JLG 450A_AJ Series II Service Manual - Manual (Page 291)

SECTION 5 - HYDRAULICS
3121180 – JLG Lift – 5-1
SECTION 5. HYDRAULICS
5.1 CYLINDER REPAIR -USA
MANUFACTURED ONLY
NOTE: Following are general procedures that apply to all
cylinders on this machine. Procedures that apply to
a specific cylinder will be so noted.
Disassembly
DISASSEMBLE CYLINDER ON A CLEAN WORK SURFACE IN A
DIRT FREE WORK AREA OR CONTAMINATION MAY DAMAGE
EQUIPMENT.
1. Connect a suitable auxiliary hydraulic power source
to cylinder port block fitting.
DO NOT FULLY EXTEND CYLINDER TO THE END OF STROKE.
RETRACT CYLINDER SLIGHTLY TO AVOID TRAPPING PRESSURE.
2. Operate hydraulic power source and extend cylinder.
Shut down and disconnect power source. Adequately
support cylinder rod, if applicable.
3. If applicable, remove cartridge-type holding valve and
fittings from cylinder port block. Discard O-rings.
4. Place cylinder barrel in a suitable holding fixture. Tap
around outside of cylinder head retainer with a suit-
able hammer to break thread-locking compound.
5. Mark cylinder head and barrel with a center punch
for easy realignment. Using an allen wrench, loosen
eight cylinder head retainer cap screws and remove
cap screws from cylinder barrel.
NOTE: Steps 6 and 7 apply only to steer cylinder.
6. Loosen spanner nut retainer with spanner wrench.
Remove spanner nut from cylinder barrel.
7. Being careful not to mar rod surface, use a punch or
wooden dowel and hammer to drive rod guide about
one inch into cylinder bore. Using a screw driver,
carefully push one end of round retaining ring back
towards inside of cylinder and then slip screwdriver
tip under that end. Pull ring out of groove toward
wall mouth. Once one end of retaining ring is free
from groove, remainder can be easily pried free with
fingers or pliers.
8. Attach a suitable pulling device to cylinder rod port
block end or cylinder rod end.
Figure 5-1. Cylinder Barrel Support
Figure 5-2. Cap Screw Removal