pedal is pressed and engaged when the clutch pedal is released. When the clutch pedal is pressed, it pushes the clutch master cylinder plunger, which transmits hydraulic pressure to the clutch slave cylinder. The slave cylinder engages and compresses through the release bearing and the clutch pressure plate diaphragm spring, releasing the pressure on the clutch disc. This displacement removes the spring load from the clutch pressure plate and eliminates the coupling friction between the engine and the transmission.

Self-adjusting Clutches

Self-adjusting clutches have become the standard equipment in applications with high engine torque or with increased requirements for wear reserve. The self-adjusting clutch eliminates the increase in operating force which occurs as wear increases.

The advantages of the self-adjusting clutch are as follows:

• Constant operating force throughout the whole service life of the clutch.
• Increased service life of the clutch friction disc.
• Release bearing over-travel is prevented by the diaphragm spring end stop.
• Shorter pedal travel.
• Shorter release bearing travel throughout bearing life.

Self-adjusting clutches cannot be reset after the clutch disc has been removed and must also be replaced.

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