外文翻译变速器设计

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1、汽车变速器设计外文翻译我们知道，汽车发动机在一定的转速下能够达到最好的状态，此时发出的功率比较大，燃油经济性也比较好。因此，我们希望发动机总是在最好的状态下工作。但是，汽车在使用的时候需要有不同的速度，这样就产生了矛盾。这个矛盾要通过变速器来解决。汽车变速器的作用用一句话概括，就叫做变速变扭，即增速减扭或减速增扭。为什么减速可以增扭，而增速又要减扭呢？设发动机输出的功率不变，功率可以表示为=其中是转动的角速度，是扭距。当固定的时候，与是成反比的。所以增速必减扭，减速必增扭。汽车变速器齿轮传动就根据变速变扭的原理，分成各个档位对应不同的传动比，以适应不同的运行状况。一般的手动变速器内设置输入轴、

2、中间轴和输出轴，又称三轴式，另外还有倒档轴。三轴式是变速器的主体结构，输入轴的转速也就是发动机的转速，输出轴转速则是中间轴与输出轴之间不同齿轮啮合所产生的转速。不同的齿轮啮合就有不同的传动比，也就有了不同的转速。例如郑州日产型车手动变速器，它的传动比分别是：档1;档；档1档:档（超速档）。当汽车启动司机选择1档时，拨叉将1/档2同步器向后接合1档齿轮并将它锁定输出轴上，动力经输入轴、中间轴和输出轴上的1档齿轮，1档齿轮带动输出轴，输出轴将动力传递到传动轴上（红色箭头）。典型1档变速齿轮传动比是3:也就是说输入轴转圈，输出轴转圈。当汽车增速司机选择档时，拨叉将档同步器与档分离后接合2档齿轮并锁定

3、输出轴上，动力传递路线相似，所不同的是输出轴上的1档齿轮换成2档齿轮带动输出轴。典型2档变速齿轮传动比是2.2，:输1入轴转2.圈2，输出轴转圈，比档转速增加，扭矩降低。当汽车加油增速司机选择档时,拨叉使档同步器回到空档位置,又使3/档4同步器移动直至将3档齿轮锁定在输出轴上，使动力可以从轴入轴中间轴输出轴上的3档变速齿轮，通过3档变速齿轮带动输出轴。典型3档传动比是1.7，:输1入轴转1.圈7，输出轴转1圈，是进一步的增速。当汽车加油增速司机选择4档时，拨叉将3/档4同步器脱离3档齿轮直接与输入轴主动齿轮接合，动力直接从输入轴传递到输出轴，此时传动比1:，1即输出轴与输入轴转速一样。由于动力

4、不经中间轴，又称直接档，该档传动比的传动效率最高。汽车多数运行时间都用直接档以达到最好的燃油经济性。换档时要先进入空档，变速器处于空档时变速齿轮没有锁定在输出轴上，它们不能带动输出轴转动，没有动力输出。一般汽车手动变速器传动比主要分上述14档，通常设计者首先确定最低（1档）与最高（4档）传动比后，中间各档传动比一般按等比级数分配。另外，还有倒档和超速档，超速档又称为5档。当汽车要加速超过同向汽车时司机选择5档，典型5档传动比是。.87，也就是用大齿轮带动小齿轮，当主动齿轮转。.8圈7时，被动齿轮已经转完1圈了。倒档时输出轴要向相反方向旋转。如果一对齿轮啮合时大家反向旋转，中间加上一个齿轮就会变

5、成同向旋转。利用这个原理，倒档就要添加一个齿轮做“媒介”，将轴的转动方向调转，因此就有了一根倒档轴。倒档轴独立装在变速器壳内，与中间轴平行，当轴上齿轮分别与中间轴齿轮和输出轴齿轮啮合时，输出轴转向会相反。通常倒档用的同步器也控制5档的接合，所以5档与倒档位置是在同一侧的。由于有中间齿轮，一般变速器倒档传动比大于1档传动比，增扭大，有些汽车遇到陡坡用前进档上不去就用倒档开上去。从驾驶平顺性考虑，变速器档位越多越好，档位多相邻档间的传动比的比值变化小，换档容易而且平顺。但档位多的缺点就是变速器构造复杂，体积大，现在轻型汽车变速器一般是45档。同时，变速器传动比都不是整数，而是都带小数点的，这是因为

