ENGINE AR-PRIMARY 3158100 - Caterpillar

Figure 58 - Torsional Load Reinforcements Rule 4 - Consider the effect on the entire beam before adding a reinforcement. Relatively small reinforcing plates added to a beam may reduce the stresses directly under the plate, but they have a tendency to increase stresses at each end of the beam (Figure 59). A long tapered plate is much better because it spreads the load uniformly through the beam instead of concentrating it in two spots.
Figure 59 - Long reinforcing plates distribute the load evenly along the beam. Rule 5 - Avoid making transverse welds at the ends of reinforcements. Transverse welds create high stress areas that usually lead to cracking. Once a crack has formed, it will progress across the beam until it eventually causes a failure. The end of the reinforcing plate should be left open (Figure 60). Again, the ends are tapered to spread the load over a greater area of the beam.
Figure 60 - Transverse welds at the end of reinforcing plates should be avoided. Rule 6 - Use gusset reinforcements to reduce stresses in sharp corners and other small areas. Gussets should be designed and installed so the forces are distributed and transmitted uniformly and are not concentrated in one spot. Gussets can be triangular or they can be designed with a radius (Figure 61). They should not be welded in the sharp corners created by the machine components and the gusset. Welding in these areas creates localized overstressed conditions that originate cracks. The thickness of the gusset should be about the same as or slightly less than the thickness of the plates it is reinforcing. If possible, the gusset should be welded on both the inside and outside.
Figure 61 - Gussets reduce stresses in sharp corners and other small areas.Controlling Heat Distortion
Figure 62 - Members can be pulled into alignment by shrinking of the weld.Distortion due to thermal expansion and contraction is a problem with all types of welds. There are three basic methods of minimizing distortion: peening, jigs and fixtures, and special welding techniques. With the first method, the weld metal is stretched immediately after it is deposited by a series of hammer blows. Peening has limited application in service welding, however, because of the lack of precision possible with hand peening and the possibility of strain hardening the weld metal. When the work is clamped in a special jig or fixture, the clamping force overcomes the force of thermal contraction of the weld deposit, and the deposit itself stretches. This method, too, has limited application in service welding because of the expense of special jigs and the difficulty of clamping large components.Special techniques in the positioning of welding members and special pass sequence is usually the simplest method for controlling distortion in service welding. Members can be positioned initially somewhat out of alignment, and the shrinking of the weld deposit can be relied upon to pull the member into the proper position (Figure 62). A pass sequence that builds the deposit