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1、一.IntroductiontoHowAutomaticTransmissionsWorkIfyouhaveeverdrivenacarwithanautomatictransmission,thenyouknowthattherearetwobigdifferencesbetweenanautomatictransmissionandamanualtransmission:Thereisnoclutchpedalinanautomatictransmissioncar.Thereisnogearshiftinanautomatictransmissio
2、ncar.Onceyouputthetransmissionintodrive,everythingelseisautomatic.Boththeautomatictransmission(plusitstorqueconverter)andamanualtransmission(withitsclutch)accomplishexactlythesamething,buttheydoitintotallydifferentways.Itturnsoutthatthewayanautomatictransmissiondoesitisabsolutely
3、amazing!PurposeofanAutomaticTransmissionJustlikethatofamanualtransmission,theautomatictransmission'sprimaryjobistoallowtheenginetooperateinitsnarrowrangeofspeedswhileprovidingawiderangeofoutputspeeds.Withoutatransmission,carswouldbelimitedtoonegearratio,andthatratiowouldhavetobes
4、electedtoallowthecartotravelatthedesiredtopspeed.Ifyouwantedatopspeedof80mph,thenthegearratiowouldbesimilartothirdgearinmostmanualtransmissioncars.You'veprobablynevertrieddrivingamanualtransmissioncarusingonlythirdgear.Ifyoudid,you'dquicklyfindoutthatyouhadalmostnoaccelerationwhe
5、nstartingout,andathighspeeds,theenginewouldbescreamingalongnearthered-line.Acarlikethiswouldwearoutveryquicklyandwouldbenearlyundriveable.Sothetransmissionusesgearstomakemoreeffectiveuseoftheengine'storque,andtokeeptheengineoperatingatanappropriatespeed.Whentowingorhaulingheavyob
6、jects,yourvehicle'stransmissioncangethotenoughtoburnupthetransmissionfluid.Inordertoprotectthetransmissionfromseriousdamage,driverswhotowshouldbuyvehiclesequippedwithtransmissioncoolers.Thekeydifferencebetweenamanualandanautomatictransmissionisthatthemanualtransmissionlocksandunl
7、ocksdifferentsetsofgearstotheoutputshafttoachievethevariousgearratios,whileinanautomatictransmission,thesamesetofgearsproducesallofthedifferentgearratios.TheplanetarygearsetisthedevicethatmakesthispossibleinanautomatictransmissionThePlanetaryGearsetFromlefttoright:theringgear,pla
8、netcarrier,andtwosungearsWhenyoutakeapar