Student Guide_ENUS_液压-检修基本原理-学员指南

HYDRAULICSHYDRAULICSFUNDAMENTALSOFSERVICEFOS1007WSTUDENTGUIDEServicing,testing,andmaintenanceguideforhydraulicsystemsinoff-roadvehicles,trucks,buses,andautomobiles.Wehavealong-rangeinterestinVocationalEducationCopyright©1967,1972,1979,1987,1992,1999,2005,2006.LithoinU.S.A.DEERE&COMPANY,Moline,IL/SeventhEdition/Allrightsreserved.ISBN0-86691-337-8ThismaterialisthepropertyofDeere&Company,JohnDeerePublishing,alluseand/orreproductionnotspecificallyauthorizedbyDeere&Company,JohnDeerePublishingisprohibited.VisitUsontheInternet(FOS)isaseriesofmanualscreatedbyDeere&Company.Eachbookintheseriesisconceived,researched,outlined,edited,andpublishedbyDeere&Company,JohnDeerePublishing.Authorsareselectedtoprovideabasictechnicalmanuscriptthatcouldbeeditedandrewrittenbystaffeditors.PUBLISHERDEERE&COMPANYJOHNDEEREPUBLISHINGoneJohnDeerePlaceMoline,IL61265–800–522–7448EDITORIALSTAFFLoriDhabaltThisStudentGuideisdividedintoblocksthatincludethefollowinginformation:LearningObjectives,StudyGuide,Assignments,andReviewQuestions.EachguidewaswrittenbyDeere&Company,JohnDeerePublishingstaffincooperationwiththetechnicalwriters,illustrators,andeditorsatAlmon,Inc.—afull-servicetechnicalpublicationscompanyheadquarteredinWaukesha,Wisconsin().FORMOREINFORMATION:Thisbookisoneofmanybookspublishedonagriculturalandrelatedsubjects.FormoreinformationortorequestaFREECATALOG,call1–800–522–7448orsendyourrequesttoaddressaboveor:ACKNOWLEDGEMENTS:JohnDeeregratefullyacknowledgeshelpfromthefollowinggroups:AeroquipCorporation,AmericanOilCompany,CessnaAircraftCompany,Char-LynnCompany,CommercialShearingandStampingCompany,GreerHydraulics,Inc.,GresenManufacturingCompany,H7drecoDivisionofNewYorkAirBrakeCompany,NationalFluidPowerAssociation,TheNudayCompany,OwatonnaToolCompany,SunOilCompany,SundstrandCorp.,TexacoInc.,VickersInc.1Hydraulics1HYDRAULICS—HOWITWORKSSTUDENTGUIDELEARNINGOBJECTIVESAttheconclusionofthischapter,youwillbeableto:1.Explainthebasicprinciplesofhydraulics.2.Explainhowabasichydraulicsystemworks.3.Compareopen-andclosed-centerhydraulicsystems.4.Listsomecommonusesforhydraulicsystems.HYDRAULICS—HOWITWORKS2HydraulicsOBJECTIVE#1:Explainthebasicprinciplesofhydraulics.DISCUSSIONQUESTIONS1.Whatarethebasicpropertiesofliquidsinahydraulicsystem?a)b)c)d)e)f)g)h)2.Definethetermspressure,displacement,andflow,andgivethecustomaryunitsofmeasureforeach.a)Pressure:b)Displacement:c)Flow:Hydraulics3HYDRAULICS—HOWITWORKS3.Definetheterms,force,work,andpower,andgivethecustomaryunitsofmeasureforeach.a)Force:b)Work:c)Power:4.Discusstheconceptsofthespringandsolenoidsastheyaffecttheoperationofhydraulicvalves.a)Spring:b)Solenoid:HYDRAULICS—HOWITWORKS4HydraulicsOBJECTIVE#2:Explainhowabasichydraulicsystemworks.DISCUSSIONQUESTIONS5.Whereisthepowersourceforahydraulicsystem?Howispowerproduced?6.Whereistheworkdoneinahydraulicsystem?Howisworkproduced?7.Whatdoesacheckvalvedo?8.Howisthehydraulicreservoirusedinahydraulicsystem?9.Whatcontrolstheflowofoilinahydraulicsystem?10.Whatpartofthemachineisusedtocontrolthepressureinthehydraulicsystem?Howdoesitwork?a)b)Hydraulics5HYDRAULICS—HOWITWORKSOBJECTIVE#3:Compareopen-andclosed-centerhydraulicsystems.DISCUSSIONQUESTIONS11.Whatarethedefinitionsofopen-centerandclosed-centerhydraulicsystems?a)Open-Center:b)Closed-Center:12.Explaintheoilflowinanopen-centersystemwhenthecontrolvalveisinneutral.13.Inaclosed-centerhydraulicsystemwithavariable-displacementpump,explainthefollowing:a)Whathappenswhenthecontrolvalveisintheneutralpositionandthehydraulicpressurereachesthepreset(standby)level?b)Whathappenswhenthecontrolvalveopens?OPEN-CENTERSYSTEMS14.Explainthemajorpointsofasystemwithafixed-displacementpumpandanopen-centervalvewithaseriesconnection.HYDRAULICS—HOWITWORKS6Hydraulics15.Whatadvantagesdoesthesystemwithafixed-displacementpumpandanopen-center,series-parallelvalvehaveovertheseriesdesign?16.Whatarethedrawbacksofasystemwithafixed-displacementpumpandaflowdivider?17.Whatarethefeaturesofasystemwithavariable-displacementpumpandanopen-centervalve?CLOSED-CENTERSYSTEMS18.Whatspecialpartsdoyouneedforasystemwithafixed-displacementpumpandaclosed-centervalve?a)b)19.Describeasystemwithafixed-displacementpump,aflowdividerandaclosed-centervalve.Hydraulics7HYDRAULICS—HOWITWORKS20.Describeasystemwithapressure-compensatedvariable-displacementpumpandaclosed-centervalve.Whatisthefunctionofachargingpump?21.Howdoesthesystemusingaload-sensingvariable-displacementpumpandclosed-centervalvesdifferfromtheprevioussystem?22.Whyareclosed-centerhydraulicsystemspopularontoday’smachines?23.Whatisaclosed-loophydraulicsystem?HYDRAULICS—HOWITWORKS8HydraulicsOBJECTIVE#4:Listsomecommonusesforhydraulicsystems.DISCUSSIONQUESTIONS24.Listthethreetypesofpowersteeringgiveninthetextbook.Brieflytellhoweachtypediffers.a)b)c)25.Whatarehydraulicassiststeeringsystems?26.Howdohydraulicbrakesworkinamachine?27.Howdopowerbrakesoperateinamachine?Hydraulics9HYDRAULICS—HOWITWORKS28.Whataredepthanddraftcontro