Lull 944E-42 Service Manual - Manual (Page 84)

Boom
3.36 Model 644E-42/944E-42 Rev. 6/04
3.4.4 Boom Chain Tension Adjustment
Note: Always perform Section 3.4.3, “Boom Chain Ten-
sion Check,” before adjusting the boom chain tension.
1. Park the vehicle on level ground. Place the travel
select lever in the (N) NEUTRAL DETENT position,
engage the parking brake switch and raise the boom
to a horizontal (level) position. retract the boom
completely and turn the vehicle OFF.
2. Adjust the extend chain by tightening or loosening
the retract chain adjustment nut (1) on the front
underside of the outer boom (2).
3. If the chain sag measurement is less than 3.00"
(76 mm) the retract chain adjustment nut needs to
be tightened.
4. If the chain sag measurement is more than 4.00”
(102 mm) the retract chain adjustment nut needs to
be loosened.
5. Return to the cab, start the engine and cycle the
boom all the way out and all the way in several times.
6. Fully extend the boom, then retract it 2" (51 mm)
(one inch per section). Turn the vehicle OFF.
7. Measure the sag (5) in the top boom extend
chain (6) between the bottom of the chain and the
top of the intermediate boom (7) at their closest
point (5). Acceptable boom chain sag is between
3.00" (76 mm) and 4.00" (102 mm). If the
measurement is still less than 3.00" (76 mm), the
boom chain need to be readjusted.
Note: If all the adjustment has been used up on the
retract chain adjustment nut and the extend chain is not
within the range of 3.00" (76 mm) and 4.00" (102 mm)
the clevis at the top front of the outer boom will need to
be repositioned.
Note: Before proceeding with the repositioning of the
extend chain clevis, check the chain for any chain stretch
that might have occurred. Refer to Section 3.4.1, a.
“Inspection Guidelines.”
8. Return to the cab, start the engine and fully retract
the boom. With the boom horizontal, extend the
boom out approximately 2 ft (610 mm) and shut the
engine OFF.
9. At the front underside of the outer boom (2), loosen
the retract chain adjustment nut (1). Back the nut off
until the top of the nut is flush with the end of the
threaded clevis.
10. This step will require the help of an assistant. Return
to the cab, start the engine. Have the assistant
watch at the front underside of the outer boom. The
person in the cab should slowly retract the boom
until the retract chain adjustment nut touches the
clevis mounting tab (4) on the underside of the outer
boom.
11. At the front top of the outer boom (8), remove one of
the retaining rings (9) from the clevis mounting
pin (10). Remove the pin from the mounting plates.
Inspect the pin for wear or other damage. Replace
the pin if damaged.
MU4460
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OA0492
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