ESP汽车英语中英对照Unit5passageB高等教育出版社.ppt

SteeringandBrakingSystem,Asteeringsystempermitsadrivertocontrolthedirectionofmovementofhisautomobile.Itsbasicpartsareasteeringwheel,asteeringshaft,asteeringgearthatchangestherotarymotionofthesteeringshafttothereciprocatingmotionofapitmanarm,alinkagesystem,andapivotsystemforthewheels.转向系帮助驾驶员控制汽车的运动方向。它的基本组成有1个方向盘、1个转向柱、1个将转向柱回转动作转换成转向臂往返运动的转向齿轮、1套连杆机构和1个车轮转动系统。,Everysteeringsystemincludesalinkagethatconnectsthefrontwheelstoeachotherandtothesteeringgear.Theusualautomobilelinkageconsistsofapitmanarm,anidlerarm,twotierodassemblies,arelayrod,andtwoknucklearms.ThesteeringcolumnofeveryautomobilenowproducedintheUnitedStatesisdesignedtocollapseeightinchesifapredeterminedamountofforceisappliedtothesteeringwheel.每个转向系统包括一个将前轮彼此相连并连接转向齿轮的连杆机构。常见的连杆机构有转向臂、1个惰臂、2个转向拉杆总成、1个连杆和2个转向节臂。现在美国生产的每辆汽车的转向柱都被设计成当施加在转向柱上的力达到预设量时可以变形8英寸。,Afrontsuspensionsystemisdesignedtominimizetirewearandprovideacompromisebetweensteeringeaseanddirectionalstability.Directionalstabilityandsteeringqualitiesareinfluencedgreatlybytheadjustmentsthatgovernfrontwheelalignment-frontsuspensionheight,caster,steeringaxisinclination,camber,pointofintersection,andtoe-inandtoe-outonturns.前悬挂系统被设计用来实现最小的轮胎磨耗，以及轻松转向和方向稳定之间的协调。方向稳定和转向质量在很大程度上受下列控动轮定位的参数影响：前悬高度、主销后倾角、主销内倾角、前轮外倾角、主销和中心线的交点、前束和转向负前束。,Forreasonsofsafety,thesteeringlinkageandfrontsuspensionsystemofanautomobilemustalwaysbeinthebestpossiblecondition.Theymustrespondquickly,easily,andaccuratelytoanychangeindirection,regardlessofvehiclespeed.Pooradjustment,looseness,and/ordamagecancausehardsteering,wander,andrapidtirewear.基于安全考虑，转向连杆和前悬挂系统必须一一直保持存可能的最好状态。无论车速快慢，他们一定都要对任何方向上的变化反应迅速、准确且易于操作。调整不当、松动和或损坏都会引起转向困难、摇摆和轮胎的快速磨耗。,Frontsuspensionheight.Frontsuspensionheightistheverticaldistancebetweenalevelfloororalignmentmachinerackandagivenpointonavehicle.前悬高度前悬高度是悬挂定位机架与水平地面间的垂直距离。,Caster.Caster(viewedfromthesideofavehicle)istheangleformedbyalinethroughtheupperandlowerballjointsandatrueverticalline.Wherethelinethroughtheballjointstiltsfromverticaltowardtherearofthevehicle,thecasterispositive,andifittiltstowardthefront,thecasterisnegative.Thepurposeofcasteristoprovidebetterandeasiersteering,tokeepthevehiclerunningstraightahead,andtoassistinreturningthewheelstothestraightrunningpositionafteraturn.Ofalltheadjustments,casteristheonethatmostaffectsdirectionalstability.主销后倾角主销后倾角（从车辆的侧面看）是上、下球节之间的连线和垂线的夹角。当这条穿过球节的垂直的连线斜向车的后部时，主销后倾角为正。如果它向车前倾斜的话，则主销后倾角为负。主销后倾角的目的是提供更好而且容易的转向使车辆保持直行转弯后帮助车轮恢复直行位置。