汽车专业英语教学大纲
一、说明
1.课程的性质和内容
本课程是高级技工学校汽车检测与维修专业的一门专业课。主要内容：汽车基本结、仪表面板活塞和动力、点火开关的位置、变速杆位置和超速档开关、检查泄露、测试与充电、发动机冷却系统、如何识读电路图、空调系统、车在计算机、电控悬架系统、防抱死制动系统、混合动力汽车、控制汽车污染等。
2.课程的任务和要排求
通过本课程的学习，使学生了解汽车专业英语的常见句型，掌握基本的汽车专业英语词汇，熟悉车辆上的各种英文铭牌和信号，熟悉汽车维修电路图的英语表达方法，培养学生具有阅读有关汽车和保修设备的常见英语技术资料的能力。
3.教学中注意的问题
（1）作为一门工具课，本课程的以教学应以对专业词汇的表达和英语文章的理解为主，培养学生的理解能力，同时注重对学生查找资料的技能培养，例如查找专业词典、查找有关附录，以培养学生获得信息的能力。
(2)在教学中，教师要尽力消除大多数技校学生对英语的恐惧心理，听过间的对话练习，把学生带入英语学习环境中，增强学生的自信心；再结合每个单元的学习内容，通过完成每个部分的练习，督促学生完成学习任务。
(3)教师应通过多种形式的教学方法来激发学生的学习兴趣，如运用汽车专业的挂图或实物，把英语的教学特点和汽车专业的直观性教学结合起来，以加强学生的专业英语理解能力，达到专业学习和英语学习共赢的目的。
二、课时分配表
三、教学要求、内容及建议
Unit 1 The Basic Components of an Automobile
单元一汽车基本结构
教学要求
1.掌握汽车主要组成部分的专业词汇，熟悉简单的专业英语句型。
2.能够对照汽车组成图，说出各部件零件的英文单词
3.通过自我介绍的口语练习，掌握常用的口语表达方式
教学内容
1.课文部分——汽车基本结构
2.对话——自我介绍
3.阅读材料——A：传动系的布置B：底盘
教学建议
1.最好引入汽车专业的挂图与实物，把英语教学和专业的直观性教学结合起来，以提高学生的专业英语理解能力。
2.重点掌握有关汽车的基本组成方面的专业词汇。
3.组织学生进行对话练习，激发学生的学习兴趣。
4.复习相关的音标，并练习拼读单词。
Unit 2 Instrument Panel
单元二仪表面板
教学要求
1.熟悉汽车仪表盘上的各种显示器、指示灯的英文单词和词组。
2.掌握各种指示灯的作用。
3.熟悉汽车灯光信号标牌的意义。
教学内容
1.课文部分——仪表面板
2.对话——我想换一辆汽车
3.阅读材料——A：灯光信号B：中国汽车标志
教学建议
1.引入汽车仪表盘的图片，组织学生进行对话练习，激发学生的学习兴趣。
2.重点掌握有关汽车的各种显示器、指示灯等方面的汽车专业英语词汇。
3.复习相关的音标，并练习拼读单词。
Unit 3 Piston and power
单元三活塞和动力
教学要求
1.了解发动机各组成部分的作用。
2.掌握发动机各组成零件的专业英语词汇。
3.熟悉发动机的基本工作原理。
教学内容
1.课文部分——活塞和动力
2.对话——这是什么类型的发动机
3.阅读材料——A：进气行程B：四冲程火花塞点火式发动机
教学建议
1.教学中，可利用包括发动机工作过程和组成部分分种图的多媒体教学课件进行辅助教学。
2.重点掌握发动机各组成部分及零件的汽车专业英语词汇。
3.复习相关的音标，并练习拼读单词。
Unit 4 The position of key in the Ignition Switch
单元四点火开关的位置
教学要求
1.了解点火开关的五个位置及作用
2.掌握点火系统组成零件的汽车专业英语词汇
3.熟悉充电系统的简图以及点火系统的基本知识
教学内容
1.课文部分——点火开关的位置
2.对话——图中这些是什么
3.阅读材料——A：点火系统B：电子点火系统
教学建议
1.利用点火系统的多媒体教学课件进行辅助教学
2.复习相关的音标，并练习拼读单词。
Unit 5 Shif Lever Position and O/D Switch
单元五变速杆位置和超速档开关
第一章汽车总论 1)Today’s average car contains more than 15,000 separate, individual parts that must work together. These parts can be grouped into four major categories: body, engine, chassis and electrical equipment 。P1 现在的车辆一般都由15000多个分散、独立且相互配合的零部件组成。这些零部件主要分为四类：车身、发动机、底盘和电气设备。 2)The engine acts as the power unit. The internal combustion engine is most common: this obtains its power by burning a liquid fuel inside the engine cylinder. There are two types of engine: gasoline (also called a spark-ignition engine) and diesel (also called a compression-ignition engine). Both engines are called heat engines; the burning fuel generates heat which causes the gas inside the cylinder to increase its pressure and supply power to rotate a shaft connected to the power train. P3 发动机作为动力设备，常见的类型是内燃机，其原理是通过发动机缸内的液体燃料燃烧而产生能量。发动机可分为两类：汽油机（点燃式）和柴油机（压燃式），都属于热力发动机。燃料燃烧产生热量使缸内气压上升，产生的能量驱动轴旋转，并传递给动力传动系。 第二章内燃机 1)Power train system: conveys the drive to the wheels 2)Steering system: controls the direction of movement 3)Suspension system: absorbs the road shocks 4)Braking system: slows down the vehicle P4 传动系把发动机输出的扭矩传递给驱动轮。传动系包括离合器（对应机械变速器）或液力变矩器（对应液力自动变速器）、变速器、驱动轴、主减速器、差速器和驱动桥。 