Field Installation of Improved Lifting Points for the 797B MSD II Truck Body{7000, 7258} Caterpillar

Off-Highway Truck:

797B (S/N: JSM1-UP)

Introduction

This Special Instruction contains the necessary procedures and information for installing improved lifting points on the MSD II truck body. This procedure is adaptable to S/N:AJS1-414.

For the approximate weight of the truck body, refer to Special Instruction, REHS0963, "Assembly Procedure for the MSD II Truck Body for the 797 and 797B Off-Highway Truck".

Do not perform any procedures or order any parts until this publication is read thoroughly.

The recommended tools and equipment should be present during assembly. If the recommended tools or equipment are not present, assembly will be more difficult and more time will be necessary to complete the assembly.

Note: An enclosed structure is recommended for the assembly of the plate assemblies. The dispersing of the shielding gases away from the welding area must be kept to a minimum.

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Sudden movement or accidental starting of the machine can cause personal injury or death to persons on or near the machine. To prevent personal injury or death, perform the following: Park the machine on a smooth level surface. Lower the bucket and or attachments to the ground. Stop the engine and engage the parking brake. Block the wheels and install the steering frame lock. Turn the battery disconnect switch to the OFF position and remove the key. Place a Special Instruction, SEHS7332, "Do Not Operate" tag at the battery disconnect switch location to inform personnel that the machine is being worked on.

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Do not attempt to assemble this machine until you read and you understand the assembly instructions. Improper assembly procedures could result in injury or death.

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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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Personal injury or death can result from improper lifting or blocking. When a hoist or jack is used to lift any part or component, stand clear of the area. Be sure the hoist or jack has the correct capacity to lift a component. Install blocks or stands before performance of any work under a heavy component. Approximate weights of the components are shown. Clean all surfaces where parts are to be installed.

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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.

Note: The improved lifting points should only be used in order to lift the completed body assembly.

Parts List

Required Tools

Weld Specifications and Parameters

Note: Refer to Special Instruction, REHS1841, "General Welding Procedures" for all necessary information on all welding procedures.

Note: Personal breathing protection should be worn by the welders. Personal breathing protection will prevent fumes from entering the lungs of the person that is welding. Use a 1U-8088 Type H Respirator for respiratory protection.

All of the welders must be qualified in Shielded Metal Arc Welding (SMAW) and Flux Cored Arc Welding (FCAW). All of the welders must be qualified in groove welding and fillet welding in the vertical position. Refer to the American National Standards Institute (ANSI)/American Welding Society (AWS) D1.1. Prior to welding, the process must have been used by the welders during the last six months. Welding qualifications must be documented and welding qualifications must be current.

The surrounding area must be a minimum temperature of 16 °C (60 °F) before welding and during welding.

The proper stick welding electrode for Shielded Metal Arc Welding (SMAW) is E7018 American National Standards Institute (ANSI)/American Welding Society (AWS) A5.1. The finished weld will have the following minimum mechanical properties:

• 480 MPa (69600 psi) Tensile Strength

• 400 MPa (58000 psi) Yield Strength

• 22 percent elongation in 50 mm (2 inch)

• 27 N·m (20 lb ft) at −29 °C (−20 °F) Impact Toughness

The "E7018" electrodes must be stored in an electrode oven at 121 °C (250 °F). Scrap the "E7018" electrodes or recondition the "E7018" electrodes if the "E7018" electrodes get damp. Recondition the "E7018" electrodes to the manufacturer's specifications. The following table is the electrode's current settings in relation to the electrode's diameters:

Set the polarity to direct electrode positive (reverse polarity). Use the direct current. Remove the slag after every weld pass. The width of the weld should not exceed two times the electrode diameter.

As an alternative process, use the Flux Cored Arc Welding (FCAW) with E71T-1 H8 (ANSI/A5.20) welding electrode and the manufacturer's shielding gases that are specified for inside welding. The H8 implies that the electrode is designed to provide less than 8 ml/100 g of diffusible hydrogen in the weld deposit. The weld that is deposited by the flux cored welding electrode will have the following minimum mechanical properties:

• 480 MPa (69600 psi) Tensile Strength

• 400 MPa (58000 psi) Yield Strength

• 22 percent elongation in 50 mm (2 inch)

• 27 N·m (20 lb ft) at −29 °C (−20 °F) Impact Toughness

Use only flux cored welding electrodes that have been stored in undamaged packages that resist moisture or use only flux cored welding electrodes that have been stored in an oven at 120 °C (250 °F).

Welding parameters will vary due to the welding position and due to the manufacturer of the welding electrode. A 1.3 mm (0.051 inch) electrode diameter will typically have the following welding parameters:

Note: Use the manufacturer's recommended welding electrode parameter.

Set the polarity to direct electrode positive (reverse polarity). Use the direct current. Remove the slag after every weld pass. The width of the weld should not exceed two times the electrode diameter.

Refer to ""Welding Instructions" " for more welding guidelines.

Welding Instructions

Before welding on the body, verify the materials that are used. There are specific welding procedures for each material. Refer to the following procedures in order to successfully weld the materials during the assembly of the truck body.

Note: When two or more different materials need to be welded together, use the procedure for the material that has the more stringent requirements.

400 Brinell Hardness Number or 450 Brinell Hardness Number Material

The following procedure covers the requirements for welding the plate assemblies that are fabricated with 400 Brinell hardness number material or 450 Brinell hardness number material. Refer to ""Welding Specifications and Parameters" " for qualifications, safety, and welding electrode parameters. Attach the welding ground cable directly to the body assembly. Protect all of the machined areas from sparks and spatter that are produced by welding, chipping, and grinding operations.

