Manitowoc National Crane NBT40 Series, Service Manual

Page: 95 / 220

4
10
National Crane
Published 8-01-2017 Control # 287-11
4-21
NBT40 SERVICE MANUAL BOOM MAINTENANCE
Reference Figure 4-6, Figure 4-7, Figure 4-8, Figure 4-12
and Figure 4-10 for Boom Removal, Disassembly, Assembly
and Cable Tensioning.
Boom Removal
For Boom weight see Specifications in Section 9 of this
manual.
1. Extend and set machine outriggers and front stabilizer.
Boom must be completely retracted and stowed in boom
rest over front of truck.
2. If equipped, remove swing around jib according to
procedures outlined in the Set-Up Section of the
Operator’s Manual.
3. Remove hook block or downhaul weight, wind up rope
on hoist drum. Shut down truck engine.
4. Attach lifting device to the counterweight to provide even
weight distribution and raise the counterweight until
weight is removed from the boom pivot pin. Remove
counterweight retaining hardware from the boom pivot
pin and lower the counterweight until it rests on the rear
outrigger box.
5. Attach a lifting device to rod end of lift cylinder, remove
boom lift cylinder pin keeper and pin from bottom of 1st
section boom. Lower lift cylinder rod end to the deck.
6. Tag and disconnect extend cylinder lines and hoist
hydraulic and electric lines. Cap all openings. Unplug
anti-two-block/RCL cord from receptacle in turret.
7. Disconnect and cap all hoist hydraulic lines and
openings. Hoist may be removed at this point, but is not
necessary. (See “Hoist Removal” on page 5-2).
8. Attach a lifting device to provide even weight distribution
and raise the boom until weight is removed from the
boom pivot pin. Remove boom pivot pin keeper and
boom pivot pin. Lift boom free of turret.
5 Section Boom Disassembly
For reference, front (tip) is sheave case end, rear (base) is
hoist mount end, left and right are viewed from rear to front.
NOTE: All wear pads must be tagged, inspected and
r e a s s e m b l e d e x a c t l y a s t h e y h a v e b e e n
removed unless doing a complete overhaul.
Steps 1 through 3 apply to a boom that is to be disassembled
with the 1st section and jib (if equipped) left on crane. all
other steps apply to boom being removed from crane (See
“Boom Removal” on page 4-21).
1. Extend and set the outriggers and SFO.
2. Completely retract the boom and place it in a horizontal
position.
3. Tag and disconnect the hydraulic lines to the telescope
cylinder. Cap all lines and openings.
4. Loosen and remove two capscrews (11,8) and hardened
washers which anchor the 1st stage extend cylinder rod
(6) to the base of the 1st stage boom.
5. Mark the location of the nuts and washer (9,8) which
secure the 1/2/3 extend cables (10) to the rear base of
the 1st stage boom base section (1). Remove nuts and
washers from 1/2/3 extend cables at 1st stage boom
base. Mark and tag cables while leaving the cable ends
draped inside the boom.
6. Remove hardware (161,162) and access plate (160)
from top/rear of 1st section.
7. Attach a sling or chain to the tip of the 2nd stage boom
and pull the 2nd stage boom (with the 3rd, 4th and 5th
stages) out approximately one foot or until the access
openings on all boom sections align to the rear wear pad
assemblies for all boom sections. Tag and remove rear
wear pads from top of each boom section. Loosen
attaching hardware for the adjusting cam plates and all
rear top wear pads for all boom sections being removed.
8. Remove and tag attaching hardware (61,62,63) on front
tip of lower 1st stage boom section. Loosen adjustment
hardware (111,70) wear pads (18) and back plates
(22,28).
9. Remove and tag upper plate (16) and shim (136) and
hardware (23,21,56) from tip of 1st stage boom.
10. Remove and tag two upper side wear pad assemblies
(179) with keeper side wear pad (178,180) and
hardware (176,177) from tip of 1st stage boom.
11. Loosen cable adjusting nuts (151,12) on lower front 3/2/
1 retract cables (19). Remove four capscrews (27) which
retain the 3/2/1 retract cable anchors plates (150) to the
bottom tip of the 1st stage boom. Pull the retract cable
anchors out and keep retract cables taunt while pulling
2nd (with 3rd, 4th, and 5th) stage out of 1st stage.
Partially pull 2nd stage boom from boom assembly until
front tip of boom can be raised enough to remove and
tag wear pads (184,185) and hardware (20,49) from
bottom tip of 1st stage boom. Support the base end of
the 2nd stage as it exits the 1st stage boom.
12. Place 2nd stage (with 3rd, 4th and 5th) on a suitable
horizontal surface.
NOTE: Use caution not to pinch or crush retract cables
while lifting or supporting 2nd stage boom.
13. Remove capscrew and retract cable guide roller (149)
from each side of the bottom base of the 2nd stage
boom.
14. Remove the two square head setscrews (154) which
retain 3/2/1 retract sheave pin (38). Pull the retract
Reference Only