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Groundsmaster 4500--D/4700--D Hydraulic SystemPage 4 -- 59
Procedure for Cutting Deck Circuit Relief Pressure
Test
CAUTION
Prevent personal injury and/or damage to equip-
ment. Read all WARNINGS, CAUTIONS and Pre-
cautions for Hydraulic Testing at the beginning
of this section.
1. Make sure hydraulic oil is at normal operating tem-
perature by operatingthe machinefor approximately ten
(10) minutes. Make sure the hydraulic reservoir 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.
3. Determine cutting deck circuit relief pressure to be
tested:
A. For the first gear pump section (decks #2, #3, #5
and #7), cutting deck circuit relief (PRV2) is tested at
the inlet to the deck #5 motor (Fig. 49).
B. For second gear pump section (decks #1, #4 and
#6), cutting deck circuit relief (PRV1) is tested at the
inlet to the deck #1 motor (Fig. 49).
4. Thoroughly clean junction of appropriate hydraulic
inlet hose and deck motor fitting (Fig. 50). Disconnect
the hydraulic inlet hosefromthedeckmotor.
IMPORTANT: Make sure that the oil flow indicator
arrow on the tester is showing that the oil will flow
from the disconnected hose, through the tester and
into the deck motor.
5. Install tester with pressure gauge and flow meter in
series with the disconnected hose and deck motor inlet.
Make sure the tester flow control v alve is fully open.
6. After installing pressure gauge, start engine and run
at low idle speed. Check for hydraulic leakage and cor-
rect before proceeding with test.
CAUTION
Keep away from decks during test to prevent per-
sonal injury from the cutting blades.
7. Increase engine speed to high idle speed. Engage
the cutting decks.
8. Watch tester pressure gauge carefully while slowly
closing the flow control valve on tester.
9. As the circuit relief valve lifts, system pressure
should be from 3400 to 3750 PSI (235 to 258 b ar).
10.Open the tester flow control valve, disengage cutting
decks and stop the engine. Record test results.
11.If specification is not met, make sure that electrical
connections at deck control manifold are secure and
then clean or replace relief valve (PRV1 or PRV2) in the
deck control manifold (see Deck Control Manifold Ser-
vice in the Service and Repairs section of this chapter).
Also, if pressure is still low after relief valve service,
check for restriction in pump intake line. The first or
second gear pump section could also be suspected of
wear or damage (see Gear Pump Flow Test in this sec-
tion).
12.After testing is complete, disconnect tester from
deck motor and hose. Connect hydraulic hose to motor.
Figure 49
#4 Deck #1 Deck #5 Deck
#7 Deck
(GM4700)
#6 Deck
(GM4700)
#3
Deck
#2
Deck
CUTTING DECK LOCATIONS
1. Flow IN
2. Flow OUT
3. Case drain
Figure 50
Rotation Direction
2
1
3
Hydraulic
System