机电英语(第三版)

MachineElementsUnit1机电英语（第三版）青椒小助手ContentsSimulatedWriting2Reading31Speaking33

Howeversimple,anymachineisacombinationofindividualcomponentsgenerallyreferredtoasmachineelementsorparts.

Thus,ifamachineiscompletelydismantled,acollectionofsimplepartsremainssuchasnuts,bolts,springs,gears,camsandshafts—thebuildingblockofallmachinery.①无论任何简单的机床，都是由单一元件即通称为机械零件或部件组成的。因此，如果把机床完全拆卸，就可得到像螺母、螺栓、弹簧、齿轮、凸轮和轴等简单零件——所有机器的组合元件。

if引导条件状语从句,表示“如果……”｡

MachineElements

Amachineelementis,therefore,asingleunitdesignedtoperformaspecificfunctionandcapableofcombiningwithotherelements.

Sometimescertainelementsareassociatedinpairs,②suchasnutsandboltsorkeysandshafts.Inotherinstance,agroupofelementsarecombinedtoformasubassembly,suchasbearings,couplingsandclutches.

有时某些特定的元件必须成对地工作……beassociatedinpairs:成对地结合例如:Iamassociatedwithhiminbusiness.我与他两人合伙经商｡因此，机械零件就是可以执行某种具体功能，而且能与其它零件配合的简单零件。有时候某些特定的元件必须成对的工作，例如螺栓与螺母，键与轴。在有些情况下，一组零件组成一装配件，比如：轴承、联轴器与离合器。

MachineElements机器零件中最常见的是齿轮,它实际上是由轮子和杆组成的带有齿的轮子｡在轮毂或轴上旋转的齿轮驱动其他齿轮做加速或减速运动,这取决于主动齿轮的齿数｡

which引导非限制性定语从句,修饰gear;不定式短语toformatoothedwheel作结果状语;分词短语dependingupon作原因状语｡Themostcommonexampleofamachineelementisagear,which,fundamentally,isacombinationofthewheelandthelevertoformatoothedwheel.Therotationofthisgearonahuborshaftdrivesothergearsthatmayrotatefasterorslower,dependinguponthenumberofteethonthebasicwheels.③

MachineElementsOtherfundamentalmachineelementshaveevolvedfromwheelandlever.Awheelmusthaveashaftonwhichitmayrotate.Thewheelisfastenedtotheshaftswithcouplings.Theshaftmustrestinbearings,maybeturnedbyapulleywithabeltorachainconnectingittoapulleyonasecondshaft.其他基本机械零件包含轮子和杆。轮子必须装在轴上才可以转动。轮子用联轴器夹紧固定在轴上，轴必须安装在轴承里，由带或链条与第二根轴相连，并带动第二根轴转动。

MachineElements

Thesupportingstructuremaybeassembledwithboltsorrivetsorbywelding.④Properapplicationofthesemachineelementsdependsuponknowledgeoftheforceonthestructureandthestrengthofthematerialsemployed.支撑结构可由螺栓或铆钉或通过焊接固定在一起｡beassembledwith:由……安装;bywelding作方式状语｡支承结构可用螺栓、铆钉或通过焊接固定装配在一起。这些机械零件的正确使用，取决于是否懂得作用于结构上的力和所用材料的强度等相关方面的知识。

MachineElementsTheindividualreliabilityofmachineelementsbecomesthebasisforestimatingtheoveralllifeexpectancyofacompletemachine.Manymachineelementsarethoroughlystandardized.Testingandpracticalexperiencehaveestablishedthemostsuitabledimensionsforcommonstructuralandmechanicalparts.单个机械零件的可靠性成为评估整台机器使用寿命的基本因素。很多机械零件是完全标准化的。普通结构和机械部件的最适合的尺寸可以借助测试或实际经验来确定。

MachineElements

Throughstandardization,uniformityofpracticeandresultingeconomicsareobtained.Notallmachinepartsinusearestandardized,however.Intheautomotiveindustryonlyfasteners,bearings,bushings,chainsandbeltsarestandardized.Crankshaftsandconnectingrodsarenotstandardized.采用标准化可以获得实际应用上的一致性和经济上的实惠。然而，并非所有的零件都是标准的。在自动化工业中，只有紧固件、轴承、轴套、传动链和传动带是标准元件。曲轴及连杆并不是标准元件。

