1、 附录一 外文翻译 A Short Course on a part of Automatic Transmissions The automatic transmission gearbox, as an important part in automobile driving system is used to make up the shortcoming of engine torque and rotary speed. It can change the vehicle speed and tyre torque in a big scope, cut off the power
2、transfer from the engine, and also provides a reverse traveling direction for the vehicle. Therefore, the reasonability of the structure design of a transmission gearbox directly affects the vehicles dynamic performance. It is usually required shifting gears rapidly and conveniently, saving force, a
3、nd having a higher working efficiency and low working noises. The modern automatic transmission is by far, the most complicated mechanical component in todays automobile. Manual transmissions contain mechanical systems, hydraulic systems, electrical systems and computer controls, all working togethe
4、r in perfect harmony which goes virtually unnoticed until there is a problem. This article will help you understand the concepts behind what goes on inside these technological marvels and what goes into repairing them when they fail. Transmission The transmission is a device that is connected to the
5、 back of the engine and sends the power from the engine to the drive wheels. An automobile engine runs at its best at a certain RPM (Revolutions Per Minute) range and it is the transmissions job to make sure that the power is delivered to the wheels while keeping the engine within that range. It doe
6、s this through various gear combinations. In first gear, the engine turns much faster in relation to the drive wheels, while in high gear the engine is loafing even though the car may be going in excess of 70 MPH. In addition to the various forward gears, a transmission also has a neutral position w
7、hich disconnects the engine from the drive wheels, and reverse； which causes the drive wheels to turn in the opposite direction allowing you to back up. Finally, there is the Park position. In this position, a latch mechanism (not unlike a deadbolt lock on a door) is inserted into a slot in the outp
8、ut shaft to lock the drive wheels and keep them from turning, thereby preventing the vehicle from rolling. There are two basic types of automatic transmissions 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
9、 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 rear of 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 simp
10、le and straight forward going from the engine, through the torque converter, then through the transmission and drive shaft until it reaches the final drive where it is split and sent to the two rear wheels. On a front wheel drive car, the transmission is usually combined with the final drive to form
11、 what is called a transaxle. The engine on a front wheel drive car is usually mounted sideways in the car with the transaxle tucked 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 the front wheels. In this exampl
12、e, power flows from the engine, through the torque converter to a large 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 tothe two front wheel
13、s 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
14、rear drive arrangement has the transmission mounted directly to the final drive at the 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
15、 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. Transmission Components The modern automatic transmission consists of many components and sys
16、tems that are designed to work together in a symphony of clever mechanical, hydraulic and electrical technology that has evolved over the years into what many mechanically inclined individuals consider to be an art form. The cyeloid drive The cyeloid drive has the essential advnatages sueh as Wide r
17、nage of tranmsission ratio， eompact surtcture， high relibaility nad long wokrnig lief， So It gets borad application and its rsearch goes deep eonstnatly. The drive has been not only applied to traditionalt rnasmissionfield but also has alluring applieation in the aspeets of micro machine， robot gear
18、 ,preeision machine taansmission， super mini cycloid drive，asrtonaut cquipment， measurment apparatus， tenement intelligence and high-tech equipment. In the family of the cycloid drive， the AFcycloid 一 pin wheel plnaetary driver educer is a new .Trnasmission device.Compared with the common cycloid dr
19、ive， it has a series of advantages such as small volume， lihgtweight， wide range of tranmsission， diversity transmission， long lief time， high rigidiyt， high slewing precision， stbale preeision， high effieiency and stable transmission.The design of the drive daopts a lot of advnaced theories and tec
20、hnology methoods and uses a kind of innovation stureurte， so the FA drive has overcome the defect of the traditional surtcture， enhnaccd the transmissin efficency， volume,and the transmission precision. Automatic transmissions contain many gears in various combinations. In a manual transmission, gea
21、rs slide along shafts as you move the shift lever from one position to another, engaging various sized gears as required in order to provide the correct gear ratio. In an automatic transmission, however, the gears are never physically moved and are always engaged to the same gears. This is accomplis
22、hed through the use of planetary gear sets. One example of a way that this system can be used is by connecting the ring gear to the input shaft coming from the engine, connecting the planet carrier to the output shaft, and locking the sun gear so that it cant move. In this scenario, when we turn the
23、 ring gear, the planets will walk along the sun gear (which is held stationary) causing the planet carrier to mm the output shaft in the same direction as the input shaft but at a slower speed causing gear reduction (similar to a car in first gear). If we unlock the sun gear and lock any two element
24、s together, this will cause all three elements to turn at the same speed so that the output shaft will mm at the same rate of speed as the input shaft. This is like a car that is in third or high gear. Another way that we can use a Planetary gear set is by locking the planet carrier from moving, then applying power to the ring gear which will cause the sun gear to turn in the opposite direction giving us reverse gear.
