车辆与动力工程动力输出轴外文文献翻译中英文翻译外文翻译.docx
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车辆与动力工程动力输出轴外文文献翻译中英文翻译外文翻译.docx
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车辆与动力工程动力输出轴外文文献翻译中英文翻译外文翻译
Powertakeoffshaft
Thepowertakeoffshaftusuallycalledsimplythepowertakeoff,providesameanstodrivethemachinethatarebeingtowedbythetractor.theenginepowerofthetractorisbeingusednotonlytopullorcarrythemachine,butalsotooperateit.typicalexampledofmachinesthatarepowerdrivenaremowers.,balers,combine.potatoharvests,andmanurespreader.thePTOprovidesaveryusefulsourceofpower.andthealternativewouldbetofitanenginetoeachofthesemachine.thisis,ofcoursedonewherethepowerrequiredtodrivethemachinemaybegreaterthanthetractorcanbesupply.Generallymostmachinescanbepoweredbythetractor.
Powertakeoffshaftarecalssifilyaccordingtotheirlocationofthetractor,typeofthedrive.rotationspeed,andmethodofcontrol.
MosttractorareequippedwitharearPTO.someofthemhaveafrontPTO,ROW-tractorusebotharearandasidePTO.
AStothetypeofdrive,powertakeoffshaftareclassedastransmissiondrive.live,semi-independent,andground-speedtype,thetransmissiondrivePTOISdrivenfromthetractortransmissionandsoitwillstoprotatingwhenevertheengineclutchisdisengage.
ThelivePTOisdrivenfromtheenginecrankshaftthroughtheclutchdrivingmemberirrespectiveofthepositionoftheclutch.thesemi-independentPTOWILLcontinuetooperatewhilethedriverisshiftinggears,butisincapableofbeingengagedordisengagedwhilethetractorismoving.theground-speedPTOhasitsspeedproportionaltothegroundspeedofthetractor.suchAPTOfindsapplicationonrow-croptractorstooperatemachine.suchasmounteddrills.whoseworkingratemustbeinsynchronismwiththegroundspeedofthetractor.
Thepowertakeoffarestandardizedat540and1000rpm(ATnominalenginespeed)thespinedendsofPTOshaftofalltractorareofoneandsamesizeandarearrangedatoneandthesamelevelrelativetothetractorsupportsurface.whenthePTOShaftisnotused,itsendiscoveredbyaguardstampedfromsheetsteel.
Powertakeoffshaftmaybecontrolbyeithermechanicalorhydraulicmeans
LivePTOshaftcanbeengageordisengageontherunbyhydraulicorcomplexmechanicalmeans.
WhenthePTOisdisengage,sungearbrakeisreleasedandplanetcarrierisapplied.Inthiscase,PTOshaftisheldstationaryandtheplanetgeartransmitrotationfromtheinternalgeartothesungear.
WhenthePTOisengaged.sungearbrakeisappliedandplanetcarrierisreleased.Theplanetgearsnowhavetowalkaroundthesungear.astheplanetgearsrollaroundthesungear.theycarrytheplanetcarrieraroundwiththem.thusdrivingthePTOshaftwhichisrigidlyconnectedtheplanercarrier.
WhenthePTOisnotusedthePTOcontrolleverisplacedintoitsneutral(central)position.Inthiscase.boththesungearandtheplanetcarrierbrakesarereleased.
Toothedclutch1insertedintothePTOdrivinglinemakesitpossibletohaveeitherindependentorground-speedpowertakeoff.Theclutchisoperatedbyacontrolleverandcanbeplacedintothreedifferentpositions.Whentheclutchisshiftedallthewayforward(totheleft.asshowninFig.165a),driveshaft9(seeFig.164)ofthePTOnitisconnectedtothetransmissionmain(output)shafttoobtainground-speedpowertakeoff.Iftheclutchismovedallthewaybackward(totheright.asshowninFig.165b).thedriveshaftofthePTOunitwillbeconnectedtotheenginecrankshaft,andsopowertakeoffwillbeindependent.Withtheclutchinitsneutral(central)position.nodriveistransmittedtothePTOunit.
Toplacetheclutchintothe“GROUND-SPEEDPTO”position,oneshoulddisengagetheengineclutch,whereasplacingitintothe“LIVEPTO”positionrequiredthattheengineshouldbestopped.
THEHYDRAULICALLYCONTROLLEDPTOUNIT(Fig.166)includesaplanetarygearsetandaself-containedhydraulicsystem.Theunitiscontainedinacasethatisattachedtotherearaxlehousingofthetractor.
ThereductiongearsetofthePTOunitcomprisesdrivegear3carriedonshaft1anddrivengear9andhydraulicclutch10thataremountedonPTOshaft5.TheshaftsaresupportedbyballbearingshousedinboresinthePTOcase.Drivegearshaft1isdrivenfromtheenginecrankshaft,andsotheunitprovidessplinedtoitsshaftandisinconstantmeshwithahubthatisfreelysupportedbyballbearingsonthePTOshaft.
