1、Unit Four Drive Train Passage BOther Main Components of a Drive Train In addition to transmission,the drive train also includes other main components such as clutch,only used in MT cars;torque converter,only used in AT cars;differential system;drive shaft and transfer case Clutch Assembly Clutch is
2、used to engage with the engine to transmit the power to the transmission,or disengage with the engine in order to shift gears It is located between the engine and the transmission Basically,clutch assembly consists of following main parts:flywheel,clutch disk,pressure plate assembly,release bearing,
3、release fork,clutch pedal and linkage as shown in Fig.4-7 Flywheel is a drive plate bolted to the crankshaft Its functionas a drive plate is to transfer the engine torque from the engine to the transmission Clutch disk is a driven plate covered with a frictional material that moves between the flywh
4、eel and the pressure plate Pressure plate assembly bolted to the flywheel includes a metal cover,a diaphragm spring and a metal pressure ring,which provides a friction surface for the clutch disk(see Fig.4-8).Release bearing is the heart of clutch operation It activates the release fingers of the di
5、aphragm spring that moves the pressure ring back and forth to make the clutch disk engage or disengage with the flywheel Release fork is used to transfer the force from the pedal to the release bearing Clutch pedal is located on the flooron your left When you step the clutch pedal,the clutch disconn
6、ects the engine from the transmission to allow the car to change gears The clutch linkage is divided into a mechanical linkage such as a cable and a hydraulic linkage such as clutch master cylinder,reservoir and hydraulic line and slave cylinder Torque Converter AT cars use a torque converter instea
7、d of the clutch used on MT cars The torque converter is mounted between the engine and the transmission and turns as the same speed as the engine A torque converter has three main parts:impeller,turbine and stator that work together to transmit power from the engine to the transmission(see Fig.4-9)I
8、t uses hydraulic pressure to control the amount of engine power transmitted to the transmission input shaft Differential System The functions of differential system are to send power to two drive wheels and to help the car change moving direction while the car is going around the corner On a front-w
9、heel-drive car,the differential and the transmission combine together within one housing,called“transaxle”On a rear-wheel-drive car or on a four-wheel-drive(4WD)car,the differential is connected to the drive shaft(see Fig.4-10).Generally,the differential mainly consists of two side gears,two planet
10、gears and a ring gear They are all housed in one differential case The side gears are connected to the two half shafts;the planet gears are connected to the ring gear The ring gear is also called output driven gear which constantly meshes with the input drive gear on the end of the drive shaft We of
11、ten call them final drive(see Fig.4-11).When the car is going straight ahead,the both side gears rotate at the same rate So do the right and left wheels When the car is going around the corner,the two side gears rotate at different rate This means that the inner wheel must slow down,and the out whee
12、l must speed up Drive shaft and Transfer Case On a rear-wheel-drive car,a drive shaft is used to transmit the power from the transmission to the differential between the two rear drive wheels(see Fig.4-12).Many 4WD cars use two drive shafts,with one drive shaft between the transfer case and rear dri
13、ve axle and the other one between the transfer case and front drive axle(see Fig.4-13).The transfer case is only used to control the power to the front and rear drive axles Four-Wheel-Drive(4WD)and All-Wheel-Drive(AWD)Vehicles 4WD and AWD are often found on off-road vehicles such as SUV 4WD is divid
14、ed into two types:part time drive and real time drive The former is switched from two-wheel drive to four-wheel drive manually with a button The latter is automatically switched from two-wheel drive to four-wheel drive according to the road conditions AWD is full time drive,that is,4 wheels offer dr
15、iving force all the timeNew Words and Expressions assembly sembli n 总成;装配 frictional friknl adj 摩擦的 linkage likid n 联动装置 activate ktiveit vt 使活动 disconnect disknekt vt 断开 cable keibl n 拉线 combine kmbain vt 结合 hydraulic line液压管路 axle ksl n 车轴Common Automobile Terms clutch klt n 离合器 differential difre
16、nl n 差速器 torque converter液力变矩器 drive shaft传动轴 transfer case分动器 clutch disk从动盘 pressure plate压盘 release bearing分离轴承 release fork分离叉 diaphragm spring膜片弹簧 pressure ring压环 clutch master cylinder离合器主缸Common Automobile Terms slave cylinder从动缸 impeller impel n 泵轮 turbine tbain n 涡轮 stator steit n 导轮 transaxle trnsksl n变速驱动桥;变速差速器 side gear侧齿轮,半轴齿轮 final drive主减速器 rear drive axle后驱动桥 front drive axle前驱动桥 part time drive分时驱动 real time drive适时驱动 full time drive全时驱动
