Q: How Does a Clutch Engage and Disengage?

The clutch is designed to engage and disengage the connection between the engine flywheel and the transmission input shaft. The clutch is operated by pushing on the clutch pedal inside the vehicle, which causes the clutch to disengage, and as the pedal is released the clutch will engage.

Depending on the type of system the vehicle has, it will either have a hydraulic operated clutch or cable operated clutch. They both will push in on the clutch pressure plate to take pressure off of the clutch disc so no connection between the engine and transmission happens.

The clutch cable system starts with the operator pressing on the clutch pedal. The pedal is mounted on a shaft and then to a lever. The lever is connected to the clutch cable. When the lever moves the cable inside, the cable is pulled through the casing and on the transmission, while the other end of the cable is connected to the clutch lever. The lever is pulled by the cable. The other end of the lever is attached to the release bearing. As the lever is moved, it uses the release bearing and pushes in the clutch pressure plate to release the clutch and disengage it.

The hydraulic type clutch system uses a hydraulic master cylinder operated by using the pedal and push rod. The master cylinder is connected using hydraulic lines to a slave cylinder on the transmission to push on the clutch, similar to the cable system pulling on the lever. There is a different type of slave cylinder that replaces the release bearing and presses in the clutch without use of a lever.

The clutch itself consists of a pressure plate, clutch disc, release bearing, and flywheel. The clutch disc is attached to the input shaft of the transmission on a splined shaft. The disc is sandwiched between the flywheel and the pressure plate. The release bearing is used to push on the release fingers of the pressure plate. If the pressure plate is engaged then it pushes on the clutch disc against the flywheel and locks the engine to the transmission input shaft. When the release bearing pushes in on the pressure plate fingers, it relieves pressure on the clutch disc and disengages the connection from the engine and transmission.