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1、THEBRAKEBIBLEBrakes-whatdotheydo?Thesimpleanswer:theyslowyoudown.Thecomplexanswer:brakesaredesignedtoslowdownyourvehiclebutprobablynotbythemeansthatyouthink.Thecommonmisconceptionisthatbrakessqueezeagainstadrumordisc,andthepressureofthesqueezingactioniswhatslowsyoudown.Thisi
2、nfactisonlypartoftheequation.Brakesareessentiallyamechanismtochangeenergytypes.Whenyou'retravellingatspeed,yourvehiclehaskineticenergy.Whenyouapplythebrakes,thepadsorshoesthatpressagainstthebrakedrumorrotorconvertthatenergyintothermalenergyviafriction.Thecoolingofthebrakesdi
3、ssipatestheheatandthevehicleslowsdown.It'stheFirstLawofThermodynamics,sometimesknownasthelawofconservationofenergy.Thisstatesthatenergycannotbecreatednordestroyed,itcanonlybeconvertedfromoneformtoanother.Inthecaseofbrakes,itisconvertedfromkineticenergytothermalenergy.Angular
4、force.Becauseoftheconfigurationofthebrakepadsandrotorinadiscbrake,thelocationofthepointofcontactwherethefrictionisgeneratedalsoprovidesamechanicalmomenttoresisttheturningmotionoftherotor.Thermodynamics,brakefadeanddrilledrotors.Ifyourideamotorbikeordrivearacecar,you'reprobab
5、lyfamiliarwiththetermbrakefade,usedtodescribewhathappenstobrakeswhentheygettoohot.Agoodexampleiscomingdownamountainpassusingyourbrakesratherthanyourenginetoslowyoudown.Asyoustarttocomedownthepass,thebrakesonyourvehicleheatup,slowingyoudown.Butifyoukeepusingthem,therotorsordr
6、umsstayhotandgetnochancetocooloff.Atsomepointtheycan'tabsorbanymoreheatsothebrakepadsheatupinstead.Ineverybrakepadthereisthefrictionmaterialthatisheldtogetherwithsomesortofresinandoncethisstartstogettoohot,theresinstartstovapourise,formingagas.Becausethegascan'tstaybetweenth
7、epadandtherotor,itformsathinlayerbetweenthetwowhilsttryingtoescape.Thepadslosecontactwiththerotor,reducingtheamountoffrictionandvoila.Completebrakefade.Thetypicalremedyforthiswouldbetogetthevehicletoastopandwaitforafewminutes.Asthebrakecomponentscooldown,theirabilitytoabsorb
8、heatreturnsandthenexttimeyouusethebrakes,theyseemtoworkjustfine.Thistypeofb