外文翻譯--自動變速箱的車手動變速箱

1 附 錄 附錄 A. Manual Transmission Its no secret that cars with manual transmissions are usually more fun to drive than the automatic-equipped counterparts. If you have even a passing interest in the act of driving, then chances are you also appreciate a fine-shifting manual gearbox. But how does a manual transmission actually work? A history hows that manual transmissions preceded automatics by several decades. In fact， up until General Motors offered an automatic in 1938, all cars were of the shift-it-yourself variety. While its logical for many types of todays vehicles to be equipped with an automaticsuch as a full -size sedan, SUV or pickupthe fact remains that nothing is more of a thrill to drive than a tautly suspended sport sedan, snort coupe or two-sealer equipped with a precise-shifting five-or six-speed gearbox We know whicn types or cars have manual trannies. Now lets take a look at how they work. From the most basic four-speed manual in a car from the60s to the most high-tech six-speed one in a car of today, the principles of a manual gearbox are the same. The driver must shift from gear to gear. Normally, a manual transmission bolts to a clutch housing (or bell housing） , in turn, bolts to the back of the engine. If the vehicle has front-wheel drive, the transmission still attaches to the engine in a similar fashion but is usually referred to as a transaxle. This is because the transmission, differential and drive axles are one complete unit. In a front-wheel-drive car, the transmission also serves as part of the front axle for the front wheels. In the remaining text, a transmission and a transaxle will both be referred to using the term transmission. The function of any transmission is transferring engine power to the driveshaft and rear wheels (or axle halfshafts and front wheels in a front-wheel-drive vehicle). Gears inside the transmission change the vehicles drive-wheel speed and torque in relation to engine speed and torque Lower(numerically higher) gear ratios serve as torque multipliers and help the engine to develop enough power to accelerate from a standstill. Initially, power and torque from the engine comes into the front of the transmissions and rotates the main drive gear (or input shaft), which meshes with the cluster or counter 2 shaft geara series of gears forged into one piece that resembles a cluster of gears. The cluster-gear assembly rotates any time the clutch is engaged to a running engine， whether or not the transmission is in gear or in neutral. There are two basic types of manual transmissions. The sliding-gear type and the constant-mesh design. With the basicand now obsoletesliding -gear type， nothing is turning inside the transmission case except the main drive gear and cluster gear when the trans is in neutral. In order to mesh the gears and apply engine power to move the vehicle, the driver presses the clutch pedal and moves the shifter handle, which in turn moves the shift linkage and forks to slide a gear along the mainshaft, which is mounted directly above the cluster. Once the gears are meshed, the clutch pedal is released and the engines power is sent to the drive wheels. There can be several gears on the mainshaft of different diameters and tooth counts, and the transmission shift linkage is designed so the driver has to unmesh one gear before being able to mesh another. With these older transmissions, gear clash is a problem because the gears are all rotating at different speeds. All modern transmissions are of the constant-mesh type, which still uses a similar gear arrangement as the sliding-gear type. However， all the mainshaft gears are in constant mesh with the cluster gears. This is possible because the gears on the mainshaft are not splined to the shaft, but are free to rotate on it. With a constant-mesh gearbox, the main drive gear, cluster gear and all the mainshaft gears are always turning, even when the transmission is in neutral. Alongside each gear on the mainshaft is a dog clutch, with a hub thats positively splined to the shaft and an outer ring that can slide over against each gear. Both the mainshaft gear and the ring of the dog clutch have a row of teeth. Moving shift linkage moves the dog clutch against the adjacent mainshaft gear, causing the teeth to interlock and solidly lock the gear to the mainshaft. To prevent gears from grinding or clashing during engagement, a