What Does a Clutch Brake Do?
The clutch brake, or clutch, of a car is responsible for allowing you to stop without the engine dying. The car's engine can keep running while your car is at a complete stop, and when you start moving again the engine can pull the car forward. As long as a car is on, the car's engine is always turning. When you are moving forward, the wheels are connected to the engine and are turning, too. However, when you stop, the wheels stop turning but the engine doesn't. If the wheels stayed connected to the engine, they would cause the engine to die because it could not turn. The clutch allows you to disconnect the transmission from the engine so it doesn't die when you stop.
Engaging the Clutch Brake
The clutch connects two shafts in the car. One that lets the engine turn and one that lets the transmission turn. When the car is in motion they're both connected and the wheels and engine work together. To engage the transmission and engine, you must release the clutch pedal and brake, or in an automatic car release the brake. A piece called the flywheel connects to the engine while another piece known as the pressure plate connects to the transmission. When you release the clutch and/or brake, the pressure plate connects the transmission to the engine and they begin to spin together, causing the car to move forward.
Disengaging the Clutch Brake
When you apply pressure to the clutch and/or brake in your car, cable or hydraulic pistons will apply pressure to a release fork which, in turn, will press a throw-out bearing into the center of the diaphragm spring. The diaphragm spring is pushed in and it pulls the pressure plate away. Once the pressure plate has enough pressure applied to it, it becomes completely disconnected and the engine and transmission are no longer spinning together. Slight pressure will only disconnect it slightly, causing the car to slow. Once full pressure is applied, the car stops completely and will not move until the clutch and/or brake is released and the pressure plate reconnects the transmission and engine. The brake pedal of the car also applies pressure to the wheels of the car to make sure it stops quickly.