Repair of Cracks in Rear Track Roller Frame{4151} Caterpillar

Track-Type Tractor:

D9N (S/N: 1JD1-UP; 6XJ1-UP)

D9R (S/N: ABK1-1051; ACL1-1141,1143-1144; 7TL1-UP; 8BL1-UP)

Introduction

This procedure describes the repair process for track roller frames with cracks in tube welds, skirt welds, and castings. Cracks that occur can be repaired by welding and reinforcing in order to extend the life of the track roller frame.

Do not perform any procedure in this special instruction until the information has been read and understood.

After the repair is complete, prepare the machine for service. Refer to the Operation and Maintenance Manual.

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Personal injury or death can result from improper assembly procedures. Do not attempt any assembly until you have read and understand the assembly instructions.

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The machine must be on a level, hard surface before a separation of the track is made. Any time a separation of both tracks is made, the machine must have blocks correctly positioned so the machine will not move.

• Permit only one operator on the machine. Keep all other personnel away from the machine.

• Move the machine to a smooth horizontal location. Move away from working machines and personnel. Lower the bulldozer blade to the ground.

• Engage the parking brake.

• Stop the engine.

• Remove the track roller frames. Refer to Disassembly and Assembly, SENR5387, "D9R Track-Type Tractor Power Train".

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Grease is under high pressure. Grease coming out of the relief valve under pressure can penetrate the body causing injury or death. Do not watch the relief valve to see if grease is escaping. Watch the track or track adjustment cylinder to see if the track is being loosened. Loosen the relief valve only one turn.

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Keep away from the front of the machine when the track is pushed off the final drive. A minimum distance of 7.6 m (25 ft) is needed in front of the track to permit the track to move out onto the floor.

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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.

General Weld Specifications

The following welding processes are recommended for this repair.

Required Parts

Illustration 1	g00591924
Left Track Roller Frame (A) Outside (B) Top (C) Inside (machine side)

Illustration 2	g00591916
Right Track Roller Frame (A) Outside (B) Top (C) Inside (machine side)

Identification of Frame Configuration

There are four different frame configurations which may be encountered.

Type One

Illustration 3	g00729965

D9R (S/N: 7TL1-848; 8BL1-1049) Track-Type Tractors with this configuration were built between April 1995 and July 1997. Some later D9N (S/N: 6XJ; 1JD) Track-Type Tractors will also have this configuration. These frames were built without inside reinforcement plates (B) and (C) for the skirt. Refer to illustration 4. These frames are without the modifications that were recommended in Special Instruction, SEHS9998-01.

These frames have tube welds with a depth of 18 mm (0.7 inch). The most visible indication of this frame configuration is the presence of outer rear reinforcement plates (A) and (D) for the skirt with a thickness of 20 mm (0.8 inch) and a height of 65 mm (2.6 inch). Refer to illustration 3.

Type Two

Illustration 4	g00730098

D9R (S/N: 7TL1-848; 8BL1-1049) Track-Type Tractors with the modifications that were recommended in Special Instruction, SEHS9998-01 will have this configuration. These frames were also built between April 1995 and July 1997 but these frames were repaired by using the previously released instructions.

The most visible indication of a repaired frame is the presence of a reinforcement plate for the rear tube weld. This is commonly known as rear saddle plate (E). These frames will also contain additional plates (A), (B), (C), and (D) for reinforcement of the lower skirt. Outer rear reinforcement plates (A) and (D) for the skirt will have a thickness of 20 mm (0.8 inch) and a height of 140 mm (5.5 inch). Refer to illustration 4.

Note: Plate (E) will be removed during this repair procedure.

Refer to Table 6 for the required parts for this repair on a frame with this configuration.

Type Three

Illustration 5	g00730169

D9R (S/N: 7TL849-1255; 8BL1050-1453) Track-Type Tractors will have this configuration. These frames were built between August 1997 and October 1999.

The most visible indication of this frame configuration is the presence of outer rear reinforcement plates (A) and (D) for the skirt with a thickness of 20 mm (0.8 inch) and a height of 140 mm (5.5 inch). These frames will not be equipped with saddle plates (E) from the type two configuration. These frames were built with inside reinforcement plates (B) and (C) for the skirt. These frames have rear tube welds with a depth of 23.8 mm (0.94 inch).

Refer to Table 6 for the required parts for this repair on a frame with this configuration.