constant-mesh, fully synchronized manual transmission is equipped with synchronizers. A synchronizer typically consists of an inner-splined hub, an outer sleeve, shifter plates， lock rings（ or springs） and blocking rings. The hub is splined onto the mainshaft between a pair of main drive gears. Held in place by the lock rings， the shifter plates position the sleeve over the hub while also holding the floating blocking rings in proper alignment. A synchros inner hub and sleeve are made of steel, but the blocking ringthe part 3 of the synchro that rubs on the gear to change its speedis usually made of a softer material, such as brass. The blocking ring has teeth that match the teeth on the dog clutch. Most synchros perform double dutythey push the synchro in one direction and lock one gear to the mainshaft. Push the synchro the other way and it disengages from the first gear, passes through a neutral position, and engages a gear on the other side. Thats the basics on the inner workings of a manual transmission. As for advances, they have been extensive over the years, mainly in the area of additional gears. Back in the 60s, four-speeds were common in American and European performance cars Most of these transmissions had 1:1 final-drive ratios with no overdrives. Today, overdriven five-speeds are standard on practically all passenger cars available with a manual gearbox. Overdrive is an arrangement of gearing that provides more revolutions of the driven shaft（ the driveshaft going to the wheels） than the driving shaft（ crankshaft of the engine） . For example, a transmission with a fourth-gear ratio of 1:1 and a fifth-gear ratio of 0.70:1 will reduce engine rpm by 30 percent, while the vehicle maintains the same road speed. Thus, fuel efficiency will improve and engine wear will be notably reduced. Today, six-speed transmissions are becoming more and more common. One of the first cars sold in America with a six-speed was the 89 Corvette. Designed by Chevrolet and Zahnradfabrik Friedrichshafen（ ZF） and built by ZF in Germany, this tough-as-nails six-speed was available in the Corvette up to the conclusion of the 96 model year. Today， the Corvette uses a Tremec T56 six-speed mounted at the back of the car. Many cars are available today with six-speeds, including the Mazda Miata, Porsche Boxster S and 911, Dodge Viper, Mercedes-Benz SLK320, Honda S2000, Toyota Celica GT-S and many others. Some of these gearboxes provide radical 50-percent (0.50:1) sixth-gear overdrives such as in the Viper and Corvette, while others provide tightly spaced gear ratios like in the S2000 and Celica for spirited backroad performance driving. While the bigger cars mentioned above such as the Viper and Vette often have two overdrive ratios（ fifth and sixth） the smaller cars like the Celica and S2000 usually have one overdriven gear ratio（ sixth) and fifth is 1:1. Clearly a slick-shifting manual transmission is one of the main components in a fun-to-drive car, along with a powerful engine， confidence-inspiring suspension and competent brakes. 4 附錄 B. 手動變速器 相對于自動變速箱的車手動變速箱汽車開起來有更好的駕駛樂趣這是眾所周知的。哪怕你對駕駛僅有一點興趣，那么你也會對一個齒輪變速器的完美工作刮目相看。那么手動變速器到底是怎么工作的呢？ 手動變速器在幾十年以前就被自動變速箱所取代了，事實上從前的車都是配備的手動變速箱，直到 1938 年通用汽車公司推出第一款自動變速車。今天的諸多車輛像轎車、越野車、小型載貨 汽車采用自動變速是很符合邏輯的，因為沒有任何事會比駕駛一個配有 5-6 個檔的手動變速箱的車更令人緊張不安了。 現(xiàn)在讓我們看看他們是怎么工作的。從 60 年代的四速手動到今天的最高六速變速器的基本原理是沒有改變的。駕駛員仍然要操縱齒輪使其相互嚙合。通常，變速器與離合器殼連接，離合器的另一面再同發(fā)動機相連。如果是前輪驅(qū)動的車仍然是這種簡單的連接方式，但要稱其為驅(qū)動橋，這是因為變速箱和驅(qū)動軸是一個整體的機構(gòu)。在前驅(qū)車上變速箱也是前輪驅(qū)動橋的一部分。在過去的概念中變速器跟驅(qū)動橋被統(tǒng)稱為變速驅(qū)動橋。 變速箱的功能就是將發(fā)動 機的動力傳遞給驅(qū)動軸和后輪（前驅(qū)車是傳遞給半軸和前輪）通過變速箱中的齒輪改變了發(fā)動機傳給車輪的速度和扭矩。低傳動比能夠增大扭矩使發(fā)動機有足夠的加速能量。 起初，發(fā)動機將動力和扭力傳給變速箱的輸入軸，輸入軸上的齒輪與中間軸上的齒輪嚙合，從而形成一個齒輪組。這個齒輪組的任何一次轉(zhuǎn)動都是離合器與運轉(zhuǎn)的發(fā)動機相連的結(jié)果，總之變速器就是一個齒輪的組合體。 有兩種手動變速器?；瑒有偷暮统Ш闲偷??；瑒有偷模ㄒ呀?jīng)不用）變速器處于空檔時，除了主動齒輪和齒輪組轉(zhuǎn)動其他都是不轉(zhuǎn)的。為了使齒輪嚙合從而讓發(fā)動機輸出的動力帶動汽車運 動駕駛員要踏下離合器踏板同時操作換檔桿。換檔桿會聯(lián)動換檔撥叉帶動安裝在輸入軸上的相應齒輪沿輸入軸移動。一旦齒輪嚙合，釋放離合器踏板后發(fā)動機動力就會傳給驅(qū)動輪。輸入軸上會有多個不同直徑不同齒數(shù)的齒輪。因為換檔是聯(lián)動的所以駕駛員必須使已經(jīng)嚙合的齒輪分離才能使另一對齒輪嚙合。 由于齒輪嚙合時的速度不同，老式變速箱會有換檔沖擊的問題。 現(xiàn)代的變速箱都是常嚙合型的，齒輪布置是沿用滑動型的布置方式。然而所有主軸上的齒輪與中間軸上齒輪都是常嚙合的，這是因為主軸上的齒輪在軸上是可以來回移動的而不是用花鍵鏈連接的。即使變速箱 處于空檔狀態(tài)，常嚙合型變速箱上的各個5 齒輪都是在轉(zhuǎn)動的。 主軸上每個齒輪旁邊都有一個爪式離合器（接合套），花鍵轂用內(nèi)花鍵連接在主軸上的花鍵上。主軸上的齒輪和接合套的外環(huán)都有花鍵。當操縱換檔桿時就會使接合套對著主軸齒輪移動，最終使接合套與齒輪互鎖從而使齒輪嚙合隨主軸轉(zhuǎn)動。 為了避免齒輪換檔同步前嚙合時產(chǎn)生的接合齒間沖擊，手動變速器上安裝了同步器。同步器由花鍵轂、套筒、撥叉、彈簧、鎖環(huán)等組成。花鍵轂