1、Unit SixSuspension System and Steering System Passage ASuspension System The 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 passengers Basic components of
2、suspension 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 wheel Springs There are four major types of spring in use today:coil spring,air spring,leaf spring and torsion bar
3、 as shown in Fig.6-1a Coil 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 wheels Air 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 vibrations Leaf 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 s
5、ingle unit Leaf springs can provide good stability and excellent suspension for the tow vehicles Torsion 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 performance Shock
6、absorber The 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).The
7、 faster the suspension moves,the more resistance the shock absorber provides Anti-sway bar Anti-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.6-
8、3).Common types of suspension The 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 harmony MacPherson strut suspension MacPherson 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 weight Double wishbones suspe
10、nsion Double 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 whee
11、l moving up and down perpendicularly to the road surface and to ensure good handling Multi-link suspension Multi-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 advan
12、tages of this type suspension are to offer not only the pleasant comfort but also good handling,especially for off-road driving Torsion beam suspension Torsion beam suspension in fact is only a half-independent rear suspension often used on less expensive cars Two trailing arms are connected by mean
13、s 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 Expressions sway swei n 摇摆 torsion tn n 扭转,扭曲;转矩 twisting t
14、wisti n 扭转 bounce bauns n 跳;弹力 stabilizer steibilaiz n 稳定器;安定装置 strut strt n 支柱 perpendicularly p:pndikjulli adv 垂直地;直立地 geometry dimtri n 几何学;几何图形 beam bim n 横梁Common Automobile Terms service brake行车制动器 parking brake驻车制动器 foot brake脚踏制动器,脚刹 hand brake驻车制动器,手刹 disk brake盘式制动器 drum brake鼓式制动器 brake p
15、ad制动衬块 friction lining摩擦片,摩擦衬片 brake caliper制动钳 brake fluid制动液 floating caliper浮动制动钳,浮钳Common Automobile Termssuspension sspenn n 悬架anti-sway bar横向稳定杆(器)coil spring螺旋弹簧air spring空气弹簧leaf spring钢板弹簧torsion bar扭杆弹簧shock absorber减振器MacPherson strut suspension麦弗逊滑柱式悬架double wishbones suspension双叉臂悬架multi-link suspension多连杆式悬架torsion beam suspension扭力梁悬架trailing arm拖拽臂