Type Four

Illustration 6	g00730178

D9R (S/N: 7TL1256-UP; 8BL1454-UP) Track-Type Tractors will have this configuration. These frames were built beginning in November 1999.

These frames have the same configuration. These frames will appear visually identical to the frame in Type Three. These frames have been stress relieved prior to machining. In order to identify this frame configuration, the letters "SR" will be stamped on the mounting surface for the cover plate on the recoil spring oil compartment.

Note: The repair procedure for Type Three and Type Four frames is identical.

Note: The alignment of the rear track roller frame for D9R (S/N: 7TL1212-UP) and (S/N: 8BL1422-UP) Track-Type Tractors was changed in order to improve undercarriage life. The changes include a longer equalizer bar, minor bogies that are unique right versus left, and a pivot shaft bore that is machined at an angle. These frames are not compatible with D9N frames. These frames are not compatible with D9R (S/N: 7TL1-1211) and (S/N: 8BL1-1421) frames.

Possible Crack Locations

Illustration 7	g00730469

Cracks have been reported in the following locations.

• Circular welds (F), (G), and (H)

• Skirt weld (J) and the adjacent casting material

• Weld (K) for the saddle plate and the adjacent casting material

Note: Carefully inspect the entire roller frame for any cracks.

Repair of Cracks in Steel Castings

Cracks that have formed in the casting may be repairable. Four factors should be considered when you are deciding whether a crack in the casting can be repaired.

• The structural integrity of the casting in the location of the crack

• The geometry of the casting in the location of the crack

• The accessibility of the crack

• The economic factor relative to replacement

These cracks must be repaired prior to the ""Procedure For Repairing Weld (Part 1)" ". If the crack has propagated completely through the casting, the back side of the crack will be repaired during the procedure.

Cracks in the wall of the casting must be accessible from the inside of the component. There must be a sufficient area for back gouging and welding.

Cracks must be completely removed for an effective repair. Weld these cracks by using good welding practices.

Cracks in the pivot shaft bore and the recoil bore which extend into the bore should not be repaired.

Repair Positions

Illustration 8	g00730592
(SS) Pivot Shaft Seal

The following positions will be referenced throughout the procedures:

(P1) Upright

(P2) Pivot Shaft Seal-Down

(P3) Pivot Shaft Seal-Up

(P4) Upside-Down

Procedure For Repairing Weld (Part 1)

1. Rotate the frame to position (P1). Refer to Illustration 8.

Note: If the frame that is being repaired is Type 2, then rear reinforcement plate (E) must be removed by using a carbon arc or a torch. Refer to illustration 4. Fill any voids that exist from the removal of the plate and grind the surface smooth. Identify any cracks in the casting and repair these cracks. Refer to ""Repair of Cracks in Steel Castings" ".

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Illustration 9	g00592380

2. Remove the welds on the top of the frame. There are three welds on the top of the frame that are subject to cracking. Start with the welds that have visible cracks. If there are no visible cracks, penetrate into these areas by using a carbon arc in order to determine whether cracks are present at the bottom of the weld. Start at the top dead center of welds (F), (G), and (H) and penetrate to the depth that is shown in illustrations 11, 12, and 13. Penetrate the welds for a length of 76 mm (2.99 inch). Use a pencil grinder to smooth the surface of these areas and apply some dye penetrant in order to check for cracks. If no cracks are present, reweld these areas by using a weaving technique.

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Illustration 10	g00592105
(A) Tube Weld (typical example) (B) Skirt

3. If cracks are found, use carbon arc in order to remove weld (A). The depth of rear tube weld (H) is 18.8 mm (0.74 inch) on roller frames that are Type 1 and Type 2. The depth of rear tube weld (H) is 23.8 mm (0.94 inch) on roller frames that are Type 3 and Type 4. Remove the entire weld from point (C) to point (D). Do not remove the weld past points (C) and (D). Points (C) and (D) are the ends of weld (A) that meet skirt (B) .

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Illustration 11	g00592123
Front Weld Joint See Callout (F) in Illustration 9. (S) 2 mm (0.08 inch) (T) 18.8 mm (0.74 inch) for Type 1, Type 2, Type 3, and Type 4

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Illustration 12	g00592154
Center Weld Joint See Callout (G) in Illustration 9. (S) 2 mm (0.08 inch) (T) 18.8 mm (0.74 inch) for Type 1, Type 2, Type 3, and Type 4

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Illustration 13	g00592167
Rear Weld Joint See Callout (H) in Illustration 9. (S) 2 mm (0.08 inch) (T) 18.8 mm (0.74 inch) for Type 1 and Type 2 (T) 23.8 mm (0.94 inch) for Type 3 and Type 4

Note: It is important to remove the weld to the bottom of the joints. Refer to Illustrations 11, 12, and 13. Do not penetrate past the depth of the joint in order to prevent burn-through.