5)Drum brakes have a drum attached to the wheel hub, and braking occurs by means of brake shoes expanding against the inside of the drum. With disc brakes, a disc attached to the wheel hub is clenched between two brake pads. P6 鼓式制动器的制动鼓和轮毂连接，制动蹄张开压紧制动鼓内侧从而产生制动。在盘式制动器上，连着轮毂的制动盘被紧紧夹在两个制动块之间。 1)Linking the piston by a connecting rod to a crankshaft causes the gas to rotate the shaft through half a turn.The power stroke"uses up"the gas,so means must be provided to expel the burnt gas and recharge the cylinder with a fresh petrol-air mixture:this control of gas movement is the duty of the valves;An inlet valve allows the mixture to enter at the right time and an exhaust valve lets out the burnt gas after the gas has done its job . P10 活塞通过连杆和曲轴连接，使得气体带动曲轴旋转半圈。作功冲程耗尽了所有的气体，这样就必须采取相应的措施排出废气并且向气缸内充入新的可燃混合气：气体的运动由气门来控制。进气门使可燃混合气在恰当的时刻进入气缸，排气门使燃烧后的废气排出气缸。 2)The spark-ignition engine is an internal-combustion engine with externally supplied in ignition,which converts the energy cntained in the fuel to kinetic energy.The cycle of operations is spread over four piston strokes. To complete the full cycle it takes two revolutions of the crankshaft. P11 火花点火式发动机是由外部提供点火的内燃机，从而将含在燃料内的能量转化成动能。发动机的一个工作循环分布在活塞的四个行程中，一个完整的工作循环曲轴需要转动两圈。 3)The oil pump in the lubricating system draws oil from the oil pan and sends it to all working parts in the engine. The oil drains off and runs down into the pan. Thus,there is constant circulation of oil between the pan and the working parts of the engine. P15
Unit 1 翻译技巧（一） 翻译概述 1.把下面的英语段落翻译成汉语。 没有哪个政治体制是完美的；但是很多美国人都会告诉你，如果他们会嫉妒 我们的一样东西的话，那就是我们英国传统的为期三周的大选，因为它的简洁就 是一种仁慈----是对选民和政治家们双方的仁慈：他们拿它跟美国四年一度的总 统选举中进行的那些耗时几个月的战争相比。 2. 把下面的汉语段落翻译成英语。 Someone has once prophesied that once cigarettes disappear from the surface of the earth, the whole world may be in chaos. This might be an exaggeration, but the danger of smoking should not be underestimated. Smoking is a curse affecting the whole globe. Let’s put foreign countries aside. China alone has hundreds of millions of smokers. Addicted smokers often say that it would be more difficult for them to endure the suffering of two hours without smoking a cigarette than a day without having meals. Smoking pollutes the air and endangers the health, consequently increasing the incidence of lung cancer greatly. Unit 2 翻译技巧(二) 直译与意译 1. 用直译法翻译下列的词语、惯用语和句子： （1）开胃酒（2）水果蛋糕（3）童装（4）人工语言（5）门铃 （6）访问学者（7）走下坡路（8）扣帽子/加标签于某人（9）随大 流（10）overtime pay （11）peanut oil （12）rice flour （13）academic journal （14）woman editor （15） evening paper （16）tear up by the roots
