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E-business environment under the logistics and distributionAbstract: e-commerce under the logistics and distribution will help reduce production business inventories and accelerate capital turnover, enhance logistics efficiency and reduce logistics costs, and stimulate the social needs and is conducive to the whole community's macro-control and promote the healthy operation of the market economy and electronic Business to develop in depth. Key words: e-commerce distributionFirst, China's development of logistics distribution E-commerce logistics entity is the core issue of the distribution items. China, as a developing country, the logistics industry to its late start, low level, the introduction of e-commerce, e-commerce did not have to support the activities of the modern logistics level. However, since e-commerce in China to settle down, people did not stop distribution of the discussion. At present, China mainly three types of e-commerce distribution model, is a full distribution system, that is, the domestic Internet-based, to various regions of the country's logistics system has been linked by agreement, a comprehensive distribution network for the entire process straight . The second category is a regional system of a single business model. Partial to the original business of a single regional distribution site for the base and be integrated, similar to a single business to business services, computer networking, the entire system of networking, and automated management. The third category is professional distribution system of the model. Such as postal communications, railway transport, air, water, Qiyun and other departments have been the perfect use of the national transport network resources to carry out specialized distribution. From across the country, China has long been subject to the impact of the planned economy, low levels of social logistics, logistics management system confusion, the existing three categories of e-commerce distribution model is not yet ripe, efficiency is not high, but in the red. Therefore, the need for China's economic development, enterprise reform and development of e-commerce logistics and distribution, learn from developed countries through the road and experience from China in 1992 began a logistics distribution center of the experimental work. In 1996 the Internal Trade issued "on strengthening the commercial development of logistics distribution center construction work of the notice," pointed out the development and construction of logistics distribution center the importance of the proposed development and construction of the guiding ideology and principle, put forward the "mechanisms and intensive Management, improve the function of the development of the logistics and enhance strength "of the reform and development principles, to establish modern logistics distribution center to change the social construction of logistics distribution centers, the development of modern network as the main direction. Second, China's logistics and distribution patterns and problems of At present, China's increased the number of e-commerce sites, transactions involving goods of daily necessities and other non-consumables, and on its e-commerce distribution model, can be divided into three types, namely operating BtoB (business to business) business model, BtoC (Business to consumers) model and the virtual logistics company model, in