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Illustration 14	g00592277

4. Remove the slag from the joint. Use a grinder to clean the joint in preparation for welding. Use a rotary file at points (C) and (D) to smooth the ends in preparation for welding.

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Illustration 15	g00730819

5. Remove the lifting eye, the center locating pad, and the rear locating pad by air arc gouging. Grind the surfaces smooth in order to blend with the casting. Refer to illustration 15.

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Illustration 16	g00592105
(A) Tube Weld (typical example) (B) Skirt

6. Use a dye penetrant in order to determine if the crack extends under skirt (B) on the inside or the outside of the frame. If the crack extends beneath skirt (B) on any of the three circular welds (A), go to ""Procedure For Repairing Weld (Part 2)" ". If the crack extends into any of the four side skirt plates, reweld the top portion of the circular weld by using the weaving technique and go to ""Procedure For Repairing Weld (Part 3)" ". If the crack does not extend beneath the skirt, continue with ""Procedure For Repairing Weld (Part 1) " ".

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Illustration 17	g00592321

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Illustration 18	g00732427

7. Start at point (E) and weld one pass to the top of the tube by using a weaving technique. Repeat for the other side of the frame. Repeat this sequence until the joint is completely welded. Use a grinder to blend in the toes. Refer to illustration 18. Remove any excess weld on the top dead center of the tube. A smooth surface will allow the reinforcement bar to fit to the tube as close as possible. The reinforcement bar will be added later in this procedure.

Installation of the Reinforcement Bar and the Reinforcements for the Skirt

Note: For any numerical callout in the following section, refer to the parts lists in ""Required Parts" " for the correct part number.

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Illustration 19	g00730886

1. Fit reinforcement bar (4) to the top of the track roller frame. Gap (X) between reinforcement bar (4) and the roller frame must not be greater than 3 mm (0.12 inch) in any location. You can improve the fit of reinforcement bar (4) by removing material from the bar in order to match the contour of the frame. The effectiveness of the bar is greatly improved when a minimal gap is present. Do not remove material from the track roller frame.

2. Tack weld bar (4) on both sides of the frame.

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NOTICE
Distortion of the track roller frame can render the frame unusable after installation of the reinforcement bar. Excessive heat must be avoided during weld installation of the reinforcement bar. Following the welding procedure will ensure that the frame can be returned to service.

3. Place an air hose with a nozzle into the opening for the recoil spring oil compartment and direct compressed air through the frame for cooling purposes. This will help to minimize the heat distortion of the bores and machined surfaces.

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Illustration 20	g00730951

Note: When you are repairing a pair of frames, weld one pass on each frame while the other frame is being cooled by a fan. Alternate the passes on each frame until the welding is complete. This should be done in addition to the cooling method in step 3.

4. With the frame in position (P1), weld one pass on the side that is closest to the machine when the frame is installed. Weld the pass in the following manner.

   1. Weld from point (B) to point (A) .

   2. Weld from point (C) to point (B) .

   3. Weld from point (D) to point (C) .

      Note: Each pass should be no more than a 6 mm (0.24 inch) weld.

Note: Do not complete this weld at this time. This weld will be completed later in step 14.

5. Rotate the frame to position (P2). Refer to Illustration 8.

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Illustration 21	g00732452

6. Weld reinforcement bar (4) on the side of the bar that is outermost from the machine when the roller frame is installed. Use the same procedure in step 4. Repeat the passes until the joint is full on this side of the bar.

   Note: Each pass should be no more than a 6 mm (0.24 inch) weld.

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Illustration 22	g00730978
Frame Configuration (Type 1)

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Illustration 23	g00730975
Frame Configuration (Type 2, Type 3, and Type 4)

7. Remove outer reinforcement plate (D) .

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Illustration 24	g00730985
(7) Outer reinforcement plate for the right track roller frame (8) Outer reinforcement plate for the left track roller frame (Y) Dimension of 26.7 mm (1.05 inch)

8. Locate new outer reinforcement plate (7) or (8) to dimension (Y). Tack weld the plate in place.

9. Weld the ends of the plate from point (B) to point (C) and point (D) to point (E) with a 16 mm (0.63 inch) fillet weld.

