National Crane Published 8-01-2017 Control # 287-11 9-21
NBT40 SERVICE MANUAL CRANE INSTALLATION
7. If the frame through the rear suspension does not meet
the minimum specifications for RBM and section
modulus, it can be reinforced by adding a reinforcing
angle as shown in Figure 9-14.
See Section Modulus Table B on page 16 for the
required size of reinforcing.
Strip all easily removable equipment from the frame
through the suspension such as spring stops (2), etc.
Butt the reinforcing angle (1, Figure 9-14) up against the
forward reinforcing (4) of the suspension. Mark the
areas that require cutting (5) so that the angle slides up
around the spring hangers (3) and against the existing
truck frame (6) and forward reinforcing (4).
Torch out the marked areas in the long leg of the angle
deep enough so that the angle can be slid up from the
underneath the frame to contact either existing truck
frame (6, Figure 9-14) or spring hanger brackets (3) (if
they extend down below the existing truck frame).
8. If reinforcing angle (1, Figure 9-14) is welded to truck
frame, cut out plug weld hole pattern as in Figure 9-12.
Slide the reinforcing angle (1, Figure 9-14) up from the
bottom, butt it to existing forward reinforcing (4) and
weld (9) rear suspension reinforcing to forward
reinforcing.
Replace as much of the spring hanger (5) cut out areas
as possible. Use the drop-off material from the cut out
(step 7), and butt weld these pieces in.
Position bar (8) on top of truck frame (6) and skip weld
as noted in Figure 9-14.
9. If reinforcing angle (1, Figure 9-14) is to be bolted on,
drill hole pattern according to Figure 9-13 and install
bolts.
Reinforce spring hanger cut outs (5, Figure 9-14) and
the weld area, suspension reinforcing to forward
reinforcing by adding bars (7) and (8).
The bars should be of the same thickness, width and
yield strength as the reinforcing angle lip. Bar (7) should
be long enough to extend at least 6" (152mm) beyond
either side of the weld or cut out areas. Weld these
reinforcing bars to the reinforcing angle (1) with length-
wise welds. Do not weld across the flanges.
Replace any equipment that had been removed.
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