机械毕业设计英文外文翻译440手动变速器 (4)

Mechanical engineering1.The porfile of mechanical engineeringEngingeering is a branch of mechanical engineerig,itstudies mechanical and power generation especially power and movement.2.The history of mechanical engineering18th century later periods,the steam engine invention hasprovided a main power fountainhead for the industrialrevolution,enormously impelled each kind of mechznicalbiting.Thus,an important branch of a newEngineering –separated from the civil engineering tools andmachines on the branch-developed together with Birmingham andthe establishment of the Associantion of Mechanical Engineersin 1847 had been officially recognized.The mechanicalengineering already mainly used in by trial and error methodmechanic application technological development into professional engineer the scientific method of which in theresearch,the design and the realm of production used .From themost broad perspective,thedemend continuously to enhance theefficiencey of mechanical engineers improve the quality of work,and asked him to accept the history of the high degreeof education and training.Machine operation to stress not only economic but also infrastructure costs to an absolute minimun.3.The field of mechanical engineeringThe commodity machinery development in the develop country,in the high level material life very great degree is decided each kind of which can realize in the mechanical engineering.Mechanical engineers unceasingly will invent the machine next life to produce the commodity,unceasingly will develop the accuracy and the complexity more and more high machine tools produces the machine.The main clues of the mechanical development is:In order to enhance the excellent in quality and reasonable in price produce to increase the precision as well as to reduce the production cost.This three requirements promoted the complex control system development.The most successful machine manufacture is its machine and the control system close fusion,whether such control system is essentially mechanical or electronic.The modernized car engin production transmission line(conveyer belt)is a series of complex productions craft mechanization very good example.The people are in the process of development in order to enable further automation of the production machinery ,the use of a computer to store and handle largevolumes of data,the data is a multifunctional machine tools necessary for the production of spare parts.One of the objectives is to fully automated production workshop,threerotation,but only one officer per day to operate.The development of production for mechanical machinery must have adequate power supply.Steam engine first provided the heat to generate power using practical methods in the old human,wind and hydropower,an increase of engin .New mechanical engineering industry is one of the challenges faced by the initial increase thermal effciency and power,which is as big steam turbine and the development of joint steam boilers basically achieved.20th century,turbine generators to provide impetus has been sustained and rapid growth,while thermal efficiency is steady growth,and large power plants per kW capital consumption is also declining.Finally,mechanical engineers have nuclear energy.This requires the application of nuclear energy particularly high reliability and security, which requires solving many new rge power plants and the nuclear power plant control systems have become highly complex electroonics,fluid,electricity,water and mechanical parts networks All in all areas related to the mechanical engineers.Small internal combustion engine,both to the type(petrol and diesel machines)or rotary-type(gas turbines and Mong Kerr machine),as well as their broad application in the field of transport should also due to mechanical enginerrs.Throughout the transport,both in the air and space,or in the terrestrial and marine,mechanial engineers created a variety of equipment and power devices to their increasing cooperation with electrical engineers,especially in the development of appropration control systems.Mechanical engineers in the development of military weapons technology and civil war ,needs a similar,though its purpose is to enhance rather than destroy their productivity.However.War needs a lot of resources to make the area of techonlogy,many have a far-reaching development in peacetime efficiency.Jet aircraft and nuclear reactors are well known examples.The Biological engineering,mechanical engineering biotechnology is a relatively new and different areas,it provides for the replacement of the machine or increase the body functions as well as for medical equipment.Artficial limbs have been developed and have such a strong movement and touch response function of the human body.In the development of artificial organ transplant is rapid,complex cardiac machines and similar equipment to enable increasingly complexsurgery,and injuries and ill patients life functions can be sustained.Someenviromental control mechanical engineers through the initial efforts to drainage or irrigation pumping to the land and to mine and ventilation to control the human environment.Modern refrigeration and air-conditioning plant commonaly used reverse heat engine,where the heat from the engine from cold places to more external heat.Many mechanical engineering products,as well as other leading technology development city have side effects on the environment,producingnoise,water and air pollution caused,destroyed land and landscape.Improve productivity and diver too fast in the commodity,that the renewable natural forces keep pace.For mechanical engineers and others,environmental control is rapidly developing area,which includes a possible development and production of small quantities of pollutants machine sequnce,and the development of new equipment and teachnology has been to reduce and eliminate pollution.4.The role of mechanical engineeringThere are four generic mechanical engineers in common to the above all domains function.The 1st function is the understanding and the research mechanical sciencefoundation.It includes the power and movement of the relationship dynamics For example,in the vibration and movement of the relationship;Automaticcontrol;Study of the various forms of heart,energy,power relations between the thermodynamic;Fluidflows; Heat transfer; Lubricant;And material properties.The 2nd function will be conducts the research,thedesing and the development,this function in turn attempts to carry on the essential change to satisfy current and the future needs.This not only calls for a clear understanding of mechanical science,and have to break down into basic elements of a complex system capacity.But also the need for synthetic and innovative inventions.The 3rd function is produces the product and the power,includeplan,operation and maintenance.Its goal lies in the maintenance either enhances the enterprise or the organization longer-tern and survivabilaty prestige at the same time,produces the greatest value by the least investments and the consumption.The 4th function is mechanical engineer’s coordinated function,including the management,theconsultation,as well as carries on the market marking in certain situation.In all these function,one kind unceasingly to use thescience for a long time the method,but is not traditional or the intuition method tendency,this is a mechanical engineering skill aspect which unceasingly grows.These new rationalization means typical names include:The operations research,the engineering economics,the logical law problem analysis(is called PABLA) However,creativity is not rationalization.As in other areas,in mechanicalengineering, to take unexpected and important way to bring about a new capacity,still has a personal,markedcharacteristice.5.The design of mechanical engineeringThe design of mechanical is the design has the mechanical property the thing or the system,suchas:the instrument and the measuring appliance in very many situations,the machine design must use the knowledge of discipline the and so on mathematics,materials science and mechanics.Mechanical engineering desginincludeing all mechanical desgin,but it was a study,because it also includes all the branches of mechsnicalengineering,such as thermodynamics all hydrodynamics in the basic disciplines needed,in the mechanical engineering design of the initial stude or mechanical design.Designstages.The entire desgin process from start to finish,in the process,a demand that is designed forit and decided to do the start.After a lot of repetition,the final meet this demand by the end of the design procees and the plan.Designconsiderations.Sometimes in a system is to decide which parts needs intensity parts of geometric shapes and size an important factor in this context that we must consider that the intensity is an important factor in the design.When we use expression design considerations,we design parts that may affect the entire system design features.In the circumstances specified in the design,usually for a series of such functions must be taken into account.Howeever,to correct purposes,we should recognize that,in many cases the design of important design considerations are not calculated or test can determine the components or systems.Especiallystudents,wheen in need to make important decisions in the design and conduct of any operation that can not be the case,they are often confused.These are not special,they occur every day,imagine,forexample,a medical laboratory in the mechanical design,from marketing perspective,people have high expectations from the strength and relevance of impression.Thick,and heavy parts installed together:to produce a solid impression machines.And sometimes machinery and spare parts from the design style is the point and not theother point of view.Our purpose is to make those you do not be misled to believe that every design decision will need reasonable mathematical methods.Manufacturing refers to the raw meterials into finished products in the enterprise.Create three distinct phases.Theyare:input,processingexprot.The first phase includes the production of all products in line with market needs essential.First there must be the demand for the product,the necessary materials,while also needs such as energy,time,human knowledge and technology resourcess . Finall,the need for funds to obtain all the other resources. Lose one stage after the second phase of the resources of the processes to be distributed.Processing of raw materials into finished products of these processes.To complete the design,based on the design,and then develop plans.Plan implemented through various production processes.Management of resources and processes to ensure efficiency and productivity.Forexample,we must carefully manage resources to ensure proper use of funds.Finally,people are talking about the product market was cast.Stage is the final stage of exporting finished or stage.Once finished just purchased,it must be delivered to the users.According to productperformance,installation and may have to conduct further debugging in addition,someproducts,especially those very complex products User training is necessary.6.The processes of materials and maunfacturingHere said engineering materials into two main categories:metals and non-ferrous,high-performance alloys and power metals.Non-metallic futher divided into plastice,syntheticrubber,composite materials and ceramics.It said the production proccess is divided into several major process,includingshape,forging,casting/founding,heattreatment,fixed/connections ,measurement/ quality control and materalcutting.These processes can be further divide into each other’s craft.Various stages of the development of the manufacturing industry Over the years,the manufacturing process has four distinct stages of development, despite the overlap.These stages are:The first phase is artisanal,the second Phase is mechanization.The third phase is automation the forth Phase is integrated.When mankind initial processing of raw materials into finished products will be,they use manual processes.Each with their hands and what are the tools manusllyproduced.This is totally integrated production take shape.A person needsindentification,collectionmaterials,the design of a product to meet that demand,the production of such products and use it.From beginning to end,everything is focused on doing the work of the human ter in the industrial revolution introduced mechanized production process,people began to use machines to complete the work accomplished previously manual. This led to the specialization.Specialization in turn reduce the manufacture of integrated factors.In this stage of development,manufacturing workers can see their production as a whole represent a specific piece of the part of the production process.Onecan not say that their work is how to cope with the entire production process,or how they were loaded onto a production of parts finished.Development of manufacting processes is the next phase of the selection process automation.This is a computer-controlled machinery and processes.At this stage,automation island began to emerge in the workshop lane.Each island represents a clear production process or a group of processes.Although these automated isolated island within the island did raise the productivity of indivdualprocesses,but the overall productivity are often not change.This is because the island is not caught in other automated production process middle,but not synchronous withthem .The ultimate result is the efficient working fast parked through automated processes,but is part of the stagnation in wages down,causingbottlenecks.To better understand this problem,you can imagine the traffic in the peak driving a red light from the red Service Department to the next scene. Occasionally you will find a lot less cars,more than being slow-moving vehicles,but the results can be found by the next red light Brance.In short you real effect was to accelerate the speed of a red Department obstruction offset.If you and other drivers can change your speed and red light simultaneously.Will advance faster.Then,all cars will be consistent,sommthoperation,the final everyone forward faster.In the workshop where the demand for stable synchronization of streamlined production,and promoted integration of manufacturing development.This is a still evolving technology.Fully integrated in the circumstances,is a computer-controllrd machinery and processing.integrated is completed through computer.For example in the preceding paragraph simulation problems,the computer will allow all road vehicles compatible with the change in red.So that everyone can steady traffic.Scientific analysis of movement,timing and mechanics ofthe disciplines is that it is composed of two pater:statics and dynamics.Statics analyzed static system that is in the system,the time is not taken into account,research and analysis over time and dynamics of the system change.Dynameics from the two componets.Euler in 1775 will be the first time two different branches: Rigid body movement studies can conveniently divided into two parts:geometric and mechanics.The first part is without taking into account the reasons for the downward movement study rigid body from a designated location to another point of the movement,and must use the formula to reflect the actual,the formula would determine the rigid body every point position. Therefore,this study only on the geometry and,morespecifically,on the entities from excision.Obviously,the first part of the school and was part of a mechanical separation from the principles of dynamics to study movement,which is more than the two parts together into a lot easier.Dynamics of the two parts are subsequently divided into two separate disciplines,kinematic and dynamics,a study of movement and the movement strength.Therefore,the primary issue is the design of mechanical systems understand its kinematic.Kinematic studies movement,rather than a study ofits impact.In a more precise kinematic studies position,displacement,rotation, speed,velocity and acceleration of disciplines,foresample,or planets orbiting research campaing is a paradigm.In the above quotation content should be pay attention that the content of the Euler dynamics into kinematic and rigid body dynamics is based on the assumption that they are based on research.In this very important basis to allow for the treatment of two separate disciplines.For soft body,soft body shape and even their own soft objects in the campaign depends on the role of power in their possession.In such cases,should also study the power and movement,and therefore to a large extent the analysis of the increased complexity.Fortunately, despite the real machine parts may be involved are more or less the design of machines,usually with heavy material designed to bend down to the lowest parts.Therefore,when the kinematic analysis of the performance of machines,it is often assumed that bend is negligible,spare parts are hard,but when the load is known,in the end analysis engine,re-engineering parts to confirm this assnmption.机械工程1.机械工程简介机械工程是工程学的一个分支，它研究机械和动力的产，尤其是力和动力。

