Toro 08743 - Page 87

Theimplement/chargepump(P2)isaxeddisplacementgerotorpumpthat
ispartofthetractionpump.Theimplement/chargepumpsuppliesoilowfor
thesteeringcircuitonmodel08745machines.Theimplement/chargepump
alsosuppliesuidowfortheliftcircuitandthechargecircuitoftheclosed
looptractionsystemforbothmodel08743and08745machines.Thepump
outputowstothesteeringcontrolvalvebeforesupplyingtheliftandcharge
circuitneedssothatthesteeringcircuithaspriority.Thesteeringandliftcircuit
pressureislimitedto5,171kPa(750psi)byareliefvalvelocatedinthesteering
valve.Thesteeringvalvealsoincludestwo10,342kPa(1500psi)reliefvalves,
oneforeachcylindersupplyportLandR.Thereliefvalvesabsorbshocksinthe
steeringcircuitwhileturningintoandoveracurbforexample.
Whenthesteeringwheelisnotbeingturnedandtheengineisrunning(hydraulic
pumpinputshaftrotating),implement/chargepumpowentersthesteering
valveatthePportandby-passestherotarymeterandsteeringcylinder.Flow
leavesthesteeringvalvethroughtheEportandisdirectedtotheliftvalveto
supplytheliftandchargecircuits.
g343422
Figure26
RightTurn
Whenarightturnismadewiththeenginerunning,turningthesteeringwheel
positionsthesteeringcontrolspoolvalvesothatowgoesthroughthebottomof
thespool.FlowenteringthesteeringcontrolvalveatthePportpassesthrough
therotarymeterandisdirectedouttheRport.Pressureextendsthesteering
cylinderforarightturn.Therotarymeterensuresthattheoilowtothecylinder
isproportionaltotheamountoftherotationofthesteeringwheel.Fluidleaving
thesteeringcylinderowsbackthroughthespoolvalve,thenouttheTportof
thesteeringvalveandreturnstothehydraulictank.Whenthesteeringwheel
reachestheendofitsrotation,thereliefvalveinthesteeringvalveopensand
directsthehydraulicowoutthesteeringvalveTporttotheoilcooleruntilthe
steeringwheelisreleased.
LeftTurn
Whenaleftturnismadewiththeenginerunning,turningthesteeringwheel
positionsthesteeringcontrolspoolvalvesothatowgoesthroughthetopof
thespool.FlowenteringthesteeringcontrolvalveatthePportpassesthrough
SandPro
®
3040and5040
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HydraulicSystem:HydraulicFlowDiagrams
20251SLRevA