Boom
3-4
31211015 6036, 6042, 8042, 10042, 10054
3.2 SAFETY INFORMATION
3.3 BOOM SYSTEM - THREE SECTION (6036,
6042, 8042 & 10042)
3.3.1 Boom System Operation
The three section boom assembly consists of first, second
and third boom section assemblies with double top boom
extend chains and a single retract chain. Boom extension and
retraction is accomplished via hydraulic power and chain
movement.
As the Extend/Retract hydraulic cylinder, which is anchored
at the rear of the second boom section and the rear of the
first boom section, begins to extend, it forces the second
boom section out of the first boom section.
The second and third boom sections are connected by
extend and retract chains. These chains are routed around
sheaves on the second boom section. As the second boom
section is forced out, the extend chain pulls the third boom
section out of the second boom section.
As hydraulic pressure is applied to the retract port on the
Extend/Retract cylinder, the second boom section is pulled
back into the first boom section, and retract chain pulls the
third boom section back into the second section.
This mechanical linkage formed by the chains and
supporting hardware extends and retracts the second and
third boom sections at the same rate.
The first boom section does not extend or retract, but lifts
and lowers via action of the lift/lower cylinder.
3.4 BOOM ASSEMBLY MAINTENANCE
These instructions must be completed in sequence. The third
boom section must be removed before removing the second
boom section. The third and second boom section must be
removed at one time before removing the first 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.
3.4.1 Boom Removal
1. Remove any attachment from quick coupler assembly.
Note: If replacing the third section boom, remove the quick
coupler from the third section. Refer to Section 3.9, “Quick
Coupler”.
2. Park the machine on a hard, level surface, level the
machine, fully retract the boom, lower the boom, place
the transmission 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 rear and side engine doors. Allow the
system fluids to cool.
5. Move the attachment tilt joystick in both directions to
relieve any trapped pressure in the attachment tilt
system. If the machine is equipped with auxiliary
controls, move the auxiliary hydraulic joystick in both
directions to relieve any trapped pressure in the
auxiliary hydraulic system.
6. Properly disconnect the battery. Refer Section 9.8,
“Battery”, for procedure.
7. Label, disconnect and cap the hydraulic hoses at the
rear of the boom. Cap all fittings to keep dirt and debris
from entering the hydraulic system.
8. Label and disconnect the boom proximity sensor at the
rear of the boom.
9. Remove the pin from the rod end of the compensation
cylinder being careful not to drop the cylinder. Lower
the cylinder onto the frame rails.
10. Remove the pin from the rod end of the lift/lower
cylinders. Lower the cylinders onto the frame rails.
11. Confirm that the boom assembly is balanced with the
sling and remove the boom assembly
pivot pin.
12. Lift the boom assembly from the machine and lower
onto suitable supports.
WARNING
DO NOT service the machine without following all safety
precautions as outlined in Section 1, “Safety Practices”, of
this manual.
WARNING
NEVER weld or drill the boom unless approved in writing
by the manufacturer. The structural integrity of the boom
will be impaired if subjected to any repair involving
welding or drilling.
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