附录How Manual Transmissions WorkIf you drive a stick-shift car, then you may have several questions floating in your head.How does the funny "H" pattern that I am moving this shift knob through have any relation to the gears inside the transmission? What is moving inside the transmission when I move the shifter?When I mess up and hear that horrible grinding sound, what is actually grinding? What would happen if I were to accidentally shift into reverse while I am speeding down the freeway? Would the entire transmission explode?In this article, we'll answer all of these questions and more as we explore the interior of a manual transmission.Cars need transmissions because of the physics of the gasoline engine. First, any engine has a redline --a maximum rpm value above which the engine cannot go without exploding. Second, if you have read How Horsepower Works, then you know that engines have narrow rpm ranges where horsepower and torque are at their maximum. For example, an engine might produce its maximum horsepower at 5,500 rpm. The transmission allows the gear ratio between the engine and the drive wheels to change as the car speeds up and slows down. You shift gears so the engine can stay below the redline and near the rpm band of its best performance.Ideally, the transmission would be so flexible in its ratios that the engine could always run at its single, best-performance rpm value. That is the idea behind the continuously variable transmission (CVT).A CVT has a nearly infinite range of gear ratios. In the past, CVTs could not compete with four-speed and five-speed transmissions in terms of cost, size and reliability, so you didn't see them in production automobiles. These days, improvements in design have made CVTs more common. The Toyota Prius is a hybrid car that uses a CVT.The transmission is connected to the engine through the clutch. The input shaft of the transmission therefore turns at the same rpm as the engine.A five-speed transmission applies one of five different gear ratios to the input shaft toproduce a different rpm value at the output shaft.A Very Simple TransmissionTo understand the basic idea behind a standard transmission, the diagram below shows a very simple two-speed transmission in neutral:Let's look at each of the parts in this diagram to understand how they fit together:The green shaft comes from the engine through the clutch. The green shaft and green gear are connected as a single unit. (The clutch is a device that lets you connect and disconnect the engine and the transmission. When you push in the clutch pedal, the engine and the transmission are disconnected so the engine can run even if the car is standing still. When you release the clutch pedal, the engine and the green shaft are directly connected to one another. The green shaft and gear turn at the same rpm as the engine.) The red shaft and gears are called the layshaft. These are also connected as a single piece, so all of the gears on the layshaft and the layshaft itself spin as one unit. The green shaft and the red shaft are directly connected through their meshed gears so that if the green shaft is spinning, so is the red shaft. In this way, the layshaft receives its power directly from the engine whenever the clutch is engaged.The yellow shaft is a splined shaft that connects directly to the drive shaft through the differential to the drive wheels of the car. If the wheels are spinning, the yellow shaft is spinning.The blue gears ride on bearings, so they spin on the yellow shaft. If the engine is offbut the car is coasting, the yellow shaft can turn inside the blue gears while the blue gears and the layshaft are motionless.Now, let's see what happens when you shift into first gear.First GearIn this picture, the green shaft from the engine turns the layshaft, which turns the blue gear on the right. This gear transmits its energy through the collar to drive the yellow drive shaft. Meanwhile, the blue gear on the left is turning, but it is freewheeling on its bearing so it has no effect on the yellow shaft.When the collar is between the two gears (as shown in the first figure), the transmission is in neutral. Both of the blue gears freewheel on the yellow shaft at the different rates controlled by their ratios to the layshaft.From this discussion, you can answer several questions:When you make a mistake while shifting and hear a horrible grinding sound, you are not hearing the sound of gear teeth mis-meshing. As you can see in these diagrams, all gear teeth are all fully meshed at all times. The grinding is the sound of the dog teeth trying unsuccessfully to engage the holes in the side of a blue gear.The transmission shown here does not have "synchros" (discussed later in the article), so if you were using this transmission you would have to double-clutch it. Double-clutching was common in older cars and is still common in some modern race cars. In double-clutching, you first push the clutch pedal in once to disengage the engine from the transmission. This takes the pressure off the dog teeth so you can move the collar into neutral. Then you release the clutch pedal and rev the engine to the "right speed." The right speed is the rpm value at which the engine should be running in the next gear. The idea is to get the blue gear of the next gear and the collar rotating at the same speed so that the dog teeth can engage. Then you push the clutch pedal in again and lock the collar into the new gear. At every gear change you have to press and release the clutch twice, hence the name "double-clutching."You can also see how a small linear motion in the gear shift knob allows you to change gears. The gear shift knob moves a rod connected to the fork. The fork slides the collar on the yellow shaft to engage one of two gears.In the next section, we'll take a look at a real transmission.A Real TransmissionThere are three forks controlled by three rods that are engaged by the shift lever. Looking at the shift rods from the top, they look like this in reverse, first and second gear: Keep in mind that the shift lever has a rotation point in the middle. When you push the knob forward to engage first gear, you are actually pulling the rod and fork for first gear back.You can see that as you move the shifter left and right you are engaging different forks (and therefore different collars). Moving the knob forward and backward moves the collar to engage one of the gears。

