Toro Groundsmaster 7210 - Lift Circuit (Raise)

LiftCircuit(Raise)
Asingle-sectiongearpumpisdirectlycoupledtothetransmissionwhichisdriven
bytheengine.Thisgearpumpsupplieshydraulicowforraisingandloweringthe
cuttingdeck(orimplement).Thepumptakesitssuctionfromthehydraulictank.
Duringtheconditionsofnotraisingorloweringthecuttingdeck(orimplement),
owfromthegearpumpisbypassedbythelift-controlmanifolddirectlytotheoil
coolerandthentothetransmission.Theowthenreturnstothehydraulictank.
Note:Toraisethecuttingdeck,theenginemustbeinrunningcondition.
ElectricalLiftControl
Thelift-controlmanifoldisequippedwiththe2solenoidvalvesforelectrical
controloftheliftcircuit.Adecklift/lowerswitchontherightsidetractionleveris
usedtoraisethecuttingdeck(orimplement).
Whenthetopofthelift/lowerswitchispressed(momentaryposition),boththe
solenoidvalves(A/S1andB/S2)inthedeckliftmanifoldareenergizedtocause
thevalvestoshift.TheenergizedsolenoidvalveB/S1preventsthegearpump
owfrombypassingtheliftcylinder.TheenergizedsolenoidvalveA/S1allows
thehydraulicowfromthegearpumptothecylinderheadoftheliftcylinder.The
liftcylinderextends,causingthecuttingdecktoraise.Theuiddisplacedfrom
therodendoftheliftcylinderisroutedtotheoilcooler,transmission,andthento
thehydraulictank.Anoriceinthemanifoldcontrolstheextendingspeedofthe
liftcylinderwhileraisingthecuttingdeck.
Theloadontheliftcylindercausestheliftcircuitpressuretoincrease.Ifthelift
circuitpressurereachestheimplementreliefvalvepressure20,700kPa(3,000
psi),thereliefvalveinthegearpumpshiftstoallowthepumpowtoreturnto
thehydraulictank.Thisconditionoccursinboththeraiseandlowermodes.
Whenthetopofthelift/lowerswitchisreleased,boththesolenoidvalves(A/S1
andB/S2)inthedeckliftmanifoldarede-energized.Thede-energizedsolenoid
valveB/S2allowsthegearpumpowtobypasstheliftcylinder,returningto
theoilcooler,transmission,andthentothehydraulictank.Thede-energized
solenoidvalveA/S1preventsthehydraulicowtoandfromtheliftcylinderto
keepthecuttingdeckintheraisedposition.
HydraulicSystem:HydraulicSchematics
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Groundsmaster7210
16222SLRevC