Groundsmaster 4500--D/4700--D Hydraulic SystemPage 4 -- 47
NOTE: Adjustable relief valve (RV) in the 4WD/2WD
control manifold reduces rear axle motor pressure
created in down hill, dynamic braking conditions to pre-
vent rear wheel lock up.
ProcedureforRearTractionCircuitRelief(RV)Pres-
sure Test
1. Make sure hydraulic oil is at normal operating tem-
peraturebyoperatingthemachineforapproximatelyten
(10) minutes. Make sure the hydraulic tank is full.
2. Park machine on a level surface with the cutting
decks lowered and off. Make sure engine is off and the
parking brake is engaged.
CAUTION
Prevent personal injury and/or damage to equip-
ment. Read all WARNINGS, CAUTIONS and Pre-
cautions for Hydraulic Testing at t he beginning
of this section.
3. Connect a 1000 PSI (70 bar) pressure gauge to test
portGononrearsideof4WD/2WDcontrolmanifoldun-
der operator’s platform (Fig. 36).
4. Start the engine and put throttle at full engine speed
(2870 RPM).
5. Operate the machine in Low speed with the cutting
deckslowered.Drivedownaslopeinaforwarddirection
anddecreasepressureonthetractionpedalwhilecare-
fullymonitoringthepressuregauge.Pressureshouldin-
crease until the relief valve lifts.
GAUGEREADINGTOBE520 to 570 PSI (36 to 39
bar)
6. Relief v alve (RV) is located on the left side of the
4WD/2WD control manifold in the RVport(Fig. 36). Ad-
justmentofthe reliefvalvecanbe performedasfollows:
NOTE: Do not remove thereliefvalve from the hydrau-
lic manifold for adjustment.
A. To increase relief pressure setting, remove cap
onreliefvalveandturntheadjustmentsocket on the
relief valve in a clockwise direction (Fig. 37). A 1/8
turnon thesocketwillmakeameasurablechangein
relief pressure.
B. Todecreasepressuresetting,removecaponre-
liefvalveandturntheadjustmentsocketontherelief
valveinacounterclockwisedirection (Fig.37).A1/8
turnon thesocketwillmakeameasurablechangein
relief pressure.
C. Afteradjustmentismade,recheckreliefpressure
and make additional adjustment if necessary.
1. 4WD/2WD manifold 2. Relief valve (RV)
Figure 36
1
2
FRONT
RIGHT
Figure 37
1. Relief valve cap 2. Adjustment socket
1
2
Hydraulic
System
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