Toro Groundmaster Series - Page 105

pumpoutputowstothesteeringcontrolvalvebeforesupplyingtheliftand
chargecircuitneedssothatthesteeringcircuithaspriority.
CuttingUnit(orImplement)Idle
Whentheliftsystemisnotactivelyraising,lowering,oroating(idle),uidow
entersthehydraulicmanifoldatthePport.Hydraulicpressurewilltryandraise
theliftarmsuntilthepressureopenslogiccartridgeLCandprovidesauidpath
toexitthemanifold.Whenthelogiccartridgeopensiscontrolledbyadjusting
thelogiccartridgetothedesiredweighttransfer(counterbalance).Referto
thetractionunitOperator’sManualforadditionalcounterbalanceadjustment
information.
RaisingtheCuttingUnit(orImplement)
WhentheliftswitchissettotheRaiseposition,solenoidvalveSV1isenergized,
holdinglogiccartridgeLCclosed.Hydraulicowisdirectedthroughde-energized
solenoidvalveSV2tothefront(capend)oftheliftcylinders.Thehydraulic
pressureagainstthecylinderpistonsextendstheliftcylinders.Atthesametime,
thepistonspushthehydraulicuidintheliftcylindersoutandtothehydraulic
manifold.Theextendingliftcylinderscausethecuttingunit(orimplement)to
raise.Whenthecylindersreachtheendoftheirstroke,oriftheliftarmsare
preventedfromraising,thereliefvalve(R4)inthesteeringcontrolvalveopens
anddirectsthehydraulicowthroughthemanifoldandbacktothegearpump
(P2)untiltheliftswitchisreleased.Theliftcircuitpressureislimitedto7,000to
7,500kPa(1,015to1,088psi).AcheckvalveinsolenoidvalveSV2prevents
thecylindersfromlowering.
LoweringtheCuttingUnit(orImplement)
WhentheliftswitchissettotheLOWERposition,solenoidvalveSV2isenergized
toopenapathforuidtrappedatthefront(capend)oftheliftcylinderpistonsto
escape.Theweightofthecuttingunit(orimplement)causesthecylindersto
retractandlowertheliftarms.Thespeedwhichthecylindersloweriscontrolled
byacheckorice(ORatmanifoldportC1).Theescapinguidcombineswith
theremainderoftheowfromthegearpump(P2)topassthroughtheopen
logiccartridge(LC)andexitthemanifold.Asthecylindersretract,thecylinder
pistonsdrawhydraulicuidfromthehydraulicmanifoldintotherear(rodend)of
theliftcylinders.
FloatingtheCuttingDeck(orImplement)
Asthecuttingunitmovesoverterrainwithchangingelevation,theliftarmsare
allowedtomoveupanddown(oat).Theliftcylindersareallowedtoextendand
retractifnecessarywhenoating.Afterthecuttingunitisfullylowered,solenoid
valveSV2remainsenergizedtoholdapathopenforuidatthefront(capend)
oftheliftcylinderpistontoowineitherdirectionifnecessary.Hydraulicuid
isallowedtoowfromthemanifoldtoandfromtherear(rodend)ofthelift
cylindersaswell.
Groundsmaster
®
3200,3300and3310
Page5–19
HydraulicSystem:HydraulicFlowDiagrams
19240SLRevA