在所有的调整中，主销后倾角对方向稳定性影响最大。,Steeringaxisinclination.Steeringaxisinclination-sometimescalledballjointinclination-provid.eseasiersteeringandgooddirectionalstability,anditreducestheamountofcamberneeded.Steeringaxisinclinationisafixedvaluethatchangesonlywhenthecamberisadjustedorifaballjointorthesteeringknucklespindleisdamaged.主销内倾角主销内倾角有时称作球节内倾提供较容易的转向和较好的方向稳定性，而且它可以减小所需的车轮外倾角。主销内倾角是个固定值只有当车轮外倾角被调整或者是球节或转向节销被损坏时它才会变化。,Camber.Camberisviewedfromthefrontofavehicle.Itistheanglebetweentheverticalcenterlineofawheelandatrueverticalline.Ifthewheeltiltsoutwardfromvertical,thecamberispositive.Correctcamberassistsinminimizingtirewearandkeepingiteven.车轮外倾角车轮外倾角是从车辆的前面看。它是车轮的垂直中心线和真实垂线之间的夹角。如果车轮从垂直向外倾斜，车轮外倾角是正。正确的车轮外倾角有助于实现最小轮胎磨耗而且磨耗均匀。,Toe-in.1ftheleadingedgesofthefronttiresareclosertogetherthanthetraillngedges,thewheelstoein.Toe-inadjustmentsaremadeinthesteeringlinkage,andtheyareimportantbecauseimpropertoe-incausesmuchoftheabnormalwearthatshortenstheservicelivesoftires.前束如果轮胎的前缘比后缘间距小，我们称车轮具有前束。束的调整由调整转向杆系来实现，前束非常重要是因为不合适的前束可以引起轮胎的非正常磨耗和轮胎的使用时间短缩。,Pointofintersection.Thepointofintersectionisthepointwheretheverticalcenterlineofawheel-asviewedfromthefrontofavehicle-andthelinethroughtheballjointsintersect.Ifthepointofintersectionisabovethesurfaceoftheroad,thefrontwheelswilltendtotoeinward.Thepointofintersectionisnotadjustmen.主销与轮中心线的交点主销与轮中心线的交点是轮的垂直中心线从车辆的前面看和球节之间连线的交叉点。如果主销与轮中心线的交点在道路表面上方，前轮将有前束倾向。主销与轮中心线的交点是不可调整的。,Toe-out.Whenanautomobileturnsacorner,theradiusoftheturningcircleoftheinnerwheelissmallerthanthatoftheouterwheel.Thewheelsmust,therefore,toeoutonturnsinordertoprovidethecorrectradii.Toe-outonturnsisbuiltintothesteeringlinkageandcannotbeadjusted.负前束当汽车转弯时，内部车轮的回转半径比外部车轮的小。为了提供正确的转弯半径，车轮必须实现负前束。转弯时车轮负前束通过转向杆系来实现，并且不可调整。,Acommontypeofautomobilebrakingsystememploysthefrictionofbrakeshoes,whichrubagainstrotatingdrumstostopavehicle.Theusualsystemmakesuseofbrakedrumsattachedtothewheels,movablebrakeshoesmountedsecurelyonthevehicleandenclosedbythedrums,ahydraulicforcesystem,andalinkagesystem.Whenthedriverappliesforcetoafootpedalinthelinkagesystem,theforceistransmittedbythehydraulicsystemtothebrakeshoes.Theforcemovestheshoesoutagainstthedrums,andthespeedofwheelrotationisreduced.常见类型的汽车制动系统采用通过制动蹄摩擦转动的制动鼓来实现车辆制动。通常的制动系统由连接车轮的制动鼓，可以移动地、牢阎地安装于车辆上的由制动鼓围起来的制动靴，液压传动系统，机械联动系统组成。当驾驶员对机械联动系统中的制动踏板施加力时，力通过液压系统传递到制动靴。力使制动靴外移压紧制动鼓，车轮旋转速度随之下降。