practice, although these three models get the recognition and application of common, but in e-commerce and distribution of convergence and optimal operation, there are still many problems, reflected in concrete : China's current social low level of information networks, network infrastructure is relatively weak, especially as e-commerce platform for the delivery and billing infrastructure lags behind, the computer penetration rate low rate of Internet users only about 8 percent and are mainly concentrated in major cities , The use of Internet users in the real rate of online shopping less than percent, electronic shopping credit has not been widely recognized. The understanding of the importance of e-commerce logistics enough. Availability of the overall level of enterprise network low ratio of less than Internet companies, logistics enterprise information construction lagged behind, logistics and distribution of specialization, social, electronic, modern low level. There have been serious problems of poor business reputation, late delivery, delivery or do not send the wrong frequent phenomenon. E-commerce logistics infrastructure is not yet perfect, logistics systems theory is not enough, the logistics technology is still very backward, China's logistics workers and practice the theory of modern logistics of the new theories, new technologies, such as integrated supply chain management, third party logistics, automation Warehouse, automatic sorting system, global positioning system (GPS), and so has just contacted. Jidong of the lack of e-commerce and e-commerce technology has practical experience in human resources, in particular the lack of Jidong e-commerce and logistics distribution to understand the innovative spirit of the compound talents. Third, logistics and healthy development of the countermeasure 1. Enhance the degree of information. Distribution of information for performance: the logistics of the database of information collection and code, the logistics of the electronic information processing and computer, the transmission of information and the standardization of real-time logistics information such as the digital storage. Therefore, the bar-code technology, database technology, electronic ordering system, electronic data exchange, radio frequency technology, management information systems, enterprise resource planning, and other advanced management strategy should be in China's logistics and distribution enterprises to promote use. Information is all modern technology and management tools of the foundation, only to achieve distribution of information can take up to the era of e-commerce distribution industry and historic task. 2. Improve the logistics management system, improve service quality. Internet shopping for the delivery time is too long and has yet to supply the phenomenon as e-commerce company in order to better serve customers, suppliers and customers should be strengthened between the exchange of information and feedback. This will save users to order processing fees, users can also save time and gradually raise awareness of online shopping sense of trust, making good steady development of e-commerce. 3. Distribution lower prices. China's large-scale development of e-commerce online shopping has been difficult, logistics and distribution costs high, especially in the type of Internet transactions, for each client to achieve door-to-door is the high cost, we must work hard to reduce costs, e-commerce solution Logistics and distribution companies and distribution services among enterprises in the prices of contradictions. 