专业英语3Word文档格式.docx
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Notethebronzefemaleconeinsertfrictionalfaceisnotsmooth,butconsistsofaseriesoftramlinegrooveswhichassistincuttingawaytheoilfilmsothatamuchlargersynchronizingtorquewillbegeneratedtospeeduptheprocess.
3.3.2Positivebaulkringsynchromeshunit(Fig.36(a,bandc))
Thegearboxmainshaftrotatesatpropellorshaftspeedand,withtheclutchdisengaged,thefirstmotionshaftgear,layshaftclustergears,andmainshaftgearsrotatefreely.
Drivetorquewillbetransmittedwhenagearwheelispositivelylockedtothemainshaft.Thisisachievedbymeansoftheoutersynchromeshhubinternalteethwhichslideovertheinnersynchromeshhubsplines(Fig.36(a))untiltheyengagewithdogteethformedontheconstantmeshgearwheelbeingselected.
Whenselectingandengagingaparticulargearratio,thegearstickslidesthesynchromeshouterhubinthedirectionofthechosengear(towardstheleft).Becausetheshiftplateisheldradiallyoutwardsbythetwoenergizingringtypespringsandtheraisedmiddlehumpoftheplaterestsinthegrooveformedontheinsideofthehub,theendoftheshiftplatecontactsthebaulkingringandpushesittowardsandovertheconicalsurface,formingpartoftheconstantmeshgearwheel(Fig.36(b)).
Thefrictionalgripbetweenthemaleandfemaleconicalmembersofthegearwheelandbaulkingringandthedifferenceinspeedwillcausethebaulkingringtobedraggedaroundrelativetotheinnerhubandshiftplatewithinthelimitsoftheclearancebetweentheshiftplatewidthandthatoftherecessedslotinthebaulkingring.Owingtothedesignedwidthoftheshiftplateslotinthebaulkingring,theteethonthebaulkingringarenowoutofalignmentwiththoseontheouterhubbyapproximatelyhalfatoothwidth,sothatthechamferedfacesoftheteethofthebaulkingringandouterhubbearuponeachother.
Asthebaulkingringisincontactwiththegearconeandtheouterhub,theforceexertedbythedriveronthegearstickpressesthebaulkingringfemaleconehardagainstthemaleconeofthegear.Frictionaltorquebetweenthetwosurfaceswilleventuallycausethesetwomemberstoequalizetheirspeeds.
Untilthistakesplace,fullengagementofthegearandouterhubdogteethispreventedbytheoutofalignmentpositionofthebaulkingringteeth.Whenthegearwheelandmainshafthaveunifiedtheirspeeds,thesynchronizingtorquewillhavefallentozerosothatthebaulkingringisnolongerdraggedoutofalignment.Thereforetheouterhubcannowovercomethebaulkandfollowthroughtomakea
positiveengagementbetweenhubandgear(Fig.36(c)).Itshouldbeunderstoodthatthefunctionoftheshiftplateandspringsistotransmitjustsufficientaxialloadtoensurearapidbringingtogetherofthematingconessothatthebaulkingringdogteethimmediatelymisalignwiththeircorrespondingouterhubteeth.Oncetheconefacescontact,theygeneratetheirownfrictiontorquewhichissufficienttoflickthebaulkingringover,relativetotheouterhub.Thusthechamfersofbothsetsofteethcontactandopposefurtherouterhubaxialmovementtowardsthegeardogteeth.
3.3.3Positivebaulkpinsynebromeshunit(Fig.37(a,b,candd))
Movementoftheselectorforksynchronizingsleevetotheleft(Fig.37(aandb))forcesthefemale(internal)conetomoveintocontactwiththemale(external)coneonthedrivegear.Frictionaltorquewillthensynchronize(unify)theinputandoutputspeeds.Untilspeedequalizationisachieved,thecollarsonthethreethrustpins(onlyoneshown)willbepressedhardintotheenlargedpositionoftheslots(Fig.35(c))inthesynchronizingsleeveowingtothefrictionaldragwhenthespeedsaredissimilar.Undertheseconditions,unlessextremepressureisexerted,thedogteethcannotbecrushedbyforcingthecollarsintothenarrowportionoftheslots.However,whenthespeedsofthesynchromeshhubanddrivegearareequal(synchronized)thecollarstendto¡
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intheenlargedportionoftheslots,thereisonlythepressureofthespringloadedballstobeovercome.Thecollarswillthenslideeasilyintothenarrowportionoftheslots(Fig.35(d))allowingthesynchronizerhubdogteethtoshiftintomeshwiththedogteethonthedrivinggear.