Proper preparation of the welding area must be conducted prior to welding. All weld joints and welding areas must be exceptionally clean. Clean the welding area with a grinder. Completely remove all paint, rust, scale, slag, dirt, moisture, grease, etc before welding.

Tight fitup of the body assemblies is very important. Ensure that every effort is made in order to minimize the gap spacing. Minimizing the gap spacing reduces the residual stresses.

In order to minimize the possibility of cracking, use large tack welds. The tack welds should have a maximum width of 8 mm (0.32 inch) and a length of 75 mm (3 inch).

A Tiger Torch can be used in order to preheat the material that is welded. Preheating is most critical during the tack welding procedure and during the welding of the root pass. Refer to Table 5 for the required preheat temperature of the weld area.

Ensure that the weld groove and 76 mm (3 inch) in each direction from the weld groove is preheated to the specified temperature. Verify the preheat temperature with a 164-3310 Infrared Thermometer or with a temperature stick.

The minimum interpass temperature should equal the preheat temperature. The maximum interpass temperature should not exceed 250 °C (480 °F).

Note: The above preheat and interpass temperatures are for mild restaint to moderate restraint. If clamping devices are utilized in order to reduce the gap spacing to less than 3 mm (0.12 inch), use the next higher preheat temperature, when possible. Additional stresses are offset by using the next higher preheat temperature.

Note: When the ambient temperature is below 0 °C (32 °F) the initial preheat temperature should be raised to 121 °C (250 °F). Preheat 76.0 mm (3.0 inch) inches in each direction from the weld joint. This will help avoid the possible heat sink of the floorplates.

All welded areas need to be inspected. Cracking that is induced from hydrogen welding normally occurs within 72 hours of welding. Allow the welded areas to cool for 48 hours to 72 hours prior to performing a visual inspection. If any welding areas are suspected of being cracked during the visual inspection, then use the dye penetrant process or the magnetic particle inspection process in order to inspect the welding areas. The welds shall be free from the following defects: cracks, porosity, undercut and incomplete fusion. All weld quality shall conform to American National Standards Institute (ANSI)/American Welding Society (AWS) D14.3.

Installation Procedure

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Illustration 1	g01630773
(1) 318-6476 Plate As (2) 318-6727 Plate As

1. Prepare all the welding areas for welding. All weld joints and welding areas must be exceptionally clean. Clean the welding area with grinder (AA). Completely remove all paint, rust, scale, slag, dirt, moisture, grease, etc before welding.

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Illustration 2	g01630776
(2) 318-6727 Plate As (A) 635 ± 5 mm (25.0 ± 0.20 inch) (W1) 12 mm (0.5 inch) Fillet weld with 1.5 mm (0.06 inch) root penetration

2. Use a suitable lifting device and position plate assembly (2) according to dimension (A) .

   Note: Plate assembly (2) weighs approximately 27.5 kg (65 lb).

3. Before tack welding, preheat the welding area to the proper preheat temperature. Refer to ""Welding Instructions" " for proper temperatures. Check for the proper temperature with Infrared Thermometer (BB) .

4. Weld plate assembly (2) to the truck body.

5. Remove the slag after every weld pass.

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Illustration 3	g01630777
(1) 318-6476 Plate As (B) 325 ± 5 mm (12.8 ± 0.20 inch) (W2) 12 mm (0.5 inch) Fillet weld with 1.5 mm (0.06 inch) root penetration

6. Use a suitable lifting device and position plate assembly (1) according to dimension (B) .

   Note: Plate assembly (1) weighs approximately 32.5 kg (75 lb).

7. Before tack welding, preheat the welding area to the proper preheat temperature. Refer to ""Welding Instructions" " for proper temperatures. Check for the proper temperature with Infrared Thermometer (BB) .

8. Weld plate assembly (1) to the truck body.

9. Remove the slag after every weld pass.

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Illustration 4	g01630774
(1) 318-6476 Plate As (C) 635 ± 5 mm (25.0 ± 0.20 inch) (W3) 12 mm (0.5 inch) Fillet weld with 1.5 mm (0.06 inch) root penetration

10. Use a suitable lifting device and position plate assembly (1) according to dimension (C) .

    Note: Plate assembly (1) weighs approximately 32.5 kg (75 lb).

11. Before tack welding, preheat the welding area to the proper preheat temperature. Refer to ""Welding Instructions" " for proper temperatures. Check for the proper temperature with Infrared Thermometer (BB) .

12. Weld plate assembly (1) to the truck body.

13. Remove the slag after every weld pass.

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Illustration 5	g01630775
(2) 318-6727 Plate As (D) 328 ± 5 mm (12.9 ± 0.2 inch) (W4) 12 mm (0.5 inch) Fillet weld with 1.5 mm (0.06 inch) root penetration

14. Use a suitable lifting device and position plate assembly (2) according to dimension (D) .

    Note: Plate assembly (2) weighs approximately 27.5 kg (65 lb).

15. Before tack welding, preheat the welding area to the proper preheat temperature. Refer to ""Welding Instructions" " for proper temperatures. Check for the proper temperature with Infrared Thermometer (BB) .

16. Weld plate assembly (2) to the truck body.

17. Remove the slag after every weld pass.

18. As needed, repaint the truck body.