JLG 450A_AJ Series II Service Manual - Manual (Page 249)

SECTION 5 - HYDRAULICS
3121290 – JLG Lift – 5-9
Main Lift Cylinder
DISASSEMBLY
Refer to Figure 5-17.
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 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 holding valve and fit-
tings from cylinder port block. Discard O-rings.
4. Place cylinder barrel in a suitable holding fixture. Tap
around outside of cylinder head end cap with hammer
to break thread-locking compound.
Figure 5-15. Cylinder Barrel Support
5. Use a strap wrench to remove cylinder end cap.
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 from barrel.
Figure 5-16. Cylinder Rod Support
7. Using suitable protection, clamp cylinder rod in a vise or
similar holding fixture as close to piston as possible.
8. Loosen setscrew and remove nut from rod. Remove pis-
ton.
9. Remove and discard piston O-ring, seal ring, and backup
rings.
10. Mark spacer location. Loosen setscrew and remove
spacer.
11. Remove rod from holding fixture. Remove cylinder head
and end cap. Discard O-ring, wear ring, rod seal, and
wiper.