10. If your frame configuration is Type 1, continue to step 11. If your frame configuration is Type 2, Type 3, or Type 4, go to step 13.

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Illustration 25	g00731066

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Illustration 26	g00592617

11. Position plate (2) and tack weld plate (2) in place. Weld a 10 mm (0.39 inch) plug weld (Q) completely. Weld around plate (2) by using a 10 mm (0.39 inch) fillet weld with a 1.5 mm (0.06 inch) penetration.

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Illustration 27	g00592628

12. Position plate (3) and tack weld plate (3) in place. Weld a 10 mm (0.39 inch) plug weld (R) completely. Weld around plate (3) by using a 10 mm (0.39 inch) fillet weld with a 1.5 mm (0.06 inch) penetration.

13. Rotate the frame to position (P3). Refer to Illustration 8.

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Illustration 28	g00731061

14. Complete the weld on reinforcement bar (4). Follow the same procedure in step 4.

    Note: Each pass should be no more than a 6 mm (0.24 inch) weld.

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Illustration 29	g00731119
Frame Configuration (Type 1)

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Illustration 30	g00731151
Frame Configuration (Type 2, Type 3, and Type 4)

15. Remove existing outer reinforcement plate (A) from this side of the track roller frame.

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Illustration 31	g00731154

16. Position new outer reinforcement plate (5) for the right track roller frame or plate (6) for the left track roller. Position the plate along the bottom of the roller frame and allow the best fit around the pivot shaft cavity. Tack weld the plate in place.

17. Weld the ends of the plate from point (F) to point (L) and from point (G) to point (K) with a 16 mm (0.63 inch) fillet weld. Weld the area around the pivot shaft cavity from point (H) to point (J) with a 15 mm (0.59 inch) bevel groove weld.

    Note: Be careful around the alignment hole for the pivot shaft seal. Do not remove the hole and do not weld over the hole.

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Illustration 32	g00731170

18. If the frame is Type 1, repeat steps 11 and 12 for plates (2) and (3) on this side of the track roller frame.

19. Rotate the track roller frame to position (P4). Refer to Illustration 8.

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Illustration 33	g00731180

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Illustration 34	g00592669

20. Weld the bottom of outer reinforcement plates (5) and (7) for the right track roller frame or outer reinforcement plates (6) and (8) for the left track roller frame. This is a 15 mm (0.59 inch) bevel groove weld.

    Note: If any of the cracks in the castings have penetrated completely through the casting, this is the time for repair of the underside of these cracks. Gouge the remaining area of the crack and use good welding practices to repair the underside of the crack. Grind the welds to a smooth finish.

21. Rotate the frame to position (P1). Refer to Illustration 8.

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Illustration 35	g00731154
(5) Outer reinforcement plate for the right track roller frame (6) Outer reinforcement plate for the left track roller frame

22. Complete the welding for plate (5) or (6). Weld from point (L) to point (H) and from point (J) to point (K) with a 14 mm (0.55 inch) bevel groove weld.

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Illustration 36	g00730985
(7) Outer reinforcement plate for the right track roller frame (8) Outer reinforcement plate for the left track roller frame (Y) Dimension of 26.7 mm (1.05 inch)

23. Complete the welding for plate (7) or (8). Weld from point (B) to point (E) with a 14 mm (0.55 inch) bevel groove weld.

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Illustration 37	g00731207
(1) Lifting Hook (Z) Dimension of 40 ± 3 mm (1.57 ± 0.12 inch)

24. Install new lifting hook (1) to dimension (Z). Use a 15 mm (0.59 inch) fillet weld completely around both legs of the hook.

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Illustration 38	g00731233

25. Weld the end of reinforcement bar (4) from point (M) to point (N) with a 12 mm (0.47 inch) fillet weld.

26. Weld the end of reinforcement bar (4) from point (O) to point (P) with a 12 mm (0.47 inch) bevel groove weld.

27. Grind all welds so there is a smooth transition at the toe of the welds. Do not remove any base metal. Do not remove any metal from the reinforcement plate.

    Note: After the frame has cooled, fit the key to the bore at the twister resister. If the key is tight, use a rotary grinder.

