Toro Groundsmaster 4500-D Series User Manual

TractionCircuit:LOWMode
Thetractioncircuitpistonpumpisavariabledisplacementpumpthatisdirectly
coupledtotheengineywheel.Thispumputilizesanintegralelectro−hydraulic
servopistonassemblythatcontrolstherateanddirectionofhydraulicow.
Pressingthetractionpedalrotatesapotentiometerthatprovidesaninputtothe
machineTECcontroller.ThecontrollerinturnsendsacorrespondingPWM
(PulseWidthModulation)outputtotheelectronicpumpcontroltorotatethe
pumpswashplateaccordinglytocontrolpumpoutputanddirection.Theswash
plateanglesensorisattachedtothepumptoprovidethepositionoftheswash
plate.Tractioncircuitoilisdirectedtothedualdisplacementfrontwheelandrear
axlemotors.Operatingpressureonthehighpressuresideoftheclosedtraction
circuitloopisdeterminedbytheamountofloaddevelopedatthewheelandaxle
motors.Asthetractionloadincreases,circuitpressurecanincreasetorelief
valvesettings:350bar(5075PSI)inforwardand360bar(5225PSI)inreverse.
Iftractioncircuitpressureexceedsthereliefsetting,oilowsthroughthepiston
pumpreliefvalvetothelowpressuresideoftheclosedlooptractioncircuit.
Frontwheelandrearaxlemotorsarepositivedisplacement,twospeedvariable
motors.Thedualdisplacementwheelandaxlemotorsallowoperationin
eitherLOW(mow)orHigh(transport)speed.Themotorsarespringbiasedto
maximumdisplacementforLOWspeedandarehydraulicallyshiftedtominimum
displacementforHighspeed.Therearaxlemotorincludesaushingvalve
thatbleedsoffasmallamountofhydraulicoilforcoolingoftheclosedloop
tractioncircuit.Thechargecircuitreplenishesoilthatisbledfromthetraction
circuitbytheushingvalve.
TheSmartPower
TM
featurepreventstheenginefromslowingdowninheavyload
conditions(e.g.cuttingtallgrass)byautomaticallydecreasingthetractionspeed
ifnecessary.Withareducedtractionspeed,thecuttingbladescancontinueto
beatoptimumspeed.
Anoptionaltractioncircuitowdividerisavailablethatequallysplitstractionpump
owbetweenthefrontwheelmotorsandrearaxlemotortopreventexcessive
circuitowgoingtoaspinningwheel.Ifequipped,thefronttractionmanifold
whichincludestheowdividerismountedtotherightsideofthefrontframe.
Thepistonpump,frontwheelmotorsandrearaxlemotorusesmallamountsof
hydraulicuidforinternallubrication.Fluidisdesignedtoleakacrosstraction
pumpandmotorcomponentsintothecasedrain.Thisleakageresultsintheloss
ofhydraulicuidfromtheclosedlooptractioncircuitthatmustbereplaced.The
chargecircuitisdesignedtoreplacethistractioncircuitleakage.Thegearpump
sectionthatsuppliesoiltothesteeringandlift/lowercircuitsalsoprovidesoil
forthechargecircuit.
Gearpumpowforthechargecircuitisdirectedthroughtheoillterandtothe
lowpressuresideoftheclosedlooptractioncircuit.Chargepressureislimitedto
18bar(260PSI)byareliefvalvelocatedinthepistonpump.
ForwardDirection
WiththearmrestconsoleAutoandLowmodecontrolswitchintheLOWmode
position,thesolenoidvalveinthetwospeedshiftmanifoldisnotenergized.The
frontwheelmotorsandrearaxlemotorareattheirmaximumdisplacementwhen
inLOWspeedprovidingaslowertractionspeedformowingconditions.
Groundsmaster
®
4500-D/4700-D
Page5–15
HydraulicSystem:HydraulicFlowDiagrams
19245SLRevA

Toro Groundsmaster 4500-D Series Specifications

General

Brand	Toro
Model	Groundsmaster 4500-D Series
Category	Lawn Mower
Language	English