Manual transmissionManual transmission is the most basic of transmission of a type, its effect is changing, and provide the transmission reverse and neutral. Usually, the pilot on the clutch pedal through manipulation and in any HuanDangGan can choose between gear. There are a few manual transmission, such as motorcycles, cars, some transmission shift transmission allows only sequence, the transmission is called sequence shift transmission. In recent years, along with the electronic control components durability, computerized automatic switching clutch automatic shift of transmission in Europe since the start line are more and more popular, car V olkswagen and ford are sold in the city on the double clutch provide updated generation, transmission from the start with two clutches, every shift automatically switch to another group of clutch engagement, need not as quick as traditional in manual have only one group separated again clutch engagement, shifting speed is faster, more small change gear vibration.Internal structure: shaftDecorate a form of transmission shaft type usually have two and three shaft type two kinds. Usually a rear wheel drive car will adopt three axis type, i.e. input shaft transmission, the output shaft and oart. Input shaft front associated with engine, borrow clutch output shaft back-end through the flange and universal transmission device connected.Input shaft and the output shaft in the same horizontal line, with their oart parallel arrangement. From the input shaft power through the gears to preach to the output shaft oart again. In many input and output shaft transmission shaft could engage in together, so to power, then the gear oart called directly. Direct files through uniaxial transmission, the ratio of 1:1, the highest transmission efficiency. Even in the transmission directly, cannot offer the input shaft, and the output shaft is decorated in a straight line to reduce work needed to inherit the torque transmission.Reversing deviceGenerally speaking, the reverse gear reducer than can alsosynchronizerIn synchronized meshing gears have type synchronizer Settings, can make two gear engagement in the first, before the speed reached synchronizer in all of this manual geartransmission of the car has been usedClutch,The clutch is can make two gear with a separate with mechanical parts, two gear transmission power can be combined, but when to speed, so will depend on the first two gear clutch, change gear ratio, the two gear transmission power, continue again Control：GearIn simple terms, the high speed, low speed ShengDang when the time cameEvery car high speedCompared with automatic transmissionThis refers to the automatic transmission of traditional hydraulic transmission, namely through hydraulic torque converter and planetary gear transmission power automatic transmission.Advantages：transmission efficiency than automatic gearboxes for high, of course, theoretically can compare economical.maintenance will be cheaper than transmission.If you want to higher cost, can begin from both the row of convenience and high power手动变速器手动变速器是汽车变速器中最基本的一种类型，其作用是改变传动比，并提供倒档和空档。

附录外文文献Manual transmission is the most basic of transmission of a type, its effect is changing, and provide the transmission reverse and neutral. Usually, the pilot on the clutch pedal through manipulation and in any HuanDangGan can choose between gear. There are a few manual transmission, such as motorcycles, cars, some transmission shift transmission allows only sequence, the transmission is called sequence shift transmission. In recent years, along with the electronic control components durability, computerized automatic switching clutch automatic shift of transmission in Europe since the start line are more and more popular, car Volkswagen and ford are sold in the city on the double clutch provide updated generation, transmission from the start with two clutches, every shift automatically switch to another group of clutch engagement, need not as quick as traditional in manual have only one group separated again clutch engagement, shifting speed is faster, more small change gear vibration.Internal structure: shaftDecorate a form of transmission shaft type usually have two and three shaft type two kinds. Usually a rear wheel drive car will adopt three axis type, i.e. input shaft transmission, the output shaft and oart. Input shaft front associated with engine, borrow clutch output shaft back-end through the flange and universal transmission device connected.Input shaft and the output shaft in the same horizontal line, with their oart parallel arrangement. From the input shaft power through the gears to preach to the output shaft oart again. In many input and output shaft transmission shaft could engage in together, so to power, then the gear oart called directly. Direct files through uniaxial transmission, the ratio of 1:1, the highest transmission efficiency. Even in the transmission directly, cannot offer the input shaft, and the output shaft is decorated in a straight line to reduce work needed to inherit the torque transmission.Reversing deviceGenerally speaking, the reverse gear reducer than can alsosynchronizerIn synchronized meshing gears have type synchronizer Settings, can make two gear engagement in the first, before the speed reached synchronizer in all of this manual gear transmission of the car has been usedClutch,The clutch is can make two gear with a separate with mechanical parts, two gear transmission power can be combined, but when to speed, so will depend on the first two gear clutch, change gear ratio, the two gear transmission power, continue againControl：GearIn simple terms, the high speed, low speed ShengDang when the time came Every car high speedCompared with automatic transmissionThis refers to the automatic transmission of traditional hydraulic transmission, namely through hydraulic torque converter and planetary gear transmission power automatic transmission.Advantages： transmission efficiency than automatic gearboxes for high, of course, theoretically can compare economical.maintenance will be cheaper than transmission.If you want to higher cost, can begin from both the row of convenience and high power附录外文文献的中文翻译手动变速器是汽车变速器中最基本的一种类型，其作用是改变传动比，并提供倒档和空档。

附录附录A.Manual TransmissionIt’s no secret that cars with manual transmissions are usually more fun to drive than the automatic-equipped counterparts. If you have even a passing interest in the act of driving, then chances are you also appreciate a fine-shifting manual gearbox. But how does a manual transmission actually work?A history hows that manual transmissions preceded automatics by several decades. In fact，up until General Motors offered an automatic in 1938, all cars were of the shift-it-yourself variety. While it’s logical for many types of today’s vehicles to be equipped with an automatic――such as a full-size sedan, SUV or pickup――the fact remains that nothing is more of a thrill to drive than a tautly suspended sport sedan, snort coupe or two-sealer equipped with a precise-shifting five-or six-speed gearbox．We know whicn types or cars have manual trannies. Now let’s take a loo k at how they work. From the most basic four-speed manual in a car from the’60s to the most high-tech six-speed one in a car of today, the principles of a manual gearbox are the same. The driver must shift from gear to gear. Normally, a manual transmission bolts to a clutch housing (or bell housing）, in turn, bolts to the back of the engine. If the vehicle has front-wheel drive, the transmission still attaches to the engine in a similar fashion but is usually referred to as a transaxle. This is because the transmission, differential and drive axles are one complete unit. In a front-wheel-drive car, the transmission also serves as part of the front axle for the front wheels. In the remaining text, a transmission and a transaxle will both be referred to using the term transmission.The function of any transmission is transferring engine power to the driveshaft and rear wheels (or axle halfshafts and front wheels in a front-wheel-drive vehicle). Gears inside the transmission change the vehicle’s drive-wheel speed and torque in relation to engine speed and torque．Lower(numerically higher) gear ratios serve as torque multipliers and help the engine to develop enough power to accelerate from a standstill.Initially, power and torque from the engine comes into the front of the transmissions and rotates the main drive gear (or input shaft), which meshes with the cluster or countersha ft gear――a series of gears forged into one piece that resembles a cluster of gears. The cluster-gear assembly rotates any time the clutch is engaged to a running engine，whether or not the transmission is in gear or in neutral.There are two basic types of manual transmissions. The sliding-gear type and the constant-mesh design. With the basic――and now obsolete――sliding-gear type，nothing is turning inside the transmission case except the main drive gear and cluster gear when the trans is in neutral. In order to mesh the gears and apply engine power to move the vehicle, the driver presses the clutch pedal and moves the shifter handle, which in turn moves the shift linkage and forks to slide a gear along the mainshaft, which is mounted directly above the clust er. Once the gears are meshed, the clutch pedal is released and the engine’s power is sent to the drive wheels. There can be several gears on the mainshaft of different diameters and tooth counts, and the transmission shift linkage is designed so the driver has to unmesh one gear before being able to mesh another. With these older transmissions, gear clash is a problem because the gears are all rotating at different speeds.All modern transmissions are of the constant-mesh type, which still uses a similar gear arrangement as the sliding-gear type. However，all the mainshaft gears are in constant mesh with the cluster gears. This is possible because the gears on the mainshaft are not splined to the shaft, but are free to rotate on it. With a constant-mesh gearbox, the main drive gear, cluster gear and all the mainshaft gears are always turning, even when the transmission is in neutral.Alongside each gear on the mainshaft is a dog clutch, with a hub that’s positively splined to the shaft and an outer ring that can slide over against each gear. Both the mainshaft gear and the ring of the dog clutch have a row of teeth. Moving shift linkage moves the dog clutch against the adjacent mainshaft gear, causing the teeth to interlock and solidly lock the gear to the mainshaft.To prevent gears from grinding or clashing during engagement, a constant-mesh, fully "synchronized" manual transmission is equipped with synchronizers. A synchronizer typically consists of an inner-splined hub, an outer sleeve, shifter plates，lock rings（or springs）and blocking rings. The hub is splined onto the mainshaft between a pair of main drive gears. Held in place by the lock rings，the shifter plates position the sleeve over the hub while also holding the floating blocking rings in proper alignment.A synchro’s inner hub and sleeve are made of steel, but the blocking ring――the partof the synchro that rubs on the gear to change its speed――is usually made of a softer material, such as brass. The blocking ring has teeth that match the teeth on the dog clutch. Most synchros perform double duty――they push the synchro in one direction and lock one gear to the mainshaft. Push the synchro the other way and it disengages from the first gear, passes through a neutral position, and engages a gear on the other side.That’s the basics on the inner workings of a manual transmission. As for advances, they have been extensive over the years, mainly in the area of additional gears. Back in the 60’s, four-speeds were common in American and European performance cars．Most of these transmissions had 1:1 final-drive ratios with no overdrives. Today, overdriven five-speeds are standard on practically all passenger cars available with a manual gearbox.Overdrive is an arrangement of gearing that provides more revolutions of the driven shaft（the driveshaft going to the wheels）than the driving shaft（crankshaft of the engine）. For example, a transmission with a fourth-gear ratio of 1:1 and a fifth-gear ratio of 0.70:1 will reduce engine rpm by 30 percent, while the vehicle maintains the same road speed. Thus, fuel efficiency will improve and engine wear will be notably reduced. Today, six-speed transmissions are becoming more and more common. One of the first cars sold in America with a six-speed was the ’89 Corvette. D esigned by Chevrolet and Zahnradfabrik Friedrichshafen（ZF）and built by ZF in Germany, this tough-as-nails six-speed was available in the Corvette up to the conclusion of the ’96 model year. Today，the Corvette uses a Tremec T56 six-speed mounted at the back of the car.Many cars are available today with six-speeds, including the Mazda Miata, Porsche Boxster S and 911, Dodge Viper, Mercedes-Benz SLK320, Honda S2000, Toyota Celica GT-S and many others. Some of these gearboxes provide radical 50-percent (0.50:1) sixth-gear overdrives such as in the Viper and Corvette, while others provide tightly spaced gear ratios like in the S2000 and Celica for spirited backroad performance driving. While the bigger cars mentioned above such as the Viper and Vette often have two overdrive ratios（fifth and sixth）the smaller cars like the Celica and S2000 usually have one overdriven gear ratio（sixth) and fifth is 1:1.Clearly a slick-shifting manual transmission is one of the main components in a fun-to-drive car, along with a powerful engine，confidence-inspiring suspension and competent brakes.附录B.手动变速器相对于自动变速箱的车手动变速箱汽车开起来有更好的驾驶乐趣这是众所周知的。