6、啮合齿轮的齿数不是整倍数所致，两齿轮齿数是整倍数就会导致两齿轮啮合面磨损不均匀，使得轮齿表面质量产生较大的差异。手动变速器与同步器手动变速器是最常见的变速器，简称。它的基本构造用一句话概括，就是两轴一中轴，即指输入轴、轴出轴和中间轴，它们构成了变速器的主体，当然还有一根倒档轴。手动变速器又称手动齿轮式变速器，含有可以在轴向滑动的齿轮，通过不同齿轮的啮合达到变速变扭目的。典型的手动变速器结构及原理如下。输入轴也称第一轴，它的前端花键直接与离合器从动盘的花键套配合，从而传递由发动机过来的扭矩。第一轴上的齿轮与中间轴齿轮常啮合，只要轴入轴一转，中间轴及其上的齿轮也随之转动。中间轴也称副轴，轴上固连多

7、个大小不等的齿轮。输出轴又称第二轴，轴上套有各前进档齿轮，可随时在操纵装置的作用下与中间轴的对应齿轮啮合，从而改变本身的转速及扭矩。输出轴的尾端有花键与传动轴相联，通过传动轴将扭矩传送到驱动桥减速器。由此可知，变速器前进档位的驱动路径是：输入轴常啮齿轮中间轴常啮齿轮中间轴对应齿轮第二轴对应齿轮。倒车轴上的齿轮也可以由操纵装置拨动，在轴上移动，与中间轴齿轮和输出轴齿轮啮合,以相反的旋转方向输出。多数汽车都有5个前进档和一个倒档，每个档位有一定的传动比，多数档位传动比大于1，第4档传动比为1，称为直接档，而传动比小于1的第5档称为加速档。空档时输出轴的齿轮处于非啮合位置，无法接受动力传输。由于变速

8、器输入轴与输出轴以各自的速度旋转，变换档位时合存在一个同步问题。两个旋转速度不一样齿轮强行啮合必然会发生冲击碰撞，损坏齿轮。因此，旧式变速器的换档要采用两脚离合的方式，升档在空档位置停留片刻，减档要在空档位置加油门，以减少齿轮的转速差。但这个操作比较复杂，难以掌握精确。因此设计师创造出同步器，通过同步器使将要啮合的齿轮达到一致的转速而顺利啮合。目前全同步式变速器上采用的是惯性同步器，它主要由接合套、同步锁环等组成，它的特点是依靠摩擦作用实现同步。接合套、同步锁环和待接合齿轮的齿圈上均有倒角（锁止角），同步锁环的内锥面与待接合齿轮齿圈外锥面接触产生摩擦。锁止角与锥面在设计时已作了适当选择，锥面摩

9、擦使得待啮合的齿套与齿圈迅速同步，同时又会产生一种锁止作用，防止齿轮在同步前进行啮合。当同步锁环内锥面与待接合齿轮齿圈外锥面接触后，在摩擦力矩的作用下齿轮转速迅速降低（或升高）到与同步锁环转速相等，两者同步旋转，齿轮相对于同步锁环的转速为零，因而惯性力矩也同时消失，这时在作用力的推动下，接合套不受阻碍地与同步锁环齿圈接合，并进一步与待接合齿轮的齿圈接合而完成换档过程自动变速器自动变速器的选挡杆相当于手动变速器的变速杆，一般有以下几个挡位：停车、倒挡、空挡、前进、，即为速挡、，即为速挡）这几个挡位的正确使用对于驾驶自动变速器汽车的人来说尤其重要，下面就让我们一起来熟悉一下自动变速器各挡位的使用要

10、领。 口停车挡的使用发动机运转时只要选挡杆在行驶位置上，自动变速器汽车就很容易地行走。而停放时，选挡杆必须扳入位，从而通过变速器内部的停车制动装置将输出轴锁住，并拉紧手制动，防止汽车移动。 倒挡的使用位为倒挡，使用中要切记，自动变速器汽车不像手动变速器汽车那样能够使用半联动，故在倒车时要特别注意加速踏板的控制。空挡的使用位相当于空挡，可在起动时或拖车时使用。在等待信号或堵车时常常将选挡杆保持在位，同时踩下制动。若时间很短，这样做是允许的，但若停止时间长时最好换入位，并拉紧手制动。因为选挡杆在行驶位置上，自动变速器汽车一般都有微弱的行驶趋势，长时间踩住制动等于强行制止这种趋势，使得变速器油温升高

