A clutch is a subcomponent of an engine’s 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 speed, or be decoupled and spin at different speeds.
In a car, the engine spins all the time and the car wheels don’t. 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 won’t 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.
參考譯文：
離合器是發(fā)動(dòng)機(jī)傳動(dòng)系中的一個(gè)基礎(chǔ)部件，無論什么樣的發(fā)動(dòng)機(jī)，傳動(dòng)系都可以接上或脫開。離合器還可以在負(fù)載過大時(shí)在軸上“打滑”。
離合器有很多類型，但大多數(shù)離合器都有一個(gè)或多個(gè)摩擦片，用彈簧緊緊壓著飛輪。當(dāng)離合器踏板踩下時(shí)，彈簧松開，摩擦片就松動(dòng)并可以自由旋轉(zhuǎn)。
對開兩軸之間的聯(lián)結(jié)，離合器都有一個(gè)或多個(gè)摩擦片，典型的情況是，一根軸由發(fā)動(dòng)機(jī)或皮帶輪傳動(dòng)，另一根軸將動(dòng)力傳遞給其他部件。離合器就是實(shí)現(xiàn)兩軸的聯(lián)結(jié)，或者使兩軸接合，以相同的轉(zhuǎn)速運(yùn)轉(zhuǎn)；或者兩軸分離，各自以不同的轉(zhuǎn)速運(yùn)轉(zhuǎn)。
在汽車上，發(fā)動(dòng)機(jī)始終不停地運(yùn)轉(zhuǎn)，而車輪卻不能不停地轉(zhuǎn)動(dòng)。為了在發(fā)動(dòng)機(jī)不熄火的情況下使汽車停下來，車輪需要斷開與發(fā)動(dòng)機(jī)的聯(lián)系。離合器借助相互之間的打滑，使轉(zhuǎn)動(dòng)的發(fā)動(dòng)機(jī)與靜止的傳動(dòng)系平穩(wěn)接合。
飛輪與發(fā)動(dòng)機(jī)連接，離合器盤與傳動(dòng)系連接。
當(dāng)你松開踏板，膜片彈簧將壓盤逐漸壓緊在離合器盤上， 壓力依次傳到飛輪。這樣使發(fā)動(dòng)機(jī)和傳動(dòng)系輸入軸可靠地接合，使它們以相同的轉(zhuǎn)速運(yùn)轉(zhuǎn)。
離合器能傳遞的力的大小取決于離合器盤和飛輪之間的摩擦系數(shù)，以及彈簧對壓盤的壓緊力的大小。離合器的摩擦力和制動(dòng)器的摩擦力起一樣的作用，不同的是壓在地面上的重壓力變成了離合器中彈簧壓在離合器盤上的壓力。
當(dāng)踩下離合器踏板時(shí)，在分離叉上的繩索或液壓活塞，壓著分離軸承頂住膜片彈簧的中心。當(dāng)膜片彈簧的中心被推凹進(jìn)去時(shí)，在彈簧周圍的一圈餾鉚釘將壓盤后拉，使壓盤與離合器盤分離。這樣，離合器也就切斷了發(fā)動(dòng)機(jī)的傳動(dòng)。
注意離合器盤內(nèi)的彈簧組，這些彈簧幫助隔離離合器接合時(shí)的沖擊，避免沖擊傳給傳動(dòng)系統(tǒng)。
離合器的最常見的問題是盤上的摩擦材料的磨損。離合器盤上的摩擦材料類似于盤式制動(dòng)器上的摩擦片的材料、或鼓式制動(dòng)器上制動(dòng)蹄的材料——過一段時(shí)間就被磨掉了。當(dāng)摩擦材料被全部磨損或大部分磨損后，離合器就開始打滑，最終，這個(gè)離合器將失去從發(fā)動(dòng)機(jī)向車輪傳遞動(dòng)力的能力。
只有當(dāng)離合器盤和飛輪轉(zhuǎn)速不同的時(shí)候，離合器才會(huì)磨損。當(dāng)處于結(jié)合狀態(tài)時(shí)，摩擦材料與飛輪緊密接合并同步運(yùn)轉(zhuǎn)。只有當(dāng)離合器盤在飛輪上打滑時(shí)，才會(huì)出現(xiàn)磨損現(xiàn)象。因此，假如你在開車時(shí)，離合器常常打滑，那么，你的離合器就會(huì)迅速磨損。
在車上，離合器是由最左的踏板控制的。如果踏板上沒有壓力，離合器就接合（行駛），而踩下離合器，則可以讓駕駛員換擋。當(dāng)最后的踏板（加速）踩下時(shí)，離合器踏板將在同時(shí)脫開。裝有自動(dòng)變速器的汽車一般不需要離合器。在這些汽車上，變速器自動(dòng)操作，因此駕駛員不必使用離合器來換擋。
（轉(zhuǎn)載）
