Service Manual

MowCircuitCuttingDeckBladeBraking
P1
P2
M1
M2
LC1
PRV
PD
RV
3000 PSI
CD
RIGHT DECK
1.17 CID
600 PSI
.025
PUMP
RETURN
FLOW
RETURN
PRV NOT ENERGIZED
LC1 SHIFTED
PTO SWITCH OFF
G
g274970
Figure47
P1
P2
M1
M2
LC1
PRV
PD
RV
3000 PSI
CD
RIGHT DECK
1.17 CID
600 PSI
.025
PUMP
RETURN
FLOW
RETURN
PRV NOT ENERGIZED
LC1 AND RV SHIFTED
PTO SWITCH OFF
G
g274971
Figure48
WhentheoperatorturnsthePTOswitchOFForifadeckisraisedwiththePTO
switchON,PTOmanifoldproportionalreliefvalve(PRV)isde−energizedcausing
logicvalve(LC1)toshift(refertoinformationinMowCircuitinthissection).This
shiftedcartridgedirectsoilreturnoutofmanifoldportP2.Ascircuitpressure
decreases,pilotdirectionvalvePDisshiftedtoit’sneutralposition,preventing
returnowfromthedeckmotorandslowsthecuttingblades(Figure47).
Theinertiaoftherotatingcuttingblades,however,effectivelyturnsthedeck
motorintoapumpcausinganincreaseinpressureastheowfromthemotor
comesupagainsttheclosedreliefvalve(RV).Whenthispressurebuildsto
approximately41bar(600PSI),reliefvalve(RV)openswhichallowshydraulic
owtoowfromthemotor(Figure48).Whenreturnpressuredropsbelow41
bar(600PSI),reliefvalve(RV)reseatstoonceagainblockreturnowfromthe
deckmotortofurtherslowthecuttingblades.Thisactionofthebrakereliefvalve
openingoccursseveraltimesinaveryshorttimeframeasthebladesnally
cometoastop.Oncethebladeshavestopped,reliefvalve(RV)remainsseated
tokeepthedeckmotorfromrotating.
Groundsmaster
®
4000-D&4010-D
Page5–29
HydraulicSystem:HydraulicFlowDiagrams
13202SLRevF