,Frictionisgreatest-andthestoppingpowerisappliedmosteffectively-justbeforethebrakeshoeslockthewheels.Wheel-Iockcancauselossofcontrolofthevehicle,anditalwaysresultsinagreatincreaseintirewear.Brakingactionatwheelsthatareoppositeeachothermustbeequal,orthevehiclewillbepulledtooneside.制动靴在刚好锁住车轮之前，摩擦力最大即制动力被最有效地应用。车轮抱死引起对车辆控制能力的下降，而且它总会造成轮胎磨耗的剧烈增加。作用在相对的车轮间的制动力必须相等，否则车辆会偏向一侧。,Acompleteautomobilebrakingsystemalsoincludesaparkingbrakethatenablesthedrivertolockthedrivelineofhisvehiclewhenitisstopped.完整的汽车制动系统还包括可以使驾驶员在停车时能够锁止汽车传动系的驻车制动系统。Eachbrakeassemblyismountedonasteelbackingplatethatisboltedtoarearaxlehousingflangeortoafrontsteeringspindle.制动系统总成装于被拴接到后车桥管或前向轮轴的法兰盘上的制动背板上。,Brakeshoes.Theprimary(front)brakeshoe,whichhasashorterlining,isplacedsothatitfacesthefrontofthevehicle.Thesecondary(rear)shoefacestherear,andthetwoshoesareconnectedtoeachotheratthebottombytheadjustingmechanism.Theshoesareheldto,andworkagainst,padsonthebackingplate.Returnsprings,whichconnectthebrakeshoestotheanchorpin,pulltheshoesoutofcontactwiththebrakedrumwhenhydraulicpressureinthewheelcylinderisrelaxed.Whenthebrakepedalisdepressed,hydraulicpressureinthewheelcylindersmovesthepushrods,andtherodsforcethebrakeshoesagainstthebrakedrums.制动靴.有一个较短制动衬片的领制动靴（朝前）放置，面对车辆的前面。从制动靴（朝后）放置，而且这两个制动靴在底部的调整机构旁被彼此连接。制动靴和在制动背板上的衬块互相作用。当在制动分泵的液压被释放的对候，连接制动靴与定位销的回位弹簧使制动靴与制动鼓从接触状态中分离。当制动踏板被踩下时，制动分泵的液压力移动推杆，推杆使制动靴压紧制动鼓。,Bearings,WheelsandTires.Ballbearingsandtaperedrollerbearingscanbeusedtosupportandguidetherotationofthefrontwheelsofavehicle.Ofthetwo,taperedroIlerbearingsarethemostwidelyused.Acompleteballbearingassemblyforonewheelincludesaninnerrace,innerbearingassembly,outerbearingassembly,andouterrace.Acompleterollerbearingassemblyiscomposedofaninnerrace(cup),innerbearingassembly(cone),outerrace,andouterbearingassembly.Acagekeepstherollersorballsinplaceineachindividualbearingassembly.Theweightofthefrontendofanautomobileissupportedmainlybythelargerinnerbearingassemblies.轴承、车轮和轮胎球轴承和圆锥滚子轴承可以用于支持和引导车辆前轮的旋转。二者之中，圆锥滚子轴承应用最广。球轴承总成由一个内座圈、内部轴承组件、外部的轴承组件和外座组成。圆锥滚子轴承总成由内座圈（杯）、内部轴承总成（圆锥辊子）、外球座和外部的轴承总成组成。一个保持架使球或滚子在各自的轴承总成中。汽车前部重量主要由较大的内轴承总成支持。,Brakelinings.Qualitiesthatbrakefiningsmustpossessare:littleornotendencytoexpandorcompresswhenheated,resistancetomoisture,resistancetoscoring,quietandodor-freeoperation,longservicelife,andfaderesistance.Liningsarerivetedorbondedtothesteeltablesofbrakeshoes.制动衬片制动衬片必须拥有的性质是：比较小或不随着温度的变化而伸缩，抗水性，抗划痕，安静和操作时无异味，使用期并具有抗衰退性。制动衬片被铆接或焊接到制动靴的外板上。,Automobilewheelrimshavedrop-centerssothatthetirescanberemovedmoreeasily.Arimis