JLG 660SJ ANSI Service Manual - Manual (Page 179)

SECTION 5 - HYDRAULICS
3120718 – JLG Lift – 5-13
Upright Level Cylinder Removal
1. With the aid of an assistant, manually override the
Plunger Valve with a pry bar, and from Ground Con-
trol, using auxiliary power, extend the tower tele-
scope out to gain access to leveling cylinder rod
end pin #3.
2. With the main boom positioned and supported as
shown in Leveling Cylinder Removal, prepare to
remove the upright level cylinder.
3. Remove the mounting hardware from pin #1, secur-
ing leveling cylinder to upright.
4. With overhead crane supporting upper boom
assembly. Raise boom until tension is released from
cylinder pin #1.
5. Using a suitable drift, drive the barrel end attach pin
#1 through the mounting holes in the upright and
leveling cylinder.
6. Remove the mounting hardware from upright pivot
pin #2 which secures upright to tower boom assem-
bly.
7. Using a suitable drift, drive pivot pin #2 through the
mounting holes in the upright and tower boom
assembly.
8. Using all applicable safety precautions, operate the
overhead crane to move upright and upper boom
assembly forward to clear tower boom.
9. Using all applicable safety precautions, operate the
overhead crane to move upright and upper boom
assembly forward to clear tower boom.
10. After moving assemblies forward, operate overhead
crane to the left far enough to remove leveling cylin-
der.
11. Tag, disconnect and cap hydraulic lines to level cyl-
inder.
12. Remove the mounting hardware from leveling cylin-
der rod end pin #3 which secures cylinder to tower
boom fly assembly.
13. Using a suitable drift, drive leveling cylinder pin #3
through the mounting holes in the tower boom fly
and leveling cylinder, then remove leveling cylinder.
Upright Level Cylinder Installation
1. Place the leveling cylinder in position in the tower
boom, then align holes in tower boom and leveling
cylinder. Install leveling 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 rub-
ber mallet. Secure pin with mounting hardware.
6. Align holes in upright and leveling cylinder barrel
end and install leveling cylinder pin #1 using a suit-
able rubber mallet. Secure pin with mounting hard-
ware.
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 and adjust as nec-
essary.
Tower Boom Lift Cylinder Removal
1. Place machine on a flat and level surface. Place the
main boom in a horizontal position with the tele-
scope cylinder fully retracted. Place the tower boom
in a fully elevated and fully retracted position (See
Figure 5-18., Boom Positioning and Support, Cylin-
der Repair (A Models).
2. Support the main boom with a prop. Support the
upright with an overhead crane. (See Figure 5-18.,
Boom Positioning and Support, Cylinder Repair (A
Models).
3. Using slings restrain tower lift cylinder.
4. Remove mounting hardware securing the cylinder
rod pin to the tower boom. Using a suitable brass
drift, drive out the cylinder rod attach pin.
Figure 5-17. Overriding the Plunger Valve