【正文】 rotates with the input shaft because their gears are in constant mesh. The reverse gear(a single gear or a twogear cluster) rotates on an axle secured in the holes of the housing walls. The gear shift mechanism is designed for engaging gears, setting them neutral and engaging the reverse speed. The speeds are changed by shifting the gears or sleeves along the output shaft. The transmission type depends on the number of the sliding gears or sleeves. The transmission with two sliding gears or synchronizer sleeves is called tworange, with three gears, threerange. Depending on the number of forward speeds there are three,four and fivespeed transmissions. The gear shift mechanism is mounted on the top cover. The shift lever is arranged on the cover or on the bracket of the lever support.。 every time the cam rotates, the lobe es around under the valve lifter and move it upward. The lifter then carries this upward movement through the pushrod to the rocker arm. The rocker arm pivots on its support and pushes down on the valve stem, causing the valve to move down, that is, to open. After the cam has turned enough to move the lobe out from under the lifter, the heavy valve spring pulls the valve back into its seat. The spring is attached to the upper end of the valve stem by a spring retainer and lock. There is a cam for each valve (two cams per cylinder) on the engine camshaft. The camshaft is driven off the crankshaft by gears or by sprockets and a chain. When the entire cycle of events requires four piston strokes (two crankshaft revolutions), the engine is called a fourstrokecycle engine, or a fourcycle engine. The four strokes are intake, pression, power, and exhaust. On the intake stroke, the intake valve is open. The piston moves down, pulled by the rotation of the crankshaft. This piston movement creates a partial vacuum in the cylinder, and air rushes into the cylinder past the intake valve to fill up this vacuum. As the air moves toward the cylinder, it must pass through the carburetor. There it is charged with gasoline vapor. Thus, it is a mixture of air and gasoline vapor that rushes into the cylinder as the piston moves down on theintake stroke. After the piston moves down to the bottom dead center on the intake stroke, theintake valve closes. The lobe on the cam controlling the intake valve has moved out from under the valve lifter. Since the other valve is also closed, the upper end of the cylinder is sealed. Now, as the piston is pushed up by the rotating crankshaft, the mixture of air and gasoline vapor that has been drawn into the cylinder is pressed. By the time the piston has moved up to the top dead center, the mixture is pressed to a seventh or an eighth of its original volume. That is like taking a gallon of air and pressing it to a pint. The result is high pressure in the cylinder. About the time the piston reaches the top dead center on the pression stroke, an electric spark occurs at the cylinder spark plug. The spark plug is essentially two heavy wire electrodes。根據(jù)向前的速度的大小，由5速度的變速器。 換檔機(jī)構(gòu)被設(shè)計用以實現(xiàn)是連接齒輪、使其保持空檔和使其倒檔。 齒輪軸安放著一組不同齒數(shù)比的齒輪。輸入軸的前端安裝在曲軸的孔中，而末端在機(jī)身前面的孔中做旋轉(zhuǎn)運動。變速器有機(jī)殼、輸入軸和齒輪、輸出軸和齒輪、惰輪軸、回轉(zhuǎn)齒輪、齒輪組及換檔機(jī)構(gòu)組成。這樣的齒輪箱叫做固定系數(shù)變速器。變速器便是實現(xiàn)這些功能。然而，這種條件下的啟動不僅慢、有噪聲，而且不舒適。當(dāng)發(fā)動機(jī)速度增加時，滾輪的楔形物自動進(jìn)入壓力盤和外殼之間，這樣離合器轉(zhuǎn)動的越快，施加在壓力盤上的壓力便越大。通過釋放輪系統(tǒng)建立了水壓離合器部分，當(dāng)后輪的速度大于發(fā)動機(jī)的速度時，水壓離合器處于工作狀態(tài)。 在Estick裝配中，壓力盤杠桿嚙合離合器盤而不是分離的。當(dāng)踏板被推上去的時候，來自主氣缸的液壓經(jīng)過管和軟管被傳到氣力調(diào)壓器的水壓和伺服活塞上。主氣缸供應(yīng)一個附有杯子的活塞。沿壓盤和離合器蓋之間的圓周均勻分布的彈簧加住壓盤與飛輪之間的從動盤。離合器外殼是一個鋼鐵沖壓，由螺釘裝載調(diào)速器上。 汽車一般裝有干式彈力離合器。 離合器是通過摩擦獲得運行的。 離合器是一種摩擦裝置，它用于從從動機(jī)構(gòu)中聯(lián)合和拆分驅(qū)動力。到活塞到達(dá)上止點時，氣缸內(nèi)被燃燒過的氣體被清除掉。這個巨大的推力使得活塞向下，同時巨大的沖力通過連桿和曲柄傳送到機(jī)軸?；鸹ㄓ牲c火系統(tǒng)產(chǎn)生。這就類似一加侖的空氣被壓所成一品托。控制著進(jìn)氣閥的凸輪的突出部分已經(jīng)從閥門下面移走。當(dāng)空氣向氣缸移動時，它必須經(jīng)過氣化器。 如果整個循環(huán)過程需要四次活塞運動，那么該發(fā)動機(jī)就叫做四沖程發(fā)動機(jī)，或四行程發(fā)動機(jī)。當(dāng)凸輪轉(zhuǎn)動得足夠使突出部分移出挺桿之下時，承重的閥門彈簧將閥門退回到自己的位置。 閥門是通過發(fā)動凸輪軸上的凸輪被打開的。發(fā)動機(jī)機(jī)軸上的連桿和曲柄實現(xiàn)了這一轉(zhuǎn)變。 在動力產(chǎn)生的過程中燃料系統(tǒng)起著重要的作用，因為它給發(fā)動機(jī)氣缸提供汽油。它通常叫做一個內(nèi)置的燃燒發(fā)動機(jī)，因為汽油是在發(fā)動機(jī)氣缸或燃燒腔內(nèi)被燃燒的。（3） 傳動系，它將來自發(fā)動機(jī)的動力（經(jīng)過離合器、調(diào)速器、傳動軸、差分器和車軸）傳送到車輪。這一行業(yè)同樣需要受過鍛煉的、有經(jīng)驗的精英，來診斷這些機(jī)動車輛的故障、修理和更新機(jī)動車的零件、變速器、推動軸、差分器、車軸、操縱系統(tǒng)、剎車系統(tǒng)、暫停部件、空調(diào)裝置、發(fā)熱器、機(jī)身以及玻璃制造等。汽車發(fā)動機(jī)廣泛地應(yīng)用于配有巨大動力的機(jī)械中，如農(nóng)業(yè)、建筑業(yè)、制造業(yè)。汽車的基本機(jī)械機(jī)構(gòu)汽車工業(yè)是一種迅速發(fā)展的工業(yè)。汽車行業(yè)也匯聚了千千萬萬的人。汽車、運輸工具、發(fā)動機(jī)有著巨大的需求量。（2） 框架，它支持發(fā)動機(jī)、車輪、操縱和剎車系統(tǒng)，以及機(jī)身。 發(fā)動機(jī)是使得汽車運行的動力源泉。然后動力經(jīng)過傳動系傳送到發(fā)動機(jī)再到車輪，這樣車輪轉(zhuǎn)動，汽車便開始運行。在汽車車輪能夠轉(zhuǎn)動之前，活塞的線性運動必須轉(zhuǎn)變成旋轉(zhuǎn)運動。當(dāng)他們被打開時，氣體可以流通到端口。搖桿臂在它的支撐體上