4. Perfect laws and policies. E-commerce for the logistics and distribution problems, the relevant government departments should actively study the characteristics of e-commerce, the rapid development of targeted laws, regulations and policies to regulate e-commerce activities, enterprises and consumers in general to increase the confidence of e-commerce Flu. 5. Actively developing third-party logistics enterprises. "TPL" refers to the logistics business from the supply side and demand-side beyond the completion of a third party, in a sense that it is a form of logistics professionalism, "third-party logistics" in logistics management experience, Talent, technology, philosophy and other areas have certain advantages, the e-commerce transactions in both supply and demand of all the logistics activities of agent credentials, well-funded third-party logistics, the logistics can take full advantage of modern technology, is built on the foundation of modern information network technology On the logistics management software to ensure that customers at any time and any place check of goods and provision of supporting services, e-commerce transactions between the parties involved in the logistics can be entrusted to professional logistics enterprises, concentrate on developing the electronics market and business efficiency of the e-commerce BtoB transactions. The establishment of a national logistics public information platform, the development of 4PL. 4PL is a supply chain integrator, mobilization and management organizations and their complementarity of the service provider's resources, capacity and technology to provide an integrated supply chain solutions. Clearly, 4PL must meet three conditions: not the interests of the logistics side, to achieve information sharing, the ability to integrate all the logistics resources. And really meet these conditions, only a virtual network of platforms, and this is the logistics and public information platform. It provides comprehensive supply chain solutions to social integration of logistics resources, enhance the country's logistics industry integrated collaborative capabilities.电子商务环境下的物流配送摘要：电子商务下的物流配送既有利于减少生产企业库存，加速资金周转，提高物流效率，降低物流成本，又刺激了社会需求，有利于整个社会的宏观调控，促进市场经济的健康运行及电子商务向纵深发展。关键词：电子商务 物流 配送一、我国物流配送发展概况 电子商务物流的核心问题是实体物品的配送。我国作为一个发展中国家，物流业起步较晚，水平低，在引进电子商务时，并不具备能够支持电子商务活动的现代化物流水平。但自从电子商务在中国落户，人们就没有停止对物流配送问题的讨论。目前，我国主要有三类电子商务物流配送模式，一类是全程物流配送系统，即以国内互联网为基础，把全国各地区已有的物流系统通过协议联系起来，形成全方位的全程直投配送网。第二类是区域性单一业务系统改造模式。以原有局部区域性单一业务的配送站点为基础，并加以集成，把单一业务改为同类业务服务，通过计算机联网，实现整个系统的网络化、自动化管理。第三类是专业化配送系统改造模式。如邮政通讯、铁运、空运、水运、汽运等部门利用已有的完善的全国性运输网络资源进行专业化配送。从全国范围来看，我国长期以来受计划经济的影响，物流社会化程度低，物流管理体制混乱，已有的三类电子商务物流配送模式还不成熟，效率不高，而且处于亏损状态。因此，针对我国经济发展需要、企业改革及电子商务物流配送发展现状，借鉴发达国家走过的道路和经验，我国从1992年起开始了物流配送中心的试点工作。1996年原国内贸易部发出了《关于加强商业物流配送中心发展建设工作的通知》，指出了发展建设物流配送中心的重要意义，提出发展建设的指导思想和原则，同时提出了“转换机制、集约经营、完善功能、发展物流、增强实力”的改革与发展方针，确定以向现代化物流配送中心转变，建设社会化的物流配送中心，发展现代化网络为主要方向。 二、我国物流配送模式及存在的问题 目前我国电子商务网站数量大增，交易商品涉及日用品及其他非易耗品等，就其电子商务物流配送模式而言，可分为三种类型，分别是经营BtoB（商家对商家）业务的模式、BtoC（商家对消费者）的模式以及虚拟物流公司模式，在实践中这三种模式虽然得到共同的认同与应用，但在电子商务与物流配送的接轨和优化运行上还存在许多问题，具体体现在： 中国目前的社会信息网络化水平低，网络基础设施相对薄弱，特别是作为电子商务平台的传递和结算基础设施滞后，计算机普及率低，网民比率只有8%左右，并主要集中在各大中城市，网民中真正采用网上购物的比率不到，电子购物的信用没有得到广泛认同。 对电子商务物流的重要性认识不够。供货企业网络化整体水平低，上网企业比率不足，物流企业信息化建设滞后，物流配送的专业化、社会化、电子化、现代化程度低。 存在严重的商业信誉差的问题，迟送、送错或不送现象时有发生。 