FILTER GP-TRANSMISSION 7T8338 - Caterpillar

Illustration 1. Location of core hole.There have been several reports of cracks around the core hole. The cracks generally start at the hole and move radially to the welded blocks where the lines support is fastened. If repairs are not made, the cracks, in time, will move down the sides of the kingbolt housing.
Procedure For Repairs Of Cracks Around The Core Hole
1. Lower the scraper bowl completely and block the machine to prevent movement.Use the Service Manual as a reference to release the air pressure from the brake system and the retarder system and to release the charge from the accumulator for the cushion hitch.
Drain the accumulator line and remove it. Also remove the brake and retarder lines from the kingbolt housing.
2. Use an arc-air unit to cut out the cracks. Make the cuts 5 mm (.2") to 6 mm (.3") less than the full thickness of the casting. If the cracks have extended to the blocks, the blocks will have to be removed, the cracks welded and new blocks fabricated and installed.3. Weld the cracks with either E7018 or E7014 Welding Rods. Remove all weld spatter and grind the surface smooth.4. Cut a 30° chamfer around the core hole as shown in Illustration 2.
Illustration 2. Chamfer to be cut around core hole.5. Make a split ring from .38" thick, high-strength, structural steel. Cut a ring which has a 171.4 mm (6.75") outer diameter and a 76.2 mm (3.00") inner diameter in half. Put chamfers on all edges.6. Cut a 41.1 mm (1.62") length of SAE 1062 steel tube. The tube must have a 4.75" outer diameter and a .625" wall thickness. Put chamfers on all edges.7. Install the split ring and steel tube as shown in Illustration 3. Make all welds with either E7018 or E7014 Welding Rods. Grind all welds smooth.
Illustration 3. Installation of split ring and tube.8. If the blocks were removed in Step 2, make new blocks as shown in Illustration 4 from low-carbon steel.9. Install the blocks as shown in Illustration 1.10. Use the Service Manual as a reference to install the accumulator, brake and retarder lines removed in Step 1. Fill the accumulator with hydraulic oil and charge it as per the Service Manual.Remove the blocks from the machine. Start and run the engine until the air system is charged.
Move the tractor-scraper slowly, and check the operation of the accumulator, brakes and retarder.
Illustration 4. Dimensions for fabricated blocks.