TRANSMISSION AR 20R6702 - Caterpillar

Problem
The the power angle tilt bulldozer blade on certain D4C Tractors may fail.
Affected Product
Model & Identification Number
D4C (7KG1-603)
D4C LGP (9BG1-315)
Parts Needed
Not applicable.
Action Required
See attached procedure.
Service Claim Allowances
This is a 38-hour job.
Parts Disposition
Handle the parts in accordance with your Warranty Bulletin on warranty parts handling.
Attach. (1-Rework Procedure)Rework Procedure
1. Remove all brackets from the back side of the blade. Do not cut through the parent metal of the blade cell structure. See Illustration 1.2. Cut out seam welds and remove plate to gain access to the inner welds. See Illustration 2.3. Remove existing welds and weld back in place. See Illustration 3. New welds should have a 6 mm fillet or larger to repair undercutting.4. Weld and grind flush any damage done to channels or moldboard caused by removing cell structure welds in Steps 2 and 3.5. Properly prepare and weld back into position the top cell structure plate. Replace the other plates removed with new 8 mm thick high strength structural steel. See Illustration 4 for D4C Tractors and Illustration 5 for D4C LGP Tractors. These illustrations show how to fabricate and assemble the new plates.6. Grind seam welds flush for brackets to relocate.7. Locate and weld all brackets back to cell structure. See Illustration 6.8. Grind welds flush and paint. Use air-arc method instead of a cutting torch to remove all welds. This will reduce the amount of heat generated in the cutting process and help keep the blade from warping.
New welds should be done in the flat position.
Use low hydrogen weld rod/wire/process for all welds (Example: E7018). Flux core gas shield should be used if available. This is easier to control burning through.
Use structural steel with a minimum yield strength of 42,000 psi for all new plates.
All new welds should be large enough to cover all undercutting.
Repair only one channel at a time to maintain blade stiffness and reduce warping caused by heat generation.
Illustration 1
Illustration 2
Illustration 3
Illustration 4
Illustration 5
Illustration 6