Service Manual

MowCircuit
A4-sectiongearpumpiscoupledtothepiston(traction)pump.Thegearpump
sections(P1)and(P2)supplyhydraulicowforthemowcircuit.Thesegear
pumpstaketheirsuctionfromthehydraulicreservoir.
Thedeckcontrolmanifoldcontains2independentcontrolcircuitsforthefront
andrearcuttingdecks.Eachcircuitissuppliedbyitsownpumpsection.The
pumpsection(P1)supplieshydraulicpowertotherearcuttingdeckswithcircuit
controlbyproportionalreliefvalve(PRV1),reliefvalve(RV1)andlogiccartridge
(LC1)inthedeckcontrolmanifold.Thepumpsection(P2)supplieshydraulic
owforthefrontcuttingdeckswithcircuitcontrolbyproportionalreliefvalve
(PRV2),reliefvalve(RV2)andlogiccartridge(LC2)inthedeckcontrolmanifold.
BoththecircuitssharemanifoldportT,whichdrainstotheoilcooler,oillter
andhydraulicreservoir.
Thecuttingdeckmotorsareequippedwithacrossoverreliefvalvetoprevent
hydrauliccomponentdamageincaseasinglecuttingdeckstalls.
Themachinecontrollerusesinputsfromvariousmachineswitchestodetermine
whenthesolenoidsforproportionalreliefvalves(PRV1)and(PRV2)aretobe
energized.Thecontrolleralsoprovidesaslightdelayinactivationofrearcutting
decks.
PTONotEngaged
WhenthePTOswitchisintheOFFpositionorthecuttingdecksareraised,the
proportionalreliefvalves(PRV1)and(PRV2)arenotenergized,theowfrom
pumpsections(P1)and(P2)isdirectedthroughtheunshiftedproportionalrelief
valves,andoutthroughthedeckcontrolmanifoldportTandthenreturnsback
tothehydraulicreservoirthroughtheoillterandoilcooler.Inthispositionthe
hydraulicowbypassesthedeckmotors.Themanifoldlogiccartridges(LC1and
LC2)remainintheunshiftedpositiontopreventanyreturnowtothedeck
motorssothatthemotorsdonotrotate.
PTOEngaged
g186181
Figure31
WhenthePTOswitchisturnedONwiththedeckslowered,thesolenoidvalves
(PRV1andPRV2)areenergizedwithoutputsfromtheT oroElectronicController
(TEC).Theenergizedvalvesshifttodirectpumpowtowardthedeckmotors.
Ascircuitpressuretothedeckmotorsincreases,thebrakereliefcartridge(RV1
andRV2)pistonpilotsopenthereliefvalveswhichallowsuidowthroughthe
manifoldoricepositionedbeforethelogiccartridge(LC1andLC2).Thisow
HydraulicSystem:HydraulicFlowDiagrams
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