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Groundsmaster 4500--D/4700--D Hydraulic SystemPage 4 -- 61
Procedure for Deck Motor Case Drain Leakage
Test
NOTE: Over a period of time, a deck motor can wear in-
ternally. A worn motor may bypass oil to its case drain
causing the motor t o be less efficient. Eventually,
enough oil loss will cause the deck motor to stall under
heavy cutting conditions. Continued operation with a
worn, inefficient motor can generate excessive heat,
cause damage to seals and other components in the hy-
draulic system and affect quality of cut.
NOTE: Onemethodtofindafailingormalfunctioning
deck motor is to have another person observe the ma-
chine while mowing in dense turf. A bad motor will run
slower, produce fewer clippings and may cause a differ-
ent appearance on the turf.
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.
NOTE: The deck motors are connected in series. To
isolate a faulty motor, all motors in the circuit may have
to be tested by starting with the first motor in the circuit
(see Hydraulic Schematic).
3. Disconnect pressure return hose from the motor to
be tested (Fig. 52). Install tester with pressure gauge
and flow meter in series with the motor and the discon-
nected return hose. Make sure the flow control valve on
tester is fully open.
4. Disconnect the motor case drain hose (small diame-
ter hose) where it connects to bulkhead fitting at the
frame rail (not at the motor). Put a steel cap on the bulk-
head fitting; leave the case drain hose open.
CAUTION
Cutting deck blades will rotate when lowered
with PTO switch in ON position. Keep away from
cutting decks during test to prevent personal in-
jury from rotating blades. Do not stand in front of
the machine during test.
5. Sit on seat and start the engine. Increase engine
speed to high idle speed. Engage cutting decks.
6. While watching tester pressure gauge, have second
person slowly close flow control valve on tester until a
pressure of 1200 PSI (83 bar) is obtained.
NOTE: Use a graduated container, special tool
TOR4077, to measure case drain leakage.
7. Have a second person measure flow from the case
drainlineforfifteen (15) seconds, then disengage the
cutting decks and stop the engine. Record test results.
TEST RESULT S: Case drain leakage less than 22.4
ounces (662 ml) of hydraulic fluid in fifteen (15) sec-
onds (0.7 GPM / 2.7 LPM)
8. If case drain flow is more than 22.4 ounces (662 ml),
the deck motor is worn or damaged and should be re-
paired or replaced.
9. When testing is complete, disconnect tester from
motor and hose. Reconnect hose to the deck motor. Re-
move cap from bulkhead fitting and reconnect case
drain hose.
10.Repeat test for additional motors if required.
Figure 51
#4 #1 Deck #5
#7
(GM4700)
#6
(GM4700)
#3#2
CUTTING DECK LOCATIONS
1. Flow IN
2. Flow OUT
3. Case drain
Figure 52
ROTATION
2
1
DIRECTION
3
Hydraulic
System