MachineElements1.Whatisamachineelement?ExercisesⅠ.Answerthefollowingquestionsaccordingtothepassage.Amachineelementisasingleunitdesignedtoperformaspecificfunctionandcapableofcombiningwithotherelements.2.Whichisthemostcommonmachineelement?Themostcommonexampleofamachineelementisagear,which,fundamentally,isacombinationofthewheelandthelevertoformatoothedwheel.3.Whatareotherfundamentalmachineelements?Otherfundamentalmachineelementshaveevolvedfromwheelandlever.Ⅰ.Answerthefollowingquestionsaccordingtothepassage.4.Whichelementisregardedasthebasisforestimatingtheoveralllifeexpectancyofacompletemachine?Thereliabilityofindividualmachineelements.5.Whichmachineelementsarestandardizedintheautomotiveindustry?Intheautomotiveindustryonlyfasteners,bearings,bushings,chainsandbeltsarestandardized.ExercisesⅡ.Translatethefollowingphrases.1.机械零件machineelement2.简单零件simplepart 3.自动化工业theautomotiveindustry4.单一元件individualcomponent5.主动齿轮thebasicwheel6.theindividualreliabilityofmachineelements机械零件的可靠性7.theoveralllifeexpectancyofacompletemachine整台机器使用寿命8.thebuildingblockofthemachinery机器的组合元件9.thesupportingstructure支撑结构10.thestrengthofthematerials材料强度ExercisesⅢ.Fillintheblankswiththeproperwordslistedinthebox.Changethewordformifnecessary.Standardize reliable machinery componentuniformexpectancy assemble individual gearestimate1.Complexmachinesaremadeupofmovingpartssuchaslevers_________,cams,cranks,springs,beltsandwheels.2.Itcanalsobeusedto___________thepropertiesofthematerials.3.The__________isrequiredpropertiesofthemachineelements.4.AgriculturalPower____________Operationisoperatingtractorsandagriculturalequipment.gearsstandardizereliabilitymachineryExercises5.Ageneratorwillreadspecificationsofrequiredvariants,customizeaffectedcomponentsand__________themintoacustomsystem.6.Youmayuseequipments,instrumentsortoolstoidentifybadengine____________.7.Additionalextensivetestingwasperformedinbothstudiestoevaluateproductconsistencyand__________.componentsassembleuniformityExercisesStandardize reliable machinery componentuniformexpectancy assemble individual gearestimate8.Youshould__________costsandenergyproductionusingsomebaseassumptions.9.Ithasalongerlife___________thanconcreteandsteelequipment.10.Youcanemploythismethodtoanalyze_________electricalcomponentsofacompletemachineforproperoperation.expectancyindividualestimateExercisesStandardize reliable machinery componentuniformexpectancy assemble individual gearestimateⅣ.TranslatethefollowingsentencesintoEnglish.1.最常见的机械零件是齿轮,齿轮实际上是由轮子和杆组成的带齿的轮子｡Themostcommonmachineelementisthegear,whichisacombinationofthewheeland

thelevertoformatoothedwheel.2.齿轮的硬度决定了它的耐磨能力｡Thehardnessofageardeterminesitsabilitytoresistwear.3.制造业的工程师们集中精力研制标准化的零件｡Manufacturingengineershavecenteredtheireffortsonthedevelopmentofstandardizedelements.ExercisesⅣ.TranslatethefollowingsentencesintoEnglish.4.这些零件是在大批量､高规格和低成本的条件下生产的｡Thesepartsareproducedinlargequantitieswithahighdegreeofperfectionatreduced cost.5.可以说,零件表面是零件和设备的功能信息的载体｡Itseemsthattheelementsurfaceisthecarrieroffunctionalinformationforbothmachineelementandprocessingapparatus.6.这些机械零件的正确使用,取决于是否懂得作用于结构上的力和所用材料的强度等相关方面的知识｡Properapplicationofthesemachineelementsdependsuponknowledgeoftheforceon thestructureandthestrengthofthematerialsemployed.ExercisesAgearhavingtoothelementsthatarestraightandparalleltoitsaxisisknownasaspurgear.Aspurgearcanbeusedtoconnectparallelshaftsonly.Parallelshafts,however,canalsobeconnectedwithgearsofanothertype,andaspurgearcanbematedwithagearofadifferenttype.