附录A 英文文献Transmission descriptionTransmission gearbox's function the engine's output rotational speed is high, the maximum work rate and the maximum torque appears in certain rotational speed area. In order to display engine's optimum performance, must have a set of variable speed gear, is coordinated the engine the rotational speed and wheel's actual moving velocity. The transmission gearbox may in the automobile travel process, has the different gear ratio between the engine and the wheel, through shifts gears may cause the engine work under its best power performance condition. Transmission gearbox's trend of development is more and more complex, the automaticity is also getting higher and higher, the automatic transmission will be future mainstream.Automotive Transmission's mission is to transfer power, and in the process of dynamic change in the transmission gear ratio in order to adjust or change the characteristics of the engine, at the same time through the transmission to adapt to different driving requirements. This shows that the transmission lines in the automotive transmission plays a crucial role. With the rapid development of science and technology, people's car is getting higher and higher performance requirements, vehicle performance, life, energy consumption, such as vibration and noise transmission depends largely on the performance, it is necessary to attach importance to the study of transmission.Transmission gearbox's pattern the automobile automatic transmission common to have three patterns: Respectively is hydraulic automatic transmission gearbox (AT), machinery stepless automatic transmission (CVT), electrically controlled machinery automatic transmission (AMT). At present what applies is most widespread is, AT becomes automatic transmission's pronoun nearly.AT is by the fluid strength torque converter, the planet gear and the hydraulic control system is composed, combines the way through the fluid strength transmission and the gear to realize the speed changebending moment. And the fluid strength torque converter is the most important part, it by components and so on pump pulley, turbine wheel and guide pulley is composed, has at the same time the transmission torque and the meeting and parting function.And AT compare, CVT has omitted complex and the unwieldy gear combination variable transmission, but is two groups of band pulleys carries on the variable transmission. Through changes the driving gear and the driven wheel transmission belt's contact radius carries on the speed change. Because has cancelled the gear drive, therefore its velocity ratio may change at will, the speed change is smoother, has not shifted gears kicks the feeling.AMT and the hydraulic automatic transmission gearbox (AT) is the having steps automatic transmission equally. It in the ordinary manual transmission gearbox's foundation, through installs the electrically operated installment which the microcomputer controls, the substitution originally coupling's separation which, the joint and the transmission gearbox completes by the manual control elects to keep off, to shift gears the movement, realizes fluid drive.Manual transmission gear mainly uses the principle of deceleration. Transmission within the group have different transmission ratio gear pair, and the car at the time of shift work, that is, through the manipulation of institutions so that the different transmission gear pair work. Manual transmission, also known as manual gear transmission, with axial sliding in the gears, the meshing gears through different speed to achieve the purpose of torque variation. Manual shift transmission can operate in full compliance with the will of the driver, and the simple structure, the failure rate is relatively low, value for money.Automatic transmission is based on speed and load (throttle pedal travel) for two-parameter control gear in accordance with the above two parameters to automatically take-off and landing. Automatic transmission and manual transmission in common, that is, there are two-stage transmission, automatic transmission can only speed the paceto automatically shift, manual transmission can be eliminated, "setback" of the shift feel.Automatic transmission is a torque converter, planetary gears and hydraulic manipulation of bodies, through the hydraulic transmission and gear combination to achieve the purpose of variable-speed torque variation.Also known as CVT-type continuously variable CVT. This transmission and automatic transmission gear generally the biggest difference is that it eliminates the need of complex and cumbersome combination of variable-speed gear transmission, and only two groups to carry out variable-speed drive pulley.CVT transmission than the traditional structure of simple, smaller and it is not the number of manual gear transmission, no automatic transmission planetary gear complex group, mainly rely on the driving wheel, the driven wheel and the transmission ratio brought about by the realization of non-class change.Widely used in automotive internal combustion engine as a power source, the torque and speed range is very small, and complex conditions require the use of motor vehicles and the speed of the driving force in the considerable changes in the scope. To resolve this contradiction, in the transmission system to set up the transmission to change transmission ratio, the expansion of the driving wheel torque and speed range in order to adapt to constantly changing traffic conditions, such as start, acceleration, climbing and so on, while the engine in the most favorable conditions to work under the scope; in the same direction of rotation of the engine under the premise of the automobile can be driven back; the use of neutral, interruption of power transmission, in order to be able to start the engine, idle speed, and ease of transmission or power shift . Transmission is designed to meet the above requirements, so that the conditions in a particular vehicle stability.In addition to transmission can be used to meet certain requirements, but also to ensure that it and the car can have a good match, and can improve the car's power and economy to ensure that theengine in a favorable condition to increase the scope of the work of the use of motor vehicles life, reduce energy consumption, reduce noise, such as the use of motor vehicles.Today the world's major car companies CVT are very active in the study. The near future, with electronic control technology to further improve, electronically controlled Continuously Variable Transmission-type is expected to be a wide range of development and application.附录B 文献翻译变速器介绍发动机的输出转速非常高，最大功率及最大扭矩在一定的转速区出现。

汽车变速器的设计外文文献翻译、中英文翻译、外文翻译A manual n。

also known as a standard n。

XXX。

It consistsof gears。

synchros。

roller bearings。

shafts。

and gear selectors。

The main clutch assembly is used to engage and disengage the engine from XXX gears are used to select the desired。

and the sector fork moves gears from one to another using the gearshift knob。

Synchros are used to slow the gear to a。

before it is XXX。

The counter shaft holds the gears in place and against the main input and output shaft。

Unlike automatic ns。

XXX。

as there isno XXX。

Note: XXX "n Shifter" was deleted as it had no XXX.)XXX have four to six forward gears and one reverse gear。

However。

some cars may have up to eight forward gears。

while semi trucks XXX by the number of forward gears。

such as a 5-speed standard n.The n of a standard n includes three shafts: the input shaft。

