机械设计方案自动化英语翻译

原文：

CHASSIS

1.clutch

The engine produces the power to drive the vehicle . The drive line or drive train transfer the power of the engine to the wheels . The drive train consists of the parts from the back of the flywheel to the wheels . These parts inclu de the clutch , the transmission ,the drive shaft ,and the final drive assembly . The clutch which includes the flywheel ,clutch disc , pressure plate , springs , pressure plate cover and the linkage necessary to operate the clutch is a rotating mechanism between the engine and the transmission . It operates through friction which comes from contact between the parts . That is the reason why the clutch is called a friction mechanism . After engagement, the clutch must continue to transmit all engine torque to transmission depending on the friction without slippage . The clutch is also used to disengage the engine from the drive train whenever the gears in the transmission are being shifted from gear ratio to another .

To start the engine or shift the gears , the driver has to depress the clutch pedal with the purpose of disengagement the transmission from the engine . At that time , the driven members connected to the transmission input shaft are either stationary or rotating at a speed that is slower of faster than the driving members connected to engine crankshaft . There is no spring pressure on the clutch assembly parts . So there is no friction between the driving members and driven members . As the driver lets loose the clutch pedal , spring pressure increase on the clutch parts . Friction between the parts also increases . The pressure exerted by the springs on the driven members is controlled by the driver through the clutch pedal and linkage. The positive engagement of the driving and driven members is made possible 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 coupling device and transmit all engine power to the transmission , without slipping .

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 develop little power . Otherwise , the driving members are connected with the driven members too quickly and the engine would be stalled .

The flywheel is a major part of the clutch . The flywheel mounts to the engine 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 the engine to the transmission .

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 .

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 held together . However , back ¨C and ¨C forth movement of the disc on the shaft is possible . Attached to the input shaft , the disc turns at the speed of the shaft .

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 are against the flywheel . The outer side has shapes to facilitate attachment of spring and release mechanism . The two primary types of pressure plate assemblies are coil spring assembly and diaphragm spring .

In a coil spring clutch the pressure plate is backed by a number of coil springs and housed with them in a pressed ¨C steed cover bolted t o the flywheel . The spring 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 o away . When the clutch pedal is depressed a thrust pad

riding on a carbon or 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 tat the other end pull the pressure plate back against its springs . This releases pressure on the driven plate disconnecting the gearbox from the engine .

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 s pring back to its original shape . 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 plate and cause the levers to press against the pressure plate . 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 .

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 flywheel .

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 .

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 release bearing and causes the diaphragm to release the clutch plate . 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 cutch release cylinder where another

operates the clutch disengagement mechanism by a cable .

The other parts including the clutch fork , release bearing , bell ¨C housing , 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 . 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 .

2 automatic transmission

The modern automatic transmission is by far , the most complicated mechanical component in today?ˉs automobile . It is a type of transmission that sifts itself . A fluid coupling or torque converter is used instead of a manually operated clutch to connect the transmission to the engine .

There are two basic types of automatic transmission 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 . A drive shaft connects 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 trough the transmission and drive shaft until it reaches the final drive where it is split and sent to the two rear transmission .

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 tuc ked under it on the side of the engine facing the rear of the car . Front axles are connected directly to the transaxle and provide power to front wheels . In this example , power floes from the engine , through the torque converter to

a larger 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 .

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 . A much less popular rear and is connected by a drive shaft to the torque converter which is still mounted 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 . Another rear drive system mounts everything , the engine , transmission and final drive in the rear . This rear engine arrangement is popular on the Porsche.

The modern automatic transmission consists of many components and systems that 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 mechanical inclined individuals consider to be an art from . Here try to used simple , generic explanation where possible to describe these systems .

3 The Differential System

When a vehicle is cornered the inner wheel moves through a shorter distance than the outer wheel . This means that the inner wheel must slow down and the outer wheel must speed up . During this period it is desirable that each driving maintains its driving action . The differential performs these two tasks . The principle of the bevel type differential can be seen if the unit is considered as two discs and a lever .

When the vehicle is traveling straight , the lever will divide the diving force equally and both discs will move the same amount .

When the vehicle corners , the driving will still be divided equally but the

inner disc will now move through a smaller distance 。this will cause the lever to pivot about its center which will prize forward the outer disc to give it a greater movement . This action shows that the torque applied to each driving wheel is always equal ¨C hence the differential is sometimes called a torque equalizer .

