JLG 3246ES Service Manual - Manual (Page 113)

SECTION 4 - HYDRAULICS
3121166 – JLG Lift – 4-11
4.8 CYLINDER REPAIR
NOTE: The following are general procedures that apply to
all of the cylinders on this machine. Procedures that
apply to a specific cylinder will be so noted.
Disassembly
NOTICE
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 port block fitting in the manifold
located on the cylinder.
DO NOT FULLY EXTEND C YLINDER 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
applicable.
3. If applicable, remove the cartridge-type holding
valve and fittings from the cylinder port block. Dis-
card o-rings.
4. Place the cylinder barrel into a suitable holding fix-
ture.
5. Mark cylinder head and barrel with a center punch
for easy realignment. Loosen the cylinder head
setscrew.
NOTE: Steps 6 and 7 apply only to the steer cylinder.
6. Using a spanner wrench, loosen the spanner nut
retainer, and remove spanner nut from cylinder
barrel.
7. Being careful not to mar the surface of the rod, use
a punch or wooden dowel and hammer to drive
the rod guide about one inch down into the cylin-
der bore. Using a screw driver, carefully push one
end of the round retaining ring back towards the
inside of the cylinder and then slip the screwdriver
tip under that end. Pull the ring out of the groove
toward the wall mouth. Once one end of the
retaining ring is free from the groove, the remain-
der can be easily pried free using ones fingers or
pliers.
8. Attach a suitable pulling device to the cylinder rod
port block end or cylinder rod end, as applicable.
NOTICE
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.
9. With the barrel clamped securely, apply pressure
to the rod pulling device and carefully withdraw
the complete rod assembly from the cylinder bar-
rel.
10. Using suitable protection, clamp the cylinder rod
in a vise or similar holding fixture as close to the
piston as possible.
NOTE: For steer cylinder piston removal, see Steer Cylinder
Piston Removal - Cyl. p/n-1684456 on page 4-12 fol-
lowing.
11. Loosen and remove the cap screw(s), if applicable,
which attach the tapered bushing to the piston.
12. Insert the cap screw(s) in the threaded holes in the
outer piece of the tapered bushing. Progressively
tighten the cap screw(s) until the bushing is loose
on the piston.
13. Remove the bushing from the piston.
Figure 4-3. Cylinder Barrel Support
Figure 4-4. Cylinder Rod Support