外文翻译-手动变速器

1、附录A.Manual Tran smissi onIt s 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 driv ing, the n cha nces are you also appreciate a fin e-shift ing manual gearbox. But how does a manu

2、al tran smissi on actually work?A history hows that manual tran smissi ons 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 it s logical for many types of today s vehicles to be eqiwith an aut

3、omaticsuch as afiZle seda n, SUV or pickupthe fact remai ns thatnothing is more of a thrill to drive than a tautly suspendedsport sedan, snort coupe or two-sealer equipped with a precise-shift ing five-or six-speed gearboxWe know whicn types or cars have manual trannies. Now let s takeaatobow they w

4、ork. From the most basic four-speed manual in a car from the 60s)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 tran smissi on bolts to a clutch housing (or bell housing) , in turn, bolt

5、s 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 trans

6、mission 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

7、 wheels in a front-wheel-drive vehicle). Gears in side the tran smissi on cha nge the vehicle drive-wheel speed and torque in relati on to engine speed and torque Lower(numerically higher) gear ratios serve as torque multipliers and help the engine to develop eno ugh power to accelerate from a sta n

8、dstill.Initially, power and torque from the engine comes into the front of the transmissions and rotates the main drive gear (or in put shaft), which meshes with the cluster or coun tershaft geara series of gears forged in to one piece that resembles a cluster of gears. Thecluster-gear assembly rota

9、tes any time the clutch is en gaged to a running en gin,e whether or not the tran smissi on is in gear or in n eutral.There are two basic types of manual tran smissi ons. The slid in g-gear type and the constantmesh design. With the basic and now obsoleteasliylpeg nothingis tur ning in side the tran

10、 smissi on case except the main drive gear and cluster gear whe n 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 han dle, which in tur n moves the shift lin kage and forks to slide a gear along

11、 the main shaft, which is moun ted directly above the cluster. Once the gears are meshed, the clutch pedal is released and the engine is sent to the drive wheels. There can be several gears on the main shaft of differe nt diameters and tooth coun ts, and the tran smissi on shift lin kage is desig ne

12、d so the driver has to unm esh one gear before being able to mesh ano ther. With these older tran smissi ons, gear clash is a problem because the gears are all rotat ing at differe nt speeds.All moder n tran smissi ons are of the con sta nt-mesh type, which still uses a similar gear arran geme nt as

13、 the slidi ng-gear type. Howeverall the main shaft gears are in con sta nt mesh with the cluster gears. This is possible becausethe gears on the main shaft 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 main sha

14、ft gears are always turning, eve n whe n the tran smissi on is in n eutral.Alon gside each gear on the main shaft is a dog clutch, with a hub that positively splined to the shaft and an outer ring that can slide over against each gear. Both the main shaft gear and the ring of the dog clutch have a r

15、ow of teeth. Moving shift lin kage moves the dog clutch aga inst the adjace nt main shaft gear, caus ing the teeth to in terlock and solidly lock the gear to the main shaft.To preve nt gears from grinding or clash ing duri ng en gageme nt, a con sta nt-mesh, fully synchronized manual transmission is

16、 equipped with synchronizers. A synchronizer typically consists of an inner-splined hub, an outer sleeve, shifter plates, lock rings (or spri ngs) and block ing rin gs. The hub is spli ned onto the main shaft betwee n a pair of main drive gears. Held in place by the lock rings, the shifter plates po

17、sition the sleeve over the hub while also hold ing the floati ng block ing rings in proper alig nment.A synchro s inner hub and sleeve are made of steel, but the blocking ringof the syn chro that rubs on the gear to cha nge its speedisusually made of a softermaterial, such as brass. The block ing ri

18、ng has teeth that match the teeth on the dog clutch. Most syn chros perform double dutythey push the syn chro ione directi on and lockone gear to the main shaft. Push the syn chro the other way and it dise ngages from the first gear, passes through a neutral position, and engages a gear on the other

19、 side.That s the basics on the inn ework ings of a manual tran smissi on. As for adva nces, they have bee n exte nsive over the years, mainly in the area of additi onal gears. Back in the 60 spur-speeds were com mon in America n and Europea n performa nee cars. Most of these transmissions had 1:1 fi

