1、Unit SixSuspension System and Steering System Passage ASuspension SystemThe main functions of a car suspension system are to increase the friction between the tires and the road surface, to provide steering stability with good handling and to ensure the comfort of the passengersBasic components of s

2、uspension Most suspension systems have the same basic components: spring, shock absorber and anti-sway bar But they are different in type and arrangement to connect them to the frame and wheelSpringsThere are four major types of spring in use today: coil spring, air spring, leaf spring and torsion b

3、ar as shown in Fig.6-1aCoil springs are the most common type of spring used on almost all cars This type of spring is made up of a round steel rod which is wound into a shape of coil Coil springs can compress and expand to absorb the motion of the wheelsAir springs are often found on luxury cars It

4、is a rubber cylinder filled with compressed air This type of spring uses the compressed air to absorb the wheel vibrationsLeaf springs are used today on most trucks and heavy-duty vehicles This type of spring consists of several layers of metal plates of varying lengths bound together to act as a si

5、ngle unit Leaf springs can provide good stability and excellent suspension for the tow vehiclesTorsion bars are used on some light trucks and spot utility vechicles (SUV) It is a straight bar of spring steel Torsion bars use the twisting properties of a steel bar to provide spring performanceShock a

6、bsorberThe function of shock absorber is to control the movements of spring and suspension, that is, to prevent the springs from bouncing to keep the tires firmly contacting the road surface A shock absorber is basically an oil pump placed between the frame of the car and the wheels (see Fig.6-2). T

7、he faster the suspension moves, the more resistance the shock absorber providesAnti-sway barAnti-sway bar also called stabilizer bar that will help stabilize the car and reduce its side-to-side motion when it is cornering It is simply a metal rod connected to both of the lower control arms (see Fig.

8、6-3).Common types of suspensionThe modern cars use different types of suspension in front and rear axles The two front wheels are connected by the front axle and the two rear wheels are connected by the rear axle, and they must work together in perfect harmonyMacPherson strut suspensionMacPherson st

9、rut suspension is the most widely used in front independent suspension, especially for front-wheel drive cars (see Fig.6-4) It combines a shock absorber and a coil spring into a single unit The advantages of this type suspension are more compact in structure and lighter in weightDouble wishbones sus

10、pensionDouble wishbones suspension also known as an A-arm suspension (see Fig.6-5), which is another common front independent suspension It uses a shorter upper control arm and a longer lower control arm that hold the wheel to the frame The advantages of this type suspension are always to keep the w

11、heel moving up and down perpendicularly to the road surface and to ensure good handlingMulti-link suspensionMulti-link suspension is often found in rear independent suspension As the name suggests, multi-link suspension has more than 4 control arms and forms different geometries(see Fig.6-6). The ad

12、vantages of this type suspension are to offer not only the pleasant comfort but also good handling, especially for off-road driving Torsion beam suspensionTorsion beam suspension in fact is only a half-independent rear suspension often used on less expensive cars Two trailing arms are connected by m

13、eans of a cross torsion beam, which also serves as an anti-sway bar (see Fig.6-7). The advantages of this type suspension are very space-saving for it engages little width of the car so as to enlarge rear seat room, and cheap in cost New Words and Expressionssway swei n 搖擺torsion tn n 扭轉, 扭曲; 轉矩twis

14、ting twisti n 扭轉bounce bauns n 跳; 彈力stabilizer steibilaiz n 穩定器; 安定裝置strut strt n 支柱perpendicularly p: pndikjulli adv 垂直地; 直立地geometry dimtri n 幾何學; 幾何圖形beam bim n 橫梁Common Automobile Termsservice brake行車制動器parking brake駐車制動器foot brake腳踏制動器, 腳剎hand brake駐車制動器, 手剎disk brake盤式制動器drum brake鼓式制動器brake pad制動襯塊friction lining摩擦片, 摩擦襯片brake caliper制動鉗brake fluid制動液floating caliper浮動制動鉗, 浮鉗Common Automobile Termssuspension sspenn n 懸架anti-sw