SpurandHelicalGears

正齿轮和斜齿轮

轮齿是直的并平行于其轴线的齿轮称为正齿轮。正齿轮只能与平行轴传动联结。然而，平行轴还可与其他类型的齿轮传动联结，一个正齿轮可与不同类型的齿轮相啮合。Topreventjammingasaresultofthermalexpansion,toaidlubricationandtocompensateforunavoidableinaccuraciesinmanufacture,allpower-transmittinggearsmusthavebacklash.Thismeansthatonthepitchcirclesofamatinggear,thespacewidthonthepinionmustbeslightlygreaterthanthetooththicknessonthegearandviceversa.Oninstrumentgears,usingagearsplitdownitsmiddle,onehalfbeingratablerelativetotheotherscaneliminatebacklash.Aspringforcesthesplitgearteethtooccupythefullwidthofthepinionspace.

SpurandHelicalGears

为了避免受热膨胀而引起的卡死现象，方便润滑和补偿不可避免的制造误差，所有的动力传动齿轮必须有侧隙。也就是说在一对啮合齿轮的节圆上，小齿轮的齿槽宽必须稍大于大齿轮的齿厚，反过来也是如此。对于仪表齿轮，侧隙可通过将一个齿轮从中间切开而获得的两个“拼合”齿轮来消除，拼合齿轮的一半与另一半是成比例的。弹簧力能使拼合齿轮占满小齿轮的齿间全部宽度。Helicalgearshavecertainadvantages,forexample,whenconnectingparallelshafts,theyhaveahigherloadcarryingcapacitythanspurgearswiththesametoothnumbersandcutwiththesamecutter.Becauseoftheoverlappingactionoftheteeth,theyaresmootherinactionandcanoperateathigherpitch-linevelocitiesthanspurgears.Thepitch-linevelocityisthevelocityinthepitchcircle.Sincetheteethareinclinedtotheaxisofrotation,helicalgearscreateanaxialthrust.Ifusedsingle,thisthrustmustbeabsorbedintheshaftbearings.Thethrustproblemcanbeovercomebycuttingtwosetsofopposedhelicalteethonthesameblank.

SpurandHelicalGears

斜齿轮具有一些优点，比如当连接平行轴时，其承载能力高于有相同齿数并用相同刀具切削的正齿轮。因为轮齿的重合作用，其传动更加平稳，允许的节线速度比正齿轮高。节线速度是节圆上的线速度。由于轮齿倾斜于旋转轴线，所以斜齿轮会产生轴向推力。如果单独使用这种齿轮，轴向推力由轴向轴承来承担。轴向推力问题可通过在一个齿胚上加工两对斜齿来解决。Dependingonthemethodofmanufacture,thegearmaybeofthecontinuous-toothherringbonevarietyoradouble—helicalgearwithaspacebetweenthetwohalvestopermitthecuttingtooltorunout.Double—helicalgearsarewellsuitedfortheefficienttransmissionofpowerathighspeeds.Helicalgearscanalsobeusedtoconnectnonparallel,non-intersectingshaftsatanyangletooneanother.Ninetydegreesisthecommonestangle,atwhichsuchgearsareused.

SpurandHelicalGears

依照加工方法，这种齿轮可以是连续齿人字型轮齿或有退刀槽的双斜齿轮。双斜齿轮特别适合于在高速下高效传递动力。斜齿轮还能用于相互成任何角度的不平行或不交叉的轴间连接，最常见的连接角度为90°。与商业函件相比,传真和电子邮件不但快捷,而且也比快件便宜,因此其应用范围越来越广｡它们的格式与普通信函相似,但略有不同:传真信头中含有传真号码和电话号码,信内地址往往被收件人的传真号码和电话号码所代替;电子邮件则大多无信头内容,只有收件人的电子邮件地址及事由等｡传真和电子邮件

