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1、复习,翻译句子 英文专业词汇 发动机分类，发动机零件/系统; 汽车分类，汽车组成_,学习内容,本次课学习内容、目标和重点难点,学习目标,难点重点,Clutch，Manuel Transmission Propeller Shafts and Universal Joints 3. Final Drive, Differential and Axle Shaft,1.掌握手动变速汽车传动系统主要组成、各部件主要零件的英文名称 2.提高翻译技巧，能较熟练翻译课文,1.重点是英文专业术语记忆 2.难点是生词偏多,Chapter 3 Power Train 3.1 Clutches,3.1.1 New
2、 Words and Phrases,Chapter 3 Power Train 3.1 Clutches,The clutch which includes the flywheel, clutch disc, pressure plate, springs, pressure plate cover and the linkage necessary to operate the clutch is a rotating mechanism between the engine and the transmission. It operates through friction which
3、 comes from contact between the parts. That is the reason why the clutch is called a friction mechanism. After engagement, the clutch must continue to transmit all the engine torque to the transmission depending on the friction without slippage. The clutch is also used to disengage the engine from t
4、he drive train whenever the gears in the transmission are being shifted from one gear ratio to another.,Chapter 3 Power Train 3.1 Clutches,3.1.2 Text,To start the engine or shift the gears, the driver has to depress the clutch pedal with the purpose of disengagement the transmission from the engine.
5、 At that time, the driven members connected to the transmission input shaft are either stationary or rotating at a speed that is slower or faster than the driving members connected to the engine crankshaft. There is no spring pressure on the clutch assembly parts. So there is no friction between the
6、 driving members and driven members. As the driver lets loose the clutch pedal, spring pressure increases on the clutch parts. Friction between the parts also increases.,Chapter 3 Power Train 3.1 Clutches,The pressure exerted by the springs on the driven members is controlled by the driver through t
7、he clutch pedal and linkage. The positive engagement of the driving and driven members is made possible by the friction between the surfaces of the members. When full spring pressure is applied, the speed of the driving and driven members should be the same. At the moment, the clutch must act as a s
8、olid coupling device and transmit all engine power to the transmission, without slipping.,Chapter 3 Power Train 3.1 Clutches,Fig. 3-1 Structure of a clutch,Chapter 3 Power Train 3.2 Manuel Transmission,3.1.1 New Words and Phrases,Chapter 3 Power Train 3.2 Manuel Transmission,Chapter 3 Power Train 3.
9、2 Manuel Transmission,Chapter 3 Power Train 3.2 Manuel Transmission,Chapter 3 Power Train 3.2 Manuel Transmission,The modern manual transmission can provide the driver with up to six forward gear ratios. The reduction gears provide gear ratios of approximately 3.5:1 (stated as 3.5 to 1) for the lowe
10、st gear, to about 1.5:1 for the highest. The direct drive gear has a 1:1 gear ratio. The overdrive gears have a gear ratio of about 0.7:1. By selecting one of the ratios, it is possible to operate the vehicle under all normal conditions. In addition, torque is multiplied more through the differentia
11、l gears. Ratios vary from vehicle to vehicle, depending on engine horsepower and vehicle weight. A reverse gear is also used. The reverse ratio is usually about 3:1. The five-speed transmission has an overdrive ratio. The overdrive ratio is incorporated into newer transmissions to increase fuel mile
12、age and lower emissions.,Chapter 3 Power Train 3.2 Manuel Transmission,1.Transmission Gear Ratios,3.2.1 Text,A typical transmission consists of a case, four shafts, bearings, gears, synchronizers, and a shifting mechanism. 1）Transmission Case The transmission case holds the transmission gears, shaft
13、s, bearings, and washers. It bolts to the rear of the engine, or to the clutch housing. Many transmission cases and clutch housings are one-piece units. Most transmission cases are made of cast iron or aluminum and have a separate extension housing, which supports the output shaft. This housing may
14、also contain the speedometer gear. The rear engine mount is usually attached to the extension housing.,Chapter 3 Power Train 3.2 Manuel Transmission,2. Transmission Construction,2）Transmission Gear Transmission gears are made of high quality steel, carefully heat-treated to produce smooth, hard surf
15、ace gear teeth with a softer, but very tough interior. They are drop-forged (machine hammered into shape) while red hot. The teeth and other critical areas are cut on precision machinery. The teeth on transmission gears are cut into spur and helical patterns. The helical gear is superior in that it
16、runs more quietly and is stronger because more tooth area is in contact. Helical gears must be mounted firmly, since there is a tendency for them to slide apart due to the spiral shape. Gear end play in the cluster gear and some other gears and shafts is controlled by the use of bronze and steel thrust washers. These washers are installed on the end of the gear shafts between the moving gears and the stationary transmission case.,Chapter 3 Power Train 3.2 Manuel Transmission,There must be som
