- Wheel Loader:
- 988H (S/N: BXY1-UP)
Introduction
The problem that is identified below does not have a known permanent solution. Until a permanent solution is known, use the solution that is identified below.
Problem
Cracks may appear on the 248-6340 Boom and Bearing Assembly .
Solution
If a crack propagates on 248-6340 Boom and Bearing Assembly repair the cracks with by using the following procedure:
Prepare the Area for Welding
Clean the area that will be welded. Make sure that the substances that follow are removed from the area that will be welded.
- Oil
- Grease
- Paint
- Dirt
Repair Procedure
- Carefully remove all traces of the crack by air arc gouging with a torch. Ensure that the full depth of the crack is removed. Check for all traces of cracks by using dye penetrant.
 |
Protect yourself and others; read and understand this warning. Fumes and gases can be dangerous to your health. Ultraviolet rays from the weld arc can injure eyes and burn skin. Electric shock can kill. Read and understand the manufacturer's instruction and your employer's safety practices. Keep your head out of the fumes. Use ventilation, exhaust at the arc, or both, to keep fumes and gases from your breathing zone and the general area. Wear correct eye, ear and body protection. Do not touch live electric parts. Refer to the American National Standard Z49.1, "Safety in Welding and Cutting" published by the American Welding Society, 2501 N.W. 7th Street, Miami, Florida 33125: OSHA Safety and Health Standards, 29 CFR 1910, available from U.S. Dept. of Labor, Washington D.C. 20210. |
 |
|
Personal injury can result from flame cutting or welding on painted areas. The effect of gasses from burned paint is a hazard to the person doing the cutting or welding. Do not flame cut or weld on painted areas. |
|
 | |
| Illustration 1 | g01447558 |
View of the location on the boom that may crack | |
- Grind the areas that were exposed to an air carbon arc torch in Step 1. Remove all traces of carbon. The presence of traces of carbon can adversely affect the weld quality. Create a bevel that is between 60 degrees and 90 degrees. This dimension is depending on the depth of the groove. Make sure that the weld penetration is sufficient. Include the angle and the full depth of the crack. The width at the base of the groove must be sufficient enough for comfortable access of the welding torch.
- Use run off tabs to allow the weld to be extended beyond the edge of the casting.
- Preheat the service area to a minimum temperature of 121 °C (250 °F). Monitor the temperature by using 192-3750 Temperature Measuring Gp , or use 192-3755 Temperature Measuring Gp . Continue to measure the temperature throughout the repair process, and do not permit the temperature to drop below the prescribed value. If necessary, stop the welding process and heat the area again.
- The weld bead should be straight. The weld bead must not exceed 5 mm (0.2 inch) wide. Do not try to fill the width of the V-groove weld in one pass. Remove any slag from the joint. Clean the weld area and needle peen between passes.
- After needle peening, carefully inspect the pass for any signs of lack of penetration, porosity, or undercutting. If any such signs are found, grind out a part or the entire affected pass until the quality is acceptable before continuing with the repair process.
- Complete the welding process. The area that has been repaired should be about 3 mm (0.12 inch) higher than the general level of the surrounding area. Remove the run off tabs and grind the area in order to remove all traces of the individual weld beads until the repaired area is completely smooth and free of stress risers. Blend all repair welds into the general surface of the structure. All transition points must have a smooth radius. Needle peen the welded area. After the welding process is completed, check the repaired area with dye.
- Cover the repaired area with thermal blankets in order to counter the effect of any wind, and allow the structure to cool slowly to ambient temperature. The cooling should not take place at a rate more than 27 °C (80 °F) per hour.