VS(China)ElectronicsCo.,Ltd.GDProvince,P.R.China518527Tel:86-755-27711288Fax:86-755-27711289FaxCoverSheetTo:至:SalesManagerPhilipsSoundSystems(PSS)Corp.From:自:TerryMadisonMarketingManagerPhone:电话:Fax:传真:17-4821-5231317-4821-52315Phone:电话:Fax:传真:86-755-2771128886-755-27711289DateofIssue:发出日期:Sep.16,2007TotalPages:发出页数:1(Includingthispage)DearSirorMadam,RE:ComplaintaboutthePoorQualityofWoofers(低音喇叭,扩音器)Pleasebeinformedthatthewoofers(PN(产品编号):439929155236)youdeliveredonSep.15werefoundwithunacceptablyhighrateofbrokenconepaper(纸盆,喇叭中的一种物料)aftersamplinginspectionbyourQCinspectors,whichcausedconsiderabledecreaseinourdailyproduction.WeenclosetheInspectionReportherewith,andhavesent5defectivesamplestoyou.Pleasefeedbackyouranalysisreportandimprovementplanwithinoneweek.Ifthiscaserecurs,wewillhavetorejectlaterlots.YoursFaithfully,TerryMadisonMarketingManagerSample1一､传真(Fax)HerbertImport&Export.Telephone:(212)2215608Fax:(212)2215706Address:388StationStreet,NewYork,10018U.S.A.To:JohnsonCompanyDate:May23,2003Attn:EricLeeFrom:SimonDavisYourRef:2051/efOurRef::5237/nlCC:KateLongPage:1DearSir,WeareanAmericancompany;oursharesaretobeissuednextmonth.OurcompanyistobegrantedaWorldBankcreditsoon.Shouldyoubeinterestedincooperationorinbuyingourshares,pleasedonothesitatetocontactus.Welookforwardtohearingfromyou.YoursSincerely,SimonDavisManagingDirectorSample2赫伯特进出口公司电话：（212）2215608传真：（212）2215706地址：美国纽约车站街388号10018发送：约翰逊公司日期：2003年5月23日收件人：埃里克•李发件人：西蒙•戴维斯贵方编号：2051/ef我方编号：5237/nl抄送：凯特•朗页数：1先生：我方为一家美国公司，我方股票将于下月发行。本公司即将得到世界银行的一笔贷款。贵方如有兴趣与我方合作，或购买我方股票，敬请与我们联系。恭盼回复。 你忠实的 西蒙•戴维斯总经理Ref(reference)—信函参考编号,一般编号往往包括有关人员的姓名的首字母｡OurRef—我方编号,即发信人编号YourRef—贵方编号,即收信人编号Attn—收件人CC—抄送(其他收件人)以上例文中的所有内容并非每一篇传真都必须具备的,但是,每一篇传真都不能缺少的内容是:To—收件人的姓名(后面可以加地址)From(FM)—发件人的姓名(后面可以加地址) Date—发传真的日期(月份一般用字母)Fax—收件人的传真号码 Sub—事由 Thesalutation—称呼(和信函相同) Thebodyofthetelex—电邮正文(和信函相同)Regards—致意(和信函相同) Signature—署名(和信函相同)传真格式要求1.电邮的格式To—收件人的e-mail地址 Subject—主题正文Thesalutation—称呼(和信函相同)Thebodyofthetelex—电邮正文(和信函相同)Regards—致意(和信函相同) Signature—署名(和信函相同)2.英文电子邮件的基本写作技巧

其实,写电邮和写英文信相差不多,主要由称呼､正文和落款三部分构成｡写作正文时要注意以下两点:(1)首先要明确写给谁｡不同的收件人,语气不同｡写给朋友的可用一些俚语或缩写词语,但是在比较正式的场合中,就不能用俚语或缩略语｡(2)写电子邮件要直接,并多用短句,使意思清楚｡当然,对重点部分要作详细介绍｡

