汽車專業(yè)畢業(yè)設(shè)計外文翻譯---汽車的基本機(jī)械機(jī)構(gòu)

1、<p><b>　　汽車的基本機(jī)械機(jī)構(gòu)</b></p><p>　　汽車工業(yè)是一種迅速發(fā)展的工業(yè)。從十八世紀(jì)后期第一輛汽車出現(xiàn)在公路上后，這一工業(yè)便迅猛發(fā)展起來。如今全世界成千上萬的工廠生產(chǎn)著各種各樣的汽車。汽車行業(yè)也匯聚了千千萬萬的人。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)。不同類型的小型發(fā)動機(jī)也應(yīng)用于植草機(jī)、動力鋸、除雪機(jī)等類似的設(shè)備中。汽車行業(yè)是一

2、個發(fā)展著的、需求著的行業(yè)，似乎永遠(yuǎn)找不到它的盡頭和飽和點。汽車、運(yùn)輸工具、發(fā)動機(jī)有著巨大的需求量。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。</p><p>　　汽車由五個基本的機(jī)械機(jī)構(gòu)或部件組成。它們是：</p><p>　?。?）發(fā)動機(jī)，

3、它是動力的源泉，包括燃料、潤滑劑、冷卻和電氣系統(tǒng)。</p><p>　?。?）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。</p><p>　?。?）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。</p><p><b>　?。?）機(jī)身。</b></p><p>　　（

4、5）機(jī)身附件，它包括加熱器、燈光、擋風(fēng)玻璃擦等等。</p><p>　　發(fā)動機(jī)是使得汽車運(yùn)行的動力源泉。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。這是相對于外置的發(fā)動機(jī)而言的（如蒸汽發(fā)動機(jī)），其燃燒發(fā)生在發(fā)動機(jī)的外部。發(fā)動機(jī)氣缸內(nèi)的汽油的燃燒產(chǎn)生了動力。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(yùn)行。 </p><p>　　在動力產(chǎn)生

5、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。在每一個發(fā)動機(jī)氣缸里，蒸發(fā)出來的汽油和空氣組成的混合體進(jìn)入氣缸，活塞推進(jìn)氣缸，壓縮混合體，然后電火花點燃壓縮混合體，這樣活塞被迫向下。當(dāng)然，在發(fā)動機(jī)內(nèi)，活塞沒有完全推到氣缸外面，而是隨著混合體的燃燒，在氣缸內(nèi)簡單地來回移動。在汽車車輪能夠轉(zhuǎn)動之前，活塞的線性運(yùn)動必須轉(zhuǎn)變成旋轉(zhuǎn)運(yùn)動。發(fā)動機(jī)機(jī)軸上的連桿和曲柄實現(xiàn)了這一轉(zhuǎn)變。</p><p>　　閥門將燃燒過

6、的汽油蒸氣送出氣缸外面，同時把汽油蒸氣和空氣新鮮可燃混合氣送入氣缸。當(dāng)他們被關(guān)閉或固定時（也就是推到端口上），端口被封閉，這樣氣體不能流通到端口。當(dāng)他們被打開時，氣體可以流通到端口。 </p><p>　　閥門是通過發(fā)動凸輪軸上的凸輪被打開的。凸輪有一個最高點，或圓形突出部分；每次當(dāng)凸輪轉(zhuǎn)動時，突出部分在氣門挺桿之下，使得挺桿向上。挺桿將這個向上的運(yùn)動傳動到推桿再傳送到搖桿臂。搖桿臂在它的支撐體上轉(zhuǎn)動并在閥桿上推

7、下去，使得閥移到低處，也就是說閥被打開了。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。彈簧被彈簧座和鎖附在閥桿的下端。在發(fā)動機(jī)凸輪軸上每個閥門都有一個凸輪（每個氣缸兩個凸輪）。凸輪軸通過齒輪或鏈條齒和齒條受到機(jī)軸的驅(qū)動。</p><p>　　如果整個循環(huán)過程需要四次活塞運(yùn)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)。這四個行程是輸入、壓縮、發(fā)動、和排氣。</p>

