Procedure for Repairing Cracks and Strengthening the Stick Assembly{6502} Caterpillar

Excavator:

330C (S/N: JCD1-UP; JNK1-UP; CAP1-UP; CGZ1-UP)

Introduction

This Special Instruction outlines the basic steps in order to repair cracks and strengthen the 218-2197 Stick and Bearing Assembly that is used on the 330C Excavator. Cracks that occur can be repaired by welding and strengthening in order to extend the service life of the stick. Cracks can occur at three specific weld locations on the stick: the stick nose, the center boss assembly, or the stick cylinder bracket

If a crack is not propagating out of the weld, follow the rework procedure. If a crack is propagating out of the weld into a plate, photograph the crack and contact the Product Support Representative for further instructions.

Do not perform any procedure that is outlined in this publication and do not fabricate any parts until you understand the information that is contained in this document.

Reference

ReferenceParts Manual, SEBP3662

ReferenceOperation and Maintenance Manual, SEBU7437

ReferenceDisassembly and Assembly Manual, RENR5438

ReferenceCaterpillar Service Welding Guide, SEBD0512

Required Parts

All of the parts must be fabricated from carbon steel. Only fabricate the parts that are necessary to complete the rework on the stick. Use any of the following types of carbon steel or the equivalent that is shown in Table 2.

Illustration 1	g01408525
Fabricated Backup Strip (Item 3) (A) 304 mm (12 inch) (B) 25 mm (1.0 inch) (C) 10 mm (0.4 inch)

Illustration 2	g01390170
Fabricated Baffle (Item 4) (A) 304 ± 1 mm (11.97 ± 0.04 inch) (B) 152 ± 10 mm (5.98 ± 0.39 inch) (C) 199 ± 10 mm (7.83 ± 0.39 inch) (D) 397.5 ± 1 mm (15.65 ± 0.04 inch) (E) 40 ± 10 mm (1.57 ± 0.39 inch) (One Hole) (F) 10 mm (0.39 inch)

Illustration 3	g01390171
Fabricated Backup Strip (Item 5) (A) 10 ± 1.5 mm (0.4 ± 0.06 inch) (B) 372.8 ± 1.8 mm (14.68 ± 0.07 inch) (C) 378.6 ± 1.8 mm (14.91 ± 0.07 inch) (D) 25 ± 1.5 mm (1.0 ± 0.06 inch)

Illustration 4	g01390173
Fabricated Top Plate (Item 6) (A) 635.5 mm (25.02 inch) (B) 370 mm (14.6 inch) (C) 14 mm (0.6 inch) (D) 25° + 5° − 2° (Two Places) (E) 2 mm (0.08 inch) Maximum (Two Places)

Illustration 5	g01390180
Fabricated Lug (Item 7) (A) 40.0 ± 1.5 mm (1.57 ± 0.06 inch) (B) 240.4 ± 1.5 mm (9.46 ± 0.06 inch) (C) 231.3 ± 1.5 mm (9.11 ± 0.06 inch) (D) 228.8 ± 1.5 mm (9.01 ± 0.06 inch) (E) 179.4 ± 1.5 mm (7.06 ± 0.06 inch) (F) 176.6 ± 1.5 mm (6.95 ± 0.06 inch) (G) 155.3 ± 1.5 mm (6.11 ± 0.06 inch) (H) 141.3 ± 1.5 mm (5.56 ± 0.06 inch) (I) 90° Radius (J) 300° Radius (K) 57.4 ± 1.5 mm (2.26 ± 0.06 inch) (L) 93.3 ± 1.5 mm (3.67 ± 0.06 inch) (M) 112.9 ± 1.5 mm (4.45 ± 0.06 inch) (N) 109.3 ± 1.5 mm (4.30 ± 0.06 inch) (O) 122° Radius (P) 209.1 ± 1.5 mm (8.23 ± 0.06 inch) (Q) 204.6 ± 1.5 mm (8.06 ± 0.06 inch) (R) 229.7 ± 1.5 mm (9.04 ± 0.06 inch) (S) 215.1 ± 1.5 mm (8.47 ± 0.06 inch) (T) 204.0 ± 1.5 mm (8.03 ± 0.06 inch)

Welding Requirements

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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

Qualifications

Welders must be qualified for fillet welding and groove welding. The welder must be qualified in different welding angles. The angles are vertical, horizontal, etc. The welders should be qualified in the use of the welding processes that follow: Shielded Metal Arc Welding (SMAW), Flux Cored Arc Welding (FCAW) and Gas Metal Arc Welding (GMAW). Refer to ISO 9606 or "American National Standards Institiute (ANSI)/American Welding Society (AWS) Specification D1.1, or Specification D14.3" for information that regards the qualifications for the processes that follow: SMAW process, FCAW process and GMAW process. The welders must have used the process at some time within the last six months. The welders must complete the process of certification if the welders have not used the welding processes for six months.

Note: For further information, see Special Instruction, REHS1841, "General Welding Procedures".

Weld Specifications

Refer to the illustrations in this special instruction for welding symbols and specifications.

