JLG 740A, Service And Maintenance Manual

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SECTION 4 - BOOM & PLATFORM
3121160 – JLG Lift – 4-15
Inspection
1. Inspect tower boom pivot pin for wear scoring,
tapering, and ovality, or other damage. Replace pins
as necessary.
2. Inspect tower boom pivot attach points for scoring,
tapering, and ovality, or other damage. Replace pins
as necessary.
3. Inspect inner diameter of tower boom pivot bearings
for scoring, distortion, wear, or other damage.
4. Inspect lift cylinder attach pin for wear, scoring,
tapering, and ovality, or other damage. Ensure pin
surfaces are protected prior to installation. Replace
pins as necessary.
5. Inspect inner diameter of upright attach point bear-
ings for scoring, distortion, wear, or other damage.
Replace bearing as necessary.(See Paragraph 2-15
Cylinder Repair line #13 for Bearing Replacement).
6. Inspect all threaded components for damage such
as stretching, thread deformation, or twisting.
Replace as necessary.
7. Inspect structural units of tower boom assembly for
bending, cracking, separation of welds, or other
damage. Replace boom sections as necessary.
8. Inspect powertrack for damage such as cracking,
wear, or other damage. Replace links or assembly,
as necessary.
Assembly
NOTE: When installing fly section wear pads, install same
number and thickness of shims as were removed
during disassembly.
1. Measure inside dimensions of the tower base sec-
tion to determine the number of shims required for
proper fit.
2. Install side, top, bottom wear pads to the aft end of
tower fly section; shim evenly to the measurements
of the inside of the base boom section.
WHEN ASSEMBLING TOWER BOOM SECTIONS, ENSURE THAT
THE BOOM SLIDING TRAJECTORIES HAVE BEEN CLEARED OF
CHAINS, TOOLS, AND OTHER OBSTRUCTIONS.
3. Align upright leveling cylinder with attach holes in
tower fly boom. Using a soft head mallet, install the
cylinder pin into tower fly boom and secure with
mounting hardware.
4. Secure the sling and lifting device at the tower fly
boom assembly’s approximate center of gravity.
5. Slide tower fly boom assembly into the tower base
boom section, for a total of 1/32 inch (0.8 mm) clear-
ance.
6. Install wear pads into the forward position of the
tower base boom section. Shim boom, if necessary,
for a total of 1/32 inch (0.8 mm) clearance.
7. Align the telescope cylinder with the slots at the aft
end of tower base boom section, then secure cylin-
der with mounting hardware.
8. Attach internal powertrack to tower base boom at
bottom only and extended out of boom that the
powertrack links are opened at top.
9. Attach hoses and wiring harnesses at front end of
base boom and rout thru the powertrack. Secure
hoses and wiring harnesses with hose brackets.
10. Roll the powertrack back into the base boom section
and attach loose end of the powertrack to the inside
top of the fly boom section.
Installation
1. Using a suitable lifting device, position boom
assembly on turntable so that the pivot holes in both
boom and turntable are aligned.
2. Install boom pivot pin, ensuring that location of hole
in pin is aligned with attach point on turntable.
3. If necessary, gently tap pin into position with soft
headed mallet. Secure pin mounting hardware.
4. Connect all wiring connectors to the correct connec-
tors.
5. Connect all hydraulic lines of boom assembly.
6. Using all applicable safety precautions, operate lift-
ing device in order to position boom lift cylinder so
that holes in the cylinder rod end and boom struc-
ture are aligned. Insert the lift cylinder pin, ensuring
that location of hole in pin is aligned with attach
point on boom.
7. Using all applicable safety precautions, operate
machine systems and raise and extend boom fully,
noting the performance of the extension cycle.
8. Retract and lower boom, noting the performance of
the retraction cycle.