Toro 30308 - Traction Circuit (Machine Serial Number above 316000000)

TractionCircuit(MachineSerialNumberabove316000000)
Thehydraulictractioncircuitisaclosedloopsystemconsistingofavariable
displacementhydraulicpumpandahydraulicdriveaxlemotor.Thehydraulic
pumpisdrivenbyadriveshaftconnectedtotheenginecrankshaft.
ForwardDirection
Pressingthetopoftractionpedal,anglesthehydraulicpumpswashplate
tocreateaowofuid.Thisuidowisdirectedtothehydraulicmotorvia
hydraulichosesandtubeswhichturnsthefrontaxleinputshafttodrivethefront
wheelsintheforwarddirection.Theforwardtractionpressureislimitedto32,495
kPa(4,713psi)bytheforwardtractionreliefvalvelocatedinthehydraulicpump.
Theuidowingfromthemotorreturnstothevariabledisplacementpumpand
iscontinuouslypumpedthroughtheclosedlooptractioncircuitaslongasthe
tractionpedalispressed.
Theangleoftheswashplatedeterminesthestrokeofthepumppistonsand
thereforethepumpowandultimatelytractionspeed.Whenthetractionpedalis
pressedasmallamount,theswashplateangleisslightresultinginlowpump
outputandlowertractionspeed.Whenthetractionpedalispressedfully,the
pumpswashplateangleisdramaticprovidingmaximumpumpoutputand
maximumtractionspeed.
Thehydraulicpumpisequippedwithacasedraintoallownormalinternal
leakagetoberemovedfromthepump.Thecasedrainisconnectedtothe
transaxlereservoir.
Thehydraulicpumpincludesagerotorchargepump.Thechargepumpprovides
aconstantsupplyofchargeuidtotheclosedlooptractioncircuitforlubrication
andtomakeupforuidthatislostduetointernalleakageinthehydraulicpump
andmotor.Thechargepumptakesitssuctionthroughalterfromthehydraulic
reservoir(frontaxle).Thechargepumpowisdirectedtothelowpressureside
oftheclosedlooptractioncircuit.Thechargepressureislimitedto503kPa
(73psi)bythechargepressurereliefvalveinthehydraulicpump.Thecharge
pumpowinexcessoftractioncircuitchargeneedsprovideshydraulicowfor
thesteeringandliftcircuits.
HydraulicSystem:HydraulicFlowDiagrams
Page5–24
Groundsmaster
®
3280-D/3320
05138SLRevB