JLG 600SC_660SJC Service Manual - Manual (Page 152)

SECTION 5 - HYDRAULICS
5-8 – JLG Lift – 3121607
Main Lift Cylinder
DISASSEMBLY
NOTE: Refer to Figure 5-6.
CONTAMINATION MAY DAMAGE EQUIPMENT. DISASSEMBLE CYLINDER ON A
CLEAN WORK SURFACE IN A DIRT FREE WORK AREA.
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 counterbalance
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 suitable
hammer to break thread-locking compound.
Figure 5-3. Cylinder Barrel Support
5. Mark cylinder head (1) and barrel (2) with center punch
marks (3) for later realignment. Remove eight cylinder
head cap screws (4).
Figure 5-4. Marking Cylinder for Alignment
PULLING ROD OFF-CENTER CAN DAMAGE PISTON AND CYLINDER BARREL SURFACES.
USE EXTREME CARE WHEN REMOVING CYLINDER ROD, HEAD, AND PISTON.
6. Clamp barrel securely. Pull rod assembly and cylinder
head from barrel.
7. Protect cylinder rod from damage and clamp in a vise or
holding fixture as close to piston as possible.
Figure 5-5. Cylinder Rod Support