- Wheel Loader:
- 992G (S/N: 7HR1-UP; ADZ1-UP; AZX1-UP)
Introduction
This Special Instruction contains procedures that are necessary to repair the boom and the bucket stops when cracks are detected. This Special Instruction also contains alignment procedures for all bucket stops. These repairs are necessary if excess wear, cracking, or misalignment has occurred. The five repair procedures that are included in this publication are listed below.
- Surface Reconditioning and Alignment of Rack Stops
- Alignment Procedure for Dump Stops
- Transition of the Radius for Rack Stops
- Repair of Cracks on the Upper Rack Stops
- Repair of Cracks on the Lower Rack Stops and Dump Stops
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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 Society2501 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 LaborWashington, D.C. 20210 |
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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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Do not perform any procedure that is outlined in this publication until you have read and understand the information that is contained in this document.
Surface Reconditioning and Alignment of the Rack Stops
Note: The following welding procedures are needed for the repair of the upper and lower rack stops on the boom. There are two sets of rack stops on the boom. The upper rack stop will pertain to the stops that are located near the lift cylinder mount. The lower rack stop will pertain to the stops that are located near the lower bucket pin.
Build Up of the Upper Rack Stop and Alignment of the Upper Rack Stop
Note: The bucket must be installed on the machine before checking for proper alignment.
- Rack back the bucket to the upper rack stop. Check for uneven contact between the bucket tilt link and the boom.
Note: Do not use additional hydraulic force in order to make the bucket tilt link contact the rack stops that are located on both sides of the boom. Take all measurements at initial contact between the bucket and the boom. Taking measurements at initial contact will prevent twisting.
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| Illustration 1 | g00432145 |
(1) Upper rack stop. (2) Direction of welds. (3) Locations of the radius. | |
- Build up the upper rack stops as needed. Follow Steps 3 through 9 in order to build up the upper rack stops. If the left and right stops touch evenly at this point, stop here and inspect the alignment of the lower rack stops.
- Grind the wear surface of rack stop (1). Remove any excess material (mushrooming) that was caused by impact.
Note: Avoid high grinding pressures that may cause burning and discoloration.
- Preheat upper rack stop (1) to 121°C (250°F).
Show/hide table
Table 1 Recommended Welding Processes and Filler Metals Welding Process AWS Specification Welding Electrode SMAW (Stick Welding) A5.1 E7018 or Equivalent GMAW (MIG Welding) A5.18 ER70S-3 or Equivalent FCAW (Gas Shielding) A5.20 E70T-1 (1), E71T-1 (2) Show/hide table( 1 ) For the welding of horizontal positions and flat positions. ( 2 ) For the welding of all positions.
- Build up the surface of upper rack stop (1). Build up the surface with one of the processes and with one of the filler metals that are listed in Table 1.
- Weld in direction (2). The weld should be parallel to the axis of the boom. Ensure that the width of each weld does not exceed 9.53 mm (.375 inch).
- Overlap each weld 3.18 mm (.125 inch). Blend each weld with the other weld beads.
Note: Welds should be free of crater cracks, slag inclusions, porosity, or any other visible discontinuity.
- Clean the weld after each pass. Ensure that the finished weld is no less than 3.18 mm (.125 inch) (A) above rack stop (1) .
Note: Do not weld the rack stop at locations of the radius (3) .
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| Illustration 2 | g00429862 |
(1) Upper rack stop. (3) Locations of the radius. (A) 3.18 mm (.125 inch). | |
- Grind the surface of the weld smooth and grind the surface of the weld straight. Do not grind the weld below the surface of rack stop (1) .
- Verify that uniform contact exists between the bucket link and upper rack stop (1). Ensure that uniform contact exists on all sides of rack stop (1) .
Note: The upper and lower rack stops should make contact at the same time. Do not use hydraulic pressures in order to force the stops to touch at the same time. Check for even contact at initial contact only in order to prevent twisting.
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| Illustration 3 | g00432678 |
(1) Upper rack stop. | |
Build Up and Alignment of the Lower Rack Stop
- Rack the bucket back and inspect for uneven contact between the bucket and the lower rack stops.
