JLG 534D-10 - Manual (Page 32)

Boom
3.4 534D-9, 534D-10 & 544D
3.2 BOOM SYSTEM - THREE SECTION
3.2.1 Boom System Operation
The three section boom consists of the first, second and
third assemblies with second and third section extend
cables, and a single second and third section retract
cable.
As the extend/retract cylinder, which is anchored at the
rear of the first boom section, and the front of the push
beam begins to extend, it forces the second and third
boom sections out of the first boom section.
The boom sections are connected by extend and retract
cables. These cables are routed around sheaves on the
front of the push beam and the rear of the second boom
section. As the extend/retract cylinder is forced out
hydraulically, the second and third boom sections are
pulled out by the extend cables.
As hydraulic pressure is applied to the retract port on the
extend/retract cylinder, the retract cable pulls the second
and third boom sections back into the first boom section.
This mechanical linkage formed by the cables and
supporting hardware, extends and retracts the second
and third boom sections at the same rate.
The boom section lifts and lowers via action of the lift
cylinder.
3.3 BOOM MAINTENANCE - THREE
SECTION (COMPLETE REMOVAL)
These instructions must be completed in sequence. The
second and third boom sections are removed from the
first boom section.The third boom section is removed
from the second boom section.
Before beginning, conduct a visual inspection of the
machine and work area, and review the task about to be
undertaken. Read, understand and follow these
instructions.
3.3.1 Boom Removal
While the boom sections can be separated from each
other on the machine, JLG recommends against this
procedure. It is much safer, more efficient and more cost-
effective to remove the complete boom assembly from
the machine and place it on suitable supports for
separation. Work can then progress at a normal working
height.
Note: When removing a complete boom assembly use
a hoist or crane with a minimum lift capacity of 6000 lbs.
1. Remove any attachment from the quick switch
assembly. Refer to Section 3.16.1, “Disconnecting
from an Attachment.”
2. Park the machine on a hard, level surface, fully
retract the boom, level the boom assembly, place the
transmission control lever in (N) NEUTRAL, engage
the park brake and shut the engine OFF.
3. Place a Do Not Operate Tag on both the ignition key
switch and the steering wheel, stating that the
machine should not be operated.
4. Open the engine cover. Allow the system fluids to
cool.
5. Remove the battery negative (-) cable from the
battery negative (-) terminal.
6. Place a sling around the first boom section at the
balance point.
7. Take the weight off the boom assembly.
8. Label. disconnect and cap all hydraulic hoses
attached to the boom. Cap all fittings and openings
to keep dirt & debris from entering the hydraulic
system.
9. Label, disconnect any electrical cables if equipped.
10. Remove the pin from the rod end of the
compensation cylinder being careful not to drop the
cylinder. Lower the cylinder to a secure position.
11. Remove the pin from the rod end of both lift cylinders
being careful not to drop the cylinder. Lower the
cylinder to a secure position.
12. Confirm that the boom assembly is balanced with
the sling and remove the boom assembly pivot pin.
13. Lift the boom assembly from the machine and lower
onto suitable supports
WARNING
NEVER weld or drill the boom unless approved in
writing by JLG. The structural integrity of the boom
will be impaired if subjected to any repair involving
welding or drilling.