8、;<p>　　在輸入行程時，進(jìn)氣閥是被打開的，活塞受到機(jī)軸旋轉(zhuǎn)的推動，移到下面?；钊倪@個移動引起了氣缸內(nèi)的局部的真空，同時空氣通過進(jìn)氣閥推進(jìn)氣缸，以填補(bǔ)該真空。當(dāng)空氣向氣缸移動時，它必須經(jīng)過氣化器。那里充滿了汽油蒸氣。因此當(dāng)活塞在輸入端移至下端時進(jìn)入氣缸的是空氣和汽油蒸氣的混合體。</p><p>　　當(dāng)活塞在進(jìn)口端移到下止點時，進(jìn)氣閥關(guān)閉。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。因為另一

9、個閥門也是關(guān)閉的，氣缸的上端被關(guān)閉?，F(xiàn)在，當(dāng)轉(zhuǎn)動著的機(jī)軸將閥門推上時，已經(jīng)進(jìn)入氣缸的空氣和汽油蒸氣混合體被壓縮。直到活塞被推到上止點時，氣體被壓縮成原來的七分之一或八分之一。這就類似一加侖的空氣被壓所成一品托。究其原因是由于氣缸內(nèi)部的高壓。</p><p>　　在壓縮行程，當(dāng)活塞到達(dá)上止點時，氣缸火花塞產(chǎn)生一個電火花。火花塞本質(zhì)上是兩個粗鋼絲電極。火花由點火系統(tǒng)產(chǎn)生。它點燃了壓縮的空氣和汽油蒸氣混合體。由于高壓和

10、高溫，發(fā)生了急劇的燃燒。此時，活塞頂端向下的壓力達(dá)到兩噸。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。</p><p>　　在動力行程，由于汽油蒸氣的燃燒使得活塞受迫。當(dāng)活塞達(dá)到下止點時，排氣閥被打開。這時，活塞又一次被返回，它推動氣缸內(nèi)被燃燒過的氣體。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。排氣閥關(guān)閉，進(jìn)氣閥開啟?；钊谙乱粋€輸入行程時再次被返回。發(fā)動機(jī)運(yùn)行時，這四個行程持續(xù)地

11、重復(fù)著。</p><p>　　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。在汽車的應(yīng)用中，它用于與發(fā)動機(jī)調(diào)速輪相連，以提供發(fā)動機(jī)和手工傳送之間的平滑結(jié)合和正常脫離。</p><p>　　因此隨著發(fā)動機(jī)速度的降低，需要漸進(jìn)裝載的應(yīng)用，以獲得一個合理的和舒適的啟動。在裝配有手工傳動的汽車系統(tǒng)中，這可以通過一個機(jī)械離合器獲得成功。</p><p>　　離合器

12、是通過摩擦獲得運(yùn)行的。離合器的主要裝置是一個壓力盤和一個驅(qū)動板。壓力盤外加有調(diào)速輪，而驅(qū)動板和傳動輸入軸相品配。壓力盤通過彈力壓住驅(qū)動盤，這樣扭矩由于發(fā)動機(jī)和傳送的輸入軸之間的摩擦力而被傳動。</p><p>　　汽車一般裝有干式彈力離合器。之所以稱之為干的是因為壓力盤和驅(qū)動板是干的，相對于油式離合器，它是浸泡在油中運(yùn)行的。之所以稱之為彈力的是由于壓力盤和驅(qū)動板是靠彈力相互壓在一起的，同時在某個時刻被釋放到汽車的

13、齒輪或剎車裝置中。</p><p>　　除了壓力盤和驅(qū)動盤，離合器還包含有一個外殼、釋放桿、釋放軛、壓力彈簧和一個控制連接。離合器外殼是一個鋼鐵沖壓，由螺釘裝載調(diào)速器上。釋放桿通過支撐螺釘確保在外殼內(nèi)部。釋放桿的外部端被放置在壓力盤中。這樣的裝置允許壓力盤接近或離開外殼，并一直隨著調(diào)速盤而轉(zhuǎn)動。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。</p><p>　　彈簧的

