controlled by the driver through the clutch pedal and linkage.
当驾驶员松开离合器踏板，离合器主动件和从动件之间的弹簧压力开始增加，两者之间的磨擦也开始增加。驾驶员通过离合器踏板和连接杆件来控制离合器弹簧释放出来的压力。 The positive engagement of the driving and driven members is made possible by the friction between the surfaces of the members. When full spring pressure is applied, the speed of the driving and driven members should be the same. At the moment, the clutch must act as a solid coupling device and transmit all engine power to the transmission, without slipping.
离合器主动件和从动件的接合是通过这些部件表面的磨擦实现的。当弹簧压力全部释放时，主动件和从动件的速度相同。此时，离合器作为一个刚性连接装置，将发动机的全部功率传递给变速器，不产生打滑。
However, the transmission should be engaged to the engine gradually in order to operate the car smoothly and minimize torsional shock on the drive train because an engine at idle just develops little power. Otherwise, the driving members are connected with the driven members too quickly and the engine would be stalled.
发动机空转时输出的功率较小，为了使得汽车运行平滑并最小化传动系的扭力波动，变速器应该缓慢地与发动机接合。否则，如果主动件和从动件接合过快，发动机就会熄火。
The flywheel is a major part of the clutch. The flywheel mounts to the engine's crankshaft and transmits engine torque to the clutch assembly. The flywheel, when coupled with the clutch disc and pressure plate makes and breaks the flow of power from the engine to the transmission.
飞轮是离合器的一个主要部件。飞轮设置在发动机曲轴上，将发动机的转矩传递给离合器。当飞轮与离合器磨擦片和压盘接合，它可以连接或中断发动机和变速器之间的功率传递。 The flywheel provides a mounting location for the clutch assembly as well. When the clutch is applied, the flywheel transfers engine torque to the clutch disc. Because of its weight, the flywheel helps to smooth engine operation. The flywheel also has a large ring gear at its outer edge, which engages with a pinion gear on the starter motor during engine cranking.
飞轮也给离合器总成提供一个安置的位置。当踩下离合器踏板，飞轮将发动机的转矩传递给离合器磨擦片。由于飞轮的自重，它有助于发动机平稳运转。飞轮的外缘也有一个大的齿圈。启动发动机时，这个齿圈和起动机上的一个小齿轮啮合。
The clutch disc fits between the flywheel and the pressure plate. The clutch disc has a splined hub that fits over splines on the transmission input shaft. A splined hub has grooves that match splines on the shaft. These splines fit in the grooves. Thus, the two parts are held together.
离合器磨擦片位于飞轮和压盘之间。磨擦片有一个花键毂，它与变速器的输入轴花键连接。花键毂上有与输入轴花键匹配的凹槽，使得花键与凹槽相互啮合，从而将磨擦片与变速器输入轴相互连接。
However, back-and-forth movement of the disc on the shaft is possible. Attached to the input shaft, the disc turns at the speed of the shaft.
但是，变速器输入轴上的磨擦片可以前后运动。一旦磨擦片与输入轴相连，磨擦片就与输入轴的转速相同。
The clutch pressure plate is generally made of cast iron. It is round and about the same diameter as the clutch disc. One side of the pressure plate is machined smooth. This side will press the clutch disc facing against the flywheel. The outer side has various shapes to facilitate attachment of spring and release mechanisms. The two primary types of pressure plate assemblies are coil spring assembly and diaphragm spring.
