JLG 1850SJ Service Manual - Manual (Page 199)

SECTION 5 - BASIC HYDRAULIC INFORMATION & HYDRAULIC SCHEMATICS
3121619 – JLG Lift – 5-29
Boom Lift Cylinder
Refer to Figure 5-52.
DISASSEMBLY
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 PRES-
SURE.
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.
5. Mark cylinder head and barrel with center punch marks
for later realignment. Remove cylinder head cap screws.
PULLING ROD OFF-CENTER CAN DAMAGE PISTON AND C YLINDER BARREL
SURFACES. USE EXTREME CARE WHEN REMOVING CYLINDER ROD, HEAD, AND
PISTON.
6. Clamp barrel securely. Unscrew cylinder head and pull
rod assembly from barrel.
7. Protect cylinder rod from damage and clamp in a vise or
holding fixture as close to piston as possible.
ROD SUPPORT
PROTECTED ROD CLAMP
BARREL CLAMP
SUPPORT TABLE
Figure 5-49. Cylinder Barrel Support
Figure 5-50. Capscrew Removal
SUPPORT TABLE
ROD SUPPORT
Figure 5-51. Cylinder Rod Support