Case 1121F - Page 17

INTRODUCTION
Hydrauliccontamination
Contaminationinthehydraulicsystemisamajorcauseofthemalfunctionofhydrauliccomponents.Contamination
isanyforeignmaterialinthehydraulicoil.Contaminationcanenterthehydraulicsysteminseveralways.
(A)Whenyoudraintheoilordisconnectanyline.
(B)Whenyoudisassembleacomponent.
(C)Fromnormalwearofthehydrauliccomponents.
(D)Fromdamagedorwornseals.
(E)Fromadamagedcomponentinthehydraulicsystem.
Allhydraulicsystemsoperatewithsomecontamination.Thedesignofthecomponentsinthishydraulicsystemper-
mitsefcientoperationwithasmallamountofcontamination.Anincreaseinthisamountofcontaminationcancause
problemsinthehydraulicsystem.Thefollowinglistincludessomeoftheseproblems.
(A)Cylinderrodsealsleak.
(B)Controlvalvespoolsdonotreturntoneutral.
(C)Movementofcontrolvalvespoolsisdifcult.
(D)Hydraulicoilbecomestoohot.
(E)Pumpgears,housing,andotherpartswearrapidly.
(F)Reliefvalvesorcheckvalvesheldopenbydirt.
(G)Quickfailureofcomponentsthathavebeenrepaired.
(H)Cycletimesareslow;machinedoesnothaveenoughpower.
Ifyourmachinehasanyoftheseproblems,checkthehydraulicoilforcontamination.Therearetwotypesofcontam-
ination,microscopicandvisible.
Microscopiccontaminationoccurswhenveryneparticlesofforeignmaterialareinsuspensioninthehydraulicoil.
Theseparticlesaretoosmalltoseeorfeel.Microscopiccontaminationcanbefoundbyidenticationofthefollowing
problemsorbytestinginalaboratory.Examplesoftheproblems:
(A)Cylinderrodsealleak.
(B)ControlvalvespoolsdonotreturntoNEUTRAL.
(C)Thehydraulicsystemhasahighoperatingtemperature.
Visiblecontaminationisforeignmaterialthatcanbefoundbysight,touch,orodor.Visiblecontaminationcancause
asuddenfailureofcomponents.Examplesofvisiblecontamination:
(A)Particlesofmetalordirtintheoil.
(B)Airintheoil.
(C)Theoilisdarkandthick.
(D)Theoilhasanodorofburnedoil.
(E)Waterintheoil.
Ifyoundcontamination,useaPortableFiltertocleanthehydraulicsystem.
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