汽车工程专业毕业设计论文外文翻译

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1、天津工程师范学院01级毕业设计BrakesystemAnautomotivebrakemechanismisafrictiondevicedesignedtochangepowerintoheat.Whenthebrakesareapplied,theyconvertthepowerofmomentumofthemovingvehicle(kineticenergy)intoheatbymeansoffriction。Thebrakesystem,then，isabalancedsetofmechani

2、calandhydraulicdevicesusedtoretardthemotionofthevehiclebymeansoffriction。FrictionFrictionistheresistancetorelativemotionbetweentwobodiesincontact。Itiscausedbytheinterlockingofprojectionsanddepressionsofthetwosurfacesincontact。Therefore,thereislessfrictio

3、nbetweenpolishedsurfacesthanbetweenroughsurfacesFrictionvarieswithdifferentmaterialsandwiththeconditionofthematerials。Thereislessfrictionbetweensurfacesofdifferentmaterialsthanbetweenthoseofthesamematerial。Thereislessfrictionwhenonesurface(tiretread)roll

4、sovertheother(pavement)thanwhenitslides。CoefficientofFictionTheamountoffrictioncreatedisproportionaltothepressurebetweenthetwosurfacesincontactItisindependentoftheareaofsurfacecontact。Theamountoffrictiondevelopedbyanytwobodiesincontactissaidtobetheircoef

5、ficientoffriction(C.O.F.)。Thecoefficientoffrictionisfoundbydividingtheforcerequiredtoslidethe"weigh"overhesurfacebytheweightoftheobject。SeeexampleinFigure48-1。Ifa60lb.pullisrequiredtoslidea1001b.Weight,thentheC.O.F.wouldbe60dividedby100or60.Ifonly35lb.is

6、requiredtoslidethe100lb.weight,thentheC.O.F.wouldbe.35。IthasbeenestablishedthatthecoefficientoffrictionwillchangewithanyvariationoftheconditionofthesurfacesAnylubricant,ofcourse,willgreatlyreducetheC.O.F,whichiswhyitissoimportanttokeepanygreaseoil,orbrak

7、efluidfrombrakelining。EvenanextremelydampdaywillcausesomevariationinC.O.F.Figure48-1.ThecoefficientoffrictionisequaltotheforcerequiredtoslideabodyacrossasurfacedividedbytheweightofthebodyBrakingForces21天津工程师范学院01级毕业设计Tremendousforcesareinvolvedwhenbrakin

8、gavehicle。Thevehiclemustbebroughttoastopinamuchshortertimethanisrequiredtobringituptospeed。Tobettervisualizethis,comparehorsepowerrequiredtoaccelerateavehicleandhorsepowerneededtostopit。Acompactvehiclewitha75hpfourcylinder