GMC 4000 Series Service Manual page 113

Sec. 2
Page 106
FRAME
Figure 8 — Plug Patterns of Strap Reinforcements
type, should not be attached to the flanges except
in the case where a mounting bracket or crossm em ­
ber holes are already through the frame flange.
3. Plug welds may be used in a staggered 8 to
10 inch pattern when attaching reinforcements to
the web section (fig. 8).
4. Strap reinforcem ents may be plug welded
at 6 to 8 inch intervals to the flanges in some cases;
however, as pointed out, this is for section modulus
increase and should only be attempted by highly
qualified sp ecialists.
The termination of reinforcements is very
important. Reinforcement ends must be scarfed or
stress relieved to prevent localized stress con­
centration. This scarfing should not be greater
than 45 (fig. 6). It should also be strongly empha­
sized that in ca ses where several reinforcements
are used, the ends of the reinforcements must
overlap and be staggered so that the reinforcement
ends overlap by eight to ten inches.
G M C S E R V I C E M A N U A L
frame repair and reinforcem ents. Most of these
rules are discussed earlier in this section; how­
ever, the importance of adhering to them cannot
be overemphasized.
tempted only by highly qualified sp ecialists.
failure.
should not be made through frame flanges. (See
"Body Builder's Book".)
base rail material when welding is necessary.
on fram es.
frame flanges.
a frame flange.
from flange edge when repairing a broken frame.
forcem ents and base rails together.
better material than base rail.
vide adequate stress relief.
by a minimum of eight inches apart.
tery cable to prevent possible electrical damage
to generating system .
— CAUTION —
GENERAL RULES
Listed below are general rules which apply to
1. Always identify the material of base rail.
2. Frame straightening or repair must be at­
3. Always attempt to identify the cause of
4. Fifth wheel, body, and accessory mountings
5. Do not drill holes in the lower flanges.
6. Use only proper electrodes as specified for
7. Do not use oxyacetylene welding equipment
8. Do not weld reinforcements across the
9. Do not weld within 3/4 inch of the edge of
10. Remove all notches or weld build-ups
11. Do not weld cast brackets to frame.
12. Do not weld the flanges of cracked rein­
13. Do not patch cracks. Reinforce the area.
14. Reinforcement should be of the same or
15. Always scarf reinforcement ends to pro­
16. Always stagger ends of reinforcements
17. Before welding, disconnect negative bat­