4 Brake System

The breaking system is the most important system in cars . If the brakes fail , the result can be disastrous . Brakes are actually energy conversion devices , which convert the kinetic energy ( momentum ) of the vehicle into thermal ( heat ) . When stepping on the brakes , the driver commands a stopping force ten times as powerful as the force that puts the car in motion . The braking system can exert thousands of pounds of pressure on each of the four brakes .

The brake system is composed of the following basic components : the master cylinder?± which is located under the hood , and is directly connected to the brake pedal , converts driver foots mechanical pressure into hydraulic pressure . Steel brake lines?±and flexible brake hoses?connect the master cylinder to the slave cylinders?±located at each wheel . Brake fluid , specially designed to work in extreme condition , fills the system . Shoes and Pads are pushed by the salve cylinders to contact the drum and rotors thus causing drag , which ( hopefully ) slows the car .

The typical brake system consists of disk brakes in front and either disk or drum brakes in the rear connected by a system of tubes and hoses that link the brake at each wheel to the master cylinder .

Stepping on the brake pedal , a plunger is actually been pushing against in the master cylinder which forces hydraulic oil ( brake fluid ) through a series of tubes and hoses to the braking unit at each wheel . Since hydraulic fluid ( or any fluid for that matter ) cannot be compressed , pushing fluid through a pipe is just like pushing a steel bar through pipe . Unlike a steel bar , however , fluid can be directed through many twists and turns on its way to its destination , arriving with the exact same motion and pressure that

it started with . It is very important that the fluid is pure liquid and that there are no air bubbles in it . Air can compress , which causes a sponginess to the pedal and severely reduced braking efficiency . If air is suspected , then the system must be bled to remove the air . There are bleeder screws at each wheel and caliper for this purpose .

On a disk brakes , the fluid from the master cylinder is forced into a caliper where it pressure against a piston . The piton , in-turn , squeezes two brake pads against the disk ( rotor ) which is attached to the wheel , forcing it to slow down or stop . This process is similar to the wheel ,causing the wheel to stop . In either case , the friction surface of the pads on a disk brake system , on the shoes on a drum brake convert the forward motion of the vehicle into heat . Heat is what causes the friction surfaces ( lining ) of the pads and shoes to eventually wear out and require replacement .

Brake fluid is a special oil that has specifics properties . It is designed to withstand cold temperatures without thickening as well as very high temperatures without boiling . ( If the brake fluid should boil , it will cause you to have a spongy pedal and the car will be hard to stop ) .

The brake fluid reservoir is on top of the master cylinder . Most cars today have a transparent reservoir so that you can see the level without opening the cover . The brake fluid lever will drop slightly as the brake pads wear . This is a normal condition and no cause for concern . If the lever drops noticeably over a short period of time or goes down to about two thirds full , have your brakes checked as soon as possible . Keep the reservoir covered expect for the amount of time you need to fill it and never leave a can of brake fluid uncovered . Brake fluid must maintain a very high boiling point . Exposure to air will cause the fluid to absorb moisture which will lower that boiling point .

The brake fluid travels from the master cylinder to the wheels through a series of steel tubes and reinforced rubber hoses . Rubber hoses are only used in places that require flexibility , such as at the front wheels , which move up and down as well as steer . The rest of the system uses non-

corrosive seamless steel tubing with special fittings at attachment points . If a steel line requires a repair , the best procedure is to replace the complete line . If this is nit practical , a line can be repaired using special splice fittings that are made for brake system repair . You must never use brass compression?±fittings or copper tubing repair a brake system . They are dangerous and illegal .

5 Basic Parts of Steering System

The steering converts the steering ¨Cwheel rotary motion into a turn motion of the steered wheels of the vehicle .

The basic steering system in most cars is the same . The steering gear of steering box is the heart of the steering system .This is usually next to the engine . A shaft extends from the back of the steering gear . This shaft is connected to the steering column or steering shaft . The steering wheel is at the top of the steering column . Another shaft comes from the bottom of the steering gear . This shaft connects to the arms , rods , and links . This parts assembly , called the steering linkage , connects the steering gear to the parts at the wheels . The wheels and tires mount to the steering knuckles , As shown in fig , the knuckles are pivoted at the top and bottom . Thus , the wheels and rites can turn from side top side .

While the steering system may look complicated , it works quite simply . When a driver drives a car straight down the road , the steering gear is centered . The gear holds the linkage centered so that the wheels and tires point straight ahead . When the driver turns the steering wheel , the steering shaft rotates and the steering gear moves toward that side . The shaft coming out the bottom of the steering gear turns , as well . When the shaft turns , it pulls the linkage to one side and makes the steering knuckles turn slightly about their pivot points . Thus , the steering knuckle , spindle , wheels , and tires turn to one side , causing the car to turn .

