JLG G12-55A Service Manual - Manual (Page 39)

3-5 G10-55A, G12-55A
Boom
3.4 COMPLETE BOOM REMOVAL/
INSTALLATION
3.4.1 Complete Boom Removal
1. Remove any attachment from the quick switch
assembly. Refer to the appropriate operation and
safety manual.
2. Remove the quick switch assembly. Refer to Section
3.9.1, “Quick Switch Removal.”
3. If equipped, remove the Boom Head Mounted
Winch. Refer to Section 3.10.1, “Boom Head-
Mounted Winch Removal.”
4. Park the machine on a hard, level surface, level the
machine, fully retract the boom, raise the boom,
place the transmission control lever in
(N) NEUTRAL, engage the park brake and shut the
engine OFF.
5. Place a Do Not Operate Tag on both the ignition key
switch and the steering wheel, stating that the
machine should not be operated.
6. Open the engine cover. Allow the system fluids to
cool.
7. Properly disconnect the battery.
8. Support the front of the boom by placing a sling
behind the boom head.
9. Label, disconnect and cap all hydraulic hoses for the
extend/retract and tilt circuits. Cap all fittings and
openings to keep dirt & debris from entering the
hydraulic system.
10. Support the lift/lower cylinder on the left side of the
machine. Remove the lock bolt and rod end pin.
Lower the lift/lower cylinder onto the frame rails.
Repeat this step for the right side lift/lower cylinder.
11. Support the compensation cylinder. Remove the lock
bolt and rod end pin. Lower the compensation
cylinder onto the frame rails.
12. Lower the boom to a level position and place a
suitable support under the boom head. Reposition
the slings to each end of the boom.
13. Remove the bolt securing the boom pivot pin. Pull
out the boom pivot pin.
14. Lift the complete boom off machine and set on level
ground or supports.
3.4.2 Complete Boom Installation
1. Park the machine on a hard, level surface, place the
transmission control lever in (N) NEUTRAL, engage
the park brake, chock the wheels and shut the
engine OFF.
2. Using suitable slings, balance the boom assembly,
lift and carefully guide the boom into place. Align the
frame pivot bore with the boom assembly pivot bore.
3. Install the boom pivot pin.
4. With the sling still in place, install the compensation
cylinder, pins and bolts.
5. With the sling still in place, install the rod end of the
left lift/lower cylinder, pin and lock bolt. Repeat for
the right side lift/lower cylinder.
Note: Raising the boom up or down with the sling may
be necessary so the boom, compensation and lift/lower
cylinder bores can be aligned for easier pin installation.
Note: Grease the boom pivot bore, compensation
cylinder rod ends, lift/lower cylinder rod end and pins
before installing.
6. Uncap and reconnect the previously labeled
hydraulic hoses to the extend/retract cylinder.
7. Uncap and connect any remaining hydraulic fittings
to their appropriate locations.
8. Recheck the wear pad gaps to ensure they meet the
minimum gap requirement. Shim if necessary.
9. Ensure that the boom chains are properly adjusted.
Refer to Section 3.7, “Boom Section Separation
Adjustment.”
10. Properly connect the battery.
11. Start the engine and operate all boom functions
several times. Check for leaks, and check the
hydraulic fluid level in the reservoir; add fluid if
required.
12. Install the quick switch assembly. Refer to Section
3.9.2, “Quick Switch Installation.”
13. If equipped, install the Boom Head Mounted Winch.
Refer to Section 3.10.2, “Boom Head-Mounted
Winch Installation.”
14. Clean up all debris, hydraulic fluid, etc., in, on, near
and around the machine.
15. Close and secure the engine cover.
16. Remove the Do Not Operate Tags from both the
ignition key switch and the steering wheel.
17. Install the previously remove attachment to the quick
switch assembly. Refer to the appropriate operation
and safety manual.