National Crane Published 8-01-2017 Control # 287-11 4-9
NBT40 SERVICE MANUAL BOOM MAINTENANCE
4. Clean and inspect all cable assemblies according to wire
rope inspection procedures in this section. Pay
particular attention to any wire breakage at the end
connections. Replace cable assemblies as required.
Lubricate all cable assemblies as required. Lubricate all
cable assemblies before reinstalling them in boom.
5. Inspect all sheave pins for nicks, gouges or pitting due to
rust in the bearing surface area. Replace if any damage
is evident.
6. Inspect all grease fittings and grease paths in pins to
ensure proper grease flow. Clean and replace as
required.
7. Inspect all wear pads for gouges or uneven wear on
surface area. Replace if any damage is evident. Replace
all lubricating plugs in all wear pads as necessary.
8. Apply multipurpose grease (MPG) to all wear pad
surfaces.
Four Section Boom Assembly
NOTE: Torque all hardware to their specified torque value
See “Fasteners And Torque Values” on page 1-7.
NOTE: Apply medium strength thread locking adhesive/
sealant using Loctite Type 243 according to Loctite
recommendations to all hardware and torque.
NOTE: Do not use Loctite on any cable threaded ends.
Always use the jam nuts and/or nuts provided.
NOTE: Install cables in their natural untwisted condition.
Do not twist cables. Twisting of cables will result in
damage or failure of cable. When initially
assembling threaded ends of cables, thread the
first nut on past the flat so adjustment can be made
later.
NOTE: Apply multipurpose grease (MPG) to all wear pads
and contact surfaces.
For reference, front (tip) is sheave case end, rear (base) is
hoist mount end, left and right are viewed from rear to front.
4th Section Boom Assembly
1. Assemble upper loadline sheaves (94) and bearings
(95) into the 4th stage sheave case (4).
a. Install sheave pin (90) in left side of the upper
sheave case.
NOTE: Install spacers (92) between sheaves and between
sheaves and side plates.
b. Install small spacer (92).
c. Install sheaves assembly (94,95) near the sheave
case side plates with the grease fitting (93) facing
the side plate to allow for greasing.
d. Install spacer (91).
e. Install center sheave assembly (94,95) with grease
fitting (93) facing either side.
f. Install top sheaves assembly (94,95) to the left hand
side of the boom with the spacer (91) to the right
hand side.
g. Install keeper plates (82) to both sides of the sheave
case using bolt (81) and washer (21).
2. Assemble lower loadline sheaves (94) and bearings (95)
into the 4th stage sheave case (4).
a. Install sheave pin (96) in left side of the sheave
case.
NOTE: Install spacers (92) between sheaves and between
sheaves and side plates.
b. Install small spacer (92).
c. Install sheaves (94,95) near the sheave case side
plates with the grease fitting (93) facing the side
plate to allow for greasing.
d. Install small spacer (92).
e. Install center sheave's (94) with grease fitting facing
either side.
f. Install sheaves (94) to the right hand side of the
boom.
g. Install the spacer (92).
h. Install link (128) to outside of sheave case.
i. Install keeper plates (127) to right side of the sheave
case using bolt (81) and washer (21).
j. Install keeper plates (82) to left side of the sheave
case using bolt (81) and washer (21).
k. Install tube (110) in lower forward sheave case.
l. Install hitch pins three (89) in sheave case.
3. Install bottom rear wear pad (68), shims (67) with
capscrew (69) to the base of the 4th stage boom (4).
4. Install two side wear pads (42) and shims (41) onto the
rear base of the 4th stage boom (4). Shim according to
calibration instructions in this section or as pads were
originally removed and tagged.
NOTE: Apply multipurpose grease (MPG) to all wear pads
and contact surfaces.
5. Raise and support the 4th stage boom (4) in front of the
3rd stage boom (3).
4th and 3rd Section Boom
1. Install 4th stage boom (4) into 3rd stage boom (3)
approximately five feet. Figure 4-7.
Reference Only
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