14、安裝依賴于外殼和壓力盤提供的發(fā)射孔和插槽。為了防治彈簧過熱，壓力盤插槽配有熱的絕緣墊圈。</p><p>　　液壓制動離合器分離裝置由一個踏板、分離彈簧、主氣缸、氣力調(diào)壓器、管道、軟管、分離叉的桿組成。主氣缸供應(yīng)一個附有杯子的活塞。氣力調(diào)壓器用以降低踏板力以分離離合器。調(diào)壓器包括內(nèi)置伺服機(jī)構(gòu)的兩個機(jī)架。機(jī)架供應(yīng)氣力的、水壓的、伺服的活塞。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

15、服活塞上。</p><p>　　自動離合器理所當(dāng)然被應(yīng)用在美國和歐洲的汽車中。美國發(fā)動機(jī)"E-stick"離合器消除了踏板物理運(yùn)行的需要。一個德國的汽車制造者設(shè)計了一個自動的離合器系統(tǒng)叫做"Hydrak"，它由一個液力飛輪連接著一個干燥的轉(zhuǎn)盤。</p><p>　　在"E-stick"裝配中，壓力盤杠桿嚙合離合器盤而不是分離的。同

16、樣，當(dāng)變速</p><p>　　器的運(yùn)動處于正常時，離合器處于閑置狀態(tài)，直到伺服系統(tǒng)被油壓應(yīng)用到的時候。</p><p>　　"Hydrak"系統(tǒng)只有杠桿正常時才開始運(yùn)行。這激勵了一個用以分離離合器轉(zhuǎn)盤的調(diào)壓器系統(tǒng)。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)。機(jī)械離合器的運(yùn)行由一個特殊的裝置控制著，它依賴于后車輪是否處于牽

17、引狀態(tài)或被汽車的推力推動。</p><p>　　在克萊斯特汽車和美國通用汽車中，用到了一個不平常的離合器壓盤系統(tǒng)。叫做半離心式離合器，壓盤有六個圓柱滾輪，它在離心力的作用下向外運(yùn)動，直至觸到外殼。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。</p><p>　　變速器是安裝在汽車發(fā)動機(jī)和驅(qū)動輪之間某個點上的控制速度和功率變化的

18、裝置。它提供了一種方法，該方法使得在行使的每一個特殊情況下，發(fā)動機(jī)每分鐘的轉(zhuǎn)數(shù)和主動輪每分鐘的轉(zhuǎn)數(shù)達(dá)到最好的配合。</p><p>　　對于水平路面，如果沒有變速器，汽車可以通過發(fā)動機(jī)的加速和離合器的連接而啟動。然而，這種條件下的啟動不僅慢、有噪聲，而且不舒適。此外，它還將在發(fā)動機(jī)和汽車驅(qū)動部分產(chǎn)生一個巨大的拉伸。</p><p>　　這樣為了獲得平滑的啟動并且能過越過和爬上山坡，必須提供

19、一個功率比，用以對扭矩和發(fā)動機(jī)的轉(zhuǎn)動力成倍地增加。同樣需要一個速比以避免高速公路上過高的發(fā)動機(jī)轉(zhuǎn)速/每分鐘。變速器便是實現(xiàn)這些功能。</p><p>　　變速器需要設(shè)計的是：改變從發(fā)動機(jī)曲軸到傳動軸被傳送的扭矩、使汽車逆向運(yùn)動、當(dāng)長時間停車或靠邊行使時將發(fā)動機(jī)從驅(qū)動路線上分離出來。當(dāng)慣性大、牽引阻力小的時候，應(yīng)對車輪施加一個比在一般平路上行使時還要大的扭矩使汽車全負(fù)荷運(yùn)轉(zhuǎn)或全負(fù)荷爬坡。為了配合這些變化的扭矩的需要