About car engine Of all automobile components,an automobile engie is the most complicated assembly with dominant effects on the function of an autombile.So, the engine is generally called the"heat"of an automobile. 在汽车的所有部件中，汽车发动机是最复杂的组件，其对整车性能有着决定性的作用。因而发动机往往被称作发动机的“心脏”。 There are actually various types of engines such as electric motors,stream engines,andinternal combustion engines.The internal combustion engines seem to have almost complete dominance of the automotive field.The internal combustion engine,as its name indicates,burns fuel within the cylinders and converts the expanding force of the combustion into rotary force used to propel the vehicle. 事实上，按动力来源分发动机有很多种，如电动机、蒸汽机、外燃机等。然而内燃机似乎在发动机领域有着绝对的统治地位。就像其字面意思一样，内燃机的染料在气缸内燃烧，通过将燃烧产生气体的膨胀力转换成转动力来驱动发动机前进。 Engine is the power source of the automobile.Power is produced by the linear motion of a piston in a cylinder.However,this linear motion must be changed into rotary motion to turn the wheels of cars or trucks.The puston attached to the top of a connecting rod by a pin,called a piston pin or wrist pin.The bottom of the connecting rod is attached to the crankshaft.The connecting rod transmits the up-and-down motion of the piston to the crankshaft,which changes it into rotary motion.The connecting rod is mounted on the crankshaft with large bearings called rod bearing.Similar bearings, called main bearings,are used to mount the crankshaft in the block. 发动机是整部车的动力来源。能量来自于活塞在气缸内的（往复）直线运动。然而这种（往复）直线运动必须要转换成旋转运动才能驱动车轮。活塞与连杆通过一个销来连接，这个销称为活塞销。连杆的下部连接于曲拐。连杆把活塞的上下往复运动传递给曲拐，从而将往复直线运动转变成旋转运动。连杆和曲拐的连接使用大的轴承，称之为连杆轴承，类似的轴承也用于将曲轴连接到机体，称之为主轴承。 They are generally two different types of cooling system:water-cooling system and air-cooling system.Water-cooling system is more common.The cooling medium, or coolant, in them is either water or some low-freezing liquid, called antifreeze.A water-cooling system consists of the engine water jacket, thermostat, water pump, radiator, radiator cap, fan, fan drive belt and neccessary hoses. 主要有两种类型的冷却系统：水冷和风冷。水冷系统更为普遍。系统所用冷却介质或是冷却液常委水或其他低凝固点液体，称为抗凝剂。一个完整的水冷系统包括机体水套，节温器，水泵，散热器，散热器罩，风扇，风扇驱动皮带和必需的水管。 A water-cooling system means that water is used as a cooling agent to circulate through the engine to absorb the heat and carry it to the radiator for disposal.The ebgine is cooled mainly through heat transfer and heat dissipation.The heat generated by the mixture burned in the engine must be transferred from the iron or aluminum cylinder to the waterin the water jacket.The outside of the water jacket dissipates some of the heat to the air surrounding it, but most of the heat is carried by the cooling water to the radiator for dissipation.When the coolant temperature in the system reaches 90°,the termostat valve open fully, its slanted edge shutting off
Text A词汇答案 Unit 1 A. 1. were bulging with 2. multitude 3. crave 4. indulge in 5. abandon themselves 6. fastidious 7. mused on 8. soothing B. 1. faculty 2. besiege 3. stick to 4. laborious 5. profusion 6. file out 7. judicious 8. decipher 9. poignant 10. by degrees Unit 2 A. 1. annual 2. opponents 3. distinctions 4. ferociously 5. revered 6. overlooks 7. extra 8. celebrity B. 1. constructive 2 transformation 3. combat 4. status 5. severely 6. falling apart 7. effective 8. discouraged 9. cautious 10. wiped out Unit 3 A. 1. borrowings 2. exuberance 3. is flexible 4. instrument 5. diminishing 6. was bound to 7. accumulate 8. dominant B. 1. bound to 2 expansion 3. inclined 4. accumulate 5. conquest 6. stabilization 7. preserve 8. reduce 9. ingratiate 10. dominant
