JLG 1850SJ Service Manual - Manual (Page 223)

SECTION 5 - BASIC HYDRAULIC INFORMATION & HYDRAULIC SCHEMATICS
3121619 – JLG Lift – 5-53
Boom Telescope Cylinder
Refer to Figure 5-98.
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 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.
3. Place cylinder barrel in a suitable holding fixture.
4. Remove check valves (3), counterbalance valves (4), and
fittings from valve block (2). Discard O-rings. Remove
four capscrews (1) and valve block from rod (7). Discard
O-rings (5, 6).
5. Mark cylinder head (23) and barrel (28) with center
punch marks for later realignment. Remove two cap-
screws (27) and bracket (26).
6. Remove six remaining capscrews (25) and washers (24).
7. Tap around outside of Cylinder Head with a suitable
hammer to break thread-locking compound. Unscrew
Cylinder Head (23).
PULLING ROD OFF-CENTER CAN DAMAGE PISTON AND C YLINDER BARREL
SURFACES. USE EXTREME CARE WHEN REMOVING CYLINDER ROD, HEAD, AND
PISTON.
8. Clamp barrel securely. Pull rod assembly and cylinder
head from barrel.
9. 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 5-95. Cylinder Barrel Support
23
24
27
26
28
25
Figure 5-96. Port Block And Rod Removal
SUPPORT TABLE
ROD SUPPORT
Figure 5-97. Cylinder Rod Support