11、，油液容易变质。尤其在空调器工作、发动机怠速较高的情况下更为不利。有些驾驶员为了节油，在高速行驶或下坡时将选挡杆扳到位滑行，这很容易烧坏变速器，因为这时变速器输出轴转速很高，而发动机却在怠速运转，油泵供油不足，润滑状况恶化，易烧坏变速器。前进挡的使用正常行驶时将选挡杆放在位，汽车可在挡或挡之间自动换挡。位是最常用的行驶位置。需要掌握的是：由于自动变速器是根据油门大小与车速高低来确定挡位的，所以加速踏板操作方法不同，换挡时的车速也不相同。如果起步时迅速将加速踏板踩下，升挡晚，加速能力强，到一定车速后，再将加速踏板很快松开，汽车就能立即升挡，这样发动机噪声小，舒适性好。位的另一个特点是强制低挡，便

12、于高速时超车，在位行驶中迅速将加速踏板踩到底，接通强制低挡开关就能自动减挡，汽车很快加速，超车之后松开加速踏板又可自动升挡。S位低挡的使用自动变速器在位或位上处于低挡范围，可以在坡道等情况下使用。下坡时换入位或位能充分利用发动机制动，避免车轮制动器过热，导致制动效能下降。但是从位换入位或位时，车速不能高于相应的升挡车速，否则发动机会强烈振动，使变速器油温急剧上升，甚至会损坏变速器。另外在雨雾天气时，若路面附着条件差，可以换入位或位，固定在某一低挡行驶，不要使用能自动换挡的位置，以免汽车打滑。同时必须牢记，打滑时可将选挡杆推入位，切断发动机的动力，以保证行车安全。原文：Transmissiond

13、esignAsweallknow,automobileenginetoacertainspeedcanbeachievedunderthebestconditions,whencomparedissuedbythepower,fueleconomyisrelativelygood.Therefore,wehopethattheengineisalwaysinthebestofconditionstoworkunder.However,theuseofmotorvehiclesneedtohavedifferentspeeds,thuscreatingaconflict.Transmission

14、throughthisconflicttoresolve.AutomotiveTransmissionrolesumupinonesentence,calledvariablespeedtwisting,twistingorslowdownthegrowthratebyincreasingtorsional.Whycanslowdownbytwisting,andthegrowthratebutalsobytwisting?Forthesameenginepoweroutput,powercanbeexpressedasN=wT,wherewistheangularvelocityofrota

15、tion,andTNiuju.WhenNfixed,wandTisinverselyproportionaltothe.Therefore,thegrowthratewillreducetwisting,twistingslowdownwillincrease.AutomotiveTransmissionspeedgearbasedontheprincipleofvariabletwistedintovariousstallsofdifferenttransmissionratiocorrespondingtoadapttodifferentoperationalconditions.Gene

16、raltosetupamanualgearboxinputshaft,intermediateshaftandoutputshaft,alsoknownasthethree-axis,aswellasDaodangaxis.Three-axisisthemaintransmissionstructure,inputshaftspeedisthespeedoftheengine,theoutputshaftspeedistheintermediateshaftandoutputshaftgearmeshingbetweendifferentfromthespeed.Differentgearsa

17、redifferenttransmissionratio,andwillhaveadifferentspeed.ForexampleZhengzhourichanZN6481W2Gmanualtransmissioncar-SUV,itstransmissionratioare:1File3.704:1;stalls2.202:1;stalls1.414:1;stalls1:15stalls(speedingfile)0.802:1.Whendriverschoosealaunchvehiclestalls,Plectrumwillbe1/2filesynchronizationengagem

18、entwithabackstallgearandoutputshaftlockit,thepowerinputshaft,intermediateshaftandoutputshaftgearofastall,astalltheoutputshaftgeardriven,andtheoutputshaftpowerwillbetransmittedtothedriveshaft(redarrow).AtypicalstallBiansuchiluntransmissionratiois3:1,thatistosaythreelapstotheinputshaftandoutputshaftto