20、，用到一個特殊的齒輪箱。這樣的齒輪箱叫做固定系數(shù)變速器。</p><p>　　由主動齒輪和從動齒輪組成的齒輪鏈中，主動齒輪上的扭矩將增加很多倍，因為主動齒輪的齒數(shù)大于從動齒輪的齒數(shù)。</p><p>　　為了滿足變化的操作條件，需要提供不同的扭矩，因此變速器里加入了幾組不同齒數(shù)比的齒輪。</p><p>　　如果在主動齒輪和從動齒輪之間引進(jìn)中間齒輪，從動齒輪的轉(zhuǎn)動方

21、向?qū)兓?lt;/p><p>　　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。</p><p>　　鐵鑄的機(jī)殼有一個上蓋和側(cè)蓋并有用于裝軸的孔。底面和另一側(cè)面提供了用于裝油和排油的孔。</p><p>　　輸入軸是剛鑄的，又主動齒輪和輪緣構(gòu)成整體。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(yùn)動。輸入軸這樣布置以便

22、只有主動齒輪和齒圈安裝在箱體內(nèi)，而伸出變速器外的軸的花鍵部分用來支承離合器從動盤轂。輸出端是用花鍵連接的，并隨著安裝在輸入軸孔中的滾動軸承的的前端而休息。輸出端的另一端在變速器機(jī)身的滾動軸承中做旋轉(zhuǎn)運(yùn)動。</p><p>　　齒輪軸安放著一組不同齒數(shù)比的齒輪。這組齒輪安裝在輪軸上的滾動軸承上，或和軸安裝在一起，即機(jī)身的孔的軸承中。閑置的軸始終隨著輸入軸而轉(zhuǎn)動，因為它們的齒輪是保持嚙合的。回轉(zhuǎn)齒輪（單個齒輪或兩個齒

23、輪組）由機(jī)身上的孔確保在軸輪上轉(zhuǎn)動。</p><p>　　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。沿著輸出軸齒輪的變換將引起速度的變化。變速器的類型依賴于滑動齒輪的個數(shù)。有兩個滑動齒輪或同步嚙合套的叫做2-范圍，三個齒輪的叫做3-范圍。根據(jù)向前的速度的大小，由3-、4-、5-速度的變速器。換檔機(jī)構(gòu)安裝在蓋的頂端上。換檔桿安裝在蓋上或水平支座的托座上。</p><p>&l

24、t;b>　　譯文</b></p><p>　　The basic mechanisms Of Automobiles</p><p>　　The automobile industry is a fast developing industry. From the later 18th century when the first automobile was put o

25、n road, this industry has developed tremendously. Now there are thousands of factories all over the world manufacturing </p><p>　　numerous types of automobiles. This industry employs crores of men and women

26、directly and indirectly in allied industries. The automobile engines are also being used </p><p>　　in engine powered machines for agriculture, construction and manufacturing processes. Various types of small

27、 engines are also being used in lawn movers, power </p><p>　　saws, snow removers and similar equipment. The automobile industry is a developing </p><p>　　and demanding industry which does not fi

28、nd its end or saturation point. There is a great demand for varied types of automotive products, vehicles and engines. </p><p>　　There is also a great demand for trained and experienced persons in this indus

29、try for diagnosing motor vehicle troubles, repairing and replacing engines components, transmissions, propeller shafts, differentials, axles, steering system components,brake system components, suspension components, air

30、-conditioners, heaters, body and glass work. </p><p>　　The automobile consists of five basic mechanisms, or components. These are :</p><p>　　(1) The engine, which is the source of power, includ

31、ing the fuel, lubricating, </p><p>　　cooling, and electric systems</p><p>　　(2) The frame, which supports the engine, wheels, steering and brake systems, </p><p><b>　　and bod

32、y</b></p><p>　　(3) The power train, which carries the power from the engine(through the clutch,transmission, drive shaft, differential, and axles)to the car wheels </p><p>　　(4) The car

