Toro Field Pro 6040 - Page 81

chargepumpandacoolingfan.Theleftsidepistonpumpdrivesanexternal
xeddisplacementgearpumpforattachmenthydraulicneeds.Thetraction
pumpsaredrivenbytheengineviaasingleV-belt.V-belttensioniscontrolledby
aspringloadedidler.
ForwardDirection
WiththeenginerunningandthetractioncontrolleversintheNEUTRALposition,
thetractionpumpssupplynoowtothewheelmotors.Whenatractioncontrol
leverismovedintheFORWARDdirection,thelinkagefromtheleverpositionsthe
swashplateinthetractionpumpsooilowsouttheAportonthetopofthe
pump.Oilowfromthepumpisdirectedtothewheelmotortoturnitinthe
forwarddirection.Maximumforwardtractionpressureislimitedbya20,000kPa
(2900psi)reliefvalvelocatedinthesideofthepumpassembly.
Theangleoftheswashplatedeterminesthestrokeofthepumppistonsand
thereforethevolumeofhydraulicuidowandultimatelywheelmotorspeed.
Whenthetractioncontrolleverismovedasmallamount,theswashplateangle
isslightresultinginlowpumpoutputandlowertractionspeed.Whenthetraction
controlleverismovedfully,thepumpswashplateangleisdramaticproviding
signicantpumpoutputandmaximumtractionspeed.
Hydraulicuidowingfromthewheelmotorreturnstothepiston(traction)pump
Bportonthetopofthepump.Hydraulicuidiscontinuouslypumpedthrough
theclosedlooptractioncircuitaslongasthetractioncontrolleverisinthe
FORWARDrangeofmovement.
Note:TheAportandtheforwardreliefvalvearelocatedonthesideofthepump
oppositethetractioncontrollinkage.TheBportislocatedonthesamesideof
thepumpasthetractioncontrollinkage.
ReverseDirection
Thetractioncircuitoperatesessentiallythesameinreverseasitdoesinthe
forwarddirection.However,theowthroughthecircuitisreversed.Whena
tractioncontrolleverismovedintheREVERSEdirection,thelinkagefromthe
leverpositionstheswashplateinthetractionpumpsooilowsouttheBporton
thetopofthepump.Oilowfromthepumpisdirectedtothewheelmotorto
turnitinthereversedirection.Maximumreversetractionpressureislimitedbya
20,000kPa(2900psi)reliefvalvelocatedinthesideofthepumpassembly.
Hydraulicuidowingfromthewheelmotorreturnstothepiston(traction)pump
Aportonthetopofthepump.Hydraulicuidiscontinuouslypumpedthrough
theclosedlooptractioncircuitaslongasthetractioncontrolleverisinthe
REVERSErangeofmovement.
Note:TheBportandthereversereliefvalvearelocatedonthesamesideof
thepumpasthetractioncontrollinkage.TheAportislocatedonthesideofthe
pumpoppositethetractioncontrollinkage.
TractionCircuitCharge
Thepiston(traction)pumpsareequippedwithcasedrainstoallownormal
internaluidleakagetoberemovedfromthepumps.Thecasedrainsare
connectedtothehydraulicreservoir.
Axeddisplacementpump(locatedintherightsidepistonpump)providesa
constantsupplyofchargeuidtotheclosedlooptractioncircuits.Thecharge
uidprovideslubricationfortractioncircuitcomponentsandalsoreplenishes
thetractioncircuitoilthatislostduetointernalleakage.Chargepumpow
isdirectedtothepistonpumpsandthelowpressuresideoftheclosedloop
tractioncircuits.Chargepressureislimitedto620kPa(90psi)byareliefvalve
FieldPro®6040
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HydraulicSystem:HydraulicFlowDiagrams
22267SLRevA