本科毕业设计（论文）英文资料翻译*****指导教师：孙飞豹（副教授）学科、专业：车辆工程沈阳理工大学应用技术学院2011年12月20日transmission used in automobilesA standard transmission or manual transmission is the traditional type of transmission used in automobiles. The manual or standard transmission consists of a series of gears, synchros, roller bearings, shafts and gear selectors. The main clutch assembly is used to engage and disengage the engine from the transmission. Heliacal cut gears are used to select the ratio desired the sector fork move gears from one to another by using the gearshift knob. Synchros are used to slow the gear to a stop before it is engaged to avoid gear grinding, the counter shaft hold the gears in place and against the main input and output shaft. A stick shift transmission has no torque converter so there is no need for a transmission cooler. A stick shift transmission needs a simple fluid change for proper service. (there is no transmission filter in a stick shift transmission).Transmission ShifterMost manual transmissions have one reverse gear and four to six forward gears. Some cars also have eight forward gears while thirteen to twenty-four gears are present in semi trucks. To differentiate among the available standard transmissions, they are addressed by the number of forward gears. For example, if the standard transmission has five gears, it will be referred to as 5-speed standard transmission or 5-speed standard.Typical Standard Transmission ConfigurationInside the transmission shafts contain all forward and reverse gears. Most transmissions contain three shafts: input shaft, output shaft and counter or lay shaft. Other than standard transmission, there are other transmissions like continuously variable transmission, automatic transmission and semi-automatic transmission. In the manual transmission, a pair of gears inside the transmission selects the gear ratios. Whereas, in an automatic transmission, combination of brake bands and clutch packs control the planetary gear which selects the gear ratio.If there is a provision to select a gear ratio manually in automatic transmissions, the system is called a semi-automatic transmission. The driver can select from any of the gears at any pointof time. In some automobiles like racing cars and motorcycles that have standard transmissions, the driver can select the preceding or the following gear ratio with no clutch operation needed. This type of standard transmission is known as sequential transmission. In this transmission the clutch is still used for initial take off.Clutch and Flywheel AssemblyThe main clutch plays the role of a coupling device which separates the transmission and the engine. If the clutch is absent and the car comes to a stop the engine will stall. In automobiles, the clutch can be operated with the help of a pedal located on the floor of the vehicle. In an automatic transmission instead of a clutch, a torque converter is used to separate the transmission and engine.Typical Stick Shift PatternsA desired gear can be selected by a lever which is usually located on the floor in between the driver and passenger seat. This selector lever is called the gear lever or gear selector or gear shift or shifter. This gear stick can be made to move in right, left, forward and backward direction. When the gear is placed on the N position or neutral position, no gear will be selected. To move the car in the backward direction, the R gear or reverse gear should be selected.Standard transmissions are more efficient and less expensive to produce than automatic transmissions. A Standard transmission is about 15% more efficient compared to an automatic transmission. Standard transmissions are generally stronger than automatic transmissions and off road vehicles take advantage of a direct gear selection so they can withstand rough conditions. Less active cooling is also required in manual transmission system because less power is wasted.●Popular Problem ChecksCar will not go into gearClutch disc is broken completelyInternal transmission damageFailed clutch master cylinderSeized clutch slave cylinderBroken clutch fork pivotBroken clutch cableCar goes into gear but it fades out or is slippingClutch is worn out and needs replacementClutch is oil soaked from a external engine oil leakCar makes grinding noise while operating or shifting gearsOne of the roller or thrust bearings has failedThe gear synchro is worn out not forcing the gear stop before it is engaged causing a grinding gear.A counter or main shaft bearing has failed causing misalignment of the gears●Troubleshooting Noise and ProblemsIf the vehicle is running and a whirring sound is heard, then it goes away when the clutch is depressed, the transmission input bearing has failed.If the transmission is quiet in neutral but when you depress the clutch a squeaking noise is observed, a clutch throw out bearing has failed.Tips:Never let little noises go unattended; a small noise can cause a large noise and transmission operation failure. Never overload a vehicle or tow beyond the capacity this can cause premature transmission failure.汽车变速器汽车传统变速器是那种标准的手动变速器。

TRANSMISSIONManual transmission is one of the most common transmission, referredto as MT. Its basic structure in a single sentence is a central axis, twoinput shaft, namely, the axial and axial oart, they constituted the transmission of the subject, and, of course, a reverse axis. Manual transmission gear transmission and manual, contain can in axial sliding gears, through different meshing gears to change gear of torsional purpose.The typical structure and principle of the manual transmission.Input shaft also says, it's in front of the spline shaft directly withclutch platen, thus the spline set by the engine relay of torque. The firstshaft gear meshing gears, often with oart as input shaft, and the gear on oart will turn. Also called shaft, because even more solid shaft of gear. The output shaft, and the second shaft position have the drive shaftgear, may at any time and under the influence of the control devices and the corresponding oart gear, thus changing the speed and torque itself. The output shaft is associated with tail spline shaft torque transmissionshaft, through to drive to gear reducer.Predictably, transmission gear drive forward path is: input shaftgear - oart gnaws gnaws gear - because the second shaft gear - corresponding corresponding gear. Pour on the axle gear can also controldevice, by moving axis in the strike, and the output shaft gear and oart gear, in the opposite direction.Most cars have five forward and reverse gear, each one has certain ratio,the majority of gear transmission more than 1, 4 gears transmission is 1, called directly, and ratio is less than 1 of article 5 gear shift accelerated called. The output axis gear in the mesh position, can acceptpower transmission.Due to the gearbox output shaft to input shaft and the speed of theirgear rotating, transform an "synchronization problem". Two rotating speeddifferent meshing gears forcibly inevitable impact and collision damage gear. Therefore, the old transmission shift to use "two feet clutch" method, ShengDang in neutral position shift to stay for a while, in the space location on the door, in order to reduce gear speed. But this operation is more complex, difficult to grasp accurately. Thereforedesigners to create "synchronizer", through the synchronizer will makethe meshing gears reach speed and smooth.Currently the synchronous transmission adopts is inertial synchronizer, it mainly consists of joints, synchronizer lock ring etc,it is characteristic of the friction effect on achieving synchronization.Mating, synchronizer and mating locking ring gear tooth circle have chamfering (locking horns), the synchronizer lock ring inside surface ofgear engagement ring and the friction surface contact. The lock horns with cone when designing the proper choice, has been made to the surface friction of meshing gears with gear synchronous, also can rapid producesa locking function, prevent the synchronous before meshing gears. When synchronous lock ring of gear engagement with surface contact surface, the outer