JLG 1850SJ, Service And Maintenance Manual, Page: 340 / 712

SECTION 5 - BASIC HYDRAULIC INFORMATION & HYDRAULIC SCHEMATICS
5-88 3121619
Jib Lock Cylinder
Refer to Figure 5-91.
DISASSEMBLY
C 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 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.
3. Place cylinder barrel in a suitable holding fixture. Tap
around outside of cylinder head retainer with a suitable
hammer to break thread-locking compound.
4. Mark cylinder head and barrel with a center punch for
realignment. Unscrew cylinder head with pin-face span-
ner wrench.
PULLING ROD OFF-CENTER CAN DAMAGE PISTON AND C YLINDER BARREL
SURFACES. USE EXTREME CARE WHEN REMOVING CYLINDER ROD, HEAD, AND
PISTON.
5. Clamp barrel securely. Pull rod assembly and cylinder
head from barrel.
6. Protect cylinder rod from damage and clamp in a vise or
holding fixture.
REMOVE SEALS USING A BRASS OR PLASTIC PICK ONLY. DO NOT USE A KNIFE,
SHARP OBJECT, OR SCREW DRIVER. MAKE NOTE OF SEAL ORIENTATION
BEFORE REMOVING FOR PROPER INSTALLATION.
7. Remove and discard seal (2) and wear ring (3) from rod
(1).
8. Remove and discard rod wiper (11), seal (10), and two
wear rings (9) from inside of cylinder head (8).
9. Remove and discard O-ring (5), backup ring (6), and O-
ring (7) from outer groves of cylinder head.
.
.
Mark For Reassembly
Figure 5-90. Cylinder Head Removal