JLG 534D-10 - Manual (Page 63)

3.35 534D-9, 534D-10 & 544D
Boom
If the problem is caused by dirt or foreign substance
packed in the joints, clean and lubricate thoroughly
before re-installing the chain.
If the problem is caused by corrosion and rust or
bent pins, replace the chain.
c. Expose Retract Chains for Inspection
The three retract chains are only partially visible through
the rear of the boom with all the sections retracted. It is
possible to see a section of the retract chain as the boom
is slowly extended. If there is ANY question that one or all
the retract chains are damaged, the boom should be
removed and disassembled with the retract chains being
inspected and replaced if necessary.
Note: DO NOT attempt to repair a chain. Replace a
stretched or damaged chain with a new part. Always
replace both the chain and the clevis. It is recommended
that when any chain is replaced, that all chains and
clevis’ be replaced at the same time.
3.12.3 Adjusting Extend Chains
1. Raise the boom to a horizontal position and extend
the boom halfway. Place the transmission control
lever in (N) NEUTRAL, engage the park brake
switch. Shut off machine.
2. Measure the gaps (1) between the flat washers and
the rear face of the extend chain anchor at the top
front of the first boom section. The correct gap
measurement is 1/4 in (6 mm). If the gaps measure
more or less than a 1/4 in (6 mm), then the chains
must be adjusted.
3. Repeat the check for the single extend chain for the
fourth boom section (anchored at the top of the top
front of the second boom section).
4. If adjustment is needed, loosen the jam nuts on both
extend chains.
5. Tighten the extend chain adjusting nuts until the gap
between the chain flat washer and the boom anchor
is 1/4 in.
6. Torque the jam nuts to 100 lb-ft (135 Nm). DO NOT
use Loctite ® on the nuts.
7. Repeat the above steps to adjust the single extend
chain (1) for the fourth boom section (anchored at
the top of the top front of the second boom section).
3.12.4 Adjusting Retract Chains
1. Fully retract the boom and raise the boom to a
horizontal position. Place the transmission control
lever in (N) NEUTRAL, engage the park brake
switch. Shut off machine.
2. Measure the distance between the second and third
boom sections (2) to determine the adjustment
required. The correct dimension is 1/2 in (13 mm).
3. If adjustment is needed, loosen both extend chain
adjusting nuts (3)(at the first boom section anchor)
sufficient to allow realignment.
4. Loosen the retract chain jam nut (4)(located inside
the bottom front of the first boom section).
5. Tighten the retract chain, adjusting the nut to obtain
the 1/2 in (13 mm) dimension required.
6. Torque the jam nuts to 100 lb-ft (135 Nm). DO NOT
use Loctite ® on the nuts.
7. Measure the distance (5) between the third boom
section and the outer face of the boomhead on the
fourth boom section to determine the amount of
MX0500
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MX0500
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