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1、TroubleshootingHydraulicSystemProblemsIntroductiontoHydraulicSystemsIn1650,Frenchscientist,mathematicianandphilosopherBlaisePascaldiscoveredthefundamentallawofphysicsthatformsthebasisofallhydraulicsystems.Pascal’sLawstates,“Pressureappliedtoaconfined
2、fluidistransmittedundiminishedthroughouttheconfiningvesselorsystem.”Inpracticalterms,ifweapplythislawtoahydrauliccylinderormotor,anyoilpressureappliedtothepistonswillbetransmittedequallyinalldirectionswithinthefluidfilledcylinderormotor.Hydraulicsyst
3、emsmaybeverycomplex,buteverysystem,nomatterhowbasic,mustcontainareservoir,apump,variousvalvestocontroloilflow,directionandpressureandahydrauliccylinderormotortomovetheloadappliedbyoilunderpressure.(SEEFIGURE1.)FIGURE1.Abasichydraulicsystem.HydraulicS
4、ystemOperatingPrinciplesTherearetwofundamentalprinciplesthatmustbeunderstoodwhentroubleshootinghydraulicsystemproblems.1.Pumps(whichmaybevane,gear,orpistontypes)areusedinhydraulicsystemstoproducesufficientflowtoobtainthespeedrequiredfromcylindersormo
5、tors.Thisspeed(oilflow)canbeincreasedordecreasedbyusingapumpofhigherorlowercapacity,orbychangingtherelativesizeofthecylinderormotor,buttheflowofoil(speedofthecylinder)willnotbesignificantlyincreasedordecreasedbyalteringsystempressures.2.Theresistance
6、tooilflowisdirectlyrelatedtotheloadwhichthecylinderiscarryingorlifting,thereforeresistancetooilflowresultsinpressure.Theheaviertheload,thehighertheresultingpressure(subjecttothemaximumpressuresettingofthepressurereliefvalve).Ifasystemisnotmaintaining
7、correctpressureswhilethepumpismaintainingitsspecifiedflowrate,thenonlytwoconditionsmayexist;eitheranexternalleakisoccurring,whichshouldbeobviousbytheoilspill,oraninternalleakisoccurringwhichmaynotbesoobvious.Ifontheotherhand,thesystemisdevelopingexce
8、ssivepressuresduringoperation,thecauseisexcessiveresistancetoflow.Thismaybetheresultofexcessiveload,restrictedcomponents,suchaspluggedfiltersorhoses,orsomemechanicalproblemsuchasabentcylinderrod.Techniciansandtroubleshooterswouldbewelladvisedtorememb
