JLG 450A Service And Maintenance Manual page 92

SECTION 3 - TROUBLESHOOTING
.
TROUBLE
Valve Spool Sticking.
Valve leaking.
3-8
Table 3-3.Turntable Assembly - Troubleshooting
PROBABLE CAUSE
CONTROL VALVE.
Dirt in oil causing excessive temperature built-
up.
Incorrect valve mounting causing warping of the
unit.
Valve spool scored.
Return spring weak or broken.
Relief valve malfunctioning causing excessive
pressure within valve.
Dirt or other foreign material under seal.
Valve spool scored.
Excessive back pressure caused by restricted
return line to reservoir.
Damaged valve seals.
– JLG Lift –
REMEDY
Change oil using recommended viscosity and
flush system.
Loosen valve and check mounting.Repair as
necessary.
Remove valve and repair or replace as neces-
sary.
Remove valve and repair or replace as neces-
sary.
Check pressure delivery to and from valve and
repair or replace as necessary.
Remove and replace valve as necessary.
Repair or replace valve.
Remove line and clear obstruction or replace line
as necessary.
Repair or replace valve as necessary.
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