33、body </p><p>　　(5) car-body accessories, including heater ,lights, windshield wipers, and so forth</p><p>　　The engine is the source of power that makes the car move. It is usually called an in

34、ternal combustion engine because gasoline is burned inside the engine cylinders, or combustion chambers. This is in contrast to external-combustion engines(such as steam engines),where the combustion takes place outside

35、the engine. The burning of gasoline in the engine cylinders produces the power. The power is then carried from the engine through the power train to the car wheels so that the wheels turn and the</p><p>　　Th

36、e fuel system plays a vital part in the power producing process since it supplies the gasoline to the engine cylinders. In each engine cylinder, a mixture of </p><p>　　gasoline vapor and air enters the cylin

37、der, the piston pushes up into the cylinder to compress the mixture, and then an electric spark ignites the compressed mixture so that the piston is forced downward. Of course, in the engine the piston is not blown compl

38、etely out of the cylinder, the piston simply moves up and down in the cylinder-up to compress as the mixture burns. The piston straight-line motion must be changed to rotary motion before it can be used to make the car w

39、heels rotate. A conne</p><p>　　The engine valves get the burned gasoline vapor out of the engine cylinder and</p><p>　　bringing fresh changes of gasoline vapor and air into the cylinder. There a

40、re two openings ,or ports, in the enclosed end of the cylinder ,each containing a valve. The valve are accurately machined plugs on long stems. When they are closed, or seated (that is, moved up into the ports), the port

41、s are sealed off and gas cannot pass through the ports. When the valve is open, gas can pass through the port</p><p><b>　　.</b></p><p>　　The valves are opened by cams on the engine c

42、amshaft. The cam has a high point,</p><p>　　or lobe; every time the cam rotates, the lobe comes around under the valve lifter and move it upward. The lifter then carries this upward movement through the push

43、rod 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,

44、 the heavy valve spring pulls the valve back into its seat. The spring is attached to the upper end of the valve stem</p><p>　　When the entire cycle of events requires four piston strokes (two crankshaft <

45、;/p><p>　　revolutions), the engine is called a four-stroke-cycle engine, or a four-cycle engine. The four strokes are intake, compression, power, and exhaust.</p><p>　　On the intake stroke, the int

46、ake valve is open. The piston moves down, pulled </p><p>　　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 v

47、alve 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 int

48、o the cylinder as the piston moves down on theintake stroke.</p><p>　　After the piston moves down to the bottom dead center on the intake stroke, the</p><p>　　intake valve closes. The lobe on th

49、e 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

50、 mixture of air and gasoline vapor that has been drawn into the cylinder is compressed. By the time the piston has moved up to the top dead center, the mixture is compressed to a seventh or an eighth of its original volu

51、me. That is like taking a</p><p>　　About the time the piston reaches the top dead center on the compression stroke, an electric spark occurs at the cylinder spark plug. The spark plug is essentially two heav

52、y wire electrodes; the spark jumps between these electrodes. The spark is produced by the ignition system. It ignites, or sets fire to, the compressed air-gasoline-vapor mixture. Rapid combustion takes place; high temper

53、atures and </p><p>　　pressures result. At this instant, the downward pressure on the top of the piston may amount to as much as 2tons. This powerful push forces the piston down, and a power impulse is transm

54、itted to the crankshaft through connecting rod and the crank.</p><p>　　The piston is forced down by the pressure of the burning gasoline vapor during</p><p>　　the power stroke. When the piston r

55、eaches the bottom dead center, the exhaust valve opens. Now, as the piston starts back up again, it forces the burned gases from the cylinder. By the time the piston has reached the top dead center the cylinder is cleare

56、d of the burned gases. The exhaust valve closes and the intake valve opens. Then ,the piston starts back down again on the next intake stroke. The four cycles, or piston strokes, are continuously repeated while the engin

57、e is running. </p><p>　　The Clutches </p><p>　　A clutch is a friction device used to connect and disconnect a driving force from a driven member. In automotive application, it is used in conjun

