汽车专业英语 黄星 刘春波 黄汽驰 6

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1、UNIT6IntroductiontoBrakeSystemPart ITechnicalandPracticalReadingPassageABrakeSystem(I)Thebreakingsystemisthemostimportantsystemincars.Ifthebrakesdon’tworkeffectively,theresultcanbedisastrous.Sogoodbrakesareessentialforsafety.Thebrakesystemmakesamovingcaronroadslo

2、wdownandstop.Thetypicalbrakesystemconsistsofdiskbrakesinfrontandeitherdiskordrumbrakesintherearconnectedbyasystemoftubesandhosesthatlinkthebrakeateachwheeltothemastercylinder.Seefigure6-1.Figure6-1DiskBrakeThediskbrakesarethebestbrakewehavefoundsofar,andisfastrepl

3、acingdrumbrakesontherearwheelsofmoderncars.Thefunctionistocausetwofrictionpadstopressoneithersideofadiskrotatingalongwiththewheel.Thegreatestadvantageofdiskbrakesisthattheyprovidesignificantlybetterresistanceto“brakefade”comparedtodrumtypebrakingsystem.Themaincomp

4、onentsofadiskbrakeare:diskorrotor,whichismountedtothehub,brakepads,andcaliper,whichcontainsapiston.Seefigure6-2.Figure6-2DiskBrakeModuleAbrakediskorrotorusuallyismadeofcastironwithhighlymachinedsurfaceswherethebrakepadscontactit.Therearetwobrakepadsthataremountedi

5、nthecaliper,oneoneachsideofrotor.Seefigure6-3.Figure6-3Thebrakeliningusedtobemadeprimarilyofasbestosbecauseofitsheatabsorbingpropertiesandquietoperation.Asbestos,however,hasbeenoutlawedduetohealthrisk,sonewmaterialsarebeingused.Therearetwomaintypesofcalipers:float

6、ingcalipersandfixedcalipers.Thesingle-pistonfloating-caliperdiscbrakeisself-centeringandself-adjusting.Thecaliperisabletoslidefromsidetosidesoitwillmovetothecentereachtimethebrakesareapplied.Also,sincethereisnospringtopullthepadsawayfromthedisk,thepadsalwaysstayin

7、lightcontactwiththerotor.Twopiston-floatingcalipersarefoundonmoreexpensivecarsandcanprovideanimprovedbraking“feel”.Seefigure6-4.Figure6-4Four-piston-fixedcalipersaremountedrigidlytothesupportandarenotallowedtomove.Instead,therearetwopistonsoneachsidethatpressthepa

8、dsagainsttherotor.Fourpistoncalipershaveabetterfeelandaremoreefficient,butaremoreexpensivetoproduceandcostmoretoservice.ThistypThistypeofcaliperisusuall