离合器压盘通常由铸铁做成。压盘为圆形，与磨擦片直径大约相同。压盘的一面是光滑的。
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这个光滑面压着面向飞轮的磨擦片。另一面有着不同的形状，以便于弹簧和分离装置的连接。目前主要使用的两种压盘是螺旋弹簧压盘和膜片弹簧压盘。
In a coil spring clutch the pressure plate is backed by a number of coil springs and housed with them in a pressed-steel cover bolted to the flywheel. The springs push against the cover. Neither the driven plate nor the pressure plate is connected rigidly to the flywheel and both can move either towards it or away. 对于螺旋弹簧离合器，压盘后端是多个螺旋弹簧。螺旋弹簧位于一个与飞轮螺栓固定的由钢板冲压制成的壳内。弹簧压着外壳。从动盘和压盘都没有和飞轮刚性连接，两者可以相对运动。
When the clutch pedal is depressed a thrust pad riding on a ball thrust bearing is forced towards the flywheel. Levers pivoted so that they engage with the thrust pad at one end and the pressure plate at the other end pull the pressure plate back against its springs. This releases pressure on the driven plate disconnecting the gearbox from the engine.
当踩下离合器踏板，位于球节分离轴承上的止推垫被推向飞轮。控制杆转动，一端与止推垫相连，另一端与压盘相连，克服弹簧压力将压盘拉回，从而分离了从动盘上的压力，将变速器与发动机分开。
Diaphragm spring pressure plate assemblies are widely used in most modern cars. The diaphragm spring is a single thin sheet of metal which yields when pressure is applied to it. When pressure is removed the metal springs back to its original shape. 膜片弹簧离合器被广泛应用于现代轿车上。膜片弹簧是一个薄金属板弹簧片。当施加压力时，弹簧片收缩。当压力去除，金属弹簧恢复原状。
The center portion of the diaphragm spring is slit into numerous fingers that act as release levers. When the clutch assembly rotates with the engine these weights are flung outwards by centrifugal forces and cause the levers to press against the pressure plate.
膜片弹簧中间部分切成许多充当分离杠杆的分离指。当离合器与发动机一起旋转时，在离心力作用下，重量被甩向外缘，使得分离指压向压盘。
During disengagement of the clutch the fingers are moved forward by the release bearing. The spring pivots over the fulcrum ring and its outer rim moves away from the flywheel．The retracting spring pulls the pressure plate away from the clutch plate thus disengaging the clutch. 当离合器分离时，分离指被分离轴承推动。弹簧在支撑环转动，外缘离开飞轮。缩回的弹簧将压盘从从动盘拉开，从而分离离合器。
When engaged the release bearing and the fingers of the diaphragm spring move towards the transmission. As the diaphragm pivots over the pivot ring its outer rim forces the pressure plate against the clutch disc so that the clutch plate is engaged to the flywheel.
当离合器接合时，分离轴承和膜片弹簧的分离指向变速器移动。当膜片弹簧在支撑环转动，弹簧外缘将压盘压向离合器磨擦片，从而接合离合器和飞轮。
The advantages of a diaphragm type pressure plate assembly are its compactness, lower weight, fewer moving parts, less effort to engage，reduces rotational imbalance by providing a balanced force around the pressure plate and less chances of clutch slippage.
膜片弹簧离合器的优点是结构紧凑，重量轻，运动部件较少，接合操纵轻便。由于膜片弹簧给压盘提供了平衡力从而减小了旋转的不平衡和滑磨出现的几率。
The clutch pedal is connected to the disengagement mechanism either by a cable or, more commonly, by a hydraulic system. Either way, pushing the pedal down operates the disengagement mechanism which puts pressure on the fingers of the clutch diaphragm via a
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release bearing and causes the diaphragm to release the clutch plate.
离合器踏板使用绳索或更多地使用液压系统与分离装置连接。无论采用哪种方式，踩下踏板，操纵分离机构，通过分离轴承对离合器膜片弹簧指施加压力，均可解除膜片弹簧对离合器盘的压紧。
With a hydraulic mechanism, the clutch pedal arm operates a piston in the clutch master cylinder. This forces hydraulic fluid through a pipe to the clutch release cylinder where another piston operates the clutch disengagement mechanism. The alternative is to link the clutch pedal to the disengagement mechanism by a cable.
