2008/09/08 Caterpillar

Motor Grader:

16G (S/N: 93U1-UP)

16H (S/N: 6ZJ1-UP; ATS1-UP)

Use the following information for the inspection and weld repair of the front axle of the listed motor graders.

All welders must be qualified in the Flux Cored Arc Welding (FCAW) process for a groove weld or a fillet weld.

Refer to the following American National Standards Institute - American Welding Society ANSI/AWS standard: D1.1. Prior to welding, the process must have been used by the welders during the last six months. Welding qualifications must be documented and welding qualifications must be current.

The proper electrode for stick welding for Shielded Metal Arc Welding (SMAW) is E7018. Refer to ANSI/AWS standard A5.5. The finished weld will have the following minimum mechanical properties:

• 480 MPa (69600 psi) Tensile Strength

• 400 MPa (58000 psi) Yield Strength

• 22% elongation

• 27 N·m (20 lb ft) at −29 °C (−20 °F) Impact Toughness

The following table is the electrode's current settings in relation to the electrode's diameters:

The E7018 electrodes are low hydrogen electrodes. The electrodes must be stored in an oven at a temperature of 120 °C (250 °F). If the electrodes get damp, scrap the electrodes or recondition the electrodes to the manufacturer's specifications.

Set the polarity to direct electrode positive (reverse polarity). Use the direct current. Remove the slag after every pass. The width of the weld should not exceed two times the electrode diameter. Remove the slag after every pass.

Use the FCAW process with E71T-1 (ANSI/A5.20) welding electrode and the manufacturer's specified shielding gases for inside welding.

If the base metal is below 32 °C (90 °F), the base metal must be preheated to a minimum of 70 °C (158 °F). This temperature must be maintained during cutting and welding the part.

Clean the area that will be welded. Remove any oil, grease, paint and dirt. Attach the welding ground cable directly to the axle assembly. Protect all machined surfaces from sparks or spatter.

The welds should be free of the following defects: cracks, porosity, undercut and incomplete fusion.

The FCAW process may be used as an alternate welding process. Use E71T-1 ANSI/AWS A5.20 welding electrodes and the shielding gases that are recommended by the manufacturer. The weld that is deposited by these electrodes will have the following mechanical properties.

• 480 MPa (69600 psi) Tensile Strength

• 400 MPa (58000 psi) Yield Strength

• 22% elongation

• 27 N·m (20 lb ft) at −18 °C (0 °F) Impact Toughness

The welding parameters will vary because of the position of the weld and the manufacturer of the welding electrode. Refer to the following chart for the welding parameters for the electrode that is 1.30 mm (0.052 inch) in diameter.

Use the following procedure to repair the axle assembly.

1. Visually inspect the welds on the axle assembly for cracks. Use the liquid dye penetrant or the magnetic particle inspection process in order to detect small cracks.

2. Completely remove the faulty weld by air arc gouging or grinding.

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Illustration 1	g00811069

3. Form the weld grooves with a 12 mm (0.5 inch) bevel (A) or a 5.0 mm (0.12 inch) bevel (B) .

4. Weld the groove with weld passes that do not exceed two times the diameter of the electrode. If the alternate welding process is used, the size of the fillet weld should not exceed 7.9 mm (0.31 inch).

   Note: Remove slag from the weld after each weld pass.

5. Grind the welds in order to blend all tie-in welds and corner welds.

6. Visually inspect the repair of the welds.

   Note: The welds should be free of the following defects: cracks, porosity, undercut and incomplete fusion.