20、nal-drive ratios with no overdrives. Today, overdriven five-speeds are sta ndard on practically all passe nger cars available with a manual gearbox.Overdrive is an arran geme nt of geari ng that provides more revoluti ons of the drive n shaft (the driveshaft going to the wheels than the driving shaf

21、t(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-spee

22、d tran smissi ons are beco ming more and more com mon. One of the first cars sold in America with a six- speed was the 89 Corvetfesigned 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

23、 the 96 model(yearette)dayuses a Tremec T56 six-speed moun ted at the back of the car.Many cars are available today with six-speeds, in clud ing the Mazda Miata, Porsche Boxster S and 911, Dodge Viper, Mercedes-Be nz SLK320, Ho nda S2000, Toyota Celica GT-S and many others. Some of these gearboxes p

24、rovide 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 overdri

25、ve 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-shifti ng manual tran smissi on is one of the mai n comp onents in a fun-to-drive car, along with a powerful engine, con fide nce-i nspiri ng suspe n

26、sion and compete nt brakes.附录B.手动变速器相对于自动变速箱的车手动变速箱汽车开起来有更好的驾驶乐趣这是众所周知 的。哪怕你对驾驶仅有一点兴趣，那么你也会对一个齿轮变速器的完美工作刮目相看。 那么手动变速器到底是怎么工作的呢？手动变速器在几十年以前就被自动变速箱所取代了， 事实上从前的车都是配备的 手动变速箱，直到1938年通用汽车公司推出第一款自动变速车。今天的诸多车辆像 轿车、越野车、小型载货汽车采用自动变速是很符合逻辑的，因为没有任何事会比驾 驶一个配有5-6个档的手动变速箱的车更令人紧张不安了。现在让我们看看他们是怎么工作的。从 60年代的四速手动到今天的最

27、高六速变 速器的基本原理是没有改变的。驾驶员仍然要操纵齿轮使其相互啮合。通常，变速器 与离合器壳连接，离合器的另一面再同发动机相连。如果是前轮驱动的车仍然是这种 简单的连接方式，但要称其为驱动桥，这是因为变速箱和驱动轴是一个整体的机构。 在前驱车上变速箱也是前轮驱动桥的一部分。 在过去的概念中变速器跟驱动桥被统称 为变速驱动桥。变速箱的功能就是将发动机的动力传递给驱动轴和后轮（前驱车是传递给半轴和 前轮）通过变速箱中的齿轮改变了发动机传给车轮的速度和扭矩。 低传动比能够增大 扭矩使发动机有足够的加速能量。起初，发动机将动力和扭力传给变速箱的输入轴，输入轴上的齿轮与中间轴上的 齿轮啮合，从而形成

28、一个齿轮组。这个齿轮组的任何一次转动都是离合器与运转的发 动机相连的结果，总之变速器就是一个齿轮的组合体。有两种手动变速器。滑动型的和常啮合型的。滑动型的（已经不用）变速器处于 空档时，除了主动齿轮和齿轮组转动其他都是不转的。 为了使齿轮啮合从而让发动机 输出的动力带动汽车运动驾驶员要踏下离合器踏板同时操作换档杆。换档杆会联动换档拨叉带动安装在输入轴上的相应齿轮沿输入轴移动。一旦齿轮啮合，释放离合器踏板后发动机动力就会传给驱动轮。输入轴上会有多个不同直径不同齿数的齿轮。因为 换档是联动的所以驾驶员必须使已经啮合的齿轮分离才能使另一对齿轮啮合。由于齿轮啮合时的速度不同，老式变速箱会有换档冲击的问题。现代的变速箱都是常啮合型的，齿轮布置是沿用滑动型的布置方式。然而所有主 轴上的齿轮与中间轴上齿轮都是常啮合的， 这是因为主轴上的齿轮在轴上是可以来回 移动的而不是用花键链连接的。 即使变速箱处于空档状态，常啮合型变速箱上的各个 齿轮都是在转动的。主轴上每个齿轮旁边都有一个爪式离合器（接合套），花键毂用内花键连接在主 轴上的花键上。主轴上的齿轮和接合套的外环都有花键。 当操纵换档杆时就会使接合 套对着主轴齿轮移动，最终使接合套与齿轮互锁从而使齿轮啮合随主轴转动。为了避免齿轮换档同步前啮合时产生的接合齿间冲击，手动变速