外文翻译--手动变速器

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1、附录ManualtransmissionOverviewManualtransmissionsoftenfeatureadriver-operatedclutchandamovablegearsele——ctor.Mostautomobilemanualtransmissionsallowthedrivertoselectanyforwardgearratio("gear")atanytime,butsome,suchasthosecommonlymountedonmotorcyclesandsometypesofracingcar

2、s,onlyallowthedrivertoselectthenext-higherornext-lowergear.Thistypeoftransmissionissometimescalledasequentialmanualtransmission.Sequentialtransmissionsarecommonlyusedinautoracingfortheirabilitytomakequickshifts.Manualtransmissionsarecharacterizedbygearratiosthataresele

3、ctablebylockingsel—ectedgearpairstotheoutputshaftinsidethetransmission.Conversely,mostautomatictr—ansmissionsfeatureepicyclic(planetary)gearingcontrolledbybrakebandsand/orclutchpackstoselectgearratio.Automatictransmissionsthatallowthedrivertomanuallyselectt—hecurrentge

4、ararecalledManumatics.Amanual-styletransmissionoperatedbycompute—risoftencalledanautomatedtransmissionratherthananautomatic.Contemporaryautomobilemanualtransmissionstypicallyusefourtosixforwardgearsandonereversegear,althoughautomobilemanualtransmissionshavebeenbuiltwit

5、hasfewastwoandasmanyaseightgears.Transmissionforheavytrucksandotherheavyequipmentusuallyhaveatleast9gearssothetransmissioncanofferbothawiderangeofg—earsandclosegearratiostokeeptheenginerunninginthepowerband.Someheavyvehi—cletransmissionshavedozensofgears,butmanyaredupl

6、icates,introducedasanacciden—tofcombininggearsets,orintroducedtosimplifyshifting.Somemanualsarereferredtobythenumberofforwardgearstheyoffer(e.g.,5-speed)asawayofdistinguishingbetweenautomaticorotheravailablemanualtransmissions.Similarly,a5-speedautomatictransmissi—onis

7、referredtoasa"5-speedautomatic"TheearliestformofamanualtransmissionisthoughttohavebeeninventedbyLouisR—enéPanhardandEmileLevassorinthelate19thcentury.Thistypeoftransmissionoffere—dmultiplegearratiosand,inmostcases,reverse.Thegearsweretypicallyengagedbysli—dingthemonthe

8、irshafts—hencetheterm"shiftinggears,"whichrequiredalotofcarefultimingandthrottlemanipulationwhenshifting,sothatthegea