外文翻译--齿轮机构

《外文翻译--齿轮机构》由会员上传分享，免费在线阅读，更多相关内容在行业资料-天天文库。

1、翻译部分英文原文GearmechanismsGearmechanismsareusedfortransmittingmotionandpowerfromoneshafttoanotherbymeansofthepositivecontactofsuccessivelyengagingteeth.Inabout2,600B.C.,Chineseareknowntohaveusedachariotincorporatingacomplexseriesofgearslikethoseillustratedin

2、Fig.2.7.Aristotle,inthefourthcenturyB.C.wroteofgearsasiftheywerecommonplace.InthefifteenthcenturyA.D.,LeonardodaVincidesignedamultitudeofdevicesincorporatingmanykindsofgears.Incomparisonwithbeltandchaindrives,geardrivesaremorecompact,canoperateathighspee

3、ds,andcanbeusedwhereprecisetimingisdesired.Thetransmissionefficiencyofgearsisashighas98percent.Ontheotherhand,gearsareusuallymorecostlyandrequiremoreattentiontolubrication,cleanliness,shaftalignment,etc.,andusuallyoperateinaclosedcasewithprovisionforprop

4、erlubrication.Gearmechanismscanbedividedintoplanargearmechanismsandspatialgearmechanisms.Planargearmechanismsareusedtotransmitmotionandspatialgearmechanisms.Planargearmechanismsareusedtotransmitmotionandpowerbetweenparallelshafts,andspatialgearmechanisms

5、betweennonparallelshafts.Typesofgears(1)Spurgears.ThespurgearhasacylindricalpitchsurfaceandhasstraightteethparalleltoitsaxisasshowninFig.2.8.Theyareusedtotransmitmotionandpowerbetweenparallelshafts.Thetoothsurfacesofspurgearscontactonastraightlineparalle

6、ltotheaxesofgears.Thisimpliesthattoothprofilesgointoandoutofcontactalongthewholefacewidthatthesametime.Thiswillthereforeresultinthesuddenloadingandsuddenunloadingonteethasprofilesgointoandoutofcontact.Asaresult,vibrationandnoiseareproduced.(2)Helicalgear

7、s.Thesegearshavetheirtoothelementsatanangleorhelixtotheaxisofthegear(Fig.2.9).Thetoothsurfacesoftwoengaginghelicalgearsinnplanargearmechanismscontactonastraightlineinclinedtotheaxesofthegears.Thelengthofthecontactlinechangesgraduallyfromzerotomaximumandt

8、henfrommaximumtozero.Theloadingandunloadingoftheteethbecomegradualandsmooth.Helicalgearsmaybeusedtotransmitmotionandpowerbetweenparallelshafts[Fig.2.9(a)]orshaftsatanangletoeachother[Fig.2.9(d)].Aherringbonegear[Fig.2.9(c)