58、ction with an engine flywheel to provide smooth engagement and disengagement of the engine and manual transmission.</p><p>　　Since an internal combustion engine develops little power or torque at low rpm, &l

59、t;/p><p>　　it must gain speed before it will move the vehicle. However, if a rapidly rotating engine is suddenly connected to the drive line of a stationary vehicle, a violent shock will result.</p><

60、p>　　So gradual application of load, along with some slowing of engine speed, is needed to provide reasonable and comfortable starts. In vehicles equipped with a manual transmission, this is accomplished by means of a

61、mechanical clutch.</p><p>　　The clutch utilizes friction for its operation. The main parts of the clutch are a pressure plate, and a driven disk. The pressure plate is coupled with the flywheel, while the dr

62、iven disk is fitted to the transmission input shaft. The pressure plate is pressed to the disk by the springs so that the torque is transmitted owing to friction forces from the engine to the input shaft of the transmiss

63、ion. Smooth engagement is ensured by slipping of the disk before a full pressure is applied.</p><p>　　The automobiles are equipped with a dry spring-loaded clutch. The clutch is termed "dry" becaus

64、e the surfaces of the pressure plate and driven disks are dry incontrast to oil-bath clutches in which the plate and disks operate in a bath of oil. It is called "spring-loaded" because the pressure plate and t

65、he driven disk are always pressed to each other by springs and are released only for a time to shift gears or to brake the automobile.</p><p>　　In addition to the plate and disk, the clutch includes a cover,

66、 release levers, a release yoke, pressure springs and a control linkage. The clutch cover is a steel stamping bolted to the flywheel. The release levers are secured inside the cover on the supporting bolts. The outer en

67、ds of the release levers are articulated to the pressure plate. Such a construction allows the pressure plate to approach the cover or move away from it, all the time rotating with the flywheel. The springs spaced aro<

68、;/p><p>　　The springs are installed with the aid of projections and sockets provided on the cover and pressure plate. The pressure plate sockets have thermal-insulation gaskets for protecting the springs agains

69、t overheating.</p><p>　　The clutch release mechanism can be operated either mechanically or hydraulically. The mechanically-operated release mechanism consists of a pedal,a return spring, a shaft with lever,

70、 a rod, a release yoke lever, a release yoke, a release ball bearing with support and a clutch release spring. When the clutch pedalis depressed, the rod and shaft with yoke shift the released bearing and support assembl

71、y. The release bearing presses the inner ends of the release levers, the pressure plate is moved </p><p>　　The clutch hydraulically-operated release mechanism consists of a clutch pedal, </p><p>

72、;　　clutch release spring, a main cylinder, a pneumatic booster, pipelines and hoses and a lever of the clutch release yoke shaft. The main cylinder accommodates a piston with a cup. The pneumatic booster serves to decrea

73、se the pedal force required to disengage the clutch. The booster includes two housings with the servo diaphragm clamped in between. The housing accommodates pneumatic, hydraulic and servo plungers. When the clutch pedal

74、is pushed, the fluid pressure from the main cylinder is transmi</p><p>　　The servo arrangement is intended for automatic change of the air pressure in the pneumatic cylinder proportionally to the force appli

75、ed to the pedal. The plunger moves with the diaphragm, the outlet valve closes and the inlet valve opens thus admitting the compressed air to the pneumatic plunger piston. The forces created by the pneumatic and hydrauli

76、c plungers are added together and are applied through the push rod to the release yoke shaft lever, the lever turns the shaft and the release yoke</p><p>　　Automatic clutches were used in certain U.S. and Eu

77、ropean cars. American Motors"E-stick" clutch eliminated the need for physical operation of the clutch pedal. A German car maker engineered an automatic clutch system called "Hydrak", which consisted o

78、f a fluid flywheel connected to a single, dry disk clutch.</p><p>　　In the "E-Stick" set up, the pressure plate levers "engage" the clutch disk rather than "release" them. Also,

