Toro Groundsmaster 5900 Series - Page 120

Note:SeeTractionCircuitOperation(page5–14)foradescriptionofgeneral
functionofthetractioncircuit.
Whenthehighrangetractionspeed(transport)isselected,solenoidvalve(SV)
inthetractionmanifoldisenergizedbytheslaveT oroelectroniccontroller.The
shiftedsolenoidvalve(SV)spooldirectschargepressureinthetractionmanifold
toshiftallsix(6)pressuredifferentialvalves(PD1,PD2,PD3,PD4,PD5and
PD6)inthemanifold.
Whenthemachineisinthehighspeedrange,tractionmanifoldsteeringorices
(OR1andOR2),reliefvalve(RV1)andcheckvalvesCV1andCV2haveno
function.
Withthehighrangetractionspeed(transport)selectedandthetractionpedalin
theneutralposition,theswashplateinthepistonpumpisnotrotatedsothereis
nooilowfromthepumpandnomachinetractionmovement.
ForwardDirection
Withthehighrangetractionspeedselectedandthetractionpedalpushedin
theforwarddirection,oilfromthepistonpumpisroutedoutpumpportAand
thentotractionmanifoldportP1.TheshiftedPD1valveinthetractionmanifold
preventspistonpumphydraulicowfromreachingtherearwheelmotors.With
owblockedtotherearwheelmotors,allpistonpumpowisdirectedtothefront
wheelmotorswheninthehighspeedrange.
Totalpistonpumpowisroutedinparalleltohalfthedisplacementofthefront
wheelmotorsthroughportsA1ofthemotorstodrivethefrontmotorsattransport
speed.Highermachinetransportspeedispossibleduetoallofthepumpow
beingroutedtoonesectionofeachofthefrontwheelmotors.
TheshiftedPD1,PD2andPD3valvesinthetractionmanifoldallowtherear
wheelmotorstoremainlledwithhydraulicoilwhiletheyfree−wheelinhigh
speedrange.Wheninhighspeed,casepressureintherearwheelmotorskeeps
themotorpistonsretractedtoreducerollingresistanceoftherearwheels.
OilfromthefrontmotorsexitsthemotorsthroughportRandre−entersthe
tractionmanifoldthroughportsM9andM10.Thisreturnoilisroutedtothe
shuttlevalve(SH)thatisshiftedbyfrontwheeltractionpressure.Wheninhigh
speedrange,approximately18.6LPM(4.8GPM)ofhydraulicuidisreleased
fromtheclosedlooptractioncircuitthroughtheshiftedshuttlevalve(SH)and
shiftedPD6.Thisreleaseofoilfromthetractioncircuitloopisalsonecessaryto
keeptherearwheelmotorpistonsretractedwheninthehigh(transport)speed
range.Returnoilthatisnotbledfromthetractioncircuitisreturnedtothepiston
pumpthroughtractionmanifoldportP2andpistonpumpportB.
TheshiftedPD4andPD5valvesinthetractionmanifoldrecirculatereturnoil
fromthedrivenfrontwheelmotorstothesecondsectionofthefrontmotors
throughportsA2ofthemotors.Thisrecirculatedowprovidescoolingand
lubricationofthefrontwheelmotorswhenintransportspeedrange.
HydraulicSystem:HydraulicFlowDiagrams
Page5–20
Groundsmaster
®
5900&5910
16227SLRevB