附录
Manual Transmission
It’s no cret 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?三国志13好玩吗
A history hows that manual transmissions preceded automatics by veral decades. In fact, up until General Motors offered an automatic in 1938, all cars were of the shift-it-yourlf var iety. While it’s logical for many types of today’s vehicles to be equipped with an automatic---such as a full-size dan, SUV or pickup----the fact remains that nothing is more of a thrill to drive than a tautly suspended sport dan, sport coupe or two-ater equipped with a preci-shifting five-or six-speed gearbox.
We know which types of cars have manual trannies. Now let’s take a look at how they work. From the most basic four-speed manual trannies. Now let’s take a look at how they work.From the most basic four-speed manual in a car from the’60s 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 ,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 becau the transmission, differential and drive axles are one complete unit. In a front-wheel-drive car, the transmission also rves 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 . Gears inside the transmission change the vehicle’s drive-wheel speed and torque in relation to inside the transmission change the vehicle’s drive-wheel speed and torque in
注册执业资格relation to engine speed and torque. Lower gear ratios rve 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 transmission and rotates the main drive gear, which meshes with the cluster or counter shaft gear----a ries of gears forged into one piece that rembles a cluster of gears. The cluster-gear asmbly rotates any time the clutch is engaged to a running engine, whether or not the transmission is in gear or in neutral.
舞姿优美的句子There are two basic types of manual transmissions. The sliding-gear type and the constant-mesh de
sign. With the basic---and now obsolete---sliding-gear type, nothing is turning inside the transmission ca 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 press 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 relead and the engine’s power is nt to the drive wheels. There can be veral 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 the older transmissions, gear clash is a problem becau the gears are all rotating at different speeds.
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All modern transmissions are of the constant-mesh type, which still us 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 becau 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 that’s positively splined to the shaft and an outer ring that can slide over against each gear. Both the
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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 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 synchro’s inner hub and sleeve are made of steel, but the blocking ring----the part of the synchro that rubs on the gear to change its speed----is 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 duty----they push the synchro in one direction and lock one gear to the mainshaft. Push the synchro the other way and it dingages from the first gear, pass through a neutral position, and engages a gear on the other side.
That’s 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 the transmissions had 1:1 final-drive ratios with no overdrives. Today, overdriven five-speeds are standard on practically all pasnger cars available with a manual gearbox.
Overdrive is an arrangement of gearing that provides more revolutions of the driven shaft than the driving shaft. 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’89Corvette. Designed by Chevr olet and
Zahnradfabrik Friedrichshafen 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 us 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 9
11, Dodge Viper, Mercedes-Benz SLK320, Honda S2000,Toyota Celica GT-S and many others. Some of the gearboxes provide radical 50-percent 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 the smaller cars like the Celica and S2000 usually have one overdriven gear ratio 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.
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手动变速器
错别字的危害
驾驶手动变速器汽车比驾驶自动装置的汽车更有乐趣，这显然已经不是什么秘密了。如果你有驾驶兴趣，那么你就会更喜欢手动变速箱。但是手动变速箱到底是如何工作的呢？
志在必得的意思手动变速器要早于自动变速器几十年。事实上，直到1938年通用汽车公司提供自动变速器以前，所有的轿车都采用的手动变速器。现在的很多车辆都装备了自动变速器，如全尺寸轿车，运动型多功能车或皮卡车——事实上是没有什么能比驾驶配备了五挡或六挡变速箱的跑车或运动双座跑车更令人兴奋的了。
我们知道哪些类型的车配备有手动变速箱。现在让我们来看看他们是如何工作的。我们从最基本的六十年代的四挡手动变速箱到今天最高技术的六挡变速箱来看，其手动变速箱的工作原理是相同的。驾驶员必须从一档换到另一档。通常，从一个手动变速器的螺栓到离合器壳体，反过来，从螺栓到发动机的背面。如果车辆前轮驱动，变速器仍依附于发动机工作，但通常又被送交给变速驱动桥。这是因为变速器，差速器和驱动轴是一个完整的装置。在剩下的文章中，变速器和变速驱动桥都将由术语传动装置来表示。
变速器的功能是将发动机的动力传送到传动轴和后轮。变速器中的传动装置以及与变速器内部相关联的扭矩改变了汽车驱动轮的转速。低扭矩齿轮可使扭矩倍增，并且帮助引擎从静止状态加速来发出足够的动力。
起初，来自于发动机的动力和扭矩进入到变速器的前部，并且使主驱动齿轮旋转，它与齿轮组或副轴齿轮——一组单片齿轮组成的齿轮组共同啮合。齿轮组旋转时离合器就开始运行引擎，无论是否在传送动力中的齿轮还是处于空挡中的齿轮。
手动变速箱的基本类型有两种。滑动齿轮类型和常啮合设计类型。随着基础型号滑动齿轮式的淘汰，当传动装置设置在空挡时，除了主动齿轮和齿轮组以外，其余皆没有什么变化。为了啮合齿轮并使发动机提供动力来移动车辆，司机按下离合器踏板以及移动换档手柄，从而改变联动，使拨叉沿主轴移
动。一旦齿轮啮合时，离合器踏板被释放，发动机的动力便被传送到了驱动轮。这里可以有若干不同直径和齿数的齿
