变速箱-外文翻译

图3-2弹簧离合器变速箱从其安装图，所有大批量生产的现代卡车所采用的阶梯变速箱可分为下列几类：1）由控制类型：手动换档变速箱和自动换挡变速箱；2）通过齿轮组合传动类型：固定轴式和行星式。自动换挡变速箱在最近得到越来越广泛的应用，手动换档变速箱可细分为：1）单范围变速；2）直接驱动变速器（汽车型）；3）多范围的变速。变速箱通常设计有四个或五个速度。单范围变速箱（图3–3a型）由两个轴与离合器轴连接的传动齿轮轴1以及与减速器连接的主轴（驱动）3。滑动齿轮可以相啮合，齿轮4与齿轮5在主轴上硬性安装，从而提供不同的传动比。当在中立位置时，驱动齿轮轴和主轴不啮合而没有运动，此时将是从发动机传动。这种类型的一个五速变速箱的安装。在变速箱直接驱动输入(驱动)轴可直接耦合到输出轴上，在这种情况下，变速箱不再作为一个减速器。这张图（图3-3b型）显示了包含有3轴的传动传动齿轮轴1，通过恒定耦合的齿轮7连接到传动齿轮轴的副轴6以及主轴3。这是一个驱动齿轮轴的附加部分。滑动齿轮2以上的花键轴主要从事移动的传输，它配备了5档安装在副轴上。一旦齿轮2和齿轮8啮合将得到直接的驱动，这将来自传动齿轮轴的扭矩直接传输向主轴。从而使副轴的运行空闲。一个有5级直接驱动范围的变速箱被用于卡车。多范围的变速箱（图3–3c型）使得它有可能得到与齿轮的几对需要援助的齿轮比。虽然这些传输效率更低，但是他们有一个更广泛的齿轮口粮，而且提供一个在所有的速度范围都容易逆转的能力，这是拖拉机上非常重要的特点。图3-3变速箱3．万能杆传动万向节传动应用于现代拖拉机和卡车（取决于安装图和机械设计），因此可能具有不同的结构[9]。这是两个半万向和全万向节传动轴的主要类型。一个半万向节是一个铰链连接，可用于传输之间小角度（最多5“）旋转轴的扭矩。这种接头主要被安装在拖拉机的离合器轴和变速箱主传动轴之间，主要是因为当拖拉机在不平坦的地面移动时，他们不准确了。半万向允许在拖拉机框架的安装上有一定的误差并且不会以任何方式恶化他的性能，这基本上简化了组装程序。这种类型的大多数接头以弹性橡胶金属套管的形式设计（图3–4a的）。同样的设计用在离合器轴1上的拔叉2和拔叉5和通用接头花键轴6。有四个弹性橡胶套筒4的吊环3被安置在拔叉2至拔叉5之间。其他的高弹性联轴器的设计类似,但它的前拔叉整体是由轴6制成，而后方拔叉被安全的装置在变速箱驱动轴的花键上。扭矩可以通过一个角度在由于橡胶套管的变形而产生稍微不一致的轴间传输。拔叉5与轴之间的滑动连接，使人们有可能改变轴的长度。一个完整的万向节可以在非常大的倾斜锐角（最大30°?40°）之间传递轴扭矩。它们被用在汽车变速器（图3–4b型），因为后轴悬架的弹簧使得轴偏差大大增加。图3-4万能杆传动当一辆卡车走在崎岖不平的地面上时，普遍万向节的轴的长度是通过拨叉2在花键轴上滑动来改变的。4．主传动根据啮合的齿轮副数量卡车的主传动可能是一个单一的减速型（图3–5a型）或双减速型（图3–5b型），.中型和重型卡车的齿轮通常采用对数双减速型，从斜面驱动主传动，这给予了很高的传动比并且占据一个相对较小的体积，这对于给予了主传动箱（后轴）和地面之间足够的空隙来说非常重要。单减速型主传动被用在客运车和小负荷卡车上。5．差速器当一辆卡车或轮式拖拉机在转弯，或者进入了一个不平坦的道路，或有不同车轮半径，不同的速度必须要传送给驱动车轮时，可以通过利用差速器来实现（图3-6a型）。差速器分离的外壳由两个杯子1和4通过螺栓夹紧。左杯1提供给主传动上的从动齿轮7一个固定凸缘。其内部包含带有四个锥齿轮3（行星齿轮），在差速齿轮销上旋转自如的星形轮2。这颗行星小齿轮同车轴5上的齿轮6啮合。主传动上的从动齿轮7将旋转传输到差速器箱，从而传输到差速齿轮和行星齿轮。当卡车笔直的行驶在光滑的路面并且驱动轮的半径相同的时候，由车轴带动旋转的驱动轮执行相同数量的旋转。当他们与差速齿轮一起转动时，行星齿轮固定器，也就是轴齿轮将他们的速度调整为相等。通过这样差速器箱，车轴及其齿轮，驱动车轮都以同样的速度转动，同销连接的刨床小齿轮将没有运动。图3-5卡车主传动；1-锥齿轮2-驱动齿轮柄3-齿圈4-斯珀车道齿轮5-从动齿轮6-主传动箱7-齿轮轴当卡车在转弯时，或出于某种原因或其他的，轮子中的一个车轮和车轴对应齿轮开始旋转缓慢时，同差速齿轮一起旋转的行星齿轮将开始在轴齿轮上减速运动。这些行星齿轮开始围绕其轴（差速齿轮销上的）旋转，从而增加了其他轴齿轮的转速和相应的驱动轮速度。这种差速器在所有条件下均匀地将扭矩在轴齿轮之间分配。这有时会阻碍一辆卡车的前进。如果有一个车轮，例如，在泥泞地面，冰地或雪地，地面抓地力差将会导致车轮打滑。由于差速器将扭矩均匀的分配在了车轮之间，第二轮的牵引动力也将由于太弱而不足以推动汽车行驶更远。当打滑的车轮以2倍速度旋转时，卡车将停止前进。这样差速器将增加路面上的打滑和滑移以及在湿滑路面上急转弯时的打滑和滑移。为了消除这一缺点，一些现成的公路车（越野车，自卸车，卡车）的设计带有自锁差速器。联锁如图（3-6B型）。当套管8移动到左边，它将差速器杯同车轴5连接起来以防止2个车轴的一半转向彼此相对。由于车轴齿轮不能把比差速器箱慢，因而行星齿轮在他们的轴上保持静止而差速器本身已被锁定。当移动到右边套管将释放锁定装置。3.4汽车转向齿轮（图3-7）一辆卡车或轮式拖拉机通过方向盘转向。方向盘在驱动程序的2.TransmissionBoxIntermsoftheirgearingdiagrams,thesteppedtransmissionboxesemployedinallmass-producedmoderntruckscanbeclassifiedasfollows;bythetypeofcontrol:manual-shifttransmissionandpower-shifttransmissionBythetypeofgeartrain:fixedaxisandplanetary.Inrecenttimethepowershifttransmissionareincreasinglyapplied,manualshifttransmissionmaybesubdivided;single-rangetransmission;directdrivetransmission(automobiletype);multi-rangetransmission.Transmissionboxesareusuallydesignedwithfourorfivespeeds.Single-rangetransmissionboxes(Fig.3-3a)consistoftwoshaftsdrivegearshaft1connectedwiththeclutchshaftandmain(driven)shaft3,linkedwiththefinaldrive.