Service Manual Instruction Manual

SECTION 5 - HYDRAULICS
5-8 – JLG Lift – 3121616
Upright Level Cylinder Removal
1. With aid of an assistant, manually override Plunger Valve
with a pry bar. From Ground Control, use auxiliary power
and extend tower telescope to access leveling cylinder
rod end pin (3).
Figure 5-5. Plunger Valve Override
2. Position and support main boom as shown in Figure 5-
6., Boom Positioning and Support, Cylinder Repair.
3. Remove bolt and retaining pin from leveling cylinder to
upright pin (1).
4. Support upper boom assembly with overhead crane.
Raise boom until tension is released from cylinder pin
(1).
Figure 5-6. Boom Positioning and Support, Cylinder Repair
5. Drive barrel end attach pin (1) through mounting holes
in upright and leveling cylinder using a suitable drift.
6. Remove mounting hardware from upright to tower
boom assembly pivot pin (2).
7. Drive pivot pin (2) through mounting holes in upright
and tower boom assembly using a suitable drift.
8. Using all applicable safety precautions, operate over-
head crane to move upright and upper boom assembly
forward to clear tower boom.
9. After moving assemblies forward, operate overhead
crane left far enough to remove leveling cylinder.
10. Tag, disconnect, and cap level cylinder hydraulic lines.
11. Remove mounting hardware from leveling cylinder to
tower boom fly assembly rod end pin (3).
12. Drive leveling cylinder pin (3) through mounting holes
in tower boom fly and leveling cylinder using a suitable
drift. Remove leveling cylinder.
Upright Level Cylinder Installation
1. Place leveling cylinder in position in tower boom. Align
holes in tower boom and leveling cylinder. Install level-
ing cylinder attach pin (3) using a suitable rubber mallet.
2. Secure pin to tower boom with mounting hardware.
3. Remove cylinder port plugs and hydraulic line caps and
correctly attach lines to cylinder ports.
4. Using all applicable safety precautions, operate the
overhead crane to move upright and upper boom
assembly in proper position with tower boom.
5. Align holes in upright and tower boom assembly and
install upright pivot pin (2) using a suitable rubber mal-
let. Secure pin with mounting hardware.
6. Align holes in upright and leveling cylinder barrel end.
Install leveling cylinder pin (1) using a suitable rubber
mallet. Install keeper pin and bolt.
7. Remove overhead crane from upper boom. Activate
hydraulic system.
8. Using all applicable safety precautions, operate the
boom functions. Check for correct operation and
hydraulic leaks. Secure as necessary.
9. Check fluid level of hydraulic tank Adjust as needed.
Turntable Ref.
Lift Cylinder Ref.
Pry Bar
Plunger Valve
Boom Support
Chain
Attach
Point
Tower Lift
Cylinder
Upright
Slave Cylinder
Overhead Crane