Toro Groundsmaster 4500-D Series - Page 127

CuttingDeckLower(continued)
owfromtherodendsofthecenterve(5)deckliftcylinders.Theweightofthe
cuttingdeckscausetheliftcylinderstoextendandthecenterdeckstolower.
Anoriceintheliftcontrolmanifoldrestrictsoilowfromtheliftcylindersto
controldeckdropspeed.Additionally,anoriceinthejunctionmanifoldfurther
controlstheloweringspeedofthe#1deck.
TolowerasidecuttingdeckontheGroundsmaster4700-D(deck#6or#7),the
frontoftheappropriateliftswitchisdepressed.Theswitchactsasaninputto
theTECcontroller(T2)whichthenprovideselectricaloutputtotheappropriate
solenoidvalvesintheliftcontrolmanifold:S1,S3andS4fordeck#6orS1,S8
andS9fordeck#7.Theenergizedsolenoidvalvesshifttoallowpumpowto
thebarrelendofthedeckliftcylinderandapassageforoilfromtherodendof
thecylinder.Thecylinderextendstolowerthesidecuttingdeck.Anoriceinthe
liftmanifoldrestrictsoilowfromtheliftcylindertocontrolsidedeckdropspeed.
CuttingDeckFloat
Cuttingdeckoatallowsthefullyloweredcuttingdeckstofollowgroundsurface
contours.OnaGroundsmaster4700-D,S6(centerdecks),S4(leftdeck#6)
andS9(rightdeck#7)areenergizedfordeckoat.Theseenergizedsolenoids
provideanoilpassagetoandfromtheliftcylinderstoallowcylinderandcutting
deckmovementwhilemowing.
Counterbalance
Oncethecuttingdecksarefullylowered,theliftcontrolmanifoldproportional
reliefvalve(TS)maintainsbackpressure(counterbalance)onthedecklift
cylinders.Thiscounterbalancepressuretransferscuttingdeckweighttothe
machinetoimprovetraction.
Apressuresensorlocatedinthehydraulictubebetweenthefrontwheelandrear
axlemotorsisusedbytheTECcontroller(T1)asaninputtodeterminetraction
circuitpressure.Basedonthissensorinput,aPWM(PulseWidthModulation)
signalfromtheTECcontroller(T1)isprovidedtotheproportionalreliefvalve
(TS)tomaintaincounterbalancepressure.
Groundsmaster
®
4500-D/4700-D
Page5–25
HydraulicSystem:HydraulicFlowDiagrams
19245SLRevA