JLG 2658E3 Service Manual - Manual (Page 17)

SECTION 2 - PROCEDURES
3120878 – JLG Lift – 2-5
2. Carefully disconnect hydraulic hose from retract port
of cylinder. There will be initial weeping of hydraulic
fluid which can be caught in a suitable container.
After the initial discharge, there should be no further
leakage from the retract port.
3. Activate motor and activate cylinder extend function.
Check retract port for leakage.
4. If cylinder leakage is 6-8 drops per minute or more,
piston seals are defective and must be replaced. If
cylinder retract port leakage is less than 6-8 drops
per minute, carefully reconnect hose to retract port
and retract cylinder.
5. With cylinder fully retracted, shut down motor and
carefully disconnect hydraulic hose from cylinder
extend port.
6. Activate motor and activate cylinder retract function.
Check extend port for leakage.
7. If cylinder leakage is 6-8 drops per minute or more,
piston seals are defective and must be replaced. If
extend port leakage is less than 6-8 drops per
minute, carefully reconnect hose to extend port,
then activate cylinder through one complete cycle
and check for leaks.
Cylinders w/Single Counterbalance Valves -
Lift Cylinder
OPERATE ALL FUNCTIONS FROM GROUND CONTROL STATION
ONLY.
1. Using all applicable safety precautions, activate
hydraulic system.
WHEN WORKING ON THE LIFT CYLINDER, RAISE THE PLAT-
FORM COMPLETELY AND SUPPORT THE PLATFORM USING A
SUITABLE OVERHEAD LIFTING DEVICE.
DO NOT FULLY EXTEND LIFT CYLINDER TO END OF STROKE.
RETRACT CYLINDER SLIGHTLY TO AVOID TRAPPING PRES-
SURE.
2. Raise platform completely then retract cylinder
slightly to avoid trapping pressure. Place a suitable
overhead lifting device approximately 2.5 cm (1 in)
below the platform.
3. Shut down hydraulic system and allow machine to
sit for 10-15 minutes. Carefully remove hydraulic
hoses from cylinder port block.
4. There will be initial weeping of hydraulic fluid, which
can be caught in a suitable container. After the initial
discharge, there should not be any further leakage
from the ports. If leakage continues at a rate of 6-8
drops per minute or more, the counterbalance valve
is defective and must be replaced.
5. If no repairs are necessary or when repairs have
been made, carefully reconnect hydraulic hoses to
the appropriate ports.
6. Remove lifting device from platform, activate hydrau-
lic system and run cylinder through one complete
cycle to check for leaks.
2.9 ARM ASSEMBLY MAINTENANCE
IT IS RECOMMENDED THAT WHEN PERFORMING MAINTENANCE
ON THE ARM ASSEMBLY THE MACHINE BE PARKED IN THE
STOWED POSITION (FULLY LOWERED).
Platform Removal
Remove the platform from the arm assembly, with the plat-
form extension and rail assemblies intact, as follows:
1. Disconnect electrical control cable from platform
control box.
2. Disconnect any other options that lead to the plat-
form from the arm assembly
NOTE: The approximate weight of the platform and rail
assemblies is 227 kg (500 lb). When removing the
platform and rail assemblies, be sure the lifting
device being used is capable of handling these
weights.
3. Using an overhead crane, or suitable lifting device,
use nylon straps to support platform and rail assem-
blies.
4. Remove pin retaining hardware from front and rear
deck pins.
5. Using a suitable brass drift and a hammer, remove
pins from the pivot mounts on the under side front of
the platform and from the slide blocks in rear.
6. Using all applicable safety precautions, carefully lift
platform and rail assemblies clear of arm assembly
and lower to ground or suitable supported work sur-
face.