JLG 450A II Series, Service And Maintenance Manual

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SECTION 4 - BOOM & PLATFORM
4-2 – JLG Lift – 3121290
Main Boom Disassembly
1. Loosen jam nuts on aft end of fly boom wear pad adjust-
ment and loosen adjustments.
2. Using a portable power source, attach hose to telescope
cylinder port block. Using all applicable safety precau-
tions, activate hydraulic system and extend cylinder to
gain access to cylinder rod retaining pin. Shut down
hydraulic system.
3. Carefully disconnect hydraulic hose from retract port of
cylinder. There will be initial weeping of hydraulic fluid
which can be caught in a suitable container. After initial
discharge, there should be no further leakage from the
retract port.
4. Remove hardware securing telescope cylinder to the fly
boom section, then remove pin from fly.
5. Remove hardware securing telescope cylinder to the
base boom section.
WHEN REMOVING TELESCOPE C YLINDER FROM BOOM SECTIONS. CARE
SHOULD BE TAKEN NOT TO LEAVE CYLINDER REST ON POWERTRACK WHICH
COULD CAUSE DAMAGE TO POWERTRACK.
6. Using a suitable lifting device, remove telescope cylin-
der from boom sections.
7. Using a piece of tape, mark length of hoses and wires
from front of fly boom and bottom of base boom for
reassembly.
8. Remove hardware securing front wear pads on base
boom section. Remove wear pads.
9. Remove hardware securing powertrack to aft end of fly
boom section.
10. Using a suitable lifting device, remove fly boom from
boom section.
11. Remove hydraulic lines and electrical cables from pow-
ertrack.
12. Remove hardware securing powertrack to base boom
section. Remove powertrack.
Inspection
1. Inspect all boom pivot pins for wear, scoring or other
damage, and tapering or ovality. Replace pins as
needed.
2. Inspect lift cylinder pins for wear, scoring or other dam-
age, and for tapering or ovality. Ensure pin surfaces are
protected prior to installation. Replace pins as needed.
3. Inspect telescope cylinder rod attach pin for wear, scor-
ing or other damage. Replace pin as needed.
4. Inspect inner diameter of boom pivot bushings for scor-
ing, distortion, wear or other damage. Replace bushings
as needed.
5. Inspect wear pads for wear.
6. Inspect all threaded components for damage such as
stretching, thread deformation, or twisting. Replace as
needed.
7. Inspect structural units of boom assembly for bending,
cracking, separation of welds, or other damage. Replace
boom sections as needed.