The type of steering layout depends on the suspension system . The beam axle used on heavy commercial vehicle has a king pin fitted at each end of the axle and this pin is the pivot which allows the wheels to be steered . Cars

have independent suspension and this system has ball joints to allow for wheel movement .

6 Front Suspension

The front suspension is more complicated than the rear suspension . This is because the front wheels must move in several different directions . The wheels must move up and down with the suspension and turn left to right with the steering . Since the car goes in the direction in which the front wheels point , the alignment of the front wheels is important . The wheels must point in just the right direction for the car to move strai ght down the road and turn properly .

Modern cars uses an independent front suspension . In this system , each wheel mounts separately to the frame and has its own individual spring and shock absorber . Thus , the wheels act independently of one another . When one wheel hits a bump or hole in the road , the other wheel dose no9t deflect .

7 Wheels and Tires

To maintain grip when a vehicle is traveling at speed over a bumpy surface , a wheel must be light in weight . Also it must be strong , cheap to produce , easy to clan and simple to remove .

译文：

底盘

1 离合器

发动机产生动力来驱动车辆。传动链或传动系将发动机的动力传递给

车轮。传动部件包括飞轮后部到车轮的部分。这部分包括离合器，变速器，传动轴和后桥总成。

离合器包括飞轮，离合器盖，压盘，弹簧，压盘盖和必要的离合器操纵机构；离合器事发动机和传动装置之间的一种旋转机构。它通过各部件的摩擦起作用。这就是为什么将离合器称之为摩擦机制。安装后，离合器通过摩擦

不打滑将发动机的全部扭矩传递给变速器。当换挡时离合器也被用于切断传动系与发动机之间的动力。

为了撤销发动机的传输动力，司机不得不踩下离合器踏板来发动引擎或换挡。这时，连接变速箱输入轴的从动件是固定的或者以比连接发动机曲轴从动件较慢的速度旋转。离合器总成零件无弹性压力，所以驱动件与被驱动件之间没有摩擦传动。当司机松开离合器制动踏板时，弹性压力增加，各部件之间摩擦也有所增加。驾驶员通过离合器踏板和连接机制来控制被驱动件上弹性元件产生的压力。主动元件与从动元件机密结合就有可能在元件表面产生摩擦力。当全部弹簧压力作用时，主动元件与从动元件其速度是相同的。此时，离合器在无打滑情况下，作为连接装置将所有引擎动力传递给变速器。然而，发动机在刚刚启动时产生的动力较小，为了减少汽车传动系扭冲击力，变速器与引擎应缓慢接触。否则，若主动件与从动件迅速结合，引擎就会停滞不前。

飞轮是离合器的主要部件之一，安装在发动机曲轴上，将发动机扭矩传给离合器盘。飞轮与离合器盖，压盘相连接，就会产生或阻断传递给变速器的引擎动力。

飞轮同样是离合器总成部件所在位置。离合器工作时，飞轮将发动机扭矩传给离合器盘。其重量有助于发动机平稳运转。同样曲柄发动引擎过程中，飞轮外部边缘一较大的齿轮与发动机的固定档相连接。

飞轮安装在离合器盘和压力板之间。其花键套管枢纽，易于输入轴花键的传输。带有凹槽的毂枢纽与轴上的花键相匹配，且这些花键嵌于凹槽中。这样两部分就能联系在一起。然而轴上离合器盘的前后运动很可能依附于输入轴，以轴速旋转。

汽车离合器压盘通常是由铁铸造而成，圆形外观，其直径大约与离合器盘相同。压力板一侧加工平滑，将正对飞轮的离合器盘面压平。外侧形状方便连线弹簧释放机制的附件装置。两种主要类型的压盘总成包括螺旋弹簧和膜片弹簧总成。

螺旋弹簧离合器压盘由许多螺旋弹簧支撑，一起被安置于用螺栓固定在飞轮上的一压缩钢盖上，而弹簧反推离合器。离合器从动盘和压盘都非严格地连接在飞轮上。但都朝飞轮方向移动或远离。踩下离合器踏板就会使驱动器朝飞轮方向移动。转动杠杆使之一端与驱动器相连，挤压弹簧使另一端

与压盘背面相连，这样就可以释放从动盘的压力，切断发动机上的变速器。膜片弹簧压盘总成广泛应用于现代车辆。膜片弹簧是一单一薄金属片，受压变形，撤除压力，膜片弹簧恢复到原来状态。膜片弹簧中间的部分成若干手指状，并以此为释放杠杆。当离合器总成随发动机旋转时，离心盘向外掷出这些重量，致使杠杆挤压压盘。离合器脱离过程中，释放轴承促使这些手指向前移动，支点环及其外围的弹簧枢纽离开飞轮。撤回的弹簧将压盘拉离离合器盘，从而脱离离合器。