Slidinggearcanbemeshed.withgear4orgear5whicharerigidlyfittedonthemainshaft,providingtherebydifferentgearratios.Intheneutralposition,whenthegearsonthedrivegearshaftandthemainshaftareoutofmeshnomotionwillbetransmittedfromtheengine.Atransmissionboxofthistypewithfivespeedsisinstalled.Intransmissionboxeswithadirectdrivetheinput(driving)shaftcanbecoupleddirectlytotheoutputshaft,inwhichcasethetransmissionboxnolongeractsasareductiongear.ThediagraminFig.3-3b)showsthatthetransmissioncontainsthreeshaftsdrivegearshaft1,layshaft6coupledbyconstant-meshgear7tothedrivegearshaftandmainshaft.which3isacontinuationofthedrivegearshaft.Slidinggear2movingoverthesplinesofthemainshaftengagesthetransmissionasitcomesinmeshwithgear5fittedonthelayshaft.Adirectdriveisobtainedassoonasgear8engagesgear2andthiswilltransmittorquedirectlyfromthedrivegearshafttothemainshaft.Inthiseasethelayshaftrunsidle.Afive-rangetransmissionboxwithadirectdriveisusedintrucks.Multi-rangetransmissionboxes(Fig.3-3c)makeitpossibletoobtaintherequiredgearratiowiththeaidofseveralpairsofgears.Althoughthesetransmissionarelessefficient,theyhaveawiderrangeofgearrationsandprovideforaneasyreversalatallspeeds,averyimportantfeatureintractors.3.Universal-JointDriveUniversal-jointshaftsemployedinmoderntractorsandtrucksperformseveralfunctions(dependingonthegearingdiagramandthemachinedesign)and,asaresultmayhaveadifferentconstruction[9].Thesearetwomaintypesofshaftswithsemi-andfulluniversaljoints.Asemi-universaljointisahingedlinkwhichcanbeusedtotransmittorquebetweenshaftsrotatingatasmallangle(upto5″).Suchjointsareinstalledmainlyintractorsbetweentheclutchshaftandthetransmissionboxprimaryshaftbecausetheycomeoutofalignmentwhenthetractormovesoverunevenground.Semi-universalsallowforacertaininaccuracyinthearrangementofunitsmountedonthetractorframewithoutdeterioratinginanywaytheirperformanceandessentiallysimplifytheassemblyprocedure.Mostjointsofthistypearedesignedintheformoftanelasticrubbermetalcoupling(Fig.3-4a).Similarlydesignedforks2and5arefittedontothesplinesofclutchshaft1anduniversal-jointshaft6.Ring3withfourelasticrubbersleeves4isaccommodatedbetweenforks2and5.Theotherelasticcouplingisdesignedsimilarly,butitsfrontforkismadeintegralwithshaft6whiletherearforkissecuredonthesplinesofthetransmission-boxdrivingshaft.Torquecanbetransmittedatanangleandwiththeshaftssomewhatoutoflineduetodeformationoftherubbersleeves,Theslidingjointbetweenfork5andtheshaftmakesitpossibletochangethelengthoftheshaft.Afulluniversaljointtransmitstorquebetweenshaftsinclinedatveryacuteangles(upto30°～40°).Theyareusedinautomobiletransmissions(Fig.3-4b)becausethespring-loadedsuspensionoftherearaxlegivesrisetoaconsiderableincreaseinthemisalignmentoftheshafts.Whenatrucktravelsoverroughgroundthelengthoftheuniversal-jointshaftischangedbyfork2slippingovertheshaftsplines.4.FinalDriveThefinaldrivesoftrucksmaybeofasingle-reduction(Fig.3-5a)ordouble-reductiontype(Fig.3-5b