Usage:
D8N (9TC, 1XJ, 5TJ, 7TK),
D8R (7XM, 9EM) Track-Type Tractors
Reference: Special Instruction; SEHS9183 "Repair of D6H, D7H, and D8N Front Track Roller Frames with Worn or Damaged Key Slots".
Special Instruction; SEHS9373 "Front Track Roller Frame Repair".
Description of Change: An increase to the weld depth on the 9W-2411 Telescoping Recoil Frame Group strengthens the weld joint between the resister and the tube.
Adaptable To: The weld joint between the 7T-4215 Resister and the 7T-5071 Tube has been increased to 23 mm (.9 in) from 21 mm (.8 in). This change is effective with D8N (9TC5696, 1XJ171, 5TJ1, 7TK1), D8R (7XM1, 9EM1) Track-Type Tractors. This change is adaptable to the D8N (9TC1-5695 and 1XJ1-170) Track-Type Tractors with the original front track roller frames. The new weld depth also applies to repair a failure in a reworked track roller frame with the following procedure.
Illustration 1. 7T-5070 Tube Assembly Weld Joint (1).
1. If the nut is to be cut from the tube, cut to 390 mm (15.4 in) as shown in SESH9183.
2. Mark the orientation of the slots as referenced in SESH9183, unless you are using the FT-2256 Fixture as shown in SESH9373.
Illustration 2. D8N Tube (Nut).
3. Machine the nut to Dimension A.
NOTE: If the nut was removed, build up the pilot end of the nut with weld material before machining to maintain 395 mm (15.6 in) overall length.
Illustration 3. D8N Center Tube.
4. Measure the depth of the counterbore and rebore the counterbore to Dimension H.
NOTE: Maintain the original location of the counterbore face.
5. Weld the counterbore in the center tube with the tube standing in a vertical position. Refer to SEHS9373 for weld consumables and parameters. Use staggered fillet welds, alternating side to side, to weld the counterbore. Deposit at least 4 mm (.2 in) of material.
6. Bore the center tube counterbore to 246.5 mm (9.7 in) and the same depth as stated in Step 4. Verify that the counterbore is concentric with the tube's outside diameter within 1 mm (.04 in) of material.
NOTE: The bogie assembly must be removed from the roller frame before machining.
7. Refer to SESH9183 and SESH9373 to position and weld the nut to the center tube, for additional weld procedures.