2006/08/07 Caterpillar

Motor Grader:

24H (S/N: 7KK1-UP)

ReferenceSpecial Instruction, REHS1841, "General Welding Proceures"

Description of Change: The shaft assembly for the drawbar assembly has been updated. The weld between the shaft and the plate has been enlarged. The larger weld will strengthen the weld joint.

Adaptable To: The updated 139-6866 Shaft Assembly became effective in production with the machines 7KK323-UP. The improvement is adaptable to all earlier machines. Use the following information and the procedure in order to upgrade the shaft assembly on earlier machines.

For all qualifications and specifications, refer to the special instruction that is listed above.

1. Heat the weld area to a temperature of 260 °C (500 °F).

2. Remove the crack with the carbon arc gouging. Be sure that the crack is completely removed. This should be verified by the use of dye penetrant or magnetic particle inspection.

3. Once the crack is completely removed, clean the weld joint and the parent material. Make sure that all slag is removed.

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Illustration 1	g01284761

4. Weld the 16 mm (0.63 inch) fillet weld (1). Maintain a preheat temperature and interpass temperature of 260 °C (500 °F). Perform the weld with minimal stops and starts. Blend all tie-ins.

The 16 mm (0.63 inch) fillet weld (1) will require three or four passes. The number of passes will depend on the diameter of the electrode. The face of the weld can be slightly concave. Refer to Illustration 1. The weld toes shall have a smooth transition. Grinding the toes may be necessary in order to obtain at least a radius of 5 mm (0.2 inch). Do not grind more than 1 mm (0.04 inch) from the plate material.

Clean the weld and inspect the weld. The weld should be free of cracks, overlaps and unacceptable profile discontinuities.