二､电邮(E-mail)To:Smith885@Subject:AboutmyselfDearMrandMrsSmith,I’maChinesegirl.MynameisYangLi.I’mveryhappytoknowthatI’llstayatyourhousefortheEnglishSummerCamp.I’dliketotellyousomethingaboutmyselfsothatyoucanknowabitaboutmebeforeIarrive.I’mfifteenyearsold.Ihaveahappyfamilywiththreepeople.I’mstudyinginNo.1MiddleSchool.Welearneightsubjects.I’minterestedinallofthem.Ilikereadingandplayingthepiano.IlikeEnglishverymuch,butmyEnglishisnotgoodenough.IthinkyoucanhelpmewithmyEnglish.Ihopetomeetyousoon. YoursTruly, YangLiSample(1)在称呼处对方的名字不要拼错｡头衔也不要错,头衔､学位任选其一｡(2)人较多时,可用Ladiesandgentlemen｡Notes假如你叫方芳,在因特网上找到了一个叫Joyce的网友,现在请你根据下列要点给Joyce发e-mail,介绍你自己的一些情况｡a.方芳,中学生,家住在重庆;b.喜欢集邮和运动;c.对英语很感兴趣,会唱几首英文歌曲;d.班里同学也想找网友,希望得到帮助;e.想去英国看看｡Practice(I=interviewer主试人A=applicant应试人)Dialogue1I:What’syourpermanentaddress?A:MypermanentaddressisApt.401,126ZhongshanRoad,Nanjing.I:Whereisyourdomicileplace?A:MybirthplaceisSuzhou.I:AreyouaresidentofShanghai?A:No.I:Whereisyourdomicileplace?A:MydomicileplaceisNanjing.I:Givemeyourtelephonenumber,please.A:(Mytelephonenumberis)8563361HometownandEducationBackgroundDialogue2I:What’syouraddress?A:Myaddressis356HepingRoad,Xuzhou.I:Whereareyouworking?A:I’mworkingatPing’anHotelatHuaihaiRoad.I:Whereisyourhometown?A:MyhometownisSuzhou.I:Areyoualocalresident?A:Yes,Iam.IhavebeenlivinginSuzhousinceIgraduatedfromuniversity.HometownandEducationBackgroundDialogue3I:Wouldyoutellmesomethingaboutyoureducationalbackground?A:Yes,sir.Igraduatedfrommiddleschoolin1986,thenIenteredShanghaiPolytechnics.Igraduatedin1992,andIhaveaB.S.degree.I:Whatdepartmentdidyoustudyin?A:IwasintheDepartmentofPhysics.I:Howwereyourscoresatcollege?A:Theywereallexcellent.HometownandEducationBackgroundDialogue4I:Whichuniversitydidyougraduatefrom?A:PekingUniversity.IhadlearnedEconomicsthereforfouryears.I:What’syoureducationalbackground?A:Ifinishedprimaryschoolin1986,andenteredmiddleschoolthatSeptember.IgraduatedfromhighschoolinJulyof1992andthenIenteredPekingUniversity.I:What’syourmajorinuniversity?A:Economics.I’mespeciallyinterestedin“EconomicdevelopmentofChina”.I:Whatareyourmajorandminorsubjects?A:MymajorsubjectisEconomicsandminorsubjectisEnglish.I:Whatcoursedoyoulikebest?A:IamveryinterestedinBusinessManagementandIthinkit’sveryusefulformypresentjob.I:Whatdoyouthinkistherelationshipbetweenthesubjectsyouhavetakenandthejobyouareseekingfor?HometownandEducationBackgroundA:Ihavetakencoursesonofficeadministration,typing,reportsandcorrespondencewriting.Besides,IamalsotakingaChinesetypewritingcourse.Ithinktheseareallcloselyrelatedtoajobofajuniorsecretarybecauseitrequirestheabilitytoperformgeneralofficeworkandtoassistthemanagerinhandlingallpaperwork.I:Howareyougettingonwithyourstudies?A:Iamdoingwellatschool.I:Whatsubjectareyouleastinterestedin?A:IthinkitwasChineseHistory.Notbecausethesubjectwasboring,butthelargeamountofmaterialsthathavetobememorized.Itleftnoroomtoappreciatethewisdomofgreatpeopleinthepast.I:WhenandwheredidyoureceiveyourMBAdegree?A:IreceivedmyMBAdegreefromPekingUniversityin1994.HometownandEducationBackgroundThankYou!BearingsandShaftsUnit2机电英语（第三版）主编李翠香ContentsSimulatedWriting2Reading31Speaking33因为内外圈和保持架设计的多样化以及滚珠数目的不同，所以有许多类型的轴承。它们可以根据功能分为径向承载（轴承）、轴向（推力）承载（轴承）以及径向承载与轴向承载的组合（轴承）三种。

