MOTOR TRUCK SERVICE MANUAL
though more costly does provide the field with a time
saving advantage when replacing cross-members or
In addition to the specific recommendations given in
frame attaching parts.
these paragraphs, always remember the following
general rules of welding "good housekeeping".
If bolting is used for altering or adding to the frame,
the following precautions must be observed.
1. Surface areas and edges to be joined must be
clean and free of oil or grease.
NOTE: Bolts to be used for installing fifth wheels
must be 5/8" diameter high strength material such as I.
H. type 8 (SAE grade 8) bolts. Type 8 bolts can be
identified by the six radial lines on the head of the bolt.
Nuts must be of corresponding type.
3. Peen new welds to relieve stresses caused by
The torque value for tightening these bolts is 220-
250 ft. lbs. and is based on new bolts and nuts
lubricated with engine oil. If frame components are
Positioning of Frame Reinforcements
aluminum, flat washers must be used next to the
Whenever practical, the welding of frame
aluminum whether under head, nut or both.
reinforcements should be confined to the web of the side
rail rather than the flanges. This procedure provides the
Proper tightening of bolts and nuts is most important,
strongest possible assembly.
since the strength of the joint depends on the maximum
Avoid at all times welds made square with the side
clamping force between the members.
rail, either on webs or flanges. When welds are made at
an angle of at least 30 degrees from square, there is less
REPAIR AND REINFORCEMENTS
possibility of setting up dangerous stress concentrations
(Heat Treated Frames)
in the rail. Physical tests of the strength of various welds
have shown that a weld made at an angle of at least 30
With the use of heat treated frame rails in
degrees from the direc-tion of strain will retain the
International vehicles, it becomes advisable to outline
original physical properties of the complete rail section.
some of the procedures to be followed whenever these
frames require repair.
Use of heat is not recommended when straightening
Heat treated frame rails must not, of course, be
frames. Heat weakens the structural characteristics of
intermixed with non-heat treated rails. If one side rail is
frame members and all straightening should be done
to be replaced, the new rail material must match the old
cold. Frame members (except aluminum) which are
bent or buckled sufficiently to show cracks or weakness
after straightening, should be replaced or reinforced.
Preparation Of Frame For Repair
Repair and Reinforcements
(Aluminum Alloy Frames)
A good method to follow when repairing a cracked
frame where the crack is accessible from both sides is
The cutting and welding of aluminum alloy frames for
repair or reinforcement can be accomplished providing
correct procedures are followed and proper welding
a. Grind a V notch or groove extending along the full
equipment is utilized. The use of heat for straightening
length of the crack and slightly beyond each end of
aluminum frame rails is not recommended.
the crack. A heavy copper strip or "chill" should be
clamped to the rail side away from the groove to help
control the temperature and cooling rate. See Fig.
While most IH frames are of riveted construction,
7. NOTE: Discarded short lengths of heavy copper
there are some frames which are assembled with bolts
electrical bus bars make suitable chills.
and nuts. Bolting,