JLG 4394RT Service Manual - Manual (Page 169)

SECTION 4 - HYDRAULICS
3121249 – JLG Lift – 4-3
4.4 CYLINDER REPAIR
NOTE: The following are general procedures that apply to
all cylinders on this machine. Procedures that apply
to a specific cylinder will be so noted.
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 PRES-
SURE.
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. 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.
.
NOTE: Steps 6 and 7 apply only to the steer cylinder.
5. Using a spanner wrench, loosen the spanner nut
retainer, and remove spanner nut from cylinder bar-
rel.
6. 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 cylinder
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 remainder can be easily
pried free using ones fingers or pliers.
Figure 4-1. Lift Cylinder Holding Valve and Fitting
Removal
Figure 4-2. Cylinder Barrel Support
Figure 4-3. Lift Cylinder Cap Screw Removal