3.3.4Splitbaulkpinsynebromeshunit.(Fig.38(a,b,candd))
Thesynchronizingassemblyiscomposedoftwothickbronzesynchronizingringswithtaperedfemaleconicalbores,andsituatedbetweenthemisahardenedsteeldrivehubinternallysplinedwithexternaldogteethateachend(Fig.38(a)).Threeshoulderedpins,eachwithagroovearounditscentre,holdthebronzesynchronizingconeringsapart.Alternatingwiththeshoulderedpinsonthesamepitchcirclearediametricallysplitpins,theendsofwhichfitintoblindboresmachinedinthesynchronizingconerings.Thepinhalvesaresprungapart,sothatachamferedgroovearoundthemiddleofeachhalfpinregisterswithachamferedholeinthedrivehub.
Ifthegearboxisintheneutralposition,bothsetsofshoulderedandsplitpinsaresituatedwiththeirgroovesalignedwiththecentraldrivehub(Fig.38(aandb)).
Whenanaxialloadisappliedtothedrivehubbythegearstick,itmovesover(inthiscasetotheleft)untilthesynchronizingringisforcedagainsttheadjacentfirstmotiongearcone.Thefriction(synchronizing)torquegeneratedbetweentherubbingtaperedsurfacesdragsthebronzesynchronizingringrelativetothemainshaftanddrivehubuntilthegroovesintheshoulderedpinsarewedgedagainstthechamferededgesofthedrivehub(Fig.38(c))sothatfurtheraxialmovementisbaulked.
Immediatelytheinputandoutputshaftspeedsaresimilar,thatis,synchronizationhasbeenachieved,thespringsinthesplitpinsareabletoexpandandcentralizetheshoulderedpinsrelativetothechamferedholesinthedrivehub.Thedrivehubcannowrideoutofthegroovesfomedaroundthesplitpins,thuspermittingthedrivehubtoshiftfurtheroveruntiltheinternalandexternaldogteethofbothgearwheelhubmeshandfullyengage(Fig.38(d)).
3.3.5Splitringsynebromeshunit(Fig.3.9(a,b,candd))
Intheneutralpositiontheslidingsleevesitscentrallyoverthedrivehub(Fig.39(a)).Thispermitsthesynchronizingringexpanderbandandthrustblocktofloatwithintheconstraintsoftherecessmachineinthesideofthegearfacingthedrivehub(Fig.39(b)).
Forgearengagementtotakeplace,theslidingsleeveismovedtowardsthegearwheelselected(totheleft)untiltheinsidechamferoftheslidingsleevecontactsthebevelledportionofthesynchronizingring.Asaresult,thesynchronizingringwillbeslightlycompressedandthefrictiongeneratedbetweenthetwomembersthendragsthesynchronizingringroundinthedirectionofwhichevermemberisrotatingfastest,beitthegearordrivenhub.Atthesametime,thethrustblockispulledroundsothatitappliesaloadtooneendoftheexpanderband,whilsttheotherendisrestrainedfrommovingbytheanchorblock(Fig.3.9(c)).
Whilstthisishappeningtheexpanderisalsopushedradiallyoutwards.Consequently,therewillbeatendencytoexpandthesynchronizingslitring,butthiswillbeopposedbythechamferedmouthoftheslidingsleeve.Thisenergizingactionattemptingtoexpandthesynchronizingringpreventstheslidingsleevefromcompletelymovingoverandengagingthedogteethoftheselectedgearwheeluntilboththedrivehubandconstantmeshgearwheelarerevolvingatthesamespeed.
Whenbothinputandoutputmembersareunified,thatis,rotatingasone,therecannotbeanymorefrictiontorquebecausethereisnorelativespeedtocreatethefrictionaldrag.Thereforetheexpanderbandimmediatelystopsexertingradialforceontheinsideofthesynchronizingring.
Theaxialthrustappliedbythegearsticktotheslidingsleevewillnowbesufficienttocompressthesplitsynchronizingringandsubsequentlypermitstheslee曹操曹操曹操非凡方法vetoslideoverthegearwheeldogteethforfullengagement(Fig.39(d)).
3.4Remotecontrolledgearselectionandengagementmechanisms
Gearselectionandengagementisachievedbytwodistinctmovements:
1Theselectionoftherequiredgearshiftgateandthepositioningoftheengagementgatelever.
2Theshiftingofthechosenselectorgaterodintotheengagementgearposition.
Thesetwooperationsaregenerallyperformedthroughthemediaoftheg