19、acircle.Whenthegrowthrateofcardriverschoosetwostalls,Plectrumwillbe1/2-filesynchronizationandfileajointseparationafter2stallandlocktheoutputshaftgear,powertransmissionlinesimilar,thedifferenceisthattheoutputshaftgearofastall2stallreplacedbytheoutputshaftgeardriven.2stallBiansuchiluntypicaltransmissi

20、onratiois2.2:1,2.2lapstotheinputshaftandoutputshafttoacirclethanastallspeedincrease,lowertorque.Whenrefuelingvehicledriversgrowthstallsoption3,Plectrumto1/2backtothefreefile-synchronizationposition,andalsoallowsthe3/4filesynchronizationMobilestalluntil3intheoutputshaftgearlock,powercanbeintotheshaft

21、axis-intermediateshaft-theoutputshaftofthethreestallsBiansuchilun,ledthroughthreestallsBiansuchilunoutputshaft.3stallstypicaltransmissionratiois1.7:1,1.7lapstotheinputshaftandoutputshafttoacircleisfurthergrowth.WhencardriversOption4refuelinggrowthstalls,Plectrumwillbe3/4fromthe3-filesynchronizations

22、tallgeardirectlywiththeinputshaftgearjointinitiative,andpowertransmissiondirectlyfromtheinputshafttotheoutputshaft,thetransmissionratioat1:1,thattheinputshaftandoutputshaftspeedthesame.Thedrivingforcewithoutintermediateshaft,alsoknownasdirectfile,thefiletransmissionthanthemaximumtransmissionefficien

23、cy.Mostcarsrun-timefilesareuseddirectlytoachievethebestfueleconomy.Shiftintothefirstintervalwhen,inafreetransmissionwhenBiansuchilunoutputshaftisnotlockedin,theycannotrotatetheoutputshaftdriven,notpoweroutput.Generalautomotivemanualtransmissionthanthemain1-4stalls,usuallythefirstdesignerstodetermine

24、theminimum(onestall)andmaximum(4files)transmissionratio,themiddlestalldrivebygeometricprogressionthanthegeneraldistribution.Inaddition,therearestallsDaodangandspeeding,speedingfileisalsoknownasthefivestalls.Whenthecartoacceleratetomorethancardriverswiththechoiceoffivestalls,andatypicalfive-transmiss

25、ionratiois0.87:1,whichisdrivenbyapiniongear,thegearwhentheinitiativeto0.87zone,passivegearhavebeentransferredtoacircleoftheEnd.DaoDang,theoppositedirectiontotheoutputshaftrotation.Ifonepairofmeshinggearswhenwereverserotation,withamiddlegear,itwillbecomethesametotherotation.Useofthisprinciple,weshoul

26、daddagearDaodangthemediawillberotationaldirectionreversed,itwillhaveaDaodangaxis.Daodanginstalledinthetransmissionshaftindependentcrust,andtheintermediateshaftparallelaxisgearwiththeintermediateshaftandoutputshaftgearmeshinggears,willbecontrarytotheoutputshaft.Daodangusuallyusedforthesynchronization

27、controlalsojoinsfivestalls,stallsandDaodang5positioninthesameside.Asamiddlegear,thegeneraltransmissionDaodangtransmissionratiogreaterthan1filetransmissionratio,bytwisting,steepslopewithsomevehiclesencounteredontheprogressstallsfalterswithaDaodangboost.Ridefromthedriveroftheconsiderations,bettertrans

28、missionstall,stalladjacentstallmorethanthetransmissionchangestheratioofsmall,andeasytoshiftsmoothly.However,theshortcomingsofthestallsismoretransmissionstructureiscomplicated,bulky,lightvehicletransmissionisgenerally4-5stalls.Atthesametime,transmissionratioisnotintegral,butwithallofthedecimalpoint,i

29、tisbecauseofthegearteethmeshingisnotcausedbythewholemultiplesoftwogearteethcanleadtothewholemultiplesoftwomeshinggearsofunevenwear,makingthetoothsurfacequalityhaveagreaterdifference.ManualtransmissionandsynchronizerManualtransmissionisthemostcommontransmission,orMT.Itsbasicstructuresumupinonesentenc

30、e,isatwo-axleshaft,whereinputshaft,theshaftaxisandintermediateshaft,whichconstitutethemainbodyofthetransmissionand,ofcourse,aDaodangaxis.Manualtransmissionknownasmanualgeartransmission,whichcanbeintheaxialslidinggears,thegearsmeshingdifferentvariablespeedreachedtwistingpurpose.Typicalmanualtransmiss

