National Crane 1-21-2019 Control # 104-07 4-9
1400A SERVICE MANUAL BOOM MAINTENANCE
14. Place the 3
RD
-4
TH
-5
TH
assembly on a suitable horizontal
surface. Take care not to damage the retract cables
while lifting or supporting the 3
RD
-4
TH
-5
TH
assembly.
15. Remove 3
RD
section extend cables from the top of the
3
RD
section by removing the anchor plates and
capscrews at the rear of the section, place cables in a
area to avoid damage.
16. Remove the lower L-pads, retract cables, and retract
cable retaining capscrews from rear of 3
RD
section.
• Remove retract cable retaining plates from the rear
of the 4
TH
section.
• Remove 4
TH
section retract cables from the anchor
pocket in the 4
TH
section.
17. Remove the lock bar and hardware from extend cylinder
collar anchor pocket in the 3
RD
section.
• Lift the butt plate end of the cylinder up to disengage
the cylinder from its anchor pockets in the 3rd
section.
• Slowly pull cylinder out of the 3
RD
4
TH
5
TH
assembly.
Keep the 4
TH
section extend cables taunt and in
position to avoid damage as cylinder exits boom
assembly.
• Remove the 4
TH
section extend cable anchor in the
4
TH
section as the end of the cylinder nears the
anchor position.
18. Place cylinder assembly on a suitable horizontal
surface. Take care not to damage the extend cables
while lifting or supporting the cylinder assembly. To
remove the cables from the cylinder:
• Remove the tapered wear pads on the front of the
cylinder assembly.
• Remove the cables through the access opening
when the tapered wear pads were removed.
19. Remove cable guide and upper spacer bar from the front
top of the 3
RD
section.
• Loosen and remove hex nuts from threaded ends of
5
TH
section extend cables at rear of 3
RD
section.
• Remove top rear wear pads and cam plates from
top of 4
TH
section.
20. Attach a sling or chain to front of the 4
TH
section boom
and pull the 4
TH
-5
TH
boom assembly out of the 3
RD
section about 30 cm (12 inches). Keep the 4
TH
section
off of the lower wear pads.
21. Remove the 4 capscrews which retain the lower front
pad plate to the 3
RD
section.
• Remove the pad plate.
• Remove and tag four side wear pads with shims
from the front of the 3
RD
section.
• Pull the retract cables out and keep retract cables
taunt while pulling the 4
TH
-5
TH
section assembly out
of the 3
RD
boom section.
• Support the base end of the 4
TH
section as it exits
the 3
RD
boom. section
22. Place 4
TH
-5
TH
boom assembly on a suitable horizontal
surface. Take care not to damage the retract cables
while lifting or supporting the 4
TH
-5
TH
boom assembly.
23. Remove lower L-pads, retract cables, and retract cable
keeper from rear of 4
TH
section, coil 5
TH
section retract
cables inside of 5
TH
section. Remove upper top wear
pads and cam plates from upper rear of 5
TH
section.
24. Remove cable guide and upper spacer bar from the front
of the 4
TH
section. Remove side wear pads for the cable
retainer from front of 4
TH
section, leave 5
TH
section
extend sheaves and 5
TH
section extend cables in place.
25. Attach sling to the front of the 5
TH
section boom and pull
the 5
TH
section out of the 4
TH
until there is about 90 cm
(36 inches) of the 5
TH
still inside in the 4
TH
section. Use
caution to keep 5
TH
section extend cables from damage
as boom sections slide apart. If possible keep tension on
5
TH
section extend cables from the base end of the 4
TH
boom section during this procedure.
26. Lift 5
TH
section off the lower pads and remove pads and
hardware. Remove 5
TH
section extend sheaves and
hardware.
27. Slide 5
TH
section completely out of 4
TH
section. Support
the base end of the 5
TH
as it exits the 4
TH
section boom.
Place 5
TH
section boom on a suitable horizontal surface.
28. Remove the cable retainers and hardware from side
anchor locations on the 5
TH
section. Remove the 5
TH
section extend and retract cables from anchor points in
the side of the 5
TH
section. Place in a suitable area to
avoid damage.
29. Remove the loadline sheaves by removing retainers and
lightly tapping on sheave pin while removing sheaves
and spacers until all sheaves are removed from boom
sheave case.
Additional Maintenance, Disassembled
Boom
1. Clean all boom sections and inspect for wear, dents,
bent or crooked boom sections, gouged metal, broken
welds or any abnormal conditions. Repair or replace as
required.
2. Inspect all sheaves for excessive groove wear or
abnormal rim wear. Replace as required.
3. Inspect all sheave bearings for excessive wear or cut
inner liner material. If installed bearing diameter is 0.38
Fo
r
Reference
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