JLG 80HX_HX+6_HXER Service Manual - Manual (Page 33)

SECTION 2 - PROCEDURES
3120863 – JLG Lift – 2-11
2.9 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.
NOTE: See Figure 2-5., Figure 2-6., Figure 2-7., and Figure
2-8. for the breakdown of typical hydraulic cylinders
used on this machine.
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 THE CYLINDER TO THE END OF THE
STROKE. RETRACT THE CYLINDER SLIGHTLY TO AVOID TRAP-
PING 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.
ON CYLINDERS WITH DOUBLE HOLDING VALVES, BEFORE
REMOVING HOLDING VALVES, CRACK THE BLEEDERS TO
RELEASE PRESSURE.
3. If applicable, remove the cartridge-type holding
valve and fittings from the cylinder port block. Dis-
card the o-rings.
NOTE: Step 4 applies only to the Telescope Cylinder.
4. Remove the nuts which attach each cylinder rod
support block pull rod and withdraw the rods from
the forward end of the telescope cylinder.
5. Place the cylinder barrel into a suitable holding fix-
ture. Tap around the outside of the cylinder head
retainer with a suitable hammer to shatter the loctite
seal.
6. Using a suitable spanner wrench, loosen the cylin-
der head retainer, if applicable, and/or cylinder head
gland, and remove from cylinder barrel.
7. Attach a suitable pulling device to the cylinder rod
port block end or cylinder rod end, as applicable.
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.
8. With the barrel clamped securely, apply pressure to
the rod pulling device and carefully withdraw the
complete rod assembly from the cylinder barrel.
Figure 2-4. Cylinder Barrel Support