TheconnectionbetweenthedrivengearandthePTOshaftiseffectedbyhydraulicclutch10similartothosedescribedinSection11.4.TheclutchcomprisesaseriesofdrivinganddrivendiscsaccommodatedinadrumthatissplinedtothePTOshaft.Theclutchdrivingdiscsaremadeofsteelandequippedwithcermetlinings.Thesediscsaresplinedontothedrivegearhub.Theclutchdrivendiscsofplainsteelarearrangedalternatelybetweenthedrivingdiscsandaresplinedintotheclutchdrum.Insidetheclutchdrum,thereisannularspace12thatplaysthepartofahydrauliccylinder,intowhichfitspiston11.Thepistonissealedintheannularspaceoftheclutchdrumbyacast-ironringontheoutsideandarubberringontheinsideandisloadedbyaseriesofsprings14.
ToengagetheclutchandhencethePTOshaft,oilisdeliveredunderpressureintotheannularspaceintheclutchdrum.Thiscausesthepistontomoveagainstspringpressureandtightlycompressthepackoftheclutchdiscs,thusconnectingthePTOshafttothedrivengearofthereductiongearset.Todisengagetheclutch,theannularspaceinitsdrumisconnectedtoareturnlineleadingtooilsump7.Now,releasesprings14forcethepistontoexpeltheoilcontainedintheannularspaceandreleasetheclutchdiscs.Thepistoncarriesaseriesofpinswhich,attheendofthereturnstrokeofthepiston,bringpressuretobearagainstthediscsofbrake13thusstroppingthePTOshaft.Oilisletinandoutoftheclutchthroughpassagesdrilledintheshaft.
ThehydraulicsystemofthePTOunitincludesoilpump4,oilintakefilter8,avalvearrangement,andoillines.
Thevalvearrangementincludespressureregulatorvalve15andPTOcontrolvalve4(Fig.167)thatarecarriedinacommonhousingboltedtothefrontwallofthePTOcase.
Thepressureregulatorvalvemaintainsaconstantpressure(1Mpa)irrespectiveofthedeliveryoftheoilpump.
ThePTOcontrolvalveisessentiallyaballvalveloadedbytwospringsandoperatedbyaplungerandaneccentricheldtotheshaftofPTOcontrollever8.WhenthePTOshaftisengaged,thecontrolvalvealsodoublesasareliefvalve.
WithPTOcontrolleverinthe“OFF”position(Fig.167a).theeccentriconthecontrollevershaftreleasesthecontrolvalveplunger,whichrelievestheballvalveofspringpressure.Inthiscase,oilpump5drawsoilfromtheoilsumpofthePTOcasethroughoilintakefilter1anddeliversviathedischargelinetobothvalvesofthevalvearrangement.SincePTOcontrolvalve4isrelievedofspringpressure,theoilflowspastitandreturntothesump,someoilgoingthroughpassage3drilledinthePTOshafttolubricatethefrictiondiscsofhydrauliccultch2.
WhenthePTOcontrolleverisplacedintothe“ON”position(Fig.167b),theeccentricturnsanddepressthecontrolvalveplunger.Astheplungerisdepressed,itcompressesbothcontrolvalvespringswhich,inturn,pushthevalveagainstitsseat.Thisclosestheoilreturnpassagetothesump.Sincethereisnoescaperouteopentotheoil,thepressureinthesystemgoesup,andtheoilisforcedintoannularspace6oftheclutchandcausesthecultchpistontothePTOshaft.Theoilpressurewillriseto1Mpa,atwhichpointpressureregulatorvalve7willcomeintooperationtomaintainthispressureinvariable.Tomaketheclutchengagesmoothly,thePTOcontrollevershouldbeoperatedslowly.
designatedpersonresponsibleforsafety.Therefore,theownerwasnotincompliancewithTitle8Program.(AsofJuly1,1991theStateofCaliforniarequiresallemployerstohaveawrittensevenpointinjurypreventionprogram:
designatedsafetypersonresponsibleforimplementingtheprogram;mCaliforniaCodeofRegulations3203--InjuryandIllnessPreventionodeforensuringemployeecompliance;hazardcommunication;hazardevaluationthroughperiodicinspections;injuryinvestigationprocedures;interventionprocessforcorrectinghazards;andahealthandsafetyprogram.)
INCIDENT
OnDecember22,1991atapproximately8:
00a.m.a30yearoldmalePortuguesefarmlaborerwasdrivingafarmtractorwhichwaspullingadairyfeedwagon.Thepowertakeoffunitattherearofthetractorwasdrivingthefeeddispensingaugersysteminsidethefeedwagon.(Apowertakeoffunit(P.T.O.)isanextensionofthetractortransmissionshaftusedtopowerimplementswiththetractorengine.)Thisisacommonmethodoffeedingthedairycowsbyusingtheaugertomixthefeedandpushthecattlefeedout.TheP.T.O.wasapparentlynotfunctioningcorrectly,andtheemployeeleftthetractorengineidlingandclimbedoffthetractortochecktheattachment.TheemployeewasstandingnexttotheP.T.O.whenheturnedtoreachupandpullthehydraulicleverontherearofthetractorwhichengagesordisengagestheP.T.O.AtthistimehisleftshirtsleevewascaughtontherotatingshaftoftheP.T.O.TheemployeewaswoundaroundtheP.T.Oshaftasitrotated.TherotationoftheshaftwedgedhimintothemetalframearoundtheP.T.O.shaftandshearedhisarmalmostcompletelyoff.Healsohithisheadonthemetalframe,receivinga2centimeterlacerationonhisscalpnearthebackofhishead,andacervicalfracture.Thetractorenginestalledatthistimebecauseitwasidlingatlowspeedandjammedbythebodyofthe
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