Service Manual

LeftTurn
Whenaleftturnismadewiththeenginerunning,theturningofthesteeringwheel
positionsthesteeringcontrolvalvespoolsothattheloadsenseowisblocked
off.Withoutloadsenseow,pressuresontheendsofmanifoldcompensator
valve(EC)starttoequalizecausing(EC)tomovetowarditsneutralposition
whichallowstheneededoilowtothesteeringcontrolvalve.Oilisroutedout
manifoldportCF,intosteeringvalveportP ,throughthesteeringcontrolspool,is
drawnthroughtherotarymetersectionandouttheLporttothesteeringcylinder.
Pressureretractsthesteeringcylinderforaleftturn.Therotarymeterensures
thattheoilowtothecylinderisproportionaltotheamountoftheturningonthe
steeringwheel.Fluidleavingthecylinderowsbackthroughthesteeringvalve
Rport,thespoolvalve,outtheTportandthenreturnstothehydraulicreservoir.
Thesteeringcontrolvalvereturnstotheneutralpositionwhenturningis
completed.
SteeringReliefOperation
Whenthesteeringcylinderreachestheendofitsstrokeorifarearwheelshould
encounteranobstruction(e.g.acurb)whilesteering,thepressureinthesteering
circuitwillrise.Reliefvalve(RV1)inthecombinationmanifoldsensesthis
pressureincrease.Whensteeringcircuitpressurebuildstoapproximately93bar
(1350PSI),reliefvalve(RV1)opensandallowshydraulicowtoreturntothe
hydraulicreservoir.Thisactioncausesowacrossthereliefvalvesideoriceof
compensatorvalve(EC)whichshiftsthespoolin(EC)tosendoilawayfromthe
steeringcircuittothefanmotorcircuit.Reliefvalve(RV1)controlstheactionof
compensatorvalve(EC)andallowsthecompensatorvalvetodivertonlyenough
oilowtothesteeringcircuittomaintainreliefpressure.
HydraulicSystem:HydraulicFlowDiagrams
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Groundsmaster
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4100-D&4110-D
13203SLRevE