Welding quality is critical to the success of this rework procedure. Welds must be smooth and continuous. No overlap is allowed. Grind the ends of the welds to a smooth radius.

All welding should be done in a horizontal position. If the vertical position must be used in the welding procedure, the operation should be performed in the "vertical up" direction, instead of the "vertical down" direction.

Cover all parts before the gouging operation is performed.

The power source should be able to supply 500 Amperes or more with DC current for the welding operation. The power source should be able to gouge metal with 500 Amperes. The operation should use DC negative polarity.

The welding wire must be protected with CO₂ gas. The welding wire can be protected with a blend of Argon and CO₂ gas. Set the gas flow at the rate of 20 L/min (5.3 US gpm). When a high Argon blend is used, the correct mixture of Argon and CO₂ is 80/20.

Do not weld in windy conditions. Do not weld when temperatures are below 16 °C (61 °F).

Remove the slag after each pass of the welding electrode. The width of the weld should not exceed two times the electrode diameter.

Recommended European weld consumables: SAF Oerlikon Carbofil SG3, ESAB OK Autrod 12.64, Pittini Pitarc G9, or Thyssen® Union k56

If only manual welding is possible, use ESAB OK 48.00 with a rod diameter of 3.25 mm (0.128 inch) or the equivalent AWS A5.1 E7018 or EN ISO 2560-A E 42 4 B 42 H5.

All electrodes must be completely dried. The electrodes can be dried by heating the electrodes to the temperature of 300 °C (572 °F). The electrodes must be dried for at least 30 minutes.

Weld Inspection

The weld should not have any of the conditions that follow:

• Cracks

• Porosity

• Undercut

• Incomplete Fusion

In order to verify the quality of the weld, refer to American National Standards Institute (ANSI)/American Welding Society (AWS) Specification D14.3.

Rework Procedure

Crack Locations

Illustration 6	g01389953
Areas of the Stick That May Require Rework (1) Stick nose (2) Center boss assembly (3) Stick cylinder bracket

Illustration 7	g01408528
This illustration shows a crack in the weld for the stick nose. This damage is repairable.

Illustration 8	g01408558
This illustration shows a crack in the weld for the center boss assembly. This damage is repairable.

Illustration 9	g01408572
This illustration shows cracks in the welds for the stick cylinder bracket. This damage is repairable.

Preparing the Machine for Servicing

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Be sure all personnel are clear of the equipment while the equipment is being lowered. Failure to stay clear of the equipment while the equipment is being lowered may result in personal injury.

1. Move the machine to level ground.

2. Remove the bucket, bucket cylinder, linkage, lines from the stick, and the stick from the machine in accordance to the instructions in Disassembly and Assembly Manual, SENR5438.

3. Orient the stick in a horizontal position.

Preparing the Area for Welding

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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.

Cover all finished bores and threads. The bores and threads must be protected against damage and foreign material. Welding and gouging can damage the bores and threads. Do not allow paint to contaminate the bores or threads. Do not remove the covers until the stick is painted.

All grease, water, paint, rust, dirt, and scale must be removed before welding. Any of these materials will discharge gas which will cause porosity in the weld deposit. Water and rust will cause hydrogen embrittlement. Hydrogen embrittlement causes cracks in the weld deposit.

Remove paint, rust, dirt, and scale with a wire brush or by buffing or grinding. Shot blasting all work areas will also remove foreign material.

Remove any oil or grease that is on the stick with a Caterpillar approved solvent.

The weld bead should be free of welding spatter or slag that can pose a problem through assembly or by contamination.

If the temperature of the base metal is below 0 °C (32 °F), heat the base metal to a temperature of at least 21 °C (70 °F). Maintain the temperature of the base metal at 21 °C (70 °F) during the welding process.

Note: Heat distortion of the base metal is possible when you weld. Avoid excessive heating of the base metal. A maximum interpass temperature of 250 °C (482 °F) should be observed.

Attach the welding ground cable directly to the base metal.

Rework at the Stick Nose

Illustration 10	g01390164
(1) Backup strip (Existing) (A) 100 mm (3.9 inch) (B) 1008 mm (39.7 inch) (C) 100 mm (3.9 inch)

1. Cut transversely across the top plate at location "F" by air arc gouging. Refer to Illustration 10.

2. Remove the weld that connects the top plates at location "E" by air arc gouging. Refer to Illustration 10. Remove backup strip (1) .

3. Remove the weld that connects the side plate and the top plate between "D" and "G" by air arc gouging. Refer to Illustration 10. Repeat the procedure on the opposite side of the stick.

4. Remove the part of the top plate between "F" and "E".

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Illustration 11	g01390165
(2) Backup strip (Existing)

5. Inspect the weld quality between the last side plates. Refer to Illustration 11.

6. Check inside the stick in order to make sure that backup strip (2) is correctly positioned with no gap. Refer to Illustration 11. If the backup strip is correctly positioned, proceed to Step 9. Otherwise, continue to Step 7.

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Illustration 12	g01390166
View of "Area A" that is shown in Illustration 11 (3) Fabricated backup strip

7. Use air arc gouging to remove the weld between the last side plates. Remove backup strip (2) under the weld. Place fabricated backup strip (3) onto the same location and reweld the butt end. Make sure that there are no gaps. Tack weld inside chamfer. Those weld areas MUST be fully re-melted.

