Service Manual

HydraulicFlowDiagrams(5610-D)
TractionCircuit(5610-D)
Thehydraulictractioncircuitconsistsofavariabledisplacementpistonpump
(P5)connectedinaclosedloop,parallelcircuitto4orbitalrollervanewheel
motors.Thetractionpumpinputshaftisrotatedbyadriveshaftthatisdriven
fromtheengineywheel.
Theforwardtractioncircuitpressurecanbemeasuredatthetestportlocatedin
thehydraulictubethatconnectsthefrontwheelmotors.Thereversetraction
circuitpressurecanbemeasuredatthetestportsinthecrosstraxmanifold
(Figure72).
ForwardDirection
Pressingthetopoftractionpedal,anglesthetractionpumpswashplateto
createaowofuid.Thisuidowisdirectedtothewheelmotorsviahydraulic
hosesandtubestodrivethewheelsinforwarddirection.Thetractionpump
owisdirectedtothefrontwheelmotorsandthentotheoppositerearwheel
motorstomaximizethetraction.Toreducethetirescufngwhenturning,the
tractionsystempressureisequalizedinthecrosstraxmanifoldwithanorice
andabi-directionalreliefvalve.Thebi-directionalreliefvalveinthecrosstrax
manifoldallowrearwheelmotorstoover-runduringtightturns.Theforward
tractionpressureislimitedto25,000kPa(3,625psi)bytheforwardtractionrelief
valve(R3)locatedinthetractionpump.
Theuidowingfromthewheelmotorsreturnstothevariabledisplacement
pumpandiscontinuouslypumpedthroughthetractioncircuitaslongasthe
tractionpedalispressed.
Theangleoftheswashplatedeterminespumpowandultimatelytraction
speed.Whenthetractionpedalispressedasmallamount,asmallswashplate
rotationresultsinlowpumpoutputandlowertractionspeed.Whenthetraction
pedalispressedfully,thepumpswashplaterotatesfullytoprovidemaximum
pumpoutputandtractionspeed.
Thegearpumpsection(P3)suppliesuidowforthesteeringcircuitandalso
providesaconstantsupplyofchargeuidtotheclosedlooptractioncircuit.
Thischargeuidprovideslubricationfortractioncircuitcomponentsandalso
replenishestractioncircuituidthatislostduetointernalleakageinthetraction
circuit.
Thegearpumpsection(P3)takesitssuctionfromthehydraulicreservoir.The
chargepumpowisdirectedtothelowpressuresideoftheclosedlooptraction
circuit.Chargereliefvalve(R5)locatedinthetractionpumplimitsthecharge
reliefpressureto1,400kPa(200psi).
Thepistonpumpisequippedwithacasedraintoallowinternalleakagetobe
removedfromthepump.Thecasedrainisconnectedtothegearpumpinlet.
Thepistonpump(P5)includesaushingvalvethatbleedsoffasmallamountof
hydraulicuidforcoolingoftheclosedlooptractioncircuit.Thechargesystem
replenishesuidthatisbledfromthetractioncircuitbytheushingvalve.
ReverseDirection
Thetractioncircuitoperatesessentiallythesameinreverseasitdoesinthe
forwarddirection.However,inthereversedirectiontherearwheelmotors
arebypassedfromthecircuittopreventrearwheelspinandimprovesteering
control.Pressingthebottomofthetractionpedal,rotatesthetractionpump
swashplatetocreateaowofuid.Theuidowisdirectedtothecrosstrax
HydraulicSystem:HydraulicFlowDiagrams(5610-D)
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Reelmaster
®
5410/5510/5610Series
15216SLRevD