由于内外圈和保持架设计的多样化以及滚珠数目的不同,轴承有许多类型｡becauseof:介词短语,后接名词､动名词或动名词短语,起原因状语的作用｡例如:Becauseofhiswifebeingthere,Isaidnothingaboutit.TypesofBearings

Therearemanytypesofbearingsbecauseofvariationsinthedesignofringsandseparatorsandinthenumberofballs.①

Theycanbedividedintoclassesaccordingtotheirfunction:thosethatsupportaradial,thosethatsupportathrustload,orthosethatsupportacombinationofthrustandradialloads.1.深沟滚球轴承在深沟球轴承中，滚道深度约为滚球直径的四分之一。尽管深沟球轴承是为承受径向载荷而设计的，但在径向载荷和轴向载荷同时作用下也工作得较好，因此它是应用最广泛的一种球轴承。

在深沟径向球轴承中,滚道深度约为滚球直径的四分之一｡

approximately:相当于about或nearly,即“大约”的意思｡

One-fourth:四分之一,在句中用于比较级前,表示程度｡分数中分子用基数词,分母用序数词,如分子大于一,分母须加“s”,例如:two-fifths:五分之二｡as...as:像……一样,用于引出一个比较状语从句,两个“as”之间为形容词或副词｡TypesofBearings1.Deepgrooveradialballbearings

Indeep-grooveballbearings,theracesareapproximatelyone-fourthasdeepastheballdiameter.②

Althoughdeep-grooveballbearingsaredesignedtocarryaradialload,theyperformwellunderacombinedradialandthrustload.Forthisreason,itisthemostwidelyusedtypeofballbearing.

2.填充式滚球轴承提高轴承承载能力最有效的方式是增加滚珠数目。在填充式滚珠轴承中，通过在常规滚珠轴承的滚道上开一个槽，从那儿填充滚珠以增加滚珠数目。

在填充式滚球轴承中,通过在常规滚球轴承的滚道上开一个槽,从那儿填充滚珠来增加滚珠的数量｡“cuttinganotchintheracesofaconventionalbearing”是动名词短语,充当介词by的宾语｡“therebypermittingtheinsertionoftheballs”是现在分词短语,充当伴随状语｡

2.Filled-notchballbearings

Themosteffectivewayofincreasingbearingloadcapacityistoincreasetheballcomplement.Filled-notchballbearingisaccomplishedbycuttinganotchintheracesofaconventionalbearing,therebypermittingtheinsertionoftheballs.③TypesofBearings当滚球通过开口填充之后，用嵌块封住开口。由于开口会降低滚道的强度，所以嵌块必须设在轴承不承载的一侧。

Oncetheballshavebeeninsertedintothebearingthroughthenotch,thenotchisfilledbyaninsert.Theinsertshouldbekeptontheunloadedsideofthebearing,foritweakenstherace.TypesofBearings增加滚球之后，根据轴承尺寸大小可以使常规深沟滚球轴承的径向承载能力提高20％～40％，但其轴向承载能力仅为深沟滚球轴承的20％。

Theincreaseballcomplementmakepossiblea20to40percentincreaseinradial-loadcapacityoverthatofthenormaldeep-groovebearing,dependingonbearingsize.Thethrustcapacityofthefillednotchtypeisonly20%ofthethrustcapacityofthedeep-groovebearing.TypesofBearings3.角接触球轴承单一方向的推力轴承是最常见的角接触球轴承，这类轴承设计为组合支承径向载荷和单向推力载荷。

