外文翻译--手动变速器如何工作.docx

附录HowManua1TransmissionsWorkIfyoudriveastick-shiftcar,thenyoumayhavesevera1questionsf1oatinginyourhead.Howdoesthefunny',HpatternthatIammovingthisshiftknobthroughhaveanyre1ationtothegearsinsidethetransmission?WhatismovinginsidethetransmissionwhenImovetheshifter?WhenImessupandhearthathorrib1egrindingsound,whatisactua11ygrinding?Whatwou1dhappenif1weretoaccidenta11yshiftintoreversewhi1eIamspeedingdownthefreeway?Wou1dtheentiretransmissionexp1ode?Inthisartic1e,we11answera11ofthesequestionsandmoreasWeexp1oretheinteriorofamanua1transmission.Carsneedtransmissionsbecauseofthephysicsofthegaso1ineengine.First,anyenginehasared1ineamaximumrpmva1ueabovewhichtheenginecannotgowithoutexp1oding.Second,ifyouhavereadHowHorsepowerWorks,thenyouknowthatengineshavenarrowrpmrangeswherehorsepowerandtorqueareattheirmaximum.Forexamp1e,anenginemightproduceitsmaximumhorsepowerat5,500rpm.Thetransmissiona11owsthegearratiobetweentheengineandthedrivewhee1stochangeasthecarspeedsupands1owsdown.Youshiftgearssotheenginecanstaybe1owthered1ineandneartherpmbandofitsbestperformance.Idea11y,thetransmissionwou1dbesof1exib1einitsratiosthattheenginecou1da1waysrunatitssing1e,best-performancerpmva1ue.Thatistheideabehindthecontinuous1yvariab1etransmission(CVT).ACVThasanear1yinfiniterangeofgearratios.Inthepast,CVTscou1dnotcompetewithfour-speedandfive-speedtransmissionsintermsofcost,sizeandre1iabi1ity,soyoudidn,tseetheminproductionautomobi1es.Thesedays,improvementsindesignhavemadeCVTsmorecommon.TheToyotaPriusisahybridcarthatusesaCVT.Thetransmissionisconnectedtotheenginethroughthec1utch.Theinputshaftofthetransmissionthereforeturnsatthesamerpmastheengine.Afive-speedtransmissionapp1iesoneoffivedifferentgearratiostotheinputshafttoproduceadifferentrpmva1ueattheoutputshaft.AVerySimp1eTransmissionTounderstandthebasicideabehindastandardtransmission,thediagrambe1owshowsaverysimp1etwo-speedtransmissioninneutra1:1et's1ookateachofthepartsinthisdiagramtounderstandhowtheyfittogether:Thegreenshaftcomesfromtheenginethroughthec1utch.Thegreenshaftandgreengearareconnectedasasing1eunit.(Thec1utchisadevicethat1etsyouconnectanddisconnecttheengineandthetransmission.Whenyoupushinthec1utchpeda1,theengineandthetransmissionaredisconnectedsotheenginecanrunevenifthecarisstandingsti11.Whenyoure1easethec1utchpeda1,theengineandthegreenshaftaredirect1yconnectedtooneanother.Thegreenshaftandgearturnatthesamerpmastheengine.)Theredshaftandgearsareca11edtheIayshaft.Thesearea1soconnectedasasing1epiece,soa11ofthegearsontheIayshaftandtheIayshaftitse1fspinasoneunit.Thegreenshaftandtheredshaftaredirect1yconnectedthroughtheirmeshedgearssothatifthegreenshaftisspinning,soistheredshaft.Inthisway,theIayshaftreceivesitspowerdirect1yfromtheenginewheneverthec1utchisengaged.Theye11owshaftisasp1inedshaftthatconnectsdirect1ytothedriveshaftthroughthedifferentia1tothedrivewhee1softhecar.Ifthewhee1sarespinning,theye11owshaftisspinning.Theb1uegearsrideonbearings,sotheyspinontheye11owshaft.Iftheengineisoffbutthecariscoasting,theye11owshaftcanturninsidetheb1uegearswhi1etheb1uegearsandtheIayshaftaremotion1ess.Now,1et,sseewhathappenswhenyoushiftintofirstgear.FirstGearInthispicture,thegreenshaftfromtheengineturnstheIayshaft,whichturnstheb1uegearontheright.Thisgeartransmitsitsenergythroughtheco11artodrivetheye11owdriveshaft.Meanwhi1e,theb1uegearonthe1eftisturning,butitisfreewhee1ingonitsbearingsoithasnoeffectontheye11owshaft.Whentheco11arisbetweenthetwogears(asshowninthefirstfigure),thetransmissionisinneutra1.Bothoftheb1uegearsfreewhee1ontheye11owshaftatthedifferentratescontro11edbytheirratiostotheIayshaf1.Fromthisdiscussion,youcananswersevera1questions:Whenyoumakeamistakewhi1eshiftingandhearahorrib1egrindingsound,youarenothearingthesoundofgearteethmis-meshing.Asyoucanseeinthesediagrams,a11gearteetharea11fu11ymeshedata111imes.Thegrindingisthesoundofthedogteethtryingunsuccessfu11ytoengagetheho1esinthesideofab1uegear.Thetransmissionshownheredoesnothave,synchros,'(discussed1aterintheartic1e),soifyouwereusingthistransmissionyouwou1dhavetodoub1e-c1utchit.Doub1e-c1utchingwascommonino1dercarsandissti11commoninsomemodernracecars.Indoub1e-c1utching,youfirstpushthec1utchpeda1inoncetodisengagetheenginefromthetransmission.Thistakesthepressureoffthedogteethsoyoucanmovetheco11arintoneutra1.Thenyoure1easethec1utchpeda1andrevtheenginetothe"rightspeed.'1Therightspeedistherpmva1ueatwhichtheengineshou1dberunninginthenextgear.Theideaistogettheb1uegearofthenextgearandtheco11arrotatingatthesamespeedsothatthedogteethcanengage.Thenyoupushthec1utchpeda1inagainand1ocktheco11arintothenewgear.Ateverygearchangeyouhavetopressandre1easethec1utchtwice,hencethename"doub1e-c1utching."Youcana1soseehowasma111inearmotioninthegearshiftknoba11owsyoutochangegears.Thegearshiftknobmovesarodconnectedtothefork.Theforks1idestheco11arontheye11owshafttoengageoneoftwogears.Inthenextsection,we'11takea1ookatarea1transmission.ARea1TransmissionTherearethreeforkscontro11edbythreerodsthatareengagedbytheshift1ever.1ookin