Service Manual

PTOCircuitRelief
PRV ENERGIZED
PRV AND LC1 SHIFTED
DECK MOTOR STALLED
P1
P2
M1
M2
LC1
PRV
PD
RV
3000 PSI
CD
RIGHT DECK
1.17 CID
600 PSI
.025
PUMP
RETURN
FLOW
RETURN
G
g274969
Figure46
Maximummowcircuitpressureislimitedforeachdeckbyproportionalrelief
valve(PRV)inthePTOmanifold.Thecenterandleftdeckreliefvalvesaresetat
207bar(3000PSI)andtherightdeckreliefvalveissetat138bar(2000PSI).
Proportionalreliefvalve(PRV)andlogicvalve(LC1)worktogetherasatwo
stagecircuitrelief.Whenincreasedcircuitresistanceismet(e.g.acuttingblade
strikesanobject),thepressureincreaseisfeltattheproportionalreliefvalve.
Ifthepressureshouldexceedthereliefvalvesetting,thereliefvalvewillopen,
allowingasmallamountofhydraulicowthroughthevalve.Thisowcausesa
pressureincreasethatshiftslogicvalveLC1anddivertscircuitowawayfrom
thedeckmotortomanifoldportP2(Figure46).Whencircuitpressurelowers,
proportionalreliefvalve(PRV)closeswhichreturnslogicvalveLC1backtoits
neutralpositionallowingowtoreturntothedeckmotor.
HydraulicSystem:HydraulicFlowDiagrams
Page5–28
Groundsmaster
®
4100-D&4110-D
13203SLRevE