Manitowoc Published 10-01-2012, Control # 045-08 4-21
777 SERVICE MANUAL BOOM
4
Lacing Removal — Boom Section with a
Bent or Bowed Chord Member
1. This procedure applies to all lattice sections that have a
bent/bowed chord member. Perform the Chord
Straightness inspection on page page 4-12 to determine
if the chord is out of allowable tolerance.
2. Bent or bowed chords in a lattice section are typically the
result of some form of structural damage such as kinked
lacings. Perform a thorough inspection of the lacings
and identify the lacings that will need to be replaced.
3. Remove all of the damaged lacings by performing
Lacing Replacement steps 1-7 on page page 4-18. It
may be necessary to remove more than one lacing to
straighten the chord.
NOTE Pin another lattice section to the end of the section
being repaired or install a temporary brace if
replacing an end lacing.
4. Check the chord for straightness after removing the
damaged lacings.
It may be necessary to manipulate the chord to achieve
the desired results: use a pipe and a jack to move the
chord out or a lever-operated hoist to bring the chord in.
Check the back-to-back dimensions to the inside of the
chord on an insert.
5. Remove all grease, paint and oil from the weld zone on
the replacement lacing.
6. Fit and tack weld all of the new lacings. Use the
reference marks and any existing lacings on both sides
of the section to properly locate the new lacings.
All of the lacings should be tack welded before welding
is started.
7. Perform Lacing Replacement steps 8-14 starting on
page page 4-18.
8. Send all completed inspection reports to Manitowoc
Crane Care. Digital photographs should be taken and
submitted with the inspection reports.
Determining Amount of Stick Electrode
Needed
Use the following formula to determine approximately how
much stick electrode (weld metal) is needed to replace
lacings. Actual use could be higher or lower depending on a
number of factors outside of Manitowoc’s control, such as
over or under welding, damaged electrodes, length of
discarded electrode stubs, etc.
W=2 F
2
DL
•W = amount of weld metal that should be ordered (in
pounds)
•F = required filet weld leg size (in inches)
•D = lacing tube diameter (in inches)
•L = number of lacings being replaced (quantity)
EXAMPLE: If ten 4-1/2 in diameter lacings will be replaced
and a 3/8 in fillet weld is required —
Stick electrode can be ordered from your Manitowoc
distributor in hermetically sealed foil packs using the
following parts numbers:
W = 2 x F
2
x D x L
W = 2 x 0.375
2
x 4.50 x 10
W = 12.7 lb
E9018M-H4
Electrode Size
Quantity Part Number
1/8 in (3,2 mm) 4.4 lb Package 409758
3/32 in (2,5 mm) 3.0 lb Package 409759
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