circle in friction torque under the action of gear speed rapiddecrease (increase) or to synchronous speed equal, both locking ring spunconcurrent, relative to lock ring gear synchronous speed is zero, thus inertia moment also disappear, then in force, driven by the junction of unimpeded with synchronous lock ring gear engagement, and further to engagement with the engagement ring gear tooth and complete shift process.functional (1) change ratio, meet different driving conditions for tractionengine, the need to work in the favorable conditions and meet the speed may request. In a wide range of vehicle speed changing the size and automobile driving wheel on the size of the torque. Due to the differentdemands, automobile driving conditions of vehicle speed and torque can drive in a broad range of change. For example, in high speed can be reachedon 100km/h, while in the urban district, speed in 50km/h. In the empty flat roads, road, very little resistanceWhen When carrying carrying carrying uphill, uphill, uphill, driving driving driving resistance resistance resistance was was was great. great. great. And And And the thecharacteristics of automobile engine speed range is lesser, and torque changes more cannot meet the actual conditions range. (2) drive backward, to satisfy the need to drive car backwards. Realizing the backing, engine crankshaft are generally only to a direction,and sometimes need to back, so, often used in the transmission of reverseto realize the car drive backward.(3) in power, interruption, idle running engine starting, auto shift or need to stop the dynamic output, interrupted to transfer the power ofthe drive wheels.(4), when the clutch engagement realize gap, gearbox can not power output. For example, can ensure drivers in engine flameout loosen the clutch when leaving drivers seat.constituteBy continuously variable transmission gearbox and speed control twoparts. The main function of the variable transmission torque and speed is the change of numerical and direction, The main function of theoperation is controlled transmission mechanism, realize thetransformation of transmission ratio, shift to speed torque. Principle,Mechanical transmission main application of the principle of geartransmission velocity. Say simply, there are a number of differenttransmission gearbox group of gear pair of vehicle, and behavior, is alsoshifting gears trunk by manipulating institutions make different gearpair work. As in low-speed, ratio of gear pair work, and in high-speed, let ratio of small gear pair work.Classification,1, according to the change of transmission, transmission way, there can be divided into grade level and synthetical three.(a) : several levels of transmission ratio, can choose the fixed by gear. And can be divided into: gear axis of ordinary gear transmission and fixed gear planetary gear (part) of planetary gear transmission axisof rotation.b) stepless type transmission: ratio can be continuous variation within a certain range, commonly, mechanical and electric hydraulic typeetc.(c) comprehensive type transmission by a class type, transmission andstepless type transmission, the ratio of the maximum and minimum values can be in between the scope for several section stepless change.2, press control can be divided into compulsory manipulation, transmission, automatic control and semi-automatic control 3 kinds.(a) mandatory manipulation of transmission by direct manipulation, change gear shift lever drivers.(b) automatic control type transmission ratio of choice and change: the shift is automatic. Drivers simply manipulate accelerated pedal, transmission can according to the engine speed and load control signal signal actuator, realize the transformation of gear.(c) semi-automatic control type transmission can be divided into twokinds: one kind is part of gear, automatic shift gears, manual (mandatory)shift, Another kind is selected by button in mining under gear clutch pedalor accelerated release pedal, the executing agency to shift. Transmission of maintenance1 transmission gears maintenanceTransmission gears are always changing speed, load, gear toothsurface by bluntThe impact of load, which struck gear tooth surface (especially) damage. Common injuries are:(1) gear transmission is worn gear under normal working conditions, shows the wear uniform angled tooth gear, long wear along the directionTooth thickness shouldof the tooth should not exceed 30 percent longer,not exceed usd, Gear tooth surface area of not less than two-thirds, Running gear mesh clearance shall be commonly used, 0.15-0.26 mm to 0.8 mm limit, Gear engagement between 0.10-0.15 mm, should use limit for 0.60mm. Available batches or soft metal rivalries. If more than clearance method for measuring the pairs, should be replaced.due to fail togear clearance is mainly(2) gear teeth,broken toothmeet the requirements, gear meshing parts or work under great impact load.If you are not greater than 2mm edge of gear oil can smile ShiXiuafter-grinding continue to use, If the scope or have more than three pairs,should smile.(3) often mesh surface of the helical gear often wear face due. 10-0.30mm, in order to ensure that the axial clearance, if tooth gear good operation within the wear, can repair tank, but the amount of grinding grinding should not exceed. 50.(4) often meshing gears shaft neck, needle roller bearing and wear into seat hole hole meshing gears seat with needle bearings and shaft neckwith clearance should be 0.01 - three 0.08 mm, otherwise must be changed.2 the overhaul. Transmission shellGearbox shell is transmissions, to ensure the basis of each part of the transmission is correct position, work under load. Common injuries are:(1) the abrasion of shell bearing hole hole wear will destroy its bearing assembly relation with the bearing, the direct impact of input, output shaft transmission position relative to the hole. Bearing seat with0-0.03 mm clearance shall be used for the maximum limit, should be replacedor 0.10 mm) shell or pile hole repair.(2) shell threaded holes repair note oil ROM plug hole, dumping screwhole threads connecting bolts damage and between shellThreaded hole, can take damage with screw repair.3 transmission shaft of maintenanceTransmission in the process of operation, each bearing the torsionalmoment of change, and bending moment, JianChi part is under pressure, impact and sliding friction etc. Various axial load of common injuries are:(1) the shaft neck and neck too worn wear axis gear axis will not onlyoffset, and can bring the change gear clearance, when making noisetransmission shaft neck. Also make coordination relationship with bearingdamage, may cause ablation. So roller bearings in a place with no more than 0.02 axis wear mm needle bearing shaft neck wear with place, otherwisethan 0.07 mm landscape change or chrome.side of thein stress and more seriouswear JianChi wear(2) JianChispline. JianChi with check, when more than 0.25 or and wear with more thanusd keyway apprentice, gear engagement mm, combining with the gear with JianChi weeks, according to the mm apprentice woodruff key and shaft neckkeyways apprentice to JianChi 0.08 mm over there when the keyway weeks, or should be repaired or replaced shaft.(3) transmission shaft bending thimble resist transmission shaft withmaintenance on both ends of the roof, using pinhole batches of shaft radial micrometers, check the deviation should be less than 0.10 mm) pressure correction repair.4 synchronizer overhaulA. lock ring type inertial synchronizer ring maintenance: lock hornscone a about six degrees - 7 degrees, in use, cone Angle deformation ofrapid synchronous, and not be change in time. B. B. locking locking locking pin pin pin type type type inertial inertial inertial synchronizer: synchronizer: synchronizer: locking locking locking pin pin pin type type synchronizer major damage for cone rim wear, when, cone-disk cone rim on the thread of groove depth 0.40 mm wear to 010mm deep, should be replaced.If the cone rim are scratching, face to face, but two turning machining, must not be more than 1mm should be replaced.变速器手动变速器是最常见的变速器，简称MT MT。