3.Angularcontactbearings

Aunidirectionalthrustbearing,whichisthemostpopularformofangularcontactbearings,iscommontous.Thistypeofbearingisdesignedtosupportcombinedradialandunidirectionalthrustloads.TypesofBearings与小接触角轴承相比，这种轴承所能承受的推力载荷更大一些。接触角为零的轴承称为径向轴承，接触角为90°的轴承叫做推力轴承。与小接触角轴承相比,这种轴承所能承受的推力载荷更大些｡“thatthisbearingcansupport”是定语从句,修饰load｡

Theamountofthrustloadthatthisbearingcansupportisheavierthanthesmallercontactangle.④

Acontactangleofzerocorrespondstoaradialbearing;acontactangleof90degreescorrespondstoathrustbearing.TypesofBearings通常,自适应球轴有两列滚球,它们在外圈的公共球面滚道中滚动｡“thatrollinacommonsphericalraceintheouterring”是定语从句,修饰rowsofball｡4.自适应球轴承通常自适应球轴承有两列滚珠，它们在外圈的公共球面滚道中滚动。因为将填满滚珠的内环设计成能通过绕着轴的轴承自由调整，

4.Self-aligningballbearings

Self-aligningballbearingsnormallyhavetworowsofballthatrollinacommonsphericalraceintheouterring.⑤

Becauseofthedesign,theinnerring,withtheballcomplement,canalignitselffreelyaroundtheaxisoftheshaft.TypesofBearings当轴受载弯曲时，轴承可不受阻力地跟随轴的变形方向调整。适应轴承也可抵消滚珠在滚道中运动时所产生的振动影响，使轴承平稳运转。因此这类轴承特别适用于较难获得轴与轴承孔平行的场合。

Whentheshaftbendsunderload,thebearingwillfollowthedeflectionoftheshaftwithoutresistance,self-alignmentalsocontributestosmoothrunningbyneutralizingtheeffectoftheballswobblinginthegrooves.Thisbearingisthereforeparticularlyusefulinapplicationsinwhichitisdifficulttoobtainexactparallelismbetweentheshaftandhousingbores.TypesofBearings5.推力球轴承最简单的一类推力球轴承，保持架内的一列滚珠在静止和回转环上的两个相同的滚道中滚动。

5.Thrustballbearings

Inthetypeofthesimplestformofthrustballbearings,asinglerowofballssetinaseparatorrunsintwosimilargroovesformedinthestationaryandrevolvingringsandtherevolvingringisfixedtoashaft.TypesofBearings旋转的环与轴固接，这些滚道通常要比深沟球轴承的浅。止推球轴承的设计是承受纯推力载荷，如果有一点点径向载荷，则必须另外安装径向轴承。

Thesegroovesareusuallyshallowerthanthegrooveinadeep-grooveradialballbearing.Thrustballbearingsaredesignedtocarrypurethrustloadand,ifanyradialloadispresent,separatedradialbearingmustbeused.TypesofBearings6.滚柱轴承滚柱轴承与滚珠轴承的功能一样，但其承受的载荷要大大高于相应尺寸的滚珠轴承，因为它是线接触而不是点接触。滚柱轴承可分为三种基本类型：圆柱滚子轴承、滚针轴承和圆锥滚子轴承。

6.Roller-bearing

Rollerbearingservesthesamepurposeasballbearings,butitcansupportmuchhigherloadthancomparablysizedballbearingbecauseithaslinecontactinsteadofpointcontact.⑥