31、ionstructureandprinciplesareasfollows.Inputshaftalsosaidthatthefirstaxis,anditsfront-endSplinedrivendirectlywiththeclutchdiscsetswiththeSpline,bythetransferoftorquefromtheengine.Thefirstaxisoftheintermediateshaftandgearsmeshinggearsoften,aslongastheshaftaxistoaturn,theintermediateshaftandgearalsowil

32、lberotating.Vicealsosaidintermediateshaftaxis,theaxis-evenmorethanthesizegear.Alsoknownasthesecondoutputshaftaxis,theaxisofvarioussetsofgearstallprogresscanbemanipulatedatanytimeintheroleofthedeviceandthecorrespondingintermediateshaftgearmeshing,thuschangingitsspeedandtorque.Withtheendoftheoutputsha

33、ftsplineassociatedwiththedriveshaftthroughthedriveshafttorquetransmittedtothedriveaxlereducer.Thus,progressstallsdrivetransmissionpathis:inputshaftgearoftenrodents-oftenrodentsintermediateshaftgear-correspondingintermediateshaftgear-thesecondaxiscorrespondinggear.Reversingthegearshaftcanbemanipulate

34、dbythedevicepickintheaxismovement,andtheintermediateshaftandoutputshaftgearmeshinggears,tothecontrarytothedirectionofrotationoutput.MostcarshavefivestallsandaDaodangforward,acertaindegreeofeachstalltransmissionratio,themajorityofstallstransmissionratiogreaterthan1,4filetransmissionratioof1,knownasdi

35、rectstalls,andtransmissionratioislessthan1No.5stallcalledacceleratedstall.Freeattheoutputshaftgearinapositionofnon-engagement,unacceptablepowertransmission.Thetransmissioninputshaftandoutputshaftrotationalspeedtotheirown,transformastallwhenthereisasynchronous.Twodifferentrotationalspeedgearmeshingfo

36、rcewillimpactthecollisionoccurred,damagegear.Therefore,theoldtransmissionshifttoafeet-offapproach,orstallonthelocationofthefreestayforawhilebystallsinthefreepositionrefuelingdoors,inordertoreducethespeeddifferentialgear.However,thisoperationisrelativelymorecomplicatedanddifficulttograspaccurate.Sode

37、signerscreateasynchronized,andallowssynchronizationthroughthemeshingofgearstobeconsistentspeedandsmoothmeshing.AtpresentSynchronousTransmissionisbasedonthesynchronizationofinertia,mainlyfromjointsets,synchronouslockring,andsoon,itischaracterizedbyfrictionontheroleofsynchronization.SplicesetsGenlocke

38、ngagementringgearandtheringgearwhenithadChamfer(Lockangle),Genlockwithintheconeringgearengagementwiththequestionofconeringgearcontactfriction.LockandconeanglehasbeenmadeinthedesignofanappropriatechoicetobemadefrictionconeoftheteethmeshingwiththeringgearquicklysetspaceatthesametimewillhaveaLockrolean

39、dtopreventthegearsmeshinginsyncbefore.Whensynchronizationlockconeringgearengagementwiththequestionofconeringgearaftercontactintheeffectsoffrictiontorquegearspeedquicklylower(orhigher)withthesamespeedsynchronouslockring,thetwosynchronousrotationofthegearGenlockCentralzerospeed,thusmomentofinertiaalso

40、disappear,theninforceundertheimpetusofengagementsetsunhinderedandsynchronizationlockringgearengagement,andfurtherengagementwiththequestionofgearengagementandthecompletionGearShiftProcess.TheautomaticgearboxTheautomaticgearboxchoosestoblockthepoletheequaltomovingthestickshiftofthegearbox,havinggenera

41、llybelowseveralblocks:P(parking),R(pourtoblock),N(getemptytoblock),D(goforward),S(or2,namelyfor2blocksoon),L.(or1,namelyfor1blocksoon)Thisseveralanusageforblockingarightusagescomingdrivertheautomaticgearboxisautomotiveofpersontosayparticularlyimportant,underneathletusverymuchfamiliarwithonceautomati