电子商务物流基础尚不完善，物流理论还不够系统，物流技术还很落后，我国物流理论工作者和实践者对现代物流的新理论、新技术，如集成化供应链管理、第三方物流、自动化立体仓库、全自动分拣系统、全球定位系统（GPS）等才刚刚接触。 缺乏既懂电子商务理论和技术又有电子商务实践经验人才，尤其缺乏既懂电子商务又懂物流配送的有创新精神的复合型人才。三、物流配送健康发展的对策 1.提高信息化程度。物流配送信息化表现为：物流信息收集的数据库化和代码化、物流信息处理的电子化和计算机化、信息传递的标准化和实时化、物流信息存储的数字化等。因此,条码技术、数据库技术、电子订货系统、电子数据交换、射频技术、管理信息系统、企业资源计划等先进的管理策略，应在我国的物流配送企业大力推广运用。信息化是一切现代技术和管理手段的基础，只有实现物流配送信息化,才能承担起电子商务时代赋予物流配送业的历史任务。 2.完善物流管理系统功能,提高售后服务质量。针对网上购物出现的送货时间过长以及迟迟没有货源的现象，作为电子商务公司为了能更好的服务于顾客，应加强顾客和供货商之间信息的交流与反馈。这样可以给用户节约订单处理费用，又可以节约用户的时间，逐渐提高人们对网上购物的信任感，使得电子商务良性稳步发展。 3.降低配送服务价格。我国发展电子商务实现大规模的网上购物一直困难重重，物流配送费用偏高，特别是零售型的网上交易，为每个客户实现送货上门是高成本的，必须努力降低成本，解决电子商务公司与物流配送企业之间在配送服务价格方面的矛盾。 4.完善法律政策。针对电子商务物流配送出现的种种问题，政府有关部门应该积极研究电子商务的特点，迅速制定有针对性地法律、法规和政策，以规范电子商务活动，增加企业和广大消费者对电子商务的信任感。 5.积极发展第三方物流企业。“第三方物流”是指物流由商务的供方、需方之外的第三方完成,从某种意义上说它是物流专业化的一种形式，“第三方物流”一般在物流管理经验、人才、技术、理念等方面都具有一定的优势,对电子商务交易中供求双方的所有物流活动进行全权代理，同时第三方物流资金雄厚,可以充分利用现代物流技术,具有建立在现代信息网络技术基础上的物流管理软件,保证客户在任何时间、任何地点查看货物及提供配套的服务，参与电子商务交易的双方可以把物流委托给专业物流企业,专心于电子市场的开拓和商务效率的提高电子商务BtoB交易模式。 建立全国物流公共信息平台，发展第四方物流。第四方物流是一个供应链集成商，它调集和管理组织自己的以及具有互补性的服务提供商的资源、能力和技术，以提供一个综合的供应链解决方案。显然，第四方物流必须满足三个条件：不是物流的利益方、能实现信息共享、有能力整合所有的物流资源。而真正满足这些条件的只有一种虚拟的物流网平台，这就是全国物流公共信息平台。它能提供综合的供应链解决方案，以整合社会物流资源，提高我国物流产业的综合协同能力。

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Car partsEngine The engine is a power plant, which provides power to drive the automobile． In most automobile engines，the explosive power of the mixture of air and gasoline drives the pistons．The pistons turn a crankshaft to which they are attached The rotating force of the crankshaft makes the automobile’s wheels turn．Some automobiles are powered by another kind of engine，known as the rotary valve，rotating combustion engine or Wankel engine The rotary valve engine also draws in a mixture of air and fuel, which is then compressed and burnt．A motor revolving in an elliptical chamber is connected to a shaft，Which finally drives the rear wheels．In most automobiles．the engine is mounted at the front end of the car，with the clutch and gearbox immediately behind it；the engine, clutch and gearbox are assembled into a single unit Suspension System The function of the suspension system is to absorb vibrations due to the up and down motion of wheels．caused by the irregularities in the road surface . The springs, connecting linkages．and shock absorber comprise the suspension system of a vehicle．The suspension system is of two types: (1)Rigid system(2)Independent systemIn the rigid system, the road springs are attached to a rigid beam axle. It is mostly used in the front axle of commercial vehicles and in the car axle of all types of independent system does not have a rigid axle. Each wheel is free to move vertically without any reaction on its mating wheel. The independent system is mostly used in small cars Power TrainThe power train carries the power that the engine produces to the car wheels. It consists of the clutch (on cars with a manual transmission), transmission (a system of gears that increases the turning effort of the engine to move the automobile ),drive shaft, differential and rear clutch is required with the manual transmission system to temporarily disconnect the engine from wheels. Such disengagement of the power train from the engine is essential while changing the gear ratio or while stopping the main function of the transmission is to provide the necessary variation to the torque applied by the engine to the wheels. This is achieved by changing the gearing ratio between the engine output shaft and the drive ShaftThe drive shaft or propeller connects the gearbox and the differential unit. The drive shaft has universal joints at its ends．