当膜片弹簧的释放轴承及分离指一起向传动装置移动时，枢纽环上的隔膜枢纽的外围力量挤压离合器压盘使之与离合器盘相连。

隔膜式压盘总成的优越性在于，紧凑性，低重量，运动部件少，连接少，通过压盘周围提供的一平衡力和减少离合器打滑可能性来减少旋转不平衡性。

电缆，或者更为普遍的液压系统，将离合器踏板与撤离机制连接起来。无论哪种方式，推动踏板使撤离机制得以运行。这种机制经由释放轴承施压于离合器隔膜手指，从而使隔膜释放离合器盘。在液压机制下，离合器踏板臂操作离合器主缸的一活塞，迫使液压流体通过管道到达释放钢瓶，此时电缆通过另一活塞来操作离合器撤离机制。

其他部分包括离合器叉，轴承，铃声，住房安置盖，飞行套管等，都需要安装传动装置。离合器叉直达联动，用来操作离合器。释放轴承安装在离合器叉和压盘总成之间。贝尔涵盖固定在其底部。这种可拆卸盖使得技师检查离合器时，不用取消传输和贝尔涵盖装置。飞行套管安装在曲柄后面，控制输入轴的传输。

2 自动变速器

迄今为止，自动变速器是现代汽车最复杂的机械部件。它是自我转换的变速器。流体耦合和液力变矩器代替手工操作离合器，将变速器与发动机相连。

在后轮驱动和前轮驱动的基础上，自动变速器有两种基本类型。对于后轮驱动汽车来说，变速器通常安装在引擎的后面，位于油门踏板旁边汽车底板中心敦下方。驱动轴将变速器连接到最终驱动——位于后轴向后轮传递动力。该系统简单直流功率，从引擎通过液力变矩器，然后透过变速器和驱动轴直到最终驱动，至此分流并输送到后面的两个变速器。对于前轮驱动汽车而言，变速器通常与最终驱动相结合，形成所谓的转动轴。前轮驱动汽车的发

动机通常安装在车侧，隐于正对汽车尾部引擎一侧，前轴直接与转动轴相连，为前轮提供动力。在此例子中，功率流自发动机流出，通过变矩器到达一较大链系，经过180度流转传递给变速器（发动机旁边）, 通过变速器至最终驱动，至此分流输送到两个前轮驱动轴。

还有很多其它装置，包括前驱动车辆，这里引擎从前到后安装而不是安装在侧面。还有其他系统驱动所有的四个轮子，而这儿描述的两个系统是目前为止最受欢迎的。许多不太普遍的后方系统，是由一个驱动轴连接到仍然是安装在发动机上的变矩器。新的科威特轿车使用了这一系统。在前轮和后轮之间用来均匀地平衡重量，改善性能和运转。另一后方驱动系统在其后面安装一切装置，诸如发动机，变速器，最终驱动。这种后方引擎装置在保时捷中比较流行。

现代的自动变速器包括许多部件和系统，设计用来与行星齿轮组，液压系统，密封垫，变矩器，总揽，调制器或节流电缆和计算机控制系统形成的交响乐一起演绎。多年来，计算机控制系统已演变成机械师（更倾向于个人）所认为的一门艺术形式。这儿尝试尽可能使用简单的解释来描述这些系统。

3 差速系统

车辆转弯时，内部车轮比外部车轮移动距离较短，这就意味着内轮需减速，外轮需加速。这段时间内，每个驱动用来维持各自的驾驶都是合乎情理的。微分系统执行此两项任务。如果将此元件视为由一杠杆，两盘组成，就可以明白这种斜角式微分原理。

汽车径直向前运行时，杠杆均匀平分俯冲力，两盘跳至相同数目。汽车转弯时，驱动力同样平分，但内盘跳动会小一些，致使杠杆围绕其枢纽旋转，使得外盘运动更为剧烈。这一活动表明，作用于每个驱动轮的扭矩都是相等的。因此，微分系统也被称为力矩平衡。

4 制动系统

汽车系统中最重要的就是刹车系统。刹车失败会带来灾难性的后果。制动器其实是一种能量转换装置，将汽车动能转换成热能。司机刹车时产生的制动力是汽车运行时动力的10倍。制动系统施加数千英镑的压力作用于四个制动器。