Fuel Supply System of Gasoline Engine(UNIT SEVEN) All the gasoline engines have substantially identical fuel systems and run on a mixture consisting of fuel vapor and air. The fuel system comprises the units designed to store, clear and deliver fuel, the units intended to clean air and a unit for preparing a mixture from fuel vapor and air. In a fuel system different components are used to supply fuel from the fuel tank into the engine cylinder. Some of the important components are fuel tank, fuel pump, fuel filter, carburetor, intake manifold and fuellines or tubes connecting the tank, pump and the carburetor. The fuel tank is a fuel container used for storing fuel. It is made of sheet metal. It is attached to the vehicle frame with metal traps and is located at the rear of the vehicle. They are mounted in a boot or boot-floor pan in case of front-engined cars and small commercial vehicles. In order to strengthen the tank as well as to prevent surging of fuel when the vehicle rounds a curve of suddenly stops, baffle plates are attached to the inside of the tank. A cap is used to close the filler opening of the tank. The fuel line is attached at or near the bottom of the tank with a filtering element placed at the connection. The other components of the fuel tank are the fuel gauge sending unit, a vent pipe, receiving unit. To prevent the dirt and water from entering the luggage compartment, a sealing strip is fitted between the fuel tank and boot floor pan. Moreover to limit the transmission of frame distortion to the tank giving rise to squeaking as the metal parts get rubbed together, rubber or felt pads are often fitted between the mountings and the tank. Provision is also made against drumming of the tank by these mountings. The tank may be placed at the side of the chassis frame for convenience in case of large commercial vehicles. The length of the connecting lines or tubes from the tank to the carburetor is also restricted by this at the same time. A porous filter is attached to the outlet lines. By drawing fuel from the tank through the filter, any water in the bottom of the tank as well as any dirt into the fuel gathers on the surface of the filter. To keep the fuel always under atmospheric pressure, the filter pipe or tank is vented. In order to prevent dirt in the fuel from entering the fuel pump or carburetor, fuel filters and screens are used in the fuel system. If the dirt is not removed from the fuel, the normal operation of these units will be prevented. The engine performance will also be reduced.