DifferentialThe function of the differential is to split the power received from the propeller shaft to the rear axle shaft. It allows the rear wheels to be driven at different speeds when the vehicle takes a bend or falls into a ditch. AxlesAxles are the shafts on which road wheels are mounted. The road wheels are provided with the required drive through these axles．WheelThe automobile wheels take the load of the vehicle and also produce tractive force to move the vehicle. The wheels are also used for retardation and for stopping the SystemThe steering system is used for changing the direction of the vehicle .The major requirements in any steering mechanism are that it should be precise and easy to handle, and that the front wheels should have a tendency to return to the straight-ahead position after a turn. A gear mechanism, which is known as steering gear, is used in this system to increase the steering effort provided by the driver. This system makes the vehicle steering very easy as the driver does not have to put in much effort．Vehicle steering is not only required on a curved road but also while maneuvering on the busy traffic roads．The steering system allows the vehicle to be guided i．e．to be turned left or right. Braking SystemBrakes are required for slowing down or stopping a moving vehicle．The braking system may be operated mechanically or hydraulically. 95 percent of the braking systems in use today are of the hydraulic brake consist of two members．one rotating and the other stationary．There are various means by which the two member call be brought in contact，thus reducing the speed of the major components of the braking system are：brake pedal, master cylinder, wheel Cylinder, brake pipe，brake shoes．brake packing plant and linkages．As the load on the vehicle and the vehicle speed has increased according to recent trends．in modem days, the importance of the braking system has also increased and power brakes are now being preferred．Power brakes utilize vacuum and air pressure to provide most of the brake————applying effort.汽车部件发动机发动机是一种动力机械设备．它为汽车提供动力。在大部分汽车发动机中．空气和汽油的混合气体产生的爆炸性能量驱动活动活塞运动。活塞使它们所连接的曲轴转动。曲轴的转动力量使汽车的车轮转动。一些汽车是由另外一种发动机提供动力的，这种发动机被认为是旋转气门、旋转燃烧或汪克尔发动机。转子发动机也是吸入空气和燃料的混合气，混合气被压缩和燃烧•在一个椭圆形的室内旋转的发动机连接着一个轴，这个轴将最终驱动后面的车轮。大部分汽车中，发动机是架在汽车的前面末端的，离台器和变速箱在它后面，发动帆、离台器和变速箱被装配成一个整体。发动机工作时有很多系统都是必要的。润滑系统可以减少摩擦并减轻发动机磨损。冷却系统被用来保持发动机的温度在安全范围内。发动机必须有燃油系统保证适当数量的空气和燃料供给。空气和燃油混合物必须由点火系统在适当的时间在气缸内被点燃。最后，电子系统被用来控制启动发动机用的电动机和为发动机附件提供电能。润滑系统发动机有许多最终会被磨损的运动部件，因为它们是相对运动的。发动机使润滑油在这些运动的部件间循环，以避免因金属与金属之间的接触而导致磨损。被润滑过的部件能够因为摩擦减少而容易运动，因摩擦导致的能量损失是最小的。润滑油的第二个功能是作为冷却液和防止泄露。最后，气缸壁上的润滑油薄膜有助于活塞环密封并因此提高发动机的压缩性。冷却系统 由于燃料与空气在气缸内燃烧，从而使发动机部件温度升高。温度升高直接影响发动机的性能和发动机部件的寿命。冷却系统使发动机工作保持在有效的温度。不管驾驶条件如何，发动机系统被设计成既能防止过热又能防止过冷。燃料供给系统燃料供给系统的主要功能是以一定的比例和压力给化油器或喷射系统提供燃料，并在汽车遇到的所有情况下，满足发动机对负载、速度和坡度的需要。燃料系统也必须为汽车行驶几英里保留足够的燃料。身提供了一个安装框架。车架用方刚或盒形钢铁制造，有足够的强度支撑车身和其他构件的重量。汽车车架通常由一些焊接或铆接在一起的零件构成，从而形成最后的形状。发动机和橡胶垫被圈定在车架上。橡胶垫可以吸收振动，也可以提供这些振动的阻尼减轻乘客由于振动产生的不适。悬架系统悬架系统的功能是吸收由于路面不平使车轮上下运动所产生的振动。弹性元件、连接装置和减振器组成了汽车的悬架系统。悬架系统有两种类型：(1)刚性悬架系统(2)独立悬架系统在刚性悬架系统中，弹簧被系在刚性横梁上，这种系统主要被用在商用车辆的前轴和所有类型车辆的车轴上。独立悬架系统没有一根坚硬的轴。每个车架可以自由做垂直运动而相对应的另一侧车轮没有任何反应。独立悬架系统主要用在小汽车上。传动系统传动系把发动机产生的能量传递给车轮。它包括离台器(汽车上用手动变速器)、传动系(一系列的齿轮，把由发动机产生的转矩增强．推动汽车)、驱动轴、差速器和后挢。离合器离合器用于手动变速的传动系统。用它暂时把发动机和车轮之间的动力传递分开。当换档或停车时，把传动系和发动机的连接断开是很必要的。