刹车系统的基本组成部分，主缸，位于引擎盖下直接与刹车踏板相

连，将机械压转换成液压。钢制刹车线和灵活性制动软管将主缸与每个轮子上的汽缸连接起来。专门设计用来在极端条件下工作的制动流充满整个系统。在汽缸推动下，软垫与转子接触产生阻力，这样就有可能使车辆减速。

典型的制动系统由前面的磁盘制动器和后面的磁盘或鼓式制动器组成。每个轮子上与制动器相连的软管系统将后者连接到主缸上。

实际上，踩刹车踏板时，柱塞推挤主缸，液压油（制动液）通过一系列的管子和软管流至每个轮子的刹车元件。因为液压流体不可压缩，推动流体通过管道，就像推钢棒穿过管道一样。然而，液体可以直接通过许多曲折弯道，以与开始时同样的状态和压力直达目的地。液体纯度且内无气泡是非常重要的。压缩空气，造成严重的踏板松弛，严重降低刹车效率。如果气体是可以凝固的，系统通过释放排出其中空气。这就是每个轮子上都有螺丝钳和卡尺的目的所在。

在磁盘制动器上，主缸流体被压进一卡尺内挤压活塞。岩钉向内旋转挤压轮上依附的刹车垫，使之减慢或停下来。这个过程类似于车轮，使车轮停下来。在任一情况下，磁盘制动器或者鼓式器表面摩擦力转换成车辆向前运动的热能。热能致使摩擦力最终耗尽，从而需要新的能量代替。

制动液是一种特殊的油，具有特殊性质。用来抵御寒冷和高温。制动液煮至沸腾会造成海绵踏板情况，车就很难停下来。

制动液库在汽缸顶部。如今大多数汽车都有一透明水库，不用开盖就可以看到里面的情况。当制动垫磨损时，刹车油杆有所下降，这是一正常情况，无需担心。在很短一段时间内，如果手柄明显下降或降至到三分之二时，尽早检查刹车。时刻保持水库密封，千万不要使制动液与空气接触，除了有时需打开盖子将其加满。制动液必须维持一个非常高的沸点，接触空气液体吸收水分，沸点降低。

通过一系列的钢管和强化橡胶软管，制动液从主缸流至车轮。胶管仅仅用在那些灵活运转的地方，如前轮，方向盘的上下移动。其余系统连接处采用无腐蚀性的无缝钢管。如果需要修补钢线，最好是代替完整的钢线。如果务实的话，修复钢线时采用制动系统维修特制的接头配件，千万不能用黄铜压缩配件或铜管修复刹车系统，这是危险，非法的。

5 转向系统的基本组成

方向盘将车轮转动方向转变为车辆行驶方向。大多数汽车的基本转向

系统是相同的。舵机转向档是转向系统的核心，通常紧挨着引擎。转向档延伸出的轴与转向轴柄相连。方向盘轴在方向盘顶部，转向档下部另一轴与臂杆相连。这些被称为转向连接零件总成将转向档与车轮连接起来。车轮和轮胎安装在转向节上，如图所示，转向节在顶部和底部转动。因此，车轮和仪式可以从一边朝上向另一边旋转。

转向系统看起来可能很复杂，其实很简单。当司机开车沿着马路行驶时，舵机集中，转向档与控制中心连接，车轮和轮胎点向前直行。当司机转动方向盘，方向盘轴旋转而舵机向另一边移动，转向器底轴同样转动。朝一边拉起连接使转向节绕其支点旋转。因此，转向节、主轴、车轮和轮胎转到一边，使车子转弯。

这个类型的转向布局取决于悬架。重型商用车使用的梁轴，其两端轴都安有主连接，这种连接点使得车轮转变方向。汽车独立悬架系统存在的球接头，允许车轮的运动。

6 前悬架

前悬架比后悬架更为复杂。这是因为前轮必须朝几个不同的方向运动。悬架作用下，车轮上下移动，方向盘从左侧转至右侧。此外，前轮的直线排列相当重要，因为汽车行驶方向取决于前轮转动方向。，因此前轮必须朝着正确的方向移动，从而使汽车沿着马路向前行驶。

现代汽车使用独立的前悬架。在该系统中，每个轮子单独安置于框架上并各自拥有弹簧和减震器。这样彼此独立运作，当在路上一个车轮爆胎时，其他轮子不会偏转。

7 车轮和轮胎

汽车以一定速度在凸凹不平地面上行驶时，为了紧挨地面，车轮需轻而结实，低成本，高产出，便于寻找，易于换胎。