Vocabulary and Structure: Keys to section A: 1. reconciled 2. imperative 3. contradiction 4. existence 5. inherit 6. formidable 7. sensitive8. confess 9. Incidentally 10. conversely Keys to section B: 1. B 2.A 3. A 4.B 5. A 6. A 7. A 8.D 9.B 10.C Keys to close 2. partially 3. linked 5. positive 10. increase 9. impact 1. management 8. tolerance 7. relieve 4. builds 6. reaction Keys to Further Reading 1. C 2. C 3. A 4.D 5. B Translations 1．一位加拿大心理学教授已经鉴定出三种完美主义者：自我要求型（要求自己达到完美），要求他人型（要求别人达到完美）和被要求完美主义者（认为别人要求他们达到完美）。 2．他说完美主义者不仅怀有不现实的高标准，而且认为他们自己和别人都无法达到这些被拔高了的期望。 3．Flett教授认为有些形式的完美主义可能与情绪、身体和情感问题有关，包括抑郁症，饮食紊乱，婚姻不和谐甚至自杀。 4．她说：“我认为在一定程度上这是一个普通的压力问题。完美主义者是压力极大的人。我更愿意从整体的压力方面来看待这个问题，而不是单独从完美主义的角度来考虑。”
unit1 body 车身chassis 底盘enclosure外壳、套hood车棚、车顶sway 摇摆frame车架steering转向、操作brake 制动weld焊接rivet铆钉bolt螺钉washer垫圈vibration 振动stabilizer稳定器ride乘坐舒适性handling操作稳定性linkages转向传动机构plier钳子distributor分电器alternator交流发电机regulator调节器carburetor化油器radiator散热器、水箱defroster除冰装置sludge金属碎屑transmission变速器differential 差速器power train 传动系unitized body 承载式车身suspension system 悬架系统steering system 转向系braking system 制动系shock absorbers减震器control arms控制臂steering wheel 转向盘steering column转向管柱steering gears 转向器tie rod 横拉杆idler arm随动臂brake shoe制动蹄disc brake 盘式制动器drum brakes 鼓式制动器ignition system 点火系统exhaust system 排气系统lubrication system 润滑系oil filters 机油滤清器drive（or propeller）shaft传动轴universal joints 万向节dynamo发电机horn喇叭swived 旋转steering box转向器timing gear 正时齿轮bevel gear 锥齿轮mesh with与啮合leaf spring 钢板弹簧stub axle 转向节 unit2 longitudinal纵向的transverse横向的reciprocate往复spin旋转piston活塞ignite点火rub摩擦quart夸脱reservoir油箱mechanical机械的enclosed被附上的gallon加仑stroke冲程camshaft凸轮轴combustion燃烧disengaged脱离啮合的flywheel飞轮internal-combustion engine内燃机diesel-fuel柴油LPG=Liquefied Petroleum Gas液化石油气体CNG=Compressed natural gas压缩天然气spark ignition火花点火compression ignition压缩点火spark plug火花塞gas-turbine engine蒸汽机Stirling engine斯特灵发动机lubricating system润滑系统oil pan油底壳oil pump机油泵exhaust system排气系统emission-control system排放控制系统energy conversion能量转换air/fuel ratio空燃比connecting rod连杆TDC=Top Dead Center上止点BDC=Bottom Dead Center 下止点intake stroke进气冲程compression stroke压缩冲程power stroke作功冲程exhaust stroke排气冲程compression ratio压缩比lifter挺柱rocker摇臂retainer弹簧座seal密封件tappet 推杆lobe凸起gasket垫圈valve train配气机构cam follower气门挺柱rocker arm摇臂combustion chamber燃烧室intake valve进气阀exhaust valve排气阀valve stem气门杆valve cover气门室盖valve port阀口valve guide气门导管 unit3
INTERNAL COMBUSTION ENGINE 引擎燃烧室 1. principle of operation 原理 Engine and power : Engine is used to produce power. The chemical energy in fuel is converted to heat by the burning of the fuel at a controlled rate. This process is called combustion. If engine combustion occurs with the power chamber. ,the engine is called internal combustion engine. If combustion takes place outside the cylinder, the engine is called an external combustion engine. Engine used in automobiles are internal combustion heat engines. Heat energy released in the combustion chamber raises the temperature of the combustion gases with the chamber. The increase in gas temperature causes the pressure of the gases to increase. The pressure developed within the combustion chamber is applied to the head of a piston to produce a usable mechanical force, which is then converted into useful mechanical power. 译: 引擎和能量: 引擎为汽车提供能量，燃料的化学能通过燃烧，转化为热能，这个过程叫燃烧。假如燃烧在燃烧室，这样的发动机叫内燃机。假如燃烧在气缸外，这样的发动机叫外燃机。 用在汽车上的一般是内燃机，热能在燃烧室释放，燃烧室气体温度升高。气体温度的升高使气体的压力曾加，燃烧室内的高压气体作用在活塞头部产生可以利用的化学能，化学能转化为机械能。 Engine T erms : Linking the piston by a connecting rod to a crankshaft causes the gas to rotate the shaft through half a turn. The power stroke “uses up” the gas , so means must be provided to expel the burnt gas and recharge the cylinder with a fresh petrol-air mixture :this control of gas movement is the duty of the valves ;an inlet valve allows the new mixture to enter at the right time and an exhaust valve lets out the burnt gas after the gas has done its job. Engine terms are : TDC(Top Dead Center):the position of the crank and piston when the piston is farther away from the crankshaft. BDC(Bottom Dead Center):the position of the crank and piston when the piston is nearest to the crankshaft. Stroke : the distance between BDC and TDC; stroke is controlled by the crankshaft. Bore : the internal diameter of the cylinder. Swept volume : the volume between TDC and BDC Engine capacity : this is the swept volume of all the cylinder e.g. a four-stroke having a capacity of two liters(2000cm) has a cylinder swept volume of 50cm. Clearance volume: the volume of the space above the piston when it is at TDC. Compression ratio = (swept vol + clearance vol)\(clearance vol) Two-stroke : a power stroke every revolution of the crank.
