2013/04/03 Caterpillar

Off-Highway Truck:

797F (S/N: LAJ1-UP; WSP1-UP)

The housing design has been changed to remove a mill cut process and to provide spot faces. A needle peening process is being applied to the new castings, whether the castings have been mill cut or spot faced. The needle peen process improves surface tension stresses and will improve the robustness of the front housing casting.

Illustration 1	g03365058
Mill cut housing (A) Area of 5 second peen (B) Area of 30 second peen

A minimum of 30 seconds needle peening operation on area (B) with a minimum 5 seconds needle peening operation on the ends area (A).

Illustration 2	g03365059
Spot faced housing (A) Area of 5 second peen (C) Area of 15 second peen

A minimum of 15 seconds needle peening operation on area (C) with a minimum 5 seconds needle peening operation on the ends area (A).

Preparation

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Illustration 3	g03365060
(1) Front housing mounting bolts (2) Clip (3) Ether injection line (4) 293-5021 Elbow (5) Electronic Control Module (ECM) mounting bracket (6) ECM

1. Drain the coolant from the cooling system into a suitable container for storage or for disposal. Remove and set the following components and associated hardware aside for reuse:
   • Clip (2)

   • ECM (6)

   • ECM mounting bracket (5)

   • Elbow (4)

   • Ether injection line (3)

   • Front housing mounting bolts (1)

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Illustration 4	g03365062
(7) 6B-9664 Relief Valve (8) Air tanks

2. Drain the air from air tanks (8) use relief valves (7) .

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Illustration 5	g03365063
(9) Pressurized air lines (10) Air compressor

Note: Make sure that the air system is drained.

3. Remove pressurized air lines (9) from air compressor (10) .

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Illustration 6	g03365064
Typical view of an air compressor (10) Air compressor (11) Coolant return line (12) Coolant supply line (13) Oil supply line (14) Oil return line (15) Air supply line

Note: Use a suitable container for storage or for disposal of any excess coolant or oil.

4. Remove and set the following components and associated hardware aside for reuse:
   • Coolant return line (11)

   • Coolant supply line (12)

   • Oil supply line (13)

   • Oil drain line (14)

   • Air supply line (15)

   • Air compressor (10)

5. Cover and protect any openings from debris.

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Illustration 7	g03365065

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Illustration 8	g03375222
Acceptable peening needle ends (A) 0.50 mm (0.020 inch)

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Illustration 9	g03365066
Unacceptable peening needle ends

6. Sharpen the peening needle ends to approximately 0.50 mm (0.020 inch) with a radiused tip.

   Note: Do not exceed 1.0 mm (0.04 inch) for the radius tip.

Rework Instructions

1. Apply layout bluing to the areas that need to be needle peened.

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Illustration 10	g03365067

2. Hold the peening gun at a 45 degree angle with the needle tips concentrated in the root of the machined joint. The 45 degree angle will position the needles perpendicular to the fillet area.

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Illustration 11	g03365068

3. Rotate gun to maintain the relationship to the surface of the machined arc.

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Illustration 12	g03365069

4. Peen fillet areas for the prescribed time listed above. Hold the peening gun firmly and apply enough pressure to control the needles in the fillet area but still allow the needles to have peening action.

   Note: Make sure that the bluing has been removed from the fillet areas to ensure that the proper coverage and intensity have been achieved.

5. Reinstall all the parts that were removed during preparation and torque the fasteners.

6. Refill the cooling system.