Most automotive clutches are dry single-plate clutches with two friction surfaces. Regardless of the application, the function and purpose of a clutch is to transmit torque from a rotating driving motor to a gearbox.
A clutch requires an actuating mode to interrupt the transmission of torque. The clutch pedal is a lever method that separates the driving force from the engine to the gearbox in the vehicle. The pedal translates the parabolic swing of the clutch pedal into linear motion. This linear motion is then converted into the movement of the thrust bearing through mechanical linkage, cables, or hydraulic fluid displacement.
The flywheel has three main functions. First, it maintains rotational mass (inertia) to assist in engine rotation and provide more consistent torque transfer during operation. Second, it provides a ring gear for the starter motor to engage. Third, it provides one of the driving friction surfaces for the friction disc.
The driven friction disc is connected to the gearbox input shaft via splines. The disc drives the transmission assembly, which transfers motion to the wheels. The disc has a sacrificial friction material that can be adjusted for the clutch to control the driver when starting from a standstill. The disc also contains a sprung hub that absorbs engine vibrations during clutch engagement and torque absorption during engagement and disengagement.
The clutch pressure plate is the most critical part of the entire clutch assembly. The clutch pressure plate applies clamping force (pressure) to fix the driven friction disc between the pressure plate and flywheel. The clutch pressure plate is bolted to the flywheel, and they rotate together. The pressure plate contains a diaphragm or spring that can apply pressure on the main casting or driving surface. To release or disengage the drive, the drive diaphragm or clutch rod causes the main casting to disengage from the driven disc.
The release bearing provides an actuating medium between the rotating clutch assembly and the static clutch fork and gearbox. The bearing absorbs the forces that release the clutch and reduces wear between the rotating and non-rotating components.
The guide bearing is not present in all clutch components but is most common in RWD engine configurations. The bearing is located at the rear of the crankshaft or flywheel and locates the input shaft. Properly locating the input shaft at the rear of the crankshaft is crucial for correct clutch life and operation. Without the guide bearing, excessive wear of the splines and hub of the driven plate can cause clutch release issues.