Types of Automobiles(UNITTWO) 汽车的类型 The automobile industry is a fast developing industry. Form the later 18th century when the first automobile was put on road, this industry has developed tremendously. Now there are thousands of factories all over the world manufacturing numerous types of automobiles. This industry employs crores of men and women directly and indirectly in allied industries. The automobile engines are also being used in engine powered machines for agriculture, construction and manufacturing processes. Various types of small engines are also being used in lawn movers, power saws, snow removers and similar equipment. The automobile industry is a developing and demanding industry which does not find its end or saturation point. There is a great demand for varied types of automotive products, vehicles and engines. There is also a great demand for trained and experienced persons in this industry for diagnosing motor vehicle troubles, repairing and replacing engines components, transmissions, propeller shafts, differentials, axles, steering system components, brake system components, suspension components, air conditioners, heaters, body and glass work. 汽车产业是一个迅速发展的行业。形成后18世纪当第一汽车被放在路,这个行业的发展极大。现在有成千上万的工厂世界各地制造许多类型的汽车。这个行业雇佣了卢比的男性和女性直接和间接地在盟军的产业。汽车引擎也被用于发动机动力机器为农业、建筑业和制造业的过程。各种类型的小引擎也被用于草坪搬家公司,电锯,雪消毒剂和类似的设备。汽车行业是一个发展中国家和要求行业没有找到它的结尾或饱和点。有大量需要不同类型的汽车产品,汽车和发动机。还有一个巨大的需求训练和经验丰富的人在这个行业对诊断机动车麻烦、维修和更换引擎组件、变速箱、螺旋桨轴、差异、轴、转向系统组件,制动系统组件,悬挂组件、空调、热水器、身体和玻璃的工作。 There are numerous types of automobiles used in the world. There are in general three main classifications of the various types of vehicles. 有许多类型的汽车在世界上使用。一般有三种主要分类的各种类型的车辆。 The single-unit vehicles or load carriers. 车辆的单件或负载运营商。 Articulated vehicles. 铰接车辆。 The heavy tractor vehicles. 沉重的拖拉机车辆。 Single-unit vehicles are of conventional four-wheel type. The great majority of vehicles are of two axle design, In these vehicles the front axle is a steering non-driving axle and the rear axle is the driving axle. With the passage of time, a great many changes have taken place in the number of axles and the driving arrangements. 单一制车辆四轮类型的传统。绝大多数的车辆被两个轴的设计,在这些车辆前轴是转向非驱动轴和后轴驱动轴。随着时间的流逝,许多变化已经发生轴的数量和驾驶的安排。 In this classification, digital terms like 4×2, 4×4, 6×4etc,are commonly used. The first figure denotes the total number of wheels and the second figure the number of driving wheels. 在这个分类、数字术语像4×2、4×4、6×4等,被普遍使用。第一个图表示轮子的总数和第二