对于液压系统，离合器踏板臂推动离合器主缸的活塞。这使得油液通过管道流向离合器分离缸。在分离缸，另一个活塞推动离合器分离装置。另一种机构就是使用绳索连接离合器踏板和分离装置。
The other parts including the clutch fork, release bearing, bellhousing, bell housing cover, and pilot bushing are needed to couple and uncouple the transmission. The clutch fork, which connects to the linkage, actually operates the clutch. The release bearing fits between the clutch fork and the pressure plate assembly.
离合器的其他部件包括离合器拨叉，分离轴承，离合器壳，离合器壳体外壳和导轴衬，它们用于连接和分离变速器。离合器拨叉和控制杆相连，实际操纵离合器。分离轴承位于离合器拨叉和压盘之间。
The bell housing covers the clutch assembly. The bell housing cover fastens to the bottom of the bell housing. This removable cover allows a mechanic to inspect the clutch without removing the transmission and bell housing. A pilot bushing fits into the back of the crankshaft and holds the transmission input shaft.
离合器壳将离合器总成覆盖。离合器壳体外壳固定在离合器壳体的上面。这个可拆卸的外壳使得机械师在不必拆卸变速器和离合器壳体的条件下检查离合器。导轴衬装配在曲轴的后端，支撑变速器输入轴。
Exercises练习
①The clutch assembly is a rotating mechanism between the engine and the transmission 离合器是位于发动机和变速器之间的一个旋转的机械装置。
②The clutch is usually attached directly to the engine flywheel, and its driven member is in the form of one or more disks faced with material having high frictional properties, pressed into engagement by springs.
离合器通常与发动机飞轮直接相连。离合器的从动件由一个或多个磨擦片组成，通过压紧弹簧接合。摩擦片的表面由高磨擦系数材料覆盖。
③The material used for facing the clutch disc is similar to that used for lining brakes, being composed of woven asbestos bonded with phenol resin, and sometimes enclosing metal wire mesh to strengthen it.
离合器磨擦片表面的材料与制动衬片所用的材料类似，由酚醛树脂粘结的石棉线组成，有时还加入金属线网来增加强度。
Unit 9 Automatic Transmission 第九课自动变速器
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The modern automatic transmission is by far, the most complicated mechanical component in today’s automobile. It is a type of transmission that shifts itself. A fluid coupling or torque converter is used instead of a manually operated clutch to connect the transmission to the engine.
汽车自动变速器是迄今为止汽车上最复杂的机械部件。它是一种可以自行换档的变速器。液力耦合器或液力变矩器用于连接变速器和发动机，取代手动操纵的离合器。
There are two basic types of automatic transmissions based on whether the vehicle is rear wheel drive or front wheel drive. On a rear wheel drive car, the transmission is usually mounted to the back of the engine and is located under the hump in the center of the floorboard alongside the gas pedal position.
基于汽车采用后轮驱动还是前轮驱动，可以把自动变速器分为两类。对于后轮驱动的汽车，变速器一般安置在发动机后端，位于车厢地板中央隆起下面，位置在油门踏板位置边上。 A drive shaft connects the rear of the transmission to the final drive which is located in the rear axle and is used to send power to the rear wheels. Power flow on this system is simple and straight forward going from the engine, through the torque converter, then through the transmission and drive shaft until it reaches the final drive where it is split and sent to the two rear wheels.
位于后轴上的驱动轴连接变速器后端和主减速器，被用来将功率传递给后轮。这个系统的功率流动结构简单，功率直接从发动机流出，经过液力变矩器、变速器、驱动轴，到达主减速器，然后功率被分配传递给两个后轮。
On a front wheel drive car, the transmission is usually combined with the final drive to form what is called a transaxle. The engine on a front wheel drive car is usually mounted sideways in the car with the transaxle tucked under it on the side of the engine facing the rear of the car.
