Toro Groundsmaster 4300-D - Lift Cylinder Circuit: Lower the Cutting Decks

LiftCylinderCircuit:LowertheCuttingDecks
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Figure37
A4-sectiongearpumpiscoupledtothepiston(traction)pump.Thegearpump
section(P4)supplieshydraulicowtotheliftcontrolmanifoldandliftcylinders.
Thegearpumptakesitssuctionfromthehydraulicreservoir.
Theliftcontrolmanifoldincludes3electricallyoperatedvalves.Thesolenoid
valve(S1)isusedtodirectuidowtoextendtheliftcylinders(lowerthe
cuttingdecks)whenenergizedorretractthem(raisethecuttingdecks)when
de-energized.Thesolenoidvalve(S2)allowshydraulicowfromtherodend
oftheliftcylinderswhenenergized,andpreventshydraulicowfromthelift
cylinderswhende-energized.UsingsolenoidvalveS2inthismanneralso
helpskeepthecuttingdeckselevatedoncethemachineisswitchedOFF.The
proportionalreliefvalve(PRV)isusedtocontroltheoperationofthelogic
cartridge(LC)andactsasacircuitreliefvalve.
Note:Withtheenginerunning,thecuttingunitscanonlybeloweredifan
operatorisintheseatortheparkingbrakeisset,andthemow/speedlimiteris
intheMOWposition.Thecuttingunitscanalsobeloweredwithouttheengine
runningifthekeyswitchisintheRUNpositionandtheoperatorisintheseat.
LowertheCuttingDecks
Whenthejoystickismovedtothelowerposition,thecontrollerenergizesallof
theliftmanifoldvalves(S1,S2,andPRV).Theenergizedreliefvalve(PRV)
preventsowthroughthevalvewhichallowslogiccartridgeLCtoreturntoits
unshifted(closed)position.Withthevalvesinthisposition,thepumpowis
Groundsmaster
®
4300-D
Page4–27
HydraulicSystem:HydraulicFlowDiagrams
16226SLRevC