YOKE 6F6792 - Caterpillar

Table 9
Welding Specifications    
welding materials    
This procedure is intended for buildup of sprocket hubs due to wear.    
        Filler Metals     Current        
Pass or Weld Layer     Process     Class     Diameter     Polarity     Amps     Volts / Travel Speed (ipm)    
All     SMAW     E7018H4R    
3.2 mm (0.125 inch)     DCEP     100-125     NA    
All     FCAW     E71T-1H8    
1.2 mm (0.045 inch)     DCEP     200-240     24-27 / 10-16    
Joint Design    
Comments: See specific details for various scenarios.    Reworking the Front Hitch
This Special Instruction applies to the repair of potential fatigue cracks that may appear at the interior connection between the hitch and the cab support plate.
Illustration 3 g03411329
Rear view of front frame
Illustration 4 g03411563
Intersection of fillet weld
Illustration 5 g03411653
Front view of fatigue crack at weld toe
Illustration 6 g03411656
Top view of fatigue crack at weld toe
Inspect area (A) on the left hand and right-hand side of the front frame.In some cases, the fillet weld has extended to the very edge of the vertical cab support plate. The combination of the plate edge and fillet weld toe has created a stress concentration site in which a fatigue crack could initiate and propagate. See Illustration 5 and Illustration 6.
Remove the paint and verify the extent of the crack using either dye penetrant (PT) or magnetic particle (MT) testing equipment.
Remove the crack using a small die grinder and burring tool.
Illustration 7 g03412104
Remainder of crack left to be excavated
Frequently recheck the excavation using PT or MT to view the direction and depth. Illustration 7 depicts the remaining crack length after using MT with red powder.
Completely remove the entire crack length and depth. Fill in by welding using guidelines Table 8.
Illustration 8 g03412143
View of completed weld
Repaired fillet welds shall be restored to original 10 mm (0.39 inch) weld size.
Illustration 9 g03412175
View of blended repair area
Use a die grinder with a sanding bit to remove stress concentrations created by the weld repair. The goal is to remove any sharp corners and transitions that may reinitiate a crack. The fillet weld should transition seamlessly into the plate and there should be a radius created on the top edge of the plate. See Illustration 9 for the critical areas that need addressed.
Use paint as needed on the welded areas to protect the frame.