Manitowoc National Crane NBT40 Series, Service Manual

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4
10
National Crane
Published 8-01-2017 Control # 287-11
4-37
NBT40 SERVICE MANUAL BOOM MAINTENANCE
Cable Tightening Sequence
1. Cycle boom approximately 3 m (10 ft) out and in a few
times (.75 m, 2.5 ft per section). Fully retract the boom.
Tighten the 4/3/2 retract, 2/3/4 extend, 3/2/1 retract, 1/2/
3 extend, 5/4/3 retract and 3/4/5 extend cables.
Extend the boom a few inches before tightening retract
cables and retract the boom a few inches before
tightening extend cables to remove slack and properly
sequence bottoming out of boom sections.
2. Torque 4/3/2 retract cables (53) at front of the 2nd
section to 5.42 Nm (4 ft lbs). Start with two inside cable
ends equally, then the two outside cable ends equally.
3. Torque 2/3/4 extend cables (29) at back of 2rd section to
19.66 Nm (14.5 ft lb) each. To reach 2/3/4 extend cables,
extend the boom out approximately 610 mm (24 in.)
total, 115 mm (4.5 in) per section, and tighten through
hole in back of base section.
4. Torque 3/2/1 retract cables (19) at front of base section
to 4.07 Nm (3 ft lb), start with two inside cable ends
equally, then the next two outer cable ends, then the two
outside cable ends equally.
5. Torque 1/2/3 extend cables (10), (rear base section) to
14.91 Nm (11 ft lb) each.
6. Torque 5/4/3 retract cables (77) at the front of the 3rd
section to 5.42 Nm (4 ft lbs).
7. Torque 3/4/5 extend cables (96) at rear of 3rd section to
11.52 Nm (8.5 ft lbs). To reach 3/4/5 extend cable,
extend the boom out approximately 2.6 m (8.5 ft) total,
.65 m (2.1 ft) per section and tighten through holes in top
of base and 2nd sections.
8. Check to ensure all boom sections are bottoming out
simultaneously.
a. If the 2nd section is bottoming out first, loosen 1/2/3
extend cables, tighten 3/2/1 retract cables, and
extend and retract the boom a few feet. Torque 3/2/1
retract cables as in step 4 and torque 1/2/3 extend
cables as in step 5. Repeat until 2nd section
bottoms out correctly.
b. If 3rd section is bottoming out first, equally loosen 3/
2/1 retract cables and tighten 1/2/3 extend cables
and retract the boom a few feet. Torque 3/2/1 retract
cables as in step 4 and torque 1/2/3 extend cables
as in step 5. Repeat until 3rd section bottoms out
correctly.
c. If 4th section is bottoming out first, equally loosen 4/
3/2 retract cables. Tighten 2/3/4 extend cables and
extend and retract the boom a few feet. Torque 4/3/2
retract cables as in step 2 and torque 2/3/4 extend
cables as in step 3. Repeat until 4th section bottoms
out correctly.
d. If 5th section is bottoming out first, equally loosen 5/
4/3 retract cables, tighten 3/4/5 extend cables and
extend and retract the boom a few feet. Torque 5/4/3
retract cables as in step 6 and torque 3/4/5 extend
cables as in step 7. Repeat until 5th section bottoms
out correctly.
9. Cycle the boom a few feet out and in. If all sections are
not bottoming out simultaneously, repeat step 8.
10. Repeat steps 2 through 7 using the following torques.
Torque 4/3/2 retract cables to 10.85 Nm (8 ft lb). Torque
2/3/4 extend cables to 39.32 Nm (29 ft lbs), torque 3/2/1
retract cables to 8.13 Nm (6 ft lb). Torque 1/2/3 extend
cable to 29.83 Nm (22 ft lb), 5/4/3 retract cables to 10.85
Nm (8 ft lbs), 3/4/5 extend cables to 25.76 Nm (19 ft lbs).
11. Run the boom through a complete extend and retract
cycle. Check that all cables are properly torqued and
that all sections retract completely, repeat step 8 as
needed.
12. Cycle the boom through a complete extend and retract
cycle. Check that all cables are properly torqued and
that all sections retract completely.
13. Tightening until the retraction gap between the first and
second section and the retraction gap between the
second and the third are equal.
At this time the all extendable sections should extend and
r e t r a c t e q u a l l y a n d b o t t o m o u t a g a i n s t t h e s t o p s
simultaneously.
Reference Only