对于前轮驱动的汽车，变速器通常与主减速器集成在一起以形成变速驱动桥。前轮驱动的汽车发动机通常横置位于汽车的一侧，而变速驱动桥面向汽车后部，与发动机同侧，位于发动机的下面。
Front axles are connected directly to the transaxle and provide power to the front wheels. In this example, power flows from the engine, through the torque converter to a large chain that sends the power through a 180 degree turn to the transmission that is along side the engine. From there, the power is routed through the transmission to the final drive where it is split and sent to the two front wheels through the drive axles.
前轴与变速驱动桥直接相连，把功率传给前轮。此时，功率
从发动机流出，通过液力变矩器，经过链条180度转向，传递给位于发动机一侧的变速器，再由变速器流向主减速器，通过驱动桥被分配传递给两个前轮。
There are a number of other arrangements including front drive vehicles where the engine is mounted front to back instead of sideways and there are other systems that drive all four wheels but the two systems described here are by far the most popular. 还有许多其它的布局形式，比如：发动机竖置前驱，而不是横向布置。还有四轮驱动的系统。但是上述的两种系统是迄今应用最多的系统。
A much less popular rear drive arrangement has the transmission mounted directly to the final drive at the rear and is connected by a drive shaft to the torque converter which is still mounted
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on the engine. This system is found on the new Corvette and is used in order to balance the weight evenly between the front and rear wheels for improved performance and handling. 还有一种常见的后轮驱动布置形式是变速器直接安置在车后部的主减速器上，通过一根驱动轴与液力变矩器相连。液力变矩器还是安置在发动机上。这个系统用在新版的科尔维特（雪佛兰，一款代表美国精神的跑车），目的是均匀分布前后轮之间的重量，以提高性能和操稳性。
Another rear drive system mounts everything, the engine, transmission and final drive in the rear. This rear engine arrangement is popular on the Porsche.
另一种后驱系统将发动机、变速器和主减速器都集中在后部。这种发动机后置在保时捷上应用普遍。
The modern automatic transmission consists of many components and systems that are designed to work together in a symphony of planetary gear sets, the hydraulic system, seals and gaskets, the torque converter, the governor and the modulator or throttle cable and computer controls that has evolved over the years into what many mechanically inclined individuals consider to be an art form.
现代自动变速器由许多部件和系统组成，它们有行星齿轮组、液压系统、密封圈和密封衬垫、液力变矩器、油压调节器、自动变速器调制器、节气门拉线、电子控制装置等，经精心设计，运转协调，其中的电子控制装置经历了多年的发展，已经以巧妙的形式融入了许多人性化的设计。（意译）
Here try to use simple, generic explanations where possible to describe these systems. 下来我们尽可能用简单和通常的解释来描述这些系统。 9.1 Planetary gear sets 9.1 行星齿轮组
Automatic transmissions contain many gears in various combinations. In a manual transmission gears slide along shafts as you move the shift lever from one position to another, engaging various sized gears as required in order to provide the correct gear ratio.
自动变速器有着许多各种集成形式的齿轮。对于手动变速器，齿轮在轴上滑动，当驾驶员从一个档位切换到另一个档位时，按照要求将不同尺寸的齿轮进行啮合，从而提供正确的传动比。
In an automatic transmission, however, the gears are never physically moved and are always engaged to the same gears. This is accomplished through the use of planetary gear sets.
然而对于自动变速器，齿轮总是与相同的齿轮相啮合，在空间上并不移动。这是通过行星齿轮组实现的。
The basic planetary gear set consists of a sun gear, a ring gear and two or more planet gears, all remaining in constant mesh. The planet gears are connected to each other through a common carrier which allows the gears to spin on shafts called \ 一个基本的行星齿轮组由一个太阳轮、一个内齿圈和两个或更多的行星齿轮组成，这些部件都保持常啮合。行星齿轮通过一个公用的行星架互相相连。行星架允许行星齿轮在与其相连的轴上旋转。
One example of a way that this system can be used is by connecting the ring gear to the input shaft coming from the engine, connecting the planet carrier to the output shaft, and locking the
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