汽车专业英语.doc

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1、Fig.31.1XFig.31.2TheactualspeedofthewheelFlwillthenbe202rev/min,becauseitsforwardmotionof2rev/minrelativelytothedifferentialcageisaddedtotheforwardsmotion200rev/minofthatcage.TheactualspeedofthewheelF2willbe198rev/minbecauseitsbackwardsmotionof2rev/minrelativelytot

2、hedifferentialcageissubtractedfromtheforwardsmotionof200rev/minofthatcage.Thisistheactionthatoccurswhenacarmovesinacircle:theroadwheelsareconstrainedtomoveatdifferentspeedsanddosobyvirtueofonewheelgoingfasterthanthedifferentialcagewhiletheothergoesanequalamountslow

3、erthanthedifferentialcage.Thusthespeedofthedifferentialcageisthemeanoftheroadwheelspeeds.Whenthecarmovesinastraightline,theroadwheelsturnatthesamespeedasthedifferentialcage,andthedifferentialpinionsdonothavetoturnontheirpinsatall.Theabovedescriptionshouldmakeitclea

4、rhowtheroadwheelscanturnatdifferentspeeds;itremainstoshowthatwhensodoingtheyaredrivenwithequaltorques.InFig.3L1thebevelwheelsareshownreplacedbydiscshavingnotchesintheirperipheries.Lyingwithitsendsinthesenotchesisabeam.IfaforcePisappliedtothecenterofthebeaminadirect

5、iontangentialtothediscsasshown,thenifthebeamdoesnottumabouttheverticalaxis,orifitturnsaboutthataxiswithuniformvelocity,theforcesattheendsofthebeammustbeequalandeachwillbeequaltoP/2.Thereactionsoftheforcesactingontheendsofthebeamactonthediscs,henceequalforcesareappl

6、iedtothediscsatequaldistancesfromtheiraxes,andthereforethetwistingmomentsortorquesactingonthediscsareequal.Itshouldreadilybeseenthatthebevelpinionactsinamannerpreciselsimilartothebeam.Hencethetorquestransmittedtothedriveshaftsareequalandeachwillbeequaltohalfthetorq

7、ueappliedtothedifferentialcasebythefinaldrive.IntheactualdifferentialtheforcePappearsasapressurebetweenthebevelpinionanditspinwhiletheforcesP/2appearaspressuresbetweentheteethofthebevelpinionandthebevelwheels31/1AnotherarrangementofthebevelfinaldriveThebevelfinaldr

8、iveissometimesarrangedinadifferentmannerfromthatdescribedpreviously,generallybecausesomeotherdifferenceinaxleconstructionnecessitatesthechange.Th