JLG 110HX Service Manual - Manual (Page 35)

SECTION 2 - PROCEDURES
3120864 – JLG Lift – 2-11
BEFORE RAISING AND EXTENDING BOOM, ENSURE THAT
AREAS ABOVE AND BELOW BOOM AND PLATFORM AND AHEAD
OF PLATFORM ARE CLEAR OF ALL OBSTRUCTIONS AND PER-
SONNEL.
2. Position LIFT control switch to UP and hold until
boom reaches horizontal.
3. Position TELESCOPE control switch to OUT and
hold until boom extends approximately 1.2 meter;
measure from end of base section to end of mid
section.
4. Position LIFT control switch to UP and hold until
boom reaches maximum elevation. Shut down
engine.
5. Tag and carefully disconnect the hydraulic lines to
the telescope cylinder at control valve.
6. Observe oil flow from cylinder lines. Oil leaking from
extend port hose indicates a leaking counterbalance
valve. Oil leaking from retract port hose indicates
leakage by cylinder piston.
7. Leave boom elevated in test position for approxi-
mately one hour.
BEFORE LOWERING BOOM, ENSURE THAT AREAS BELOW
BOOM AND PLATFORM ARE CLEAR OF ALL PERSONNEL AND
OBSTRUCTIONS.
8. Position LIFT control switch to DOWN and hold until
boom reaches horizontal; check boom length
against measurement. If boom has retracted more
than 2.5 cm and oil is leaking around rod-end of
telescope cylinder (check with light and inspection
mirror), seals are defective and require replacement,
or cylinder rod is scored and cylinder requires over-
haul or replacement. If boom has retracted and oil is
leaking from counterbalance valve, the valve is
either improperly adjusted, or defective and requires
replacement.
9. Connect hydraulic lines to control valve.
Lift Cylinder
NOTE: Switches referenced in this procedure are located on
the Ground Control Panel.
1. Activate hydraulic system, properly set extendable
axles and position boom in stowed position; adhere
to all safety precautions.
NOTE: Tape measure or cord should be at least 2.1 meters
long for use in this test.
2. Attach tape measure or cord to bottom of platform.
BEFORE RAISING BOOM, ENSURE THAT AREAS ABOVE AND
BELOW BOOM AND PLATFORM ARE CLEAR OF ALL OBSTRUC-
TIONS AND PERSONNEL.
3. With boom fully retracted, place LIFT control switch
to UP and hold until platform is approximately 2
meters above ground level. Shut down engine.
4. Tag and carefully disconnect hydraulic lines to lift
cylinder at control valve. Use a suitable container to
retain any residual hydraulic fluid.
5. Observe oil flow from cylinder lines. Oil leaking from
extend port hose indicates a leaking counterbalance
valve. Oil leaking from retract port hose indicates
leakage by cylinder piston.
6. Leave boom elevated in test position for approxi-
mately one (1) hour.
7. With tape measure or cord used for reference,
check to see whether boom has lowered (crept)
more than 7.6 cm.
8. If boom has lowered and oil is leaking around rod-
end cap of cylinder, seals in cylinder are defective
and require replacement. If boom has lowered and
oil is leaking from the counterbalance valve, the
valve is either improperly adjusted or defective and
requires replacement.
E N S U R E T H AT H Y D R A U L I C L I N E S A R E C O N N E C T E D A S
MARKED PRIOR TO BEING DISCONNECTED.
9. Connect hydraulic lines to control valve.
2.9 CYLINDER CHECKING PROCEDURES
NOTE: Cylinder checks must be performed any time a cylin-
der component is replaced or when improper system
operation is suspected.
Cylinder w/o Counterbalance Valves
Steer Cylinder, Master Level Cylinder, Axle Extension Cylin-
ders
OPERATE FUNCTIONS FROM GROUND CONTROL STATION
ONLY.
1. Using all applicable safety precautions, activate
engine and fully extend cylinder to be checked. Shut
down engine.