Procedure For Repairing Weld (Part 2)

Cut Windows

Note: Perform this step only if the crack extends beneath the skirt on any of the three circular welds.

1. Rotate the track roller frame to position (P1). Refer to Illustration 8.

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Illustration 39	g00592886

2. Cut a window in the skirt for the entire width of the skirt. The height of the window should be 150 mm (6 inch) from point (W) to point (X), as shown.

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Illustration 40	g00592908

3. Gouge the weld by using air arc gouging. When the end of the crack has been reached, use a dye-penetrant in order to verify. If the crack extends beyond reach, reweld the top portion of the circular weld and go to ""Procedure For Repairing Weld (Part 3)" ".

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Illustration 41	g00592921

4. If the crack does not extend beyond reach, remove the slag and clean the joint for welding. Reweld the circular weld to 40 mm (1.57 inch) above the top of the skirt by using a weaving technique. Repeat until the joint is completely welded.

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Illustration 42	g00592934

5. Cut a backup strip and tack weld the backup strip to the inside of the bottom of the window.

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Illustration 43	g00592954

6. Replace the window and tack weld the window in place. Completely weld the window.

7. Return to step 7 of ""Procedure For Repairing Weld (Part 1) " ".

   Note: If cracks exist in the skirt plates, replace the plate or gouge the remaining crack. Weld the gouge by using a weaving technique. Grind the surface smooth.

Procedure For Repairing Weld (Part 3)

Remove the Skirt

Note: Perform this step only if the crack extends into any one of the four side skirts and the crack extends beyond reach through the window in Part 2.

1. Rotate the frame to position (P1). Refer to Illustration 8.

2. Reweld the top portion of the circular weld by using a weaving technique. Refer to step 7 in Part 1.

3. Rotate the frame to position (P2). Refer to Illustration 8.

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Illustration 44	g00592964

4. Use a carbon arc to remove the weld on the three sides around the skirt and remove the weld from the inside of the skirt on the opposite side of the frame.

5. Rotate the frame to position (P3). Refer to Illustration 8.

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Illustration 45	g00592977

6. Repeat step 4 for the opposite side of the frame.

   Note: If the crack in the circular weld does not visually extend to the belly plate, gouge the circular weld and use a dye-penetrant in order to verify. Reweld the circular weld by using a weaving technique and go to step 5 of ""Replace The Belly Plate" ". If the crack extends to the belly plate, go to ""Remove The Belly Plate and The Bottom Tube Weld" ".

Remove The Belly Plate And The Bottom Tube Weld

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Illustration 46	g00592987

1. Remove the welds on each side of the block under the belly plate.

2. Rotate the frame to position (P2). Refer to Illustration 8.

3. Repeat step 1 for this side.

4. Rotate the frame to position (P4). Refer to Illustration 8.

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Illustration 47	g00593026

5. Remove the plug weld and two side welds of the belly plate. Remove the belly plate.

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Illustration 48	g00593044

6. Burn out the weld on the bottom of the tube. Clean the slag from the groove.

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Illustration 49	g00593052

7. Weld the groove by using a weaving technique. Grind the bottom of tube in the location of the removed welds from the belly plate until the area is smooth.

Replace The Belly Plate

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Illustration 50	g00593405

1. Align the tapped holes in the belly plate with the bogie pad and tack weld the belly plate to the frame.

2. Rotate the frame to position (P2). Refer to illustration 8.

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Illustration 51	g00593409

3. Weld the block to the tube and the belly plate.

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Illustration 52	g00593414

4. Tack weld the skirts to the frame.

5. Rotate the frame to position (P3). Refer to illustration 8.

6. Repeat steps 3 and 4 for the opposite side.

7. Rotate the frame to position (P4). Refer to illustration 8.

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Illustration 53	g00593417

8. Weld the belly plate to the frame by using a weaving technique. Weld the two sides, the plug weld and the two ends.

9. Rotate the frame to position (P2). Refer to illustration 8.

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Illustration 54	g00593421

10. Finish the weld for both skirts by using a weaving technique and grind the welded areas flush with the skirt.

11. Rotate the frame to position (P3). Refer to illustration 8.

12. Repeat step 10 for the opposite skirt.

    Note: If cracks exist in the skirt plates, gouge the remaining crack and weld the gouge by using a weaving technique. Grind the surface smooth.

13. Rotate the frame to position (P1). Refer to illustration 8.

14. Return to step 7 of ""Procedure For Repairing Weld (Part 1)" ".