Note: Do not use additional hydraulic force in order to make the bucket link contact the lower rack stops on both sides. Take all measurements at initial contact between the bucket link and the boom in order to prevent twisting.
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| Illustration 4 | g00429919 |
(4) Direction of welds. (5) Lower rack stops. | |
- Build up the lower rack stops as needed. Follow Steps 3 through 9 to build up the lower rack stop. If even contact is being made between the bucket link and lower rack stops, and the upper stops are also aligned, proceed to the ""Dump Stop Alignment Procedure" ".
- Grind the wear surface of rack stop (5). Remove any excess material (mushrooming) that was caused by impact.
Note: Avoid high grinding pressures that may cause burning and discoloration.
- Preheat lower rack stops (5) to 121°C (250°F).
- Build up the surface of lower rack stop (5). Build up the surface with one of the processes and with one of the filler metals that are listed in Table 1.
- Weld in direction (4). The weld should be parallel to the axis of the boom. Ensure that each weld does not exceed a width of 9.53 mm (.375 inch).
- Overlap each weld 3.18 mm (.125 inch). Blend each weld with the other weld beads.
Note: Welds should be free of crater cracks, slag inclusions, porosity, or any other visible discontinuity.
- Clean the weld after each pass. Ensure that the finished weld is no less than 3.18 mm (.125 inch) (B) above the surface of the casting.
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| Illustration 5 | g00429998 |
Lower rack stops. (6) Finished weld surfaces. (B) 3.18 mm (.125 inch). | |
- Grind the surface of weld (6) smooth and grind the surface of weld (6) straight in order to provide uniform contact on each rack stop (5) .
- Verify that uniform contact exists between the bucket link and each lower rack stop (5). There must also be uniform contact on all sides of each rack stop.
- Grind all four corners (7) of each stop in order to form a smooth radius at each corner.
Note: All upper and lower rack stops should make contact at the same time, top and bottom, left and right. If the contact is not even, build the stops up again and recheck the alignment.
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| Illustration 6 | g00430118 |
(7) Corner of lower rack stop. | |
Alignment Procedure for the Dump Stops
Boom or bucket cracking can occur when the dump stop on the bottom side of the boom does not make full contact with the dump stop on the bottom side of the bucket. The following steps describe how to identify and correct this problem.
- Clean the boom and clean the bucket dump stops.
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| Illustration 7 | g00473153 |
Boom dump stop (bottom view of boom) . | |
- Apply a light coat of grease to the boom dump stop. The grease will help determine how much contact is being made between the boom dump stop and the bucket dump stop.
- Operate the machine until the bucket dump stop and the boom dump stop contact each other. Rack the bucket back partially in order to inspect the alignment.
- Inspect the bucket and boom dump stop in order to determine how much contact is being made. If even contact is being made across the dump stop no further action is required. If only partial or uneven contact is observed, perform the following steps.
- Remove the high spots on the boom dump stop with a hand grinder.
- Repeat Steps 2 through 4 until even contact between the bucket dump stop and boom dump stop is being made.
Note: It may be necessary to trim the edges of the boom dump stop in order to prevent hitting the weld on the bucket dump stop. Contact should be 6.4 mm (0.25 inch) from the weld beads on the bucket.
Rack Stops - Transition Radius for the Rack Stops
The following procedures are for introducing a gradual transition radius at the upper and lower rack stops. This procedure does not apply to 992G (S/N: 7HR134-UP) machines.
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| Illustration 8 | g00430243 |
Transition radius templates. (C) 40 mm (1.6 inch). (D) 20 mm (0.8 inch). | |
Upper Rack Stop
- Grind each edge of rack stop (1) in order to form radius (9). Radius (9) will blend rack stop (1) with the surface of the boom. The radius must be 40 mm (1.6 inch) minimum.
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| Illustration 9 | g00430178 |
Side view of upper rack stop. (8) Material to be removed. (9) Transition Radius. (E) 20 mm (0.8 inch) maximum. | |
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| Illustration 10 | g00430190 |
(1) Upper rack stop. (9) Transition radius. | |
- Use two disks alternately in order to grind the radius. Use one 177.9 mm (7 inch) disk and use one 101.6 mm (4 inch) disk. Both disks should be Grit-50.
