BOOM MAINTENANCE NBT40 SERVICE MANUAL
4-40 Published 8-01-2017 Control # 287-11
the lubricating plugs in the wear pads also be replaced with
new plugs. These new lube plugs initially extend 0.06 above
the pad surface and will wipe a long lasting coating of
lubricant onto the boom sliding surface.
Top Pad Replacement
NOTE: All wear pads must be tagged, inspected and
reassembled exactly as they have been
removed unless doing a complete overhaul.
1. Retract the boom completely, then extend the boom
approximately 17.75 in (4.44 in per stage) so that upper
wear pads on 3rd stage boom are visible through holes
in the top plates of the 1st and 2nd stage booms.
2. Remove capscrews from the top base of the 3rd stage
boom wear pad retaining plates and remove wear pad
retaining plates from the 3rd stage boom. Mark these
retaining plates so they can be reinstalled exactly as
they were removed. Remove 3rd stage boom wear
pads.
3. If necessary, mark the location of the nuts and loosen
the 1/2/3 extend cables and remove them from the
mounting holes at the base of the 1st stage boom. Tie
the 1/2/3 extend cables with approximately 2 ft of wire
and allow them to slack into the 1st stage boom
removing cables from notch in 3rd stage boom pads.
4. Replace the 3rd stage boom wear pads and reinstall
wear pad retaining plates onto the top plate of the 3rd
stage boom. Loctite all flathead mounting screws.
5. If necessary, reinstall the 1/2/3 extend cables into the
base of the 1st stage boom and reinstall the nuts which
secure these cables to their original location previously
marked on the threaded cable ends.
6. Extend the boom approximately 41.75 in (10.44 in per
stage) so that upper wear pads on 2nd stage boom are
visible through hole in the top plate of the 1st stage
boom.
7. Remove capscrews from the top base of the 2nd stage
boom wear pad retaining plates and slide wear pad
retaining plates towards the center of boom. Mark these
retaining plates so they can be reinstalled exactly as
removed. Remove the 2nd stage boom wear pads.
8. Replace the 2nd stage boom wear pads and reinstall
wear pad retaining plates onto the top plate of the 2nd
stage boom exactly as removed. Loctite all flathead
mounting screws.
9. Extend the boom approximately 651.00 in (162.75 in per
stage) so that base of the 4th stage boom passes the
hole in the side plate of the 3rd stage boom and base of
the 5th stage boom passes the hole in the side plate of
the 4th stage boom. Raise the 4th and 5th stage boom
tips to relieve pressure on wear pads on the top base of
the 4th and 5th stage booms.
10. Remove countersunk capscrews from the bottom of the
top plate on the base of the 4th stage boom that attach
the wear pad retaining plates to the 4th stage boom.
11. Side wear pad retaining plates and wear pads toward
base of boom and remove. Mark the wear pad retaining
plates so they can be reinstalled exactly as removed.
12. Replace the 4th stage boom wear pads and reinstall
wear pad retaining plates exactly as removed onto the
top plate of the 4th stage boom. Loctite all flathead
mounting screws.
13. Remove countersunk capscrews from bottom of the top
plate on the base of the 5th stage boom that attach the
wear pad retaining plates to the 5th stage boom.
14. Slide wear pad retaining plates and wear pads toward
base of boom and remove. Mark the wear pad retaining
plates so they can be reinstalled exactly as removed.
15. Replace the 5th stage boom wear pads and reinstall
wear pad retaining plates exactly as removed onto the
top plate of the 5th stage boom. Loctite all flathead
mounting screws. Retract the boom completely.
Bottom Pad Replacement
1. Lower the boom until the boom lift cylinder is bottomed
out and extend the boom approximately eight ft out (two
ft per stage).
2. Raise the 5th stage boom tip, until weight is removed
from the bottom pads in the 4th, 3rd, 2nd and 1st stage
booms.
3. Remove the capscrews (two in each pad) which retain
the 4th, 2nd and 1st stage boom bottom wear pads and
remove and replace pads. Reinstall capscrews, Loctite
and torque to proper tightness.
4. Mark the location of the nuts which retain the 5/4/3
retract cables to the bottom tip of the 3rd stage boom.
Loosen (to remove tension) the nuts on the 5/4/3 retract
cables. Remove capscrews from 5/4/3 retract cable
retainers and move retainers and cables towards center
of boom.
5. Remove the capscrews (two in each pad) which retain
the 3rd stage boom's bottom wear pads and remove and
replace pads. Reinstall capscrews, Loctite and torque to
proper tightness.
6. Reinstall 5/4/3 retract cable retainers and 5/4/3 retract
cables into bottom tip of the 3rd stage boom. Tighten 5/
4/3 retract cables to their original location previously
marked on the threaded cable ends.
Reference Only
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