汽车专业英语复习题 名词翻译： 1、活塞环 piston ring 2、电控系统electronic control system 3、里程表speedometer 4、发动机排量engine capacity 5、自动变速器automatic transmission 6、机油表oil gauge 7、方向盘steering wheel 8、做功冲程power stroke 9、exhaust gas废气 10. electric current电流 11. high gear高速档 12. automobile dealing汽车贸易 13. sports car 跑车 14. instrument panel仪表板 15. accelerator pedal加速踏板 16. physical property 物理性能 17、电子燃油计量系统electronic fuel metering system 18、减速slow down 19、刹车蹄brake shoe 20、General Motor 通用 21、wheel drum 车轮毂 22、TDC 上止点 23、BDC 下止点 翻译（中译英）： 上海汽车工业总公司已与德国大众和美国通用两大汽车公司建立了合资公司。 The Shanghai Auto Industry Corportion has established joint ventures with German V olkswagen and American General Motors. 四冲程发动机—曲柄旋转两圈做功一次。 Four stroke —a power stroke every other revolution of the crank. 液体冷却系由水泵、水套、发动机风扇、散热器等组成。 The liquid cooling system consists of water pumps，water jackets，engine fan ，radiator and so on. 在仪表板上，我们能看见几个显示发动机运转情况的仪表。
（6）Maintain correct viscosity (free flowing at all temperatures). 保持正确的粘度（在所有温度下自由流动）。 When the brake fluid boils, it becomes vapor. A vapor can be compressed, but a liquid cannot be compressed. Pressing on the brake pedal will compress the vapor in the lines instead of transferring the pressure through the fluid. This can lead to partial or complete braking system failure, sometimes called brake pedal fade. Mountain driving puts increased duty on brakes and brake fluid. The boiling point drops at high altitude. This naturally increases the tendency towards vapor lock. In fact, vapor lock in the hydraulic braking system is the primary reason for brake pedal fade. 当制动液沸腾时，它变成蒸汽。可以压缩蒸汽，但不能压缩液体。按压制动踏板将压缩管线中的蒸汽，而不是将压力传递通过流体。这可能导致部分或完全制动系统故障，有时称为制动踏板褪色。山地驾驶增加了刹车和制动液的使用。沸点在高海拔下降。这自然增加了气体锁定的趋势。事实上，液压制动系统中的汽油锁是制动踏板褪色的主要原因。 Vehicle manufacturers recommend brake fluid that meets or exceeds SAE (Societyof Automotive Engineers)andDOT (Department of Transportation) specifications. 车辆制造商推荐符合或超过SAE（汽车工程师协会）和DOT（运输部）规格的制动液。 Standard brake fluid (DOT 3) is composed chiefly of equal parts of alcohol and castor oil. This combination of fluids works well under normal conditions but it easily boils and becomes a vapor under heavy-duty applications. It also tends to separate when exposed to low temperatures. 标准制动液（DOT 3）主要由酒精和蓖麻油组成。这种流体组合在正常条件下工作良好，但在重载应用下容易沸腾并成为蒸气。暴露于低温时也容易分离。The increasing requirements of brake fluid led to the development of silicone brake fluid,such as DOT 5. This fluid achieved low water pickup and good corrosion protection and also provides good lubrication qualities and rubber compatibility. 制动液的要求越来越高，导致了DOT 5等硅胶制动液的开发。该液体实现了低吸水率和良好的防腐蚀性能，并且还具有良好的润滑性能和橡胶相容性。 5.Brake valves 5.闸阀 There are typically five types of valves in vehicle braking system to adjust the braking force distribution. 车辆制动系统中通常有五种类型的阀门来调节制动力分布。 (1)Metering valve （1）计量阀 Most vehicles that have front disc and rear drum brakes are equipped with metering valve. This metering valve controls, or delays the flow of brake fluid to the front brakes. The rear drum brakes take longer to respond than the front disc brakes. The valve ensures that front disc brake do not act before the rear drum brake. The delays is long enough to allow the rear drum brakes time to react. This delay is particularly necessary during light braking and on slick road surfaces.