Note: Avoid high grinding pressures that may cause burning and discoloration.
- Cut out the 40 mm (1.6 inch) template which is provided in Illustration 8. Use the template to measure the radius that was formed in Step 2.
Note: No undercuts or deep grinding marks are permitted.
Lower Rack Stop
- Grind each edge of rack stops (5) in order to form radius (10). Radius (10) will blend rack stops (5) with the surface of the boom. The radius must be 20 mm (0.8 inch) minimum.
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| Illustration 11 | g00430238 |
(5) Lower rack stops. (10) Transition radii. | |
- Cut out the 20 mm (0.8 inch) template which is provided in Illustration 8. Use the template to measure the radius that was formed in Step 1.
Note: No undercuts or deep grinding marks are permitted.
Repair of Cracks on the Upper Rack Stops
The following procedure is for repairing cracks in the upper rack stop area shown in Illustration 1. The repairs must be made if cracks are present. The procedure can be followed only if the cracks do not pass completely through the thickness of the boom. If the crack is through the thickness of the boom, the boom must be replaced.
- Ultrasound the boom near the crack in order to determine the depth of the crack. This step is optional.
- Measure the length and the depth of the cracks. Mark the length and the depth of the cracks.
- Grind the defective area until the crack is completely removed. Form a reasonably wide V-groove (12) in place of the crack. Avoid creating narrow V-grooves (13) .
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| Illustration 12 | g00430247 |
V-groove. (12) Recommended. (13) Not recommended. | |
- Use 4C-4736 Penetrant Kit to determine if the crack is completely removed. If the crack is through the thickness of the boom, weld up the groove that was formed in Step 3 and order a new boom.
Note: The machine can be operated until a new boom is installed. Inspect the crack location at the beginning of every shift until the boom is replaced.
- Preheat the repair area around the V-groove to 121°C (250°F).
- Weld the repair area with one of the processes and with one of the filler metals that are listed in Table 1.
- Maintain a minimum interpass temperature of 38°C (100°F).
- Blend each weld with the other weld beads.
Note: Each weld should be free of crater cracks, slag inclusions, porosity, and any other visible discontinuity.
- Clean the weld after each pass.
- Needle peen or hammer peen each weld pass.
- Fill the V-groove with welds. Grind the weld and buff the repair area. The repair area should be smooth with the surface of the casting.
- Ultrasound the weld area after completion of the repair. This step is optional.
Repair of Cracks on the Lower Rack Stops and Dump Stops
The following procedure is for repairing cracks at the lower rack and dump stops. The lower rack and dump stops can be repaired if the crack is through the thickness of the boom.
- Ultrasound the boom near the crack in order to determine the depth of the crack. This step is optional.
- Measure the length and the depth of the cracks. Mark the length and the depth of the cracks.
- Grind the defective area until the crack is completely removed. Form a reasonably wide V-groove (12) in place of the crack. Avoid creating narrow V-grooves (13) .
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| Illustration 13 | g00430247 |
V-groove. (12) Recommended. (13) Not recommended. | |
- Use 4C-4736 Penetrant Kit in order to make sure that the crack is completely removed.
- Preheat the repair area around the V-groove to 121°C (250°F).
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| Illustration 14 | g00473267 |
(14) Boom. (15) Back-up strip. | |
Note: Back-up strip (15) may be necessary if the crack goes through the thickness of boom (14). The strip can be fabricated from 25.4 mm (1.00 inch) x 6.4 mm (0.25 inch) mild steel. This will provide a surface to weld against.
- Weld the repair area with one of the processes and with one of the filler metals that are listed in Table 1.
- Maintain a minimum interpass temperature of 38°C (100°F).
- Blend each weld with the other weld beads.
Note: Each weld should be free of crater cracks, slag inclusions, porosity, and any other visible discontinuity.
- Clean the weld after each pass.
- Needle peen or hammer peen each weld pass.
- Fill the V-groove with welds. Grind the weld and buff the repair area. The repair area should be smooth with the surface of the casting.
- Ultrasound the weld area after completion of the repair. This step is optional.