42、cgearboxeachlyblockingsmaintheme.TheusageoftheP(theparkingblocks)Thelaunchestheluckturnsaslongaschoosetoblockthepoleindrivingtheposition,automaticgearboxcarrunaboutveryeasily.Butpark,choosetoblockthepolemustpullintoofP,frombutpasstheinternalparkingsystemingearboxmovesthedevicewilloutputthestalklockl

43、ives,combiningtotensethehandsystemmove,preventingthecarambulation.TheusageoftheR(pourtoblock)Racontrolforispouringblocking,usinginsidewantingslicingrecording,automaticgearboxcarunlikemovinggearboxcarsocanusinghalfmoving,sowhilereversingthecarwantingspecialattentionacceleratingpedal.TheusageoftheN(ge

44、temptytoblock)TheNisequaltogetemptytoblock,canwhilestartingorhouroftrailerusage.AtwaitforthesignalorblockupthecarwilloftenoftenchoosetoblockthepolekeepsintheofD,tramplingatthesametimethenextsystemmove.Iftimeisveryshort,dolikethisisanadmissionof,butifstopthetimelongtimehadbetterchangeintoofN,combinet

45、otensethehandsystemmoves.Becausechoosetoblockthepoleindrivingtheposition,theautomaticgearboxcarhasgenerallyandalltodrivethetrendfaintly,longhourstramplethesystemmovesameasadeterrentthiskindoftrend,makegearboxoilgoneup,theoilliquidchangesincharactereasily.Particularlyintheairconditionmachinework,laun

46、chthesoonhighercircumstanceinmachinebottommoredisadvantageous.Somepilotsforthesakeofstanzaoil,atmadegoodtimeorgodownslopewillchoosetoblockthepolepulltheofNskids,thisburnthebadgearboxveryeasily,launchingthemachinetorevolvessooninthehoweverbecausethegearboxoutputsatthistimethestalkturnssoonveryhigh,th

47、eoilpumpprovidestheoilshortage,lubricatingtheconditionworsen,burnthebadgearboxeasily.TheusageoftheD(goforwardtoblock)WillchoosetoblockwhenisnormaltodrivethepoleputintheofD,carcanat14block(or3block)itschangetoblockautomatically.TheofDdrivesthepositionmostincommonusely.Whatdemandcontrolis:Becausetheau

48、tomaticgearboxissoonhighandlowwithcartocometomakesuretoblockaccordingtotheacceleratorsizea,soacceleratethepedaloperationmethodisdifferent,changingtoblockthehourofthecarissoontoonotsamealike.Ifstarthourquickacceleratethepedaltramplesthebottom,risingtoblockthenight,acceleratingtheabilityisstrong,arriv

49、ingcertaincarsoonbehind,thenwillacceleratethepedalloosentoopenveryquickly,carcanrisetoblockimmediately,launchlikethisthemachinevoiceissmall,comfortablegood.TheanothercharacteristicsoftheDisacompulsorylowblocking,easytohighspeedthehourovertakesacar,willacceleratequicklyinofDdrovethepedaltrampleaftera

50、ll,connectthecompulsorylowfendoffthepassandthencanreducetoblockautomatically,thecaracceleratesveryquickly,afterovertakingacarloosentoopenthepedalofaccelerationtocanrisetoblockautomaticallyagain.TheusageoftheS,ofLlowtheusagethatblockTheautomaticgearboxininisplacedinthelowblockingthescopeonofSorofLs,c

51、anusageunderanetc.circumstance.ItchangetocanmakeuseoftolaunchwellintoofSorofLsthemechanismmove,avoidingthecarwheelsystemmovethemachineoverhot,causethesystemmovetheeffectdescentwhilegoingdownslope.ButchangeintofromtheofDofSorofL,carsooncanthigherthanrisetoblockthecarhomologouslysoon,otherwisestrongvi

52、brationinopportunitytolaunch,makegearboxoilhoicked,evenwilldamagethegearbox.Theisanotheratrainfogweatherhour,iftheroadadherestothetermbad,canchangeintoapositionfororofL,fixingatsomelyfirstlowlyblockingdriving,doingnotusecanautomaticallychangingblocking,inordertopreventthecarbeatsslippery.Mustkeepfirmlyinmindatthesametime,beattheslipperyhourcanwillchoosetoblockthepolepushesintoamotivefor,cuttingofflaunchingmachine,toingguaranteeacarthesafety.