8. Grind the weld flush with the side plates. The width of the weld should be at least 11 mm (0.4 inch).

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Illustration 13	g01390169
(4) Fabricated Baffle (B) 1008 mm (39.7 inch) (H) 90° ± 2° (I) 159 ± 5 mm (6.3 ± 0.2 inch)

9. Position fabricated baffle (4) and weld the baffle according to Illustration 13.

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Illustration 14	g01390172
(5) Fabricated backup strips (6) Fabricated top plate (J) 2 mm (0.08 inch) Maximum (K) 25° + 5° − 2°

10. Position fabricated backup strips (5) at locations "E" and "F". Refer to Illustration 14. Tack weld inside chamfer. Those weld points MUST be fully re-melted.

11. Position fabricated top plate (5) and weld the top plate according to Illustration 14. The longitudinal welds must be continuous and free of starts and stops. For the transverse weld, reweld the butt joint at both ends of plate after gouging 4 mm (0.16 inch) mini from back side of beveled plates or use flux-tab before welding (instead of gouging).

12. Grind the edge of the plate flat and chamfer 0.5 mm (0.02 inch) to 3 mm (0.12 inch) for both corners. Allow to cool slowly using a heated cover.

Rework at the Center Boss Assembly

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Illustration 15	g01390174
(C) 150 mm (6 inch)

1. Use air arc gouging to gouge the weld from "A" to "B". Refer to Illustration 15.

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Illustration 16	g01390175
(D) 25° + 5° − 2° (E) 2 mm (0.08 inch) Maximum

2. Check if there is a chamfer on the edge of the side plate that was just gouged. If there is no chamfer, chamfer that side plate. Refer to Illustration 16. Always weld in the horizontal position. Preheat at 200 °C (392 °F). Control the interpass temperature from 150 °C (302 °F) to 250 °C (482 °F).

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Illustration 17	g01390176
(F) 3 mm (0.12 inch) Minimum

3. Reweld the butt end. Refer to Illustration 17. Grind the new weld flat and smooth. Avoid any sharp edges. Do not decrease the weld width under 14 mm (0.55 inch). Repeat the same procedure on the other side of the stick. Allow to cool slowly using a heated cover.

Rework at the Stick Cylinder Bracket

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Illustration 18	g01390177
(1) Stick Cylinder Bracket (Old design) (2) Stick Cylinder Bracket (New design)

1. Determine if the stick cylinder bracket is old design (1). If the stick cylinder bracket is the old design, use the rework procedure that follows. If the stick cylinder bracket is new design (2), stop the rework procedure here. Refer to Illustration 18.

   Note: The interpass temperature should not exceed 250 °C (482 °F).

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Illustration 19	g01390193
(1) Stick Cylinder Bracket (Old design) (7) Fabricated lug (F) 30 mm (1.2 inch) (G) 12 mm (0.5 inch) (I) 5 mm (0.2 inch) Minimum (J) 30 mm (1.2 inch) (K) 12 mm (0.5 inch)

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Illustration 20	g01390196
Sequence of the Alternative Passes

2. Position fabricated lug (7) onto stick cylinder bracket (1). Weld the fabricated lug to the stick cylinder bracket from "A" to "C" according to Illustration 19. Start with a first pass and gouge a 4 mm (0.2 inch) mini from the back side of the joint to remove any inclusions. Continue welding the next passes.

   Note: Alternating the passes in the same sequence that is shown in Illustration 20 is very important.

3. Grind the weld so that the surface is completely flat. Weld "Area C" from "A" to "E" according to Illustration 19.

   Note: Following the procedure that is indicated by Illustration 19 is very important.

4. Start with the welds at the end of fabricated lugs "A" and "E". Do not make the weld in order to maintain the melted metal, only grind afterward.

5. Make the longitudinal weld, starting from "E" of the transverse weld, and ending at "B". The weld must be continuous and free of starting and stopping. Weld transversely on "A". Refer to Illustration 19.

6. Grind the welds that have just been made on "E" so that the surface of the lug end is smooth.

7. Grind the weld on "A" so the three flat surfaces are shaped continuously with the stick cylinder bracket. Allow to cool slowly using a heated cover.

8. Repeat the same rework procedure on the other stick cylinder bracket.

Painting and Coating the Stick

1. Shot blast all the welded areas and fabricated parts.

2. Paint all welds and fabricated parts. Use a Caterpillar authorized paint.

3. Remove all protective covers from the bores and threads once the paint has dried.

4. Apply the required amount of lubricant to the bores and threads. Refer to the Operation and Maintenance Manual and Service Manual for lubrication instructions.

Installation of the Stick

1. Prepare the machine and parts for reassembly.

2. Install the bucket, bucket cylinder, linkage, lines from the stick, and the stick to the machine in accordance to the instructions in Disassembly and Assembly Manual, SENR5438

3. Make sure that the machine operates according to the instructions in Operation and Maintenance Manual, SEBU7437