79、 the clutch remains disengaged until a servo unit is applied by oil pressure when the shift lever is placed "in gear" with the engine running.</p><p>　　The "Hydrak" unit also begins opera

80、tion when the lever is "in gear". This activates a booster unit, which disengages the clutch disk. The hydraulic clutch parts are bridged over by a free-wheel unit, which goes into action when the speed of the

81、rear wheels is higher than the speed of the engine. A special device controls ingagement of the mechanical clutch, depending on whether the rear axle is in traction or is pushed by car momentum. </p><p>　　A

82、more-or-less unusual clutch pressure plate set-up is used on late model Chrysler and American Motors cars. Called a semi-centrifugal clutch, the pressure plate has six cylindrical rollers which move outward under centrif

83、ugal force until they contact the cover. As engine speed increases, the rollers wedge themselves between the pressure plate and cover so that the faster the clutch rotates, the greater the pressure exerted on the pressur

84、e plate and disk.</p><p>　　Automobile Transmission</p><p>　　A transmission is a speed and power changing device installed at some point between the engine and driving wheel of the vehicle. It pr

85、ovides a means for changing</p><p>　　the ratio between engine rpm ( revol utions per minute) and driving wheels rpm to best meet each particular driving situation. </p><p>　　Given a level road ,

86、an automobile without a transmission could be made to move </p><p>　　by accelerating the engine and engaging the clutch. However, a start under these conditions would be slow, noisy and uncomfortable. In add

87、ition, it would place a tremendous strain on the engine and driving parts of the automobile.</p><p>　　So in order to get smooth starts and have power to pass and climb hills, a power ratio must be provided t

88、o multiply the torque and turning effort of the engine. Also required is a speed ratio to avoid the need for extremely high engine rpm at high road speeds. The transmission is geared to perform these functions.</p>

89、<p>　　The transmission is designed for changing the torque transmitted from the engine</p><p>　　crankshaft to the propeller shaft, reversing the vehicle movement and disengaging the engine from the dr

90、ive line for a long time at parking or coasting. A higher to rque should be applied to the wheels to set an automobile in motion or move uphill with a full load than to keep it rolling after it gets under way on level st

91、retches of the road, when inertia is high and tractive resistance is low. To meet these variable torque requirements, special gear boxes are used. Such gear boxes are called fi</p><p>　　In a gear train consi

92、sting of a driving gear and a driven gear, the torque at the driven gear will increase as many times as the number of teeth of the driven gear is larger than that of the driving gear.</p><p>　　The figure obt

93、ained by dividing the number of driven gear teeth by that of the driving gear is called gear ratio. If a train consists of several pairs of gears, the overall ratio is the product of the gear ratios of all the gear pairs

94、 in the train.</p><p>　　To provide the different torques required under the varying operating conditions</p><p>　　of a vehicle, the transmission incorporates several pairs of gears with differe

95、nt gear ratios. </p><p>　　If an intermediate gear is introduced between the driving gear and the driven gear, the rotation of the driven gear will be reversed.</p><p>　　The transmission consists

96、 of a housing, an input shaft and gear, an output and gear, an idler shaft, a reverse gear, a cluster of gears and a gear shift mechanism.</p><p>　　The cast iron housing has upper and side covers and bores f

97、or the installation of shafts. The bottom and side walls are provided with holes for filling and draining oil.</p><p>　　The input shaft is made of steel integral with the driving gear and the rim. The front

98、end of the input shaft is installed on the bearing in the bore of the crankshaft, while the rear end rotates in the bore of the front wall of the housing. The input shaft is arranged so that only the driving gear and the

99、 rim are accommodated inside the housing while the splined potion of the shaft protruding from the transmission carries the hub of the clutch driven disk. The output shaft is splined and rests </p><p>　　The

100、idler shaft carries a cluster of gears of different sizes. The cluster is mounted in the roller bearings on an axle or, together with the shaft, on bearings in the housing wall bores. The idler shaft constantly rotates w