附 錄 附錄 A Clutch Performance Analysis A clutch is a subcomponent of an engines transmission designed to allow engagement or disengagement of the engine to whatever apparatus is being driven. A clutch may also be a device on a shaft that will “slip” when higher than normal resistance is encountered.There are many different clutch designs, but most are based on one or more friction discs, pressed tightly together or against a flywheel using springs. The spring pressure is released when the clutch pedal is depressed and the discs are held less tightly and allowed to rotate freely.Clutches are useful in devices with two rotating shafts. In these devices, one of the shafts is typically driven by a motor or pulley, and the other shaft is driving another device. The clutch connects the two shafts so that they can either be locked together and spin at the same speednc.qoos.www, or be decoupled and spin at different speeds.In a car, the engine spins all the time and the car wheels dont. In order for a car to stop without killing the engine, the wheels need to be disconnected from the engine somehow. The clutch smoothly engage a spinning engine to a non-spinning transmission by controlling the slippage between them.The flywheel is connected to the engine, and the clutch plate is connected to the transmission.When your foot is off the pedal, the springs will push the pressure plate against the clutch disc, which in turn presses against the flywheel. This locks the engine to the transmission input shaft, causing them to spin at the same speed.The amount of force the clutch can hold depends on the friction between the clutch plate and the flywheel, and how much force the spring puts on the pressure plate. The friction force in the clutch works just like the blocks in the friction section of brake, except that the spring presses on the clutch plate instead of weight pressing the block into the ground.When the clutch pedal is pressed, a cable or bydraulic piston pushes on the release fork, which presses the throw-out bearing against the middle of the diaphragm spring. As the middle of the diaphragm spring is pushed in, a series of pins near the outside of the spring causes the spring to pull the pressure plate away from the clutch disc. This releases the clutch from the spinning engine.Note the springs in the clutch plate. These springs help to isolate the transmission from the shock of the clutch engaging.The most common problem with clutches is that the friction material on the disc wears out. The friction material on a clutch disc is very similar to the friction material on the pads of a disc brake, or the shoes of a drum brake-after a while, it wears away. When most or all of the friction material is gone, the clutch will start to slip, and eventually it wont transmit any power from the engine to the wheels. The clutch only wears while the clutch disc and the flywheel are spinning at different speeds. When they are locked together, the friction material is held tightly against the flywheel, and they spin in sync. It is only when to clutch disc is slipping against the flywheel that wearing occurs. So if you are the type of driver who slips the clutch a lot, you will wear out your clutch a lot faster.In a car it is operated by the left-most pedal. No pressure on the pedal means that the clutch plates are engaged (driving) , while depressing the pedal will disengage the clutch plates, allowing the driver to shift gears. When the right-most pedal (the accelerator) is pressed while the clutch pedal is being let out. Cars equipped with automatic transmissions normally do not have a clutch. On these, the transmission operates automaticaly so that the driver is not required to use a clutch to shift gears.