MANUAL GEARBOXES9.1 MANUAL GEARBOX CLASSIFICATIONGearboxes are normally classified according to the number of toothed wheelcouples (stages) involved in the transmission of motion at a given speed; in thecase of manual vehicle transmissions, the number to be taken into account isthat of the forward speeds only, without consideration of the final gear, even ifincluded in the gearbox.Therefore there are:• Single stage gearboxes• Dual stage or countershaft gearboxes• Multi stage gearboxesFigure 9.1 shows the three configurations for a four speed gearbox.It is useful to comment on the generally adopted rules of these schemes. Each wheel is represented by a segment whose length is proportional to the pitchdiameter of the gear; the segment is ended by horizontal strokes, representingthe tooth width. If the segment is interrupted where crossing the shaft, thegear wheel is idle; the opposite occurs if the segment crosses the line of theshaft without interruption. Then the wheel rotates with the shaft. Hubs arerepresented according to the same rules, while sleeves are represented with apair of horizontal strokes. Arrows show the input and output shafts. Single stage gearboxes are primarily applied to front wheel driven vehicles,because in these it is useful that the input and the output shaft are offset; inG. Genta and L. Morello, The Automotive Chassis, Volume 1: Components Design, 425Mechanical Engineering Series,c Springer Science+Business Media B.V. 2009426 9. MANUAL GEARBOXES FIGURE 9.1. Schemes for a four speed gearbox shown in three differentconfigurations:a: single stage, b: double stage and c: triple stage.conventional vehicles, on the other hand, it is better that input and output shaftsare aligned.This is why rear wheel driven vehicles usually adopt a double stage gearbox.The multi-stage configuration is sometime adopted on front wheel driven vehicles with transversal engine, because the transversal length of the gearboxcan be shortened; it is used when the number of speeds or the width of the gearsdo not allow a single stage transmission to be used.It should be noted that on a front wheel driven vehicle with transversal engine, having decided on the value of the front track and the size of the tire,the length of the gearbox has a direct impact on the maximum steering angle ofthe wheel and therefore on the minimum turning radius.The positive result on the transversal dimension of multi-stage gearboxes isoffset by higher mechanical losses, due to the increased number of engaged gearwheels.It should be noted that in triple stage gearboxes, shown in the picture, theaxes of the three shafts do not lie in the same plane, as the scheme seems toshow. In a lateral view, the outline of the three shafts should be represented asthe vertices of a triangle; this lay-out reduces the transversal dimension of thegearbox. In this case and others, as we will show later, the drawing is representedby turning the plane of the input shaft and of the counter shaft on the plane ofthe counter shaft and of the output shaft.Gear trains used in reverse speed are classified separately. The inversion ofspeed is achieved by using an additional gear. As a matter of fact, in a train ofthree gears, the output speed has the same direction as the input speed, whilethe other trains of two gears only have an output speed in the opposite direction;the added gear is usually called idler.The main configurations are reported in Fig. 9.2.In scheme a, an added countershaft shows a sliding idler, which can match two close gears that are not in contact, as, for example, the input gear of thefirst speed and the output gear of the second speed. It should be noted that, inthis scheme, the drawing does not preserve the actual dimension of the parts.9.1 Manual gearbox classification 427FIGURE 9.2. Schemes used for reverse speed; such schemes fit every type of gearboxlay-out.Scheme b shows instead two sliding idlers, rotating together; this arrange-ment offers additional freedom in obtaining a given transmission ratio. The coun-tershaft is offset from the drawing plane; arrows show the gear wheels that matchwhen the reverse speed is engaged.Scheme c is similar to a in relation to the idler; it pairs an added specificwheel on the output shaft with a gear wheel cut on the shifting sleeve of the firstand second speed, when it is in idle position.Configuration d shows a dedicated pair of gears, with a fixed idler and ashifting sleeve.The following are the advantages and disadvantages of the configurations shown in the figure.• Schemes a, b and c are simpler, but preclude the application of synchro-nizers (because couples are not always engaged), nor do they allow the useof helical gears (because wheels must be shifted by sliding).• Scheme d is more complex but can include a synchronizer and can adopt helical gears.• Schemes a, b and c do not increase gearbox length.428 9. MANUAL GEARBOXES9.2 MECHANICAL EFFICIENCYThe mechanical efficiency of an automotive gear wheel transmission is high com-pared to other mechanisms performing the same function; indeed, the value ofthis efficiency should not be neglected when calculating dynamic performanceand fuel consumption. The continuous effort of to limit fuel consumption justi-fies the care of transmission designers in reducing mechanical losses. Total transmission losses are conveyed up by terms that are both dependentand independent of the processed power; the primary terms are:• Gearing losses; these are generated by friction between engaging teeth(power dependent) and by the friction of wheels rotating in air and oil (power independent).• Bearing losses; these are generated by the extension of the contact area ofrolling bodies and by their deformation (partly dependent on and partly independent of power) and by their rotation in the air and oil (power independent).• Sealing losses; they are generated by friction between seals and rotatingshafts and are power independent.• Lubrication losses; these are generated by the lubrication pump, if present,and are power independent.All these losses depend on the rotational speed of parts in contact and, therefore, on engine speed and selected transmission ratio.Table 9.1 reports the values of mechanical efficiency to be adopted in calcu-lations considering wide open throttle conditions; these values consider a pair ofgearing wheels or a complete transmission with splash lubrication; in the sametable we can see also the efficiency of a complete powershift epicycloidal auto-matic transmission and a steel belt continuously variable transmission. For thetwo last transmissions, the torque converter must be considered as locked-up.TABLE 9.1. Mechanical efficiency of different transmission mechanisms. Mechanism type Efficiency (%)Complete manual gearboxwith splash lubrication 92–97Complete automatic transmission(ep. gears) 90–95Complete automatic gearbox(steel belt; without press. contr.) 70–80Complete automatic gearbox(steel belt; with press. contr.) 80–86Pair of cyl. gears 99.0–99.5Pair of bevel gears 90–939.2 Mechanical efficiency 429FIGURE 9.3. Contributions to total friction loss of a single stage gearbox designed for300 Nm as function of input speed.It is more correct to reference power loss measurement as a function ofrotational input speed rather than efficiency. Figure 9.3 shows the example ofa double stage transmission, in fourth speed, at maximum power; the differentcontributions to the total are shown.This kind of measurement is made by disassembling the gearbox step by step, thus eliminating the related loss.In the first step all synchronizer rings are removed, leaving the synchronizerhubs only; mechanical losses of non-engaged synchronizers are, therefore, mea-surable. The loss is due to the relative speed of non-engaged lubricated conicalsurfaces; the value of this loss depends, obviously, on speed and theselectedtransmission ratio.In the second step all rotating seals are removed.In the third step the lubrication oil is removed, and therefore, the bulk ofthe lubrication losses is eliminated; some oil must remain in order to leave thecontact between teeth unaffected.By removing those gear wheels not involved in power transmission, their mechanical losses are now measurable.The rest of the loss is due to bearings; the previous removal of parts canaffect this value.A more exhaustive approach consists in measuring the complete efficiency map; the efficiency can be represented as the third coordinate of a surface, wherethe other two coordinates are input speed and engine torque. Efficiency calcu-lations can be made by comparing input and output torque of a working trans-mission.Such map can show how efficiency reaches an almost constant value at a modest value of the input torque; it must not be forgotten that standard fuelconsumption evaluation cycles involve quite modest values of torque and there-fore imply values of transmission efficiency that are changing with torque.Figure 9.4 shows a qualitative cross section of the aforesaid map, cut atconstant engine speed. It should be noted that efficiency is also zero at input430 9. MANUAL GEARBOXESFIGURE 9.4. Mechanical efficiency map, as a function of input torque at constantengine speed; the dotted line represents a reasonable approximation of this curve, to beused on mathematical models for the prediction of performance and fuel consumption.torque values slightly greater than zero; as a matter of fact, frictionimplies acertain minimum value of input torque, below which motion is impossible.A good approximation to represent mechanical efficiency can be made using the dotted broken line as an interpolation of the real curve.9.3 MANUAL AUTOMOBILE GEARBOXES9.3.1 Adopted schemesIn manual gearboxes, changing speed and engaging and disengaging the clutchare performed by driver force only.This kind of gearbox is made with helical gears and each speed has a syn-chronizer; some gearboxes do not use show the synchronizer for reverse speed,particularly those in economy minicars.We previously discussed a first classification; additional information is thespeed number, usually between four and six.Single stage gearboxes are used in trans-axles; they are applied, with someexceptions, to front wheel driven cars with front engine and rear driven cars withrear engine; this is true with longitudinal and transversal engines. In all these situations the final drive is included in the gearbox, which istherefore also called transmission.Countershaft double stage gearboxes are used in conventionally driven cars,where the engine is mounted longitudinally in the front and the driving axle isthe rear axle. If the gearbox is mounted on the rear axle, in order to improve theweight distribution, the final drive could be included in the gearbox.9.3 Manual automobile gearboxes 431By multi-stage transmissions, some gear wheels could be used for differentspeeds. The number of gearing wheels could increase at some speeds; this nor-mally occurs at low speeds, because the less frequent use of these speeds reducesthe penalty of lower mechanical efficiency on fuel consumption.Cost and weight increases are justified by transmission length reduction,sometimes necessary on transversal engines with large displacement and morethan four cylinders.In all these gearboxes synchronizers are coupled to adjacent speeds (e.g.:first with second, third with fourth, etc.) in order to reduce overall length andto shift the two gears with the same selector rod.We define as the selection plane of a shift stick (almost parallel to the xzcoordinate body reference system plane for shift lever on vehicle floor) the planeon which the lever knob must move in order to select two close speed pairs. Forinstance, for a manual gearbox following many existing schemes, first, second,third, fourth and fifth speed are organized on three different selection planes; thereverse speed can have a dedicated plane or share its plane with the fifth speed.Figure 9.5 shows a typical example of a five speed single stage gearbox. Thefirst speed wheels are close to a bearing, in order to limit shaft deflection.In this gearbox the total number of tooth wheels pairs is the same as forthe double stage transmission shown in Fig. 9.6.While in the first gearbox there are only two gearing wheels for each speed,in the second there are three gearing wheels for the first four speeds and noneFIGURE 9.5. Scheme for a five speed single stage transmission, suitable for front wheeldrive with transversal engine.432 9. MANUAL GEARBOXESFIGURE 9.6. Scheme of an on-line double stage gearbox for a conventional lay-out.for the fifth. This property is produced by the presence of the so called constantgear wheels (the first gear pair at the left) that move the input wheels of thefirst four speeds; the fifth speed is a direct drive because the two parts of theupper shaft are joined together.The single stage gearbox in Fig. 9.5 shows the fifth speed wheel pair posi-tioned beyond the bearing, witness to the upgrading of an existing four speedtransmission; in this case the fifth speed has a dedicated selection plane.The double stage gearbox in Fig. 9.7 is organized in a completely differentway but also shows the first speed pair of wheels close to the bearing. The directdrive is dedicated to the highest speed; the fifth speed shows a dedicated selectionplane.Six speed double stage gearboxes do not show conceptual changes in com-parison with the previous examples; synchronizers