Usage:
NOTE: The information supplied in this service letter may not be valid after the termination date of this program. Do not perform the work outlined in this Service Letter after the termination date without first contacting your Caterpillar product analyst.
NOTE: This Program can only be administered after a failure occurs. The decision whether to apply the Program is made by the dealer. When reporting the repair, use "PS0877" as the Part Number and "7755" as the Group Number. Use "96" as the Warranty Claim Description Code and use "Z" as the SIMS Description Code.
Termination Date
September 30, 1999Problem
The fabricated upper front strut mount for the bearing cap used on certain 793 and 793B Trucks may crack. This fabricated strut mount can be replaced with a cast one.
Affected Product
Model & Identification Number
793 (3SJ6-56)
793B (1HL12-194)
Parts Needed
Action Required
See the attached procedure.
Service Claim Allowances
NOTE: This is a 90-hour job.
Parts Disposition
Handle the parts in accordance with your Warranty Bulletin on warranty parts handling.
Attach.
- (1-Rework Procedure)
Rework Procedure
Left Side
1. Remove the cab after disconnecting the required wiring harnesses, air, heater & hydraulic lines and control linkages, Refer to Special Instruction SEHS9301 "Assembly Procedure For Off-Highway Truck" as a guide.
2. Refer to SENR5692, Disassembly & Assembly, page 52, for information on removing the front suspension cylinders for access to the upper strut mount area.
3. Carefully remove the welds from the two 8X0519 Plates, the two 8X0518 Plates, the one 8X0517 Block and the two 8X0520 Gussets which make up the fabricated upper strut mounting. See Illustrations 1 through 7 for description and identification of the fabricated pieces.
4. Clean up all areas where welds were removed and grind smooth. Repair any cracks in the beam assembly before welding the casting in place.
5. Locate the new 117-4934 Casting, Illustration 8, for the upper strut mount per dimensions on Illustrations 9 through 11.
6. Weld the casting in place per weld call outs on Illustration 9. Locate the 7X7962 Boss and weld in place as shown on Illustration 9.
7. After welding is complete, reinstall the front suspension cylinder per SENR5692 and install the upper strut mount bearing cap using the 117-4935 Shims as required. Refer to Illustrations 12 and 13. Refer to the october 17, 1994 Service Magazine article. Tighten all mounting bolts to the correct torque specifications. See the Service Manual. Install the Cab. Tighten all mounting bolts to the correct torque specification per Special Instruction SEHS9301, pages 26 through 30, Assembly Procedure For Off-Highway Truck (793).
Right Side
1. Refer to SENR5692, Disassebly & Assembly, page 52, for information on removing the front suspension cylinder for access to the upper strut mount area.
2. Remove the steering tank from the right 8X0264 Platform, reference SENR5692, page 23, for information on removing and installing the steering hydraulic tank from the platform.
3. Refer to Illustrations 14 and 15 for location of the platform ribs. Carefully cut an access window(s) above the upper strut mount, between the ribs, so there is room to access the old and new mounts with cutting and welding equipment.
4. Carefully remove the welds from the two 8X0519 Plates, the two 8X0518 Plates, the one 8X0517 Block, and the two 8X0520 Gussets which make up the fabricated upper strut mounting. See Illustrations 1 through 7 for description and identification of the fabricated pieces.
5. Clean up all areas where welds were removed and grind smooth. repair any cracks in the beam assembly before welding the casting in place.
6. Locate the new 117-4934 Casting for the upper strut mount per dimensions on Illustrations 9 through 11.
7. Weld the casting in place per weld call outs on Illustration 9. locate the 7X7962 Boss and weld in place as shown on Illustration 9.
8. After all welding is completed on the 117-4934 Casting, attach the window(s) in the platform that were removed for access to the upper strut mount area.
9. After welding is complete, install the front suspension cylinder per SENR5692 and install the upper strut mount bearing cap using the 117-4935 Shims as required. Refer to the Service Magazine Article Dated October 17, 1994.
10. Install the steering hydraulic tank and lines per SENR5692, page 23, and fill the tank as required.
11. Refer to SENR6315, Systems Operation Testing and Adjusting for 793 Truck Suspension Cylinders, and follow the testing and adjusting procedures for front suspension cylinders.
Illustration 1
Illustration 2
Illustration 3
Illustration 4
Illustration 5
Illustration 6
Illustration 7
Illustration 8
Illustration 9
Illustration 10
Illustration 11
Illustration 12
Illustration 13
Illustration 14
Illustration 15