Rework Procedure to Install the Counterweight and Treat the Subframe Weld on the C-Series Knuckleboom Loaders {0679, 4150, 7050, 7051, 7056} Caterpillar

Knuckleboom Loader

2384C (S/N: KB6300-449; KAW251-UP)

2484C (S/N: KB7300-331; KAZ251-UP)

559C (S/N: KB4100-657; KAS205-UP)

579C (S/N: KB5100-189; KAX250-UP)

Introduction

This Special Instruction contains the information needed to install the counterweight and treat the subframe weld on the C-series Knuckleboom Loaders. Install 417-1480 Counterweight to improve the machines performance and increase stability. After installing counterweight, the subframe weld must be treated. Follow either the toe grinding or needle peening instructions to treat the subframe weld. The weld treatment procedures will improve the service life of the machine.

Do not perform any procedure in this Special Instruction until you have read the information and you understand the information.

Safety

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Accidental engine starting can cause injury or death to personnel working on the equipment. To avoid accidental engine starting, disconnect the battery cable from the negative (−) battery terminal. Completely tape all metal surfaces of the disconnected battery cable end in order to prevent contact with other metal surfaces which could activate the engine electrical system. Place a Do Not Operate tag at the Start/Stop switch location to inform personnel that the equipment is being worked on.

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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

Counterweight Installation

Required Parts for 559C and 2384C

Illustration 1	g06136987

Required Parts for 579C and 2484C

Illustration 2	g06136978

Install Procedure

Illustration 3	g06136919
Top veiw of subframe (A) Back plate

Illustration 4	g06136744
Back plate hole locations for 559C and 2384C (A) Back plate (B) 33 mm (1.3 inch) diameter (four holes) (C) 1920 ± 1 mm (75.6 ± 0.04 inch) (D) 620 ± 1 mm (24.4 ± 0.04 inch) (E) 506 ± 1 mm (19.9 ± 0.04 inch) (F) 206 ± 1 mm (8.1 ± 0.04 inch) (G) 769 ± 1 mm (30.3 ± 0.04 inch) (H) 1771 ± 1 mm (69.7 ± 0.04 inch)

1. Drill four holes through back plate (A) as shown in Illustration 4.

   Note: Back plate holes are factory installed for 579C and 2484C machines.

2. Use a suitable lifting device in order to support and position counterweight on to back plate (A).

3. Install counterweight using the required parts, refer to Table 1 for 559C and 2384C or Table 2 for 579C and 2484C. Install bolts using a torque of 1600 ± 200 N·m (1180 ± 147.5 lb ft).

Weld Treatment Procedure

Weld Treatment Area

Illustration 5	g06136343
Top view of subframe (A) Subframe

Illustration 6	g06136348
View of detail A (A) Subframe (B) Weld treatment areas

Illustration 7	g06136355
Weld treatment area location (top view of detail A) (B) Weld treatment areas (C) 485 ± 10 mm (19.1 ± 0.4 inch) (D) 350 ± 10 mm (13.8 ± 0.4 inch)

Treat the weld in the identified treatment areas shown in Illustrations 5, 6, and 7. Extending the treatment out of this area is acceptable. This area defines the minimum requirement. Follow the instructions in either Section "Toe Grinding Instructions" or "Needle Peening Instructions" to complete the subframe weld treatment.

Toe Grinding Instructions

Toe grinding, besides removing minor imperfections, will improve fatigue strength of the weldment by 30%. Care should be taken not to overheat the ground surface until the surface becomes discolored. Avoid leaving deep grinding marks that can act as stress concentrators.

1. Inspect the weld in weld treatment area (B). Repair the weld prior to toe grinding if any visible discontinuity of the weld is shown.
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   Illustration 8	g03134184
   Typical view of carbide cutter

2. Use a grinder with a carbide cutter head with a minimum working diameter of 6 mm (0.24 inch) in order to ensure that the minimum toe radius is maintained.

   Note: Only steel carbide cutters are permitted for toe grinding. Abrasive grinding disc, stones, wheels, or cutters shall not be used.

3. Locate the weld toe treatment area (B) and choose a starting point from either end, refer to Illustration 7
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   Illustration 9	g06136371
   Toe grinder position (E) 45 degree to 65 degree angle

4. Position the grinder at approximately 45 degree to 65 degree angle to the weld toe while splitting the included angle between the base metal and the weld. Refer to Illustration 9.
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   Illustration 10	g06136374
   Grind requirements (F) 0.5 mm (0.02 inch) Minimum Depth (G) Grind area (H) Weld

5. The minimum depth of grinding shall be greater than 0.5 mm (0.02 inch) below the weld toe to base plate interface or until all traces of the original weld toe have disappeared, but no greater than a maximum of 2 mm (0.08 inch) grinding depth. Refer to Illustration 10.

6. The depth of the grind should be gradual along the length of the weld until the required depth and radius are achieved.

7. Use an undercut gauge capable of measuring 0.5 mm (0.02 inch) undercut in order to measure the grind depth.

8. Repeat Steps 1 to 7 on the opposite weld treatment area (B).

9. Inspect the grind area to ensure that no defects are present.

10. Prime and paint weld areas.

Needle Peening Instructions

Note: Needle peening should not be done if the temperature is below 5° C (41° F).

1. Inspect the weld in weld treatment area (B). Repair the weld prior to needle peening if any visible discontinuity of the weld is shown.
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   Illustration 11	g06136653
   Example of a needle peening tool (M) Needle peening tool

2. Use needle peening tool (M) with 3 mm (0.12 inch) diameter needles and radius ends. Refer to Illustration 11.

3. Set the air pressure between 550 kPa (80 psi) and 690 kPa (100 psi).

4. Locate the weld toe treatment area (B) and choose a starting point from either end, refer to Illustration 7
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   Illustration 12	g06136383
   Needle peening position (L) Weld toe (M) Needle peening tool

5. Begin peening weld toe using a tool angle as shown in Illustration 12.
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   Illustration 13	g06136382
   Example of the weld after peening a third pass (L) Weld toe

6. The weld shall be peened for a sufficient time and pressure to obtain a fully dimpled weld toe as shown in Illustration 13.The dimples should overlap each other and completely cover the weld toe.

7. Use a peening time of 5 seconds per 25 mm (1 inch) for each pass. Multiple passes may be needed to obtain fully dimpled weld toe.
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   Illustration 14	g06136380
   Needle peening area (H) Weld (L) Weld toe (J) 5 mm (0.2 inch) (K) 5 mm (0.2 inch)

8. Perform needle peening until the dimple area is extended into the parent material a minimum of 5 mm (0.2 inch) from the weld toes as shown in Illustration 14.

9. Stop peening at locations shown in Illustration 7.

10. Repeat Steps 1 to 9 on the opposite weld treatment area (B).

11. Clean the area of dirt, dust, and debris.

12. Prepare the surface for finishing. Prime, and paint the affected areas around the peened welds.