JLG 1500SJ Service Manual - Manual (Page 391)

SECTION 5 - HYDRAULICS
3121262 – JLG Lift – 5-39
Jib Lock Cylinder
DISASSEMBLY
DISASSEMBLY OF THE CYLINDER SHOULD BE PERFORMED ON A
CLEAN WORK SURFACE IN A DIRT FREE WORK AREA.
1. Connect a suitable auxiliary hydraulic power source
to the cylinder port block fitting.
DO NOT FULLY EXTEND CYLINDER TO THE END OF STROKE.
RETRACT CYLINDER SLIGHTLY TO AVOID TRAPPING PRESSURE.
2. Operate the hydraulic power source and extend the
cylinder. Shut down and disconnect the power
source. Adequately support the cylinder rod, if appli-
cable.
3. Place the cylinder barrel into a suitable holding fix-
ture.
4. Using a spanner wrench, unscrew the cylinder head
from the barrel.
5. Attach a suitable pulling device to the cylinder rod
end.
EXTREME CARE SHOULD BE TAKEN WHEN REMOVING THE CYL-
INDER ROD, HEAD, AND PISTON. AVOID PULLING THE ROD OFF-
CENTER, WHICH COULD CAUSE DAMAGE TO THE PISTON AND
CYLINDER BARREL SURFACES.
7. With the barrel clamped securely, carefully withdraw
the complete rod assembly from the cylinder barrel.
8. Using suitable protection, clamp the cylinder rod in
a vise or holding fixture as close to the piston as
possible.
9. Remove and discard the piston wear ring and t-seal.
10. Remove the rod from the holding fixture. Remove
the cylinder head gland and discard all seals on the
cylinder head.
CLEANING AND INSPECTION
1. Clean all parts thoroughly in an approved cleaning
solvent.
2. Inspect the cylinder rod for scoring, tapering, ovality,
or other damage. If necessary, dress rod with
Scotch Brite or equivalent. Replace rod if necessary.
3. Inspect inner surface of cylinder barrel tube for scor-
ing or other damage. Check inside diameter for
tapering or ovality. Replace if necessary.
4. Inspect threaded portion of barrel for damage. Dress
threads as necessary.
5. Inspect piston surface for damage and scoring and
for distortion. Dress piston surface or replace piston
and rod assembly as necessary.
6. Inspect seal and o-ring grooves on piston for burrs
and sharp edges. Dress applicable surfaces as nec-
essary.
7. Inspect cylinder head inside diameter for scoring or
other damage and for ovality and tapering. Replace
as necessary.
8. Inspect threaded portion of head for damage. Dress
threads as necessary.
9. Inspect seal and o-ring grooves in head for burrs
and sharp edges. Dress applicable surfaces as nec-
essary.
10. Inspect cylinder head outside diameter for scoring
or other damage and ovality and tapering. Replace
as necessary.
11. Inspect the oil ports for blockage or the presence of
dirt or other foreign material. Repair as necessary.
12. If applicable, inspect piston rings for cracks or other
damage. Replace as necessary.