Rollerbearingcanbeclassifiedintothreebasictypes:cylindricalrollerbearing,needlerollerbearingandtaperedrollerbearing.TypesofBearings1.Doyouknowwhytherearesomanytypesofbearings?ExercisesⅠ.Answerthefollowingquestionsaccordingtothepassage.Therearemanytypesofbearingsbecauseofvariationsinthedesignofringsandseparatorsandinthenumberofballs.2.Forwhatreasonsaredeep-grooveradialballbearingsmostwidelyused?Althoughdeep-grooveballbearingsaredesignedtocarryaradialload,theyperformwellunderacombinedradialandthrustload.Forthisreason,itisthemostwidelyusedtypeofballbearing.4.Whycanrollerbearingssupportmuchhigherloadthanthesamesizeballbearings?ExercisesⅠ.Answerthefollowingquestionsaccordingtothepassage.Becauseithaslinecontactinsteadofpointcontact.3.Accordingtothetext,howmanytypescanbearingsbedividedinto?Whatarethey?Thebearingscanbedividedintosixtypes,thatis,deep-grooveballbearings,filled-notchballbearings,angularcontactbearings,self-aligningballbearings,thrustballbearingsandrollerbearings.ExercisesⅠ.Answerthefollowingquestionsaccordingtothepassage.5.Dependingonitssize,afterincreasingballcomplement,itispossibletomakea20to40percentincreaseinradial-loadcapacityoverthatofthenormaldeep-groovebearing.Isittrue?Yes,itistrue.ExercisesⅡ.Translatethefollowingphrases.1.轴承承载能力bearingloadcapacity2.径向载荷radialload3.滚柱轴承rollerbearing4.轴向载荷thrustload5.公共球面滚道commonsphericalrace6.deep-grooveradialballbearing深沟径向球轴承7.angularcontactbearing角接触球轴承 8.self-aligningballbearing自适应球轴承9.thrustballbearing推力球轴承10.filled-notchballbearing填充式滚球轴承ExercisesⅢ.Fillinthemissingwordsandexpressionsaccordingtothepassage.1.Accordingtotheirfunction,bearingscanbedividedintoradialloads,thrustloadsanda___________ofthrustandradialloads.2.Theracesareaboutone-fourthasdeepastheballdiameterin_______________bearings.3.Toincreasetheballcomplementcanmosteffectivelyincreasebearing_____________.4.Unidirectionalthrustbearingisdesignedto_________combinedradialandunidirectionalthrustloads.supportloadcapacitycombinationdeep-grooveballExercisesⅢ.Fillinthemissingwordsandexpressionsaccordingtothepassage.5.Whenitisdifficulttoobtainexactparallelismbetweentheshaftandhousingbears,____________bearingsisparticularlycommonlyused.6.Thepurposeofrollerbearingsisthesameasthatofballbearings,butrollerbearingscansupportmuch___________thancomparablysizedballbearings.7.Themosteffectivewayofincreasingbearingloadcapacityistoincrease____________________.self-aligninghigherloadtheballcomplementExercisesⅢ.Fillinthemissingwordsandexpressionsaccordingtothepassage.8.Self-aligningballbearingsnormallyhavetworowsofballsthatrollinacommon_____________intheouterring.9.Inthetypeofthesimplestformofthrustballbearings,asinglerowofballssetinaseparatorrunsintwosimilargroovesformedinthestationaryand______________.10.Rollerbearinghas____________insteadofpointcontact..linecontactrevolvingringssphericalraceExercisesⅣ.TranslatethefollowingsentencesintoEnglish.1.深沟球轴承是应用最广泛的一种球轴承｡Thedeep-grooveballbearingisthemostwidelyusedtypeofballbearing.2.多数轴承需要进行定期维护以避免过早毁损｡Manybearingsrequireperiodicmaintenancetopreventprematurefailure.3.滚柱轴承承受的载荷要大大高于相应尺寸的滚珠轴承｡Rollerbearingcansupportmuchhigherloadthancomparablysizedballbearing.ExercisesⅣ.TranslatethefollowingsentencesintoEnglish.4.预期大约多达三分之二的材料将产生相同的效果｡Approximatelytwothirdsasmanymaterialswouldbeexpectedtoproducethesameeffect.5.这一程序需要将处理器的能力提高25%｡Thisprogrammewillrequireatwenty-fivepercentincreaseinprocessorcapacity.6.一般来说轴承的表面温度与以往观测的一致｡Thesurfacetemperatureofthebearingswasgenerallythesameaswhatwaspreviouslyobserved.Virtuallyallmachinescontainshafts.Themostcommonshapeforshaftsiscircularandthecrosssectioncanbeeithersolidorhollow(hollowshaftscanresultinweightsavings).Rectangularshaftsaresometimesused,asinscrewdriverblades,socketwrenchesandcontrolknobstems.

Shafts轴实际上，几乎所有的机器中都装有轴。轴最常见的形状是圆形，其截面可以是实心圆，也