are organized to leave firstand second, third and fourth, fifth and sixth speeds on the same selection plane.As already seen, the multistage configuration shown in Fig. 9.7 allows areasonable reduction of the length of the gearbox. In this scheme, only first andsecond speeds benefit from the second countershaft; power enters the counter-shaft through a constant gear pair of wheels and flows to the output shaft at areduced speed. Third, fourth and fifth speed have a single stage arrangement.Reverse speed is obtained with a conventional idling wheel.9.3.2 Practical examplesFour speed gearboxes represented the most widely distributed solution in Europeuntil the 1970s, with some economy cars having only three speeds.9.3 Manual automobile gearboxes 433FIGURE 9.7. Scheme of a triple stage five speed gearbox, suitable for front wheel drivencar with transversal engine.With the increase in installed power, the improvement in aerodynamic per-formance and increasing attention to fuel consumption, it became necessary toincrease the transmission ratio of the last speed, having the first speed remain atthe same values; as a matter of fact car weight continued to increase and engineminimum speed did not change significantly.To achieve satisfactory performance all manufacturers developed five speedgearboxes; this solution is now standard, but many examples of six speed gear-boxes are available on the market, not limited to sports cars. Figure 9.8 shows an example of a six speed double stage transmission withthe fifth in direct drive; here the first and second pair of wheels are close to thebearing.This rule is not generally accepted; on one hand having the most stressed pairs of wheels close to the bearing allows a shaft weight containment. On theother hand, having the most frequently used pairs of wheels close to the bearingreduces the noise due to shaft deflection.Synchronizers of fourth and third speed are mounted on the countershaft; this lay-out reduces the work of synchronization, improving shifting quality by anamount proportional to the dimension of the synchronizing rings. Synchronizersof first and second gear on the output shaft are, because of their diameter, larger434 9. MANUAL GEARBOXESFIGURE 9.8. Double stage six speed gearbox (GETRAG).than those of the corresponding gear; the penalty of the synchronizationwork ispaid by the adoption of a double ring synchronizer.Synchronizers on the countershaft offer a further advantage: In idle positionthe gears are stopped and produce no rattle; this subject will be studied later on.9.3 Manual automobile gearboxes 435Figure 9.9 introduces the example of a single stage gearbox for a front longitudinal engine. The input upper shaft must jump over the differential, whichis set between the engine and the wheels. The increased length of the shaftssuggested adopting a hollow section. Because of this length the box is dividedinto two sections; on the joint between the two sections of the box additionalbearings are provided to reduce the shaft deflection.The input shaft features a ball bearing close to the engine and three otherneedle bearings that manage solely the radial loads. The output shaft has twotapered roller bearings on the differential side and a roller bearing on the oppositeside. This choice is justified by the relevant axial thrust emerging from the bevelgears.The first and second speed synchronizers are on the output shaft and featurea double ring.The reverse speed gears are placed immediately after the joint (the idlergear is not visible) and have a synchronized shift. Remaining synchronizers areset in the second section of the box on the input shaft. The output shaft endswith the bevel pinion, a part of the final ratio.It should be noted that the gears of the first, second and reverse speeds aredirectly cut on the input shaft, in order to reduce overall dimensions. Most contemporary cars use a front wheel drive with transversal engine;thenumber of gearboxes with integral helical final ratio is, therefore, dominant.In these gearboxes geared pairs are mounted from the first to the last speed,starting from the engine side. An example of this architecture is given in Fig. 9.10.Like many other transmissions created with only four speeds, it shows thefifth speed segregated outside of the aluminium box and enclosed by a thin steelsheet cover; this placement is to limit the transverse dimension of the powertrain, in the area where there is potential interference with the left wheel in thecompletely steered position.This solution is questionable as far as the total length is concerned but showssome advantage in the reduction of the span between the bearings. Each bearingis of the ball type; on the side opposite to the engine the external ring of thebearing can move axially, to compensate for thermal differential displacements.One of the toothed wheels of the reverse speed is cut on the first and secondshifting sleeve.The casing is open on both sides; one of these is the rest of one of thebearings of the final drive. A large cover closes the casing on the engine side and,in the meantime, provides installation for the second bearing of the final driveand the space for the clutch mechanism; it is also used to join the gearbox tothe engine.In this gearbox synchronizers are placed partly on the input shaft and partlyon the output shaft.Figure 9.11 shows a drawing of a more modern six speed gearbox, in which it was possible to install all the gears in a conventional single stage arrangement,thanks to the moderate value of the rated torque.436 9. MANUAL GEARBOXES FIGURE 9.9. Single stage six speed gearbox for longitudinal front engine (Audi).9.4 Manual gearboxes for industrial vehicles 437FIGURE 9.10. Five speed transmission for a transversal front engine (FIAT).Gears are arranged from the first to the sixth, starting from the engine side; as we have already said this arrangement is demanded by the objectiveof minimizing shaft deflection. Only the synchronizers of first and second speedfound no place on the input shaft; they are of the double ring type, as for thefirst speed.The reverse speed is synchronized and benefits of a countershaft not shownin this drawing.9.4 MANUAL GEARBOXES FOR INDUSTRIALVEHICLES9.4.1 Lay-out schemesThe gearboxes we are going to examine in this section are suitable for vehicles ofmore than about 4 t of total weight; lighter vehicles, usually called commercialvehicles, adopt gearboxes that are derived from automobile production, as notedin the previous section.438 9. MANUAL GEARBOXESFIGURE 9.11. Six speed transmission for a transversal front engine (FIAT).Gearboxes used in industrial vehicles also feature synchronizers; they can beshifted directly, as in a conventional manual transmission, or indirectly with theassistance of servomechanisms. Non-synchronized gearboxes are sometimes usedon long haul trucks, because of their robustness. Assisted shifting mechanismsare widespread because of the easy availability of power media. Automatic orsemi-automatic transmissions are also used, the first type especially in buses.For gearboxes with four up to six speeds, the double stage countershaft architecture represents a standard; the scheme is the same as seen before.The constant gear couple is used for all speeds but the highest. Also notableis that the lowest speed wheels are close to the bearings.As shown in the drawings of Fig. 9.12, the highest speed can be obtained either in direct drive (scheme b) or with a pair of gears (scheme a); in this lastcase the direct drive is used for the speed before the last: these architectures arecalled direct drive and overdrive.In the figure, only the last and the first before the last speed are represented.The choice between the two alternatives can be justified by the different vehicle mission; virtually the same gearbox can be used on different vehicleswith different frequently used speeds (a truck and a bus for example).9.4 Manual gearboxes for industrial vehicles 439FIGURE 9.12. Alternative constant gear schemes with last or first before the last speedin direct drive.Sometime the constant gear is set on the output shaft, after the differentspeed gears; this configuration offers the following advantages:• Reduction of the work of synchronization, because of the smaller gear di-mension at the same torque and total transmission ratio• Less stress on the input shaft and countershaftOn the other hand, the following disadvantages emerge:• Bearings rotate faster.• Constant gear wheels are more highly stressed.This applies for single range transmissions.Multiple range transmissions feature, in addition to the main gearbox, othergearboxes that multiply the number of speeds of the main gearbox by the numberof their speeds. With this architecture the total number of gear pairs might bereduced, for a given number of speeds, and, sometime the use of the gearshiftlever can be simpler.This arrangement is used when more than six speeds are necessary. A multi-ple range transmission is therefore made out of a combination of different coun-tershaft gearboxes, single range gearboxes or epicycloidal gearboxes. Each added element is called a range changer if it is conceived as being capable of using the main gearbox speeds in sequence, in two completely non-overlapping series of vehicle speeds; for example, if the main gearbox has fourspeeds, the first speed in the high range is faster than the fourth speed in thelow range.The element is called a splitter if it is intended to create speeds that areintermediate to those of the main gearbox; in this case, for example the third440 9. MANUAL GEARBOXESFIGURE 9.13. Scheme of a 16 speed gearbox for industrial vehicles; it is made with afour gear main gearbox, a double speed splitter and a double speed range changer withdirect drive.speed in the high range is faster than the third speed in the low range, but slowerthan the fourth speed in the low range.We call the gearbox with the highest number of speeds the main gearbox; the splitter and the range changer will be set in series before and after the maingearbox.Figure 9.13 shows the scheme of a gearbox featuring a splitter and a rangechanger. The splitter is made out of a pair of wheels that work as twodifferentconstant gears for the main gearbox. The countershaft can therefore be movedat two different speeds, according to the position of the splitter unit. Becausethe main gearbox has four speeds, this splitter unit can create a total of eightspeeds, one of them being in direct drive.At the output shaft of this assembly, there is a range changer unit made as a two speed double stage gearbox with direct drive; this unit multiplies bytwo the total number of obtainable speeds. The range changer is qualified by thesignificant difference between the two obtainable speeds.The range changer can be made with a countershaft gearbox or an epicy-cloidal gearbox with direct drive; the advantage in the latter case is the possi-bility of an easier automatic actuation, by braking some of the elements of theepicycloidal gear.9.4 Manual gearboxes for industrial vehicles 441 FIGURE 9.14. Transmission ratios obtained with the scheme of transmission shownin Fig. 9.15; speed identification shows the main gearbox speed with the number, thesplitter position with the first letter, the range changer position with the second; Lstands for low, H stands for high.It is also possible to place the range changer before the main gearbox andthe splitter unit after the main gearbox.A different way of defining the functions of range change units is to say thatthe splitter is a gearbox that compresses the gear sequence, because it reducesthe gap between speeds, while the range changer is a gearbox that expands thegear sequence, because it increases the total range of the transmission. Figure 9.14 explains the concept of compression; the bars represent the ratiosobtained in all shifting lever positions. Ratios obtained with the splitter unit inthe L position (the first letter in the speed identification, L stands for lower ratio)are interspersed with the ratios obtained with the splitter unit in the H position(H stands for higher ratio, in this case 1:1) and reduce the amplitude of the gearsteps of the main gearbox.The same figure also explains the concept of expansion, showing on the same graph the ratio obtained with the range changer in the H position (secondidentification letter) and the L position; the gear step between the first in lowgear and the first in high gear is as big as the range of the main gearbox, andthe total transmission range is widened.The range changer is therefore seldom used, when driving conditions changesuddenly, as, for example, when leaving a normal road for a country road thatmust be driven more slowly, or when encountering a strong slope with a fullyloaded vehicle. The splitter allows the dynamic performance of the vehicle to beimproved, making the optimum transmission ratio available to obtain the desiredpower. The splitter is therefore used frequently. In a fully loaded vehicle, forexample, all split ratios can be used in sequence during full throttle accelerationfrom a standstill.442 9. MANUAL GEARBOXESThe range changer and splitter are usually made as modular units that canbe mounted at both ends of the main gearbox, or changed with simple covers,in order to satisfy all application needs with limited total production costs.Generalizing these concepts could suggest building transmissions using。