变速籍变速箱的主要功能是通过发动机把各种必需的扭矩提供给车轮，这是通过改变发动机输出轴和驱动轴两者之阃的传动比来实现的。驱动轴驱动轴或叫推动轴与齿轮箱和差动器相连。驱动轴通常在末端具有万向节。差速器差速器的功能是把来自传动轴的能量分给后轿。当汽车转弯或掉沟时，它允许后轮以不同的逮度驱动。车轿车桥是指用来安装车轮的轴，通过这些车桥向车轮提供必需的驱动力。 车轮车轮支承着整辆车．并产生牵引力来驱动汽车。车轮也用于减速和停车。转向系统转向系统是用来改变汽车方向的，在任何转向机构中最主要的就是转向精确且容易控制，同时前轮在转向后又能自动回正。一个齿轮机构，通常认为是转向齿轮，在这个系统内用来增强由驾驶员提供的转向力，这个系统使得汽车转向非常容易，驾驶员不用费报大的力。不仅仅是在弯曲的公路上需要汽车转向，在交通拥挤的路上也需要巧妙地控制。转向系统使得汽车可以被控制向左或者向右转向。制动系统制动用来使车辆放慢速度或者停车。制动系统可以是机械制动或者液压制动。现在用的制动系统95％都是液压型的。所有的制动系统都包含两种元件，一种是旋转零件，另一种是固定零件，有各种各样方法使得这两个元件相接触而使车辆减速。制动系统的主要组成部分：制动踏扳、主制动缸、车轮制动、制动鼓、制动管路、制动蹄、制动装备和联动装置。随着汽车负载和车速的增大，目前制动系统的重要性也在增大，并且现在人们更喜欢助力制动。助力制动利用真空和空气压力来提供更好的制动力。

Car partsEngine The engine is a power plant, which provides power to drive the automobile． In most automobile engines，the explosive power of the mixture of air and gasoline drives the pistons．The pistons turn a crankshaft to which they are attached The rotating force of the crankshaft makes the automobile’s wheels turn．Some automobiles are powered by another kind of engine，known as the rotary valve，rotating combustion engine or Wankel engine The rotary valve engine also draws in a mixture of air and fuel, which is then compressed and burnt．A motor revolving in an elliptical chamber is connected to a shaft，Which finally drives the rear wheels．In most automobiles．the engine is mounted at the front end of the car，with the clutch and gearbox immediately behind it；the engine, clutch and gearbox are assembled into a single unit A number of systems are necessary to make an engine work . A lubrication system is neededto reduce friction and prevent engine wear. A cooling system is required to keep the engine’s temperature within safe limits .The engine must be provided with the correct amount of air and fuel by a fuel system． The mixture of air and fuel must be ignited inside the cylinder at just the right time by an ignition system．Finally, an electrical system is required to operate the cranking motor that starts the engine and to provide electrical energy to power engine accessoriesLubrication System An engine has many moving parts which eventually develop wear，as they move against each other．The engine circulates oil between these moving parts to prevent the metal-to-metal contact that results in wear． Parts that are oiled can move more easily with less friction and hence power loss due to friction is minimized．The secondary function of lubricant is to act as a coolant and also as a sealing medium to prevent leakages．Finally，a film of lubricant on the cylinder walls helps the tings in sealing and thus improves the engine’s compressions．Cooling System Due to the combustion of fuel with air inside the cylinder，the temperature of the engine parts increases．This increase of temperature directly affects the engine performance and the life of the engine parts．The cooling system keeps the engine operating at the efficient temperature．Whatever the driving conditions, the system is designed to prevent both overheating and overcooling．Fuel System The main function of the fuel supply system is to provide fuel to the carburetor or injection system at a rate and pressure sufficient to meet engine demands under all conditions of load，speed and gradients encountered by the vehicle．The fuel system must also have enough reserve fuel for several miles of vehicle operation．Ignition System The purpose of the ignition system is to provide assistance for the combustion of fuel either by a high voltage spark or self-ignition in each of the engine’s cylinder at the right time so that the air-fuel mixture can burn completely． The fuel supplied to the combustion chamber must be ignited to deliver power．