)dependingonthenumberofthegearpairsinmesh.Mediumandheavy-dutytrucksusuallyemploydouble-reductionbevel-spurfinaldrives,whichgiveahighgearratioandoccupyarelativelysmallvolume,whichisextremelyimportantforgivingadequateclearancebetweenthefinaldrivehousing(rearaxle)andtheroad.Single-reductionfinaldrivesareemployedinpassengercarsandtrucksofsmallload-car-ryingcapacity.5.DifferentialWhenatruckorawheeltractormakesaturn,goesoverabumpyroadorhasdifferentwheelradii,differentspeedshavetobeimpartedtothedrivingwheels,ThiscanbedonebymeansofadifferentialshowninFig.3-6a).Thesplithousingofthedifferentialconsistsoftwocups1and4clampedbybolts.Leftcup1isprovidedwithaflangetowhichdrivengear7ofthefinaldriveisattached.Theinteriorsofthehousingcontainspider2withfourbevelgears(planetpinions)3,rotatingfreelyonthespidergearpins.Theplanetpinionsaremeshedwithgears6ofaxleshafts5.Drivengear7ofthefinaldrivetransmitsrotationtothedifferentialhousingandtherebytothespidergearsandtheplanetpinions.Whenthetruckmovesstraightoverasmoothroadandthedrivingwheelshavethesameradii,bothdrivingwheelsrotatedbyaxleshaftsperformanequalnumberofrevolutions.Astheyrotatetogetherwiththespidergears,theplanetpinionsclinch,asitwere,boththeaxleshaftgearsandturnthematthesamespeed.Inthiswaythedifferentialhousing,axleshaftsandtheirgears,andboththedrivingwheelsrotateatthesamespeed,therebeingnorotationoftheplanerpinionsrelativetothepins.Whenthetruckmakesaturnorwhen,forsomereasonorother,oneofthewheelsandthecorrespondinggearoftheaxleshaftbegintorotateslower,theplanetpinionsrotatingtogetherwiththespidergearsbegintorunoverontheaxleshaftgearwiththeretardedmotion.Thesatellitesbegintorevolvearoundtheiraxles(onthespidergearpins),increasingtherebytherotationalspeedoftheotheraxleshaftgearandthecorrespondingdrivingwheel.Underallconditionssuchdifferentialwilldistributetorqueevenlybetweentheaxleshaftgears.Thissometimeswillhindertheprogressofatruck.Ifoneofthewheels,forexample,goesoverliquidmud,iceorsnow,thepoorgripinthegroundwillresultinthewheelslipping.Sincethedifferentialdistributesthetorquebetweenthewheelsequally,thetractionpoweronthesecondwheelwillalsobecometooweaktopropeltheautomobilefartheron.Thetruckwillstop,whiletheskiddingwheelwillrotateatdoublethespeed.Inthiswayadifferentialincreasesslippingandskiddingonrouteandonsharpturnsonslipperyroads.Toeliminatethisshortcoming,someoff-the-roadtrucks(cross-countryvehicles,dump,trucks)aredesignedwithaself-lockingdifferential.TheinterlockisshowninFig.3-6b).Whensleeve8ismovedtotheleft,itconnectsoneofthedifferentialcupswithaxleshaft5preventingthetwohalvesoftheaxleshaftfromturningrelativetoeachother.Sincetheaxleshaftgearcannotturnslowerthanthedifferentialhousing,theplanetpinionsremainstationaryontheiraxlesandthedifferentialitselfislocked.Whenmovedtotherightthesleevewillreleasethelockingdevice.3.4TruckSteeringGears(Fig.3-7)Atruckorawheeltractoristurnedbyasteeringwheel.Steeringwheelsinthedrive’s