797 and 797B Off-Highway Truck C175-20 Engine Retrofit Procedure Caterpillar

General Information

This Special Instruction contains the necessary information in order to retrofit the 797 and the 797B Off-Highway Truck with the C175-20 engine.

This General Information section will cover the following areas:

• Required Tools

• Approximate Weights

• Specifications for Cables, Chains, and Lifting Devices

• Weld Specifications and Parameters

Required Tools

Fabricated Tooling for the 797 Off-Highway Truck

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Illustration 1	g03410852
View of channel (AA) 285-5651 Channel (A) 50.8 mm (2 inch) (B) 50 mm (1.97 inch) (C) 556.6 mm (22 inch) (D) 456.6 mm (18 inch) (E) 24.5 mm (0.965 inch)

1. Modify channel (AA) to the dimensions that are shown in Illustration 1. Channel (AA) is used in order to locate the new front engine mounts.
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   Illustration 2	g03410905
   View of spacer (BB) ( F) 191.7 ± 0.1 mm (7.55 ± 0.004 inch) (G) 20 mm (0.79 inch)

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   Illustration 3	g03411146
   View of section A-A (BB) Spacer (H) 51 mm (2 inch) (J) 40.7 ± 0.1 mm (1.60 ± 0.003 inch) (K) 24.5 mm (0.96 inch)

2. Fabricate spacer (BB) out of "ASTM A36" steel. Spacer (BB) is used in order to locate the new front engine mounts.
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   Illustration 4	g03411164
   Side view of spacer (CC) ( L) 12 mm (0.47 inch) (M) 32 mm (1.26 inch) (N) 40.5 mm (1.59 inch)

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   Illustration 5	g03411165
   View of section B-B (CC) Spacer (P) 51 mm (2.01 inch) (R) 24.5 mm (0.96 inch)

3. Fabricate one spacer (CC) out of "ASTM A36" steel. Spacer (CC) is used in order to locate the new front engine mounts.

Fabricated Tooling for the 797B Off-Highway Truck

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Illustration 6	g02169196
Top view of plate (AB) ( A) 420 mm (16.54 inch) (B) 370 mm (14.57 inch) (C) 50 mm (1.97 inch) (D) 50 mm (1.97 inch) (E) 386.5 mm (15.22 inch) (F) 436.5 mm (17.19 inch) (G) 20.5 mm (0.81 inch)

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Illustration 7	g02173078
View A-A (H) 10 mm (0.40 inch)

1. Fabricate plate (AB) out of "ASTM A36" steel. Plate (AB) is used in order to install the new mounts for the pump drive.
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   Illustration 8	g02173080
   Top view (J) 456.7 mm (17.98 inch) (K) 24.5 mm (0.96 inch) (L) 50 ± 10 mm (1.97 ± 0.39 inch)

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   Illustration 9	g02173081
   View B-B (M) 100 ± 10 mm (3.94 ± 0.394 inch) (N) 11.5 mm (0.45 inch)

2. Fabricate plate (AC) out of "ASTM A36" steel. Plate (AC) is used in order to locate the new front engine mounts.
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   Illustration 10	g02176529
   Side view (P) 12 mm (0.47 inch) (R) 32 mm (1.26 inch) (S) 40.5 mm (1.59 inch)

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   Illustration 11	g02173097
   View C-C (T) 51 mm (2.01 inch) (U) 24.5 mm (0.96 inch)

3. Fabricate two spacer (AD) out of "ASTM A36" steel. Spacer (AD) is used in order to locate the new front engine mounts.
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   Illustration 12	g03745827
   (V) 50 mm (1.97 inch) (W) Diameter of 26.1 mm (1.03 inch) (X) 100 mm (3.94 inch) (Y) 50 mm (1.97 inch) (Z) 37.6 mm (1.48 inch) (AA) M20 x 2.5 ISO - H tap 25 mm 17.5 drill 32 mm (AE) Fabricated block (BB) 24.9 mm (0.98 inch) (CC) 9 mm (0.35 inch) (DD) 52.1 mm (2.05 inch) (EE) 63.7 mm (2.51 inch)

4. Fabricate two blocks (AE) shown as above. Use any steel material. These blocks will be used to relocate the pump drive mounts.

Approximate Weights

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Personal injury or death can result from lifting a heavy assembly. The heavy assembly can fall if using an incorrect hoist to lift the load. Be sure the hoist has the correct capacity to lift a heavy assembly. Approximate weight of the assembly is given below.

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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.

Specifications for Cables, Chains, and Lifting Devices

Use approved cables, chains, and lifting devices in order to lift components. Refer to the manufacturers literature in order to determine the application when you select the items that follow: cable, chain and lifting devices. When you lift a component, the lift angle is critical. Refer to the Illustration that follows in order to see the effect of the lift angle on the working load limit.

Illustration 13	g00629745
Lift angles for lifting slings. (A) The load capacity is 100 percent of the working load limit for the sling. (B) The load capacity is 86 percent of the working load limit for the sling. (C) The load capacity is 70 percent of the working load limit for the sling. (D) The load capacity is 50 percent of the working load limit for the sling.

Weld Specifications and Parameters

Reference: Special Instruction, REHS1841, "General 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 6 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 manufacturers specifications. The following table is the electrodes current settings in relation to the electrodes 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.

The Flux Cored Arc Welding (FCAW) with "E71T-1 H8 (ANSI/A5.20)" welding electrode and the specified shielding gases for inside welding can also be used. 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 manufacturers 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.