In a spark—ignition engine an electric spark is used for this purpose．The compression—ignition engine does not require a separate ignition system because the ignition is affected by compression of the mixture to a high pressure． Electrical System The engine’s electrical system provides energy to operate a starting motor and to power all the accessories．The main components of the electrical system are a battery，an alternator, a starting motor, ignition coil and heater．Frame The frame provides a foundation for the engine and the body of the vehicle . The flame is constructed from square or box-shaped steel members strong enough to support the weight of the body and other components. The automobile frame is usually made up of a number of members welded or riveted together to give the final shape．The engine is mounted on the frame with rubber pads which absorb vibrations and also provide damping of these vibrations．Absorption and damping of vibrations protects passengers from discomfort caused by shocks． The frame is supported on wheel axles by means of springs．This whole assembly is calledthe chassis． Suspension System The function of the suspension system is to absorb vibrations due to the up and down motion of wheels．caused by the irregularities in the road surface . The springs, connecting linkages．and shock absorber comprise the suspension system of a vehicle．The suspension system is of two types: (1)Rigid system(2)Independent systemIn the rigid system, the road springs are attached to a rigid beam axle. It is mostly used in the front axle of commercial vehicles and in the car axle of all types of independent system does not have a rigid axle. Each wheel is free to move vertically without any reaction on its mating wheel. The independent system is mostly used in small cars Power TrainThe power train carries the power that the engine produces to the car wheels. It consists of the clutch (on cars with a manual transmission), transmission (a system of gears that increases the turning effort of the engine to move the automobile ),drive shaft, differential and rear clutch is required with the manual transmission system to temporarily disconnect the engine from wheels. Such disengagement of the power train from the engine is essential while changing the gear ratio or while stopping the main function of the transmission is to provide the necessary variation to the torque applied by the engine to the wheels. This is achieved by changing the gearing ratio between the engine output shaft and the drive ShaftThe drive shaft or propeller connects the gearbox and the differential unit. The drive shaft has universal joints at its ends．DifferentialThe function of the differential is to split the power received from the propeller shaft to the rear axle shaft. It allows the rear wheels to be driven at different speeds when the vehicle takes a bend or falls into a ditch. AxlesAxles are the shafts on which road wheels are mounted. The road wheels are provided with the required drive through these axles．