2007/12/31 Caterpillar

Off-Highway Truck:

797B (S/N: JSM1-UP)

Description of Change: Additional blocks have been added to the MSD II truck body to aid in pin retention. The new retention blocks make installation of the pivot pin from the inside of the main rails possible. This improves the safety of the installation procedure. The same mounting hardware is used regardless of the direction of installation.

Adaptable To: The new retention blocks are effective with JSM 280-UP. The new retention blocks are effective with the following truck body AJS313-UP. Use the following procedure in order to adapt JSM1-279.

ReferenceRefer to Special Instruction, REHS1841, "General Welding Procedures" for additional welding instructions.

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Personal injury can result from flame cutting or welding on painted areas. The effect of gasses from burned paint is a hazard to the person doing the cutting or welding. Do not flame cut or weld on painted areas.

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Personal injury or death can result from fumes, gases and ultraviolet rays from the weld arc. Welding can cause fumes, burn skin and produce ultraviolet rays. Keep your head out of the fumes. Use ventilation, exhaust at the arc, or both, to keep fumes and gases from your breathing area. Wear eye, ear and body protection before working. Protect yourself and others; read and understand this warning. Fumes and gases can be dangerous to your health. Ultraviolet rays from the weld arc can injure eyes and burn skin. Electric shock can cause death. Read and understand the manufacturer's instructions and your employer's safety practices. Do not touch live electrical parts. See "American National Standard Z49.1, Safety in Welding and Cutting" published by the American Welding Society. American Welding Society 2501 N.W. 7th Street Miami, Florida 33125 See "OSHA Safety and Health Standards, 29 CFR 1910", available from U.S. Department of Labor. U.S. Department of Labor Washington, D.C. 20210

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Illustration 1	g01444840
(A) 50 ± 1 mm (1.97 ± 0.04 inch) (B) 50 mm (1.97 inch) (C) 25 mm (0.98 inch) (D) 50 mm (1.97 inch) (E) 25 mm (0.98 inch) (F) 10.5 mm (0.41 inch) diameter with M12 X 1.75-6H threads

1. Fabricate four blocks (1) out of plain carbon steel.

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Illustration 2	g01445864
View from the inside of body (G) (J) 5 degrees

2. Lay out the position of two blocks (1) on body (G). Draw line (K) through the center of pin (H) and the center of boss (M) .

   Note: Pin (H) is shown for illustrative purposes.

3. Draw line (L) through the center of pin (H) at angle (J) above line (K) .

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Illustration 3	g01445965
(N) 40 mm (1.57 inch) (P) 145 mm (5.71 inch)

4. Place blocks (1) with the dimensions that are given in Illustration 3.

   Note: Dimension (N) is referenced from line (L). Dimension (P) is referenced from the center of pin (H). Use these reference dimensions to locate both the upper and lower block locations.

5. Use a grinder in order to remove any paint or grease from the area that is defined in Step 4.

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Illustration 4	g01445975
(W1) 12 mm (0.5 inch) Fillet weld

6. Weld block (1) to body (G) .

7. Repeat Step 6 for the remaining block (1) .

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Illustration 5	g01445983

8. Remove boss (M). Grind the area smooth.

9. Repeat Step 2 through Step 8 for the other side of the body.

10. Attach a suitable lifting device to body (G). Raise body (G) in order to take the weight off pins (H) .

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Illustration 6	g01445992
View from the outside of body (G)

11. Remove two bolts (R), two washers (S), plate (T) and pin (H) .

    Note: Pin (H) weighs approximately 67 kg (148 lb).

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Illustration 7	g01444862

12. Install pin (H) from the inside of body (G). Use two bolts (R) and two washers (S) in order to secure plate (T) to blocks (1) .

13. Repeat Step 11 through Step 12 for the other side of body (G) .