Principles of Operation

Manual Transmission and Clutch






Principles of Operation

The transmission function is to move the vehicle from a rest position to motion. This is done by transferring the engine torque to the vehicle rear wheels. The transmission uses gears to adapt the torque to the demands of load and road conditions. It matches engine power to vehicle needs. This power is delivered from the engine flywheel to the transmission. The power is transmitted through a driver-operated clutch, which allows for engagement and disengagement of the engine to the transmission.

The transmission input shaft receives the power when the clutch is engaged. The transmission then uses a system of mainshaft gears to change the speed and torque relationship between the engine crankshaft and the transmission output shaft.

The clutch master cylinder transmits fluid pressure to the clutch slave cylinder, which in turn moves the clutch release bearing. The clutch hydraulic system uses brake fluid and shares a reservoir with the brake system. The clutch disc has frictional 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 clutch pressure plate diaphragm spring holds the clutch pressure plate against the clutch disc, so that the engine torque is transmitted to the input shaft. When the clutch is depressed, movement is transmitted through the clutch hydraulic system, which actuates the clutch release bearing. The clutch release bearing pushes on the spring center toward the flywheel. The diaphragm spring pivots at the fulcrum, relieving the load on the clutch pressure plate. Steel spring straps riveted in the clutch pressure plate cover pull the clutch pressure plate from the clutch disc, disengaging the engine torque from the transmission.