WheelThe automobile wheels take the load of the vehicle and also produce tractive force to move the vehicle. The wheels are also used for retardation and for stopping the SystemThe steering system is used for changing the direction of the vehicle .The major requirements in any steering mechanism are that it should be precise and easy to handle, and that the front wheels should have a tendency to return to the straight-ahead position after a turn. A gear mechanism, which is known as steering gear, is used in this system to increase the steering effort provided by the driver. This system makes the vehicle steering very easy as the driver does not have to put in much effort．Vehicle steering is not only required on a curved road but also while maneuvering on the busy traffic roads．The steering system allows the vehicle to be guided i．e．to be turned left or right. Braking SystemBrakes are required for slowing down or stopping a moving vehicle．The braking system may be operated mechanically or hydraulically. 95 percent of the braking systems in use today are of the hydraulic brake consist of two members．one rotating and the other stationary．There are various means by which the two member call be brought in contact，thus reducing the speed of the major components of the braking system are：brake pedal, master cylinder, wheel Cylinder, brake pipe，brake shoes．brake packing plant and linkages．As the load on the vehicle and the vehicle speed has increased according to recent trends．in modem days, the importance of the braking system has also increased and power brakes are now being preferred．Power brakes utilize vacuum and air pressure to provide most of the brake————applying effort.汽车部件发动机发动机是一种动力机械设备．它为汽车提供动力。在大部分汽车发动机中．空气和汽油的混合气体产生的爆炸性能量驱动活动活塞运动。活塞使它们所连接的曲轴转动。曲轴的转动力量使汽车的车轮转动。一些汽车是由另外一种发动机提供动力的，这种发动机被认为是旋转气门、旋转燃烧或汪克尔发动机。转子发动机也是吸入空气和燃料的混合气，混合气被压缩和燃烧•在一个椭圆形的室内旋转的发动机连接着一个轴，这个轴将最终驱动后面的车轮。大部分汽车中，发动机是架在汽车的前面末端的，离台器和变速箱在它后面，发动帆、离台器和变速箱被装配成一个整体。发动机工作时有很多系统都是必要的。润滑系统可以减少摩擦并减轻发动机磨损。冷却系统被用来保持发动机的温度在安全范围内。发动机必须有燃油系统保证适当数量的空气和燃料供给。空气和燃油混合物必须由点火系统在适当的时间在气缸内被点燃。最后，电子系统被用来控制启动发动机用的电动机和为发动机附件提供电能。润滑系统发动机有许多最终会被磨损的运动部件，因为它们是相对运动的。发动机使润滑油在这些运动的部件间循环，以避免因金属与金属之间的接触而导致磨损。被润滑过的部件能够因为摩擦减少而容易运动，因摩擦导致的能量损失是最小的。润滑油的第二个功能是作为冷却液和防止泄露。最后，气缸壁上的润滑油薄膜有助于活塞环密封并因此提高发动机的压缩性。冷却系统 由于燃料与空气在气缸内燃烧，从而使发动机部件温度升高。温度升高直接影响发动机的性能和发动机部件的寿命。冷却系统使发动机工作保持在有效的温度。不管驾驶条件如何，发动机系统被设计成既能防止过热又能防止过冷。燃料供给系统燃料供给系统的主要功能是以一定的比例和压力给化油器或喷射系统提供燃料，并在汽车遇到的所有情况下，满足发动机对负载、速度和坡度的需要。燃料系统也必须为汽车行驶几英里保留足够的燃料。点火系统点火系统的作用是在适当的时间使燃料燃烧，不管是高压电火花还是在每个发动机气缸中的自燃，以便于气体混合物的完全燃烧。提供给燃料室的燃料必须被点燃以提供能量。在一个火花点火发动机中，电火花就是用于这个目的。压缩点火发动机不需要一个独立的点火系统，因为点火会受混合气压缩压力的影响。电气系统发动机的电气系统提供能量给起动电动机并给所有附件提供电能。电气系统的主要构件是蓄电池、交流发电机、起动电动机、点火线圈和加热器。车架车架为汽车发动机和车身提供了一个安装框架。车架用方刚或盒形钢铁制造，有足够的强度支撑车身和其他构件的重量。汽车车架通常由一些焊接或铆接在一起的零件构成，从而形成最后的形状。发动机和橡胶垫被圈定在车架上。橡胶垫可以吸收振动，也可以提供这些振动的阻尼减轻乘客由于振动产生的不适。悬架系统悬架系统的功能是吸收由于路面不平使车轮上下运动所产生的振动。弹性元件、连接装置和减振器组成了汽车的悬架系统。悬架系统有两种类型：(1)刚性悬架系统(2)独立悬架系统在刚性悬架系统中，弹簧被系在刚性横梁上，这种系统主要被用在商用车辆的前轴和所有类型车辆的车轴上。独立悬架系统没有一根坚硬的轴。每个车架可以自由做垂直运动而相对应的另一侧车轮没有任何反应。独立悬架系统主要用在小汽车上。传动系统传动系把发动机产生的能量传递给车轮。它包括离台器(汽车上用手动变速器)、传动系(一系列的齿轮，把由发动机产生的转矩增强．推动汽车)、驱动轴、差速器和后挢。离合器离合器用于手动变速的传动系统。用它暂时把发动机和车轮之间的动力传递分开。当换档或停车时，把传动系和发动机的连接断开是很必要的。变速籍变速箱的主要功能是通过发动机把各种必需的扭矩提供给车轮，这是通过改变发动机输出轴和驱动轴两者之阃的传动比来实现的。驱动轴驱动轴或叫推动轴与齿轮箱和差动器相连。驱动轴通常在末端具有万向节。差速器差速器的功能是把来自传动轴的能量分给后轿。当汽车转弯或掉沟时，它允许后轮以不同的逮度驱动。车轿车桥是指用来安装车轮的轴，通过这些车桥向车轮提供必需的驱动力。 车轮车轮支承着整辆车．并产生牵引力来驱动汽车。车轮也用于减速和停车。转向系统转向系统是用来改变汽车方向的，在任何转向机构中最主要的就是转向精确且容易控制，同时前轮在转向后又能自动回正。一个齿轮机构，通常认为是转向齿轮，在这个系统内用来增强由驾驶员提供的转向力，这个系统使得汽车转向非常容易，驾驶员不用费报大的力。不仅仅是在弯曲的公路上需要汽车转向，在交通拥挤的路上也需要巧妙地控制。转向系统使得汽车可以被控制向左或者向右转向。制动系统制动用来使车辆放慢速度或者停车。制动系统可以是机械制动或者液压制动。现在用的制动系统95％都是液压型的。所有的制动系统都包含两种元件，一种是旋转零件，另一种是固定零件，有各种各样方法使得这两个元件相接触而使车辆减速。制动系统的主要组成部分：制动踏扳、主制动缸、车轮制动、制动鼓、制动管路、制动蹄、制动装备和联动装置。随着汽车负载和车速的增大，目前制动系统的重要性也在增大，并且现在人们更喜欢助力制动。助力制动利用真空和空气压力来提供更好的制动力。