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1、Unit 7 Suspension System,Part I Technical and Practical Reading,Passage A Suspension Components,The components of the suspension system perform six basic functions: 1. Maintain correct vehicle ride height 2. Reduce the effect of shock forces 3. Maintain correct wheel alignment 4. Support vehicle wei
2、ght 5. Keep the tires in contact with the road 6. Control the vehicles direction of travel,So all the suspension components must be in good working condition. There are three fundamental components of any suspension: springs, shock absorber and anti-sway bar. See figure 7-1.,Figure 7-1,Springs,The s
3、prings are a very important component of the suspension system that provides ride comfort. The springs support the weight of the car, maintain ride height, and absorb road shock. Springs are the compressible link between the frame and the body. When the car meets a bump in the road, the springs will
4、 absorb the load by compressing. There are four major spring designs in use today: coil spring, leaf spring, torsion bar, and air spring.,Coil Spring,This is the most common type of spring. The coil spring is a length of round spring steel rod that is wound into a coil. Coil springs compress and exp
5、and to absorb the motion of the wheels. It requires no adjustment and for the most part is trouble-free. See figure 7-2.,Figure 7-2,Leaf Spring,This type of spring consists of several layers of steel plates (called “leaves”)of different lengths stacked together to act as a single unit. The leaf spri
6、ngs bend and slide on each other allowing suspension movement. They are still used today on most trucks and heavy-duty vehicles. See figure 7-3.,Figure 7-3,Torsion Bar,The torsion bar is a straight or L shaped bar of spring steel. One end of a bar is anchored to the vehicle frame. The other end is a
7、ttached to a wishbone. When the wheel hits a bump, vertical motion is transferred to the wishbone and then, through the levering action, to the torsion bar providing spring action. See figure 7-4.,Figure 7-4,Air Spring,The air spring is another type of spring that is becoming more popular on passeng
8、er cars. The air spring is a rubber cylinder filled with compressed air. A piston attached to the lower control arm moves up and down with the lower control arm. This causes the compressed air to provide spring action. See figure 7-5.,Figure 7-5,Shock Absorber,Shock absorber is a device that control
9、s unwanted spring motion, which is important in keeping the tires in firm contact with the road. Shock absorbers control spring movements in both directions: when the spring is compressed and when it is extended. Without shock absorber, the spring will extend and release the energy which may allow t
10、he tires to lose contact with the road.,A shock absorber is basically an oil pump placed between the frame of the car and the wheels. The upper mount of the shock absorber connects to the frame, while the lower mount connects to the axle, near the wheel. See figure 7-6.,Figure 7-6,When the car wheel
11、 meets a bump in the road and causes the spring to coil and uncoil, the energy of the spring is transferred to the shock absorber through the upper mount, down through the piston rod and into the piston.,Orifices perforate the piston and allow fluid to leak through as the piston moves up and down in
12、 the pressure tube. Because the orifices are relatively tiny, only a small amount of fluid, under great pressure, passes through. This slows down the piston, which in turn slows down the spring.,Anti-sway Bar,Another important component of a suspension system is the anti-sway bar. This device is use
13、d along with shock absorbers to give a moving car additional stability. The anti-sway bar is simply a metal rod connected to both of the lower control arms. See figure 7-7.,Figure 7-7,When the suspension at one wheel moves up and down the anti-sway bar transfers the movement to the other wheel. This
14、 creates a more level ride and reduces vehicle sway. In particular, it combats the roll of a car on its suspension as it corners. For this reason, almost all cars today are fitted with anti-sway bars as standard equipment, although if theyre not, kits make it easy to install the bars at any time.,Ne
15、w Words,alignment lainmnt n. 调整（成直线） tire tai n. 轮胎 fundamental 7fndmentl a. 基本的，根本的 shock k n. 震动，冲击 compressible kmpresbl a. 可压缩的 link lik n. 联结，构件，链接 frame freim n. 框，结构，车架 bump bmp n. 撞击，隆起物，颠簸而行碰撞 load lud n. 负荷, 载荷，装载量 expand ikspnd v. 使膨胀，扩张 adjustment stmnt n. 调整 trouble-free 5trblfri: 无故障的（
16、不发生事故的）,layer lei n. 层 plate pleit n. 金属板，板材 stack stk v. 堆积，堆叠 bend bend v. 弯曲 anchor k v. 停泊，抛锚，固定 wishbone wibun n. 叉骨，叉形杆，叉形臂，叉形悬臂 extend ikstend v. 扩充，延伸，伸展 bounce bauns n. 跳，反跃，弹力 v. 弹跳，使跳,orifice rifis n. 孔口，节流孔 perforate p:freit v. 穿孔，凿孔，打孔 stability stbiliti n. 稳定性，安定性，稳定度 combat kmbt v. 奋斗 sway swei n. 摇，摇摆 kit kit n. 装备，工具箱,Phrases and Expressions,suspension system 悬
