Repair Procedure For The 16M Motor Grader Front Frame and Centershift Bracket{7050} Caterpillar

Motor Grader:

16M (S/N: B9H1-UP; R9H1-UP)

Introduction

This Special Instruction provides information on the areas of the frame assembly that should be inspected for cracks. The following areas are covered in this Special Instruction: general, inspection, centershift repair, TIG dressing procedure and weld quality criteria.

The supplemental product support literature should be used with the appropriate Service Manual and the appropriate Parts Manual that is available for each standard machine.

Read the entire Special Instruction. Understand the information before you perform any procedures. Understand the information before you order any parts.

Safety

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Do not attempt to assemble this machine until you read and you understand the assembly instructions. Improper assembly procedures could result in injury or death.

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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

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When a hoist is used to lift any part or assembly, stand clear of the area under the part being raised. Always make sure that the hoist has adequate lifting capacity and the wire cable is not damaged. Failure to follow this instruction could lead to injury or death. Approximate weights of the components are shown in the table which follows.

Processes for Welding

Do not weld in areas if there is a strong movement of air or in temperatures of less than 16 deg C (61 deg F).

The following welding processes are acceptable for this procedure:

• Gas metal arc welding (GMAW) Use 35 ± 5 cu ft per hour of shielding gas (75% argon and 25% carbon dioxide). The AWS Class ER70S-3 is a welding process that can be used with the following welders: Lincoln L-50 and Hobart HB-25. Comparable equipment may be used.

• Flux cored arc welding (FCAW) Use 35 ± 5 cu ft per hour of shielding gas (75% argon and 25% carbon dioxide). The FCAW process is called the AWS Class E71T-1 process.

References

ReferenceRefer to Operation and Maintenance Manual, SEBU7696, "Welding on Machines and Engines with Electronic Controls" for additional welding instructions.

ReferenceRefer to Special Instructions, REHS1841, "General Welding Procedures" for additional welding instructions.

ReferenceGuide, SEBD0512, "Service Welding Guide".

ReferenceRefer to Disassembly and Assembly, KENR6018 when you need to remove any components to repair the front frame.

Specifications for Cables, Chains, and Lifting Devices

Use approved cables, chains, and lifting devices in order to lift components. Refer to the weight from the manufacturer in order to determine the application when you select the following items: 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.

Note: The lifting devices that are shown in this publication are not Caterpillar parts.

Illustration 1	g00629745
Lift angles for lifting slings. (A) The load capacity is 100% of the working load limit for the sling. (B) The load capacity is 86% of the working load limit for the sling. (C) The load capacity is 70% of the working load limit for the sling. (D) The load capacity is 50% of the working load limit for the sling.

Replacement Parts

Illustration 2	g03664115
Bottom side of frame

Welder Qualification and Safety

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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

ReferenceSpecial Instruction, REHS1841, "General Welding Procedures".

All welders must be qualified for the material, process, and position in accordance with Caterpillar Service Manual, SEBD0512, "Service Welding Guide" or the specific requirements and rules as outlined in a recognized national or international specification standard applicable to the product being manufactured. Personal protection equipment should be worn in accordance with local safety policies. The welder must also be familiar with both the air Carbon Arc Gouging (CAC-A) and grinding processes. The welder must know how to use the processes safely.

Cleaning

Clean oil, grease, paint, dirt, and all other contaminants from the area to be repaired. Clean the area that is repaired by grinding, sanding, and rotary steel wire wheel. Area to be cleaned should extend at least 152.4 mm (5.99 inch) on all sides of the crack. Care should be taken when cleaning so that minimal base material thickness is affected.

Initial Bake and Preheat

Heat the repair area to a temperature of 100° C (212° F). Heating this area will remove all grease and thoroughly bake out any oil that may have been absorbed by the part or into the crack.

The minimum preheat temperature should be established at a distance that is at least equal to the thickness of the thickest member, but not less than 75 mm (2.95 inch) in all directions from the point of welding. Ensure that the full material volume surrounding the joint is heated. Heat the side opposite of the side which is to be welded. Measure the surface temperature next to the joint. The temperature may only be checked on the heated side. The heat source should be removed and sufficient time allowed for temperature equalization before measurement.

The interpass temperature should be checked in order to verify that the minimum preheat temperature has been maintained. The minimum preheat temperature should be maintained prior to initiating the arc for each pass. Preheat and interpass temperature can be measured with temperature indicating crayons, infrared thermometers, or thermocouples. Refer to Illustration 3 through 5.

Illustration 3	g02028619
Temperature indicating crayon

Illustration 4	g02028621
Thermometer

Illustration 5	g02028622
Type "K" thermocouple wires.

Inspection and Repair

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Illustration 6	g03664122
View of front covers

1. Remove front covers (A), (B), (C) and (D)

2. Remove the blade lift arms, refer to Disassembly and Assembly, KENR6018. Move or disconnect hydraulic and electrical lines as needed to access the centershift area for inspection and repair. Cap and cover all hydraulic and electrical lines to protect from debris and contamination. Cover the cab with weld blankets to protect the surfaces from slag and sparks.

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Illustration 7	g03664159
View of right rear inspection

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Illustration 8	g03664160
View of right rear inspection (old style fish plate)

3. Starting on the machine right side, inspect the area behind the centershift plate, refer to Illustration 7 and Illustration 8. Focus on the vertical weld seams and the four weld intersections. Look for any signs of cracking (cracked paint, visible rust seam, etc.). Magnetic particle or dye penetrant tests may be used to confirm a crack is present. Ensure that the frame top and bottom plates are inspected next to any of the weld intersections to ensure that no cracks are present. Pay particular attention to areas where weld terminations are present.

   Note: If your frame is equipped with the old style fish plates, see Illustration 8, these will be need replaced with the improved square style fish plates shown in Illustration 7. Refer to Special Instruction, REHS4249, "Front Frame Inspection and Crack Repair For 16M Motor Graders"

   If a crack is found in the vicinity of either of the rear weld intersections (locations (E) or (F), Illustration 7 or locations (G) or (H), Illustration 8), the rear vertical weld seam (between locations (E) and (F), Illustration 7), or in the top or bottom frame plates, refer to Special Instruction, REHS4249, "Front Frame Inspection and Crack Repair For 16M Motor Graders" to repair the cracks and replace the fish plates. Steps 24 through 29 in the Section "Crack Repair in bottom Plate" should be omitted. An improved bottom plate and weld procedure will be referenced later in this Special Instruction.

   If any cracking is present in the front vertical weld seam and there is no cracking present in either the top or bottom frame plates, the damaged weld can be gouged out and rewelded. The crack must be fully excavated to find the root. Multiple weld passes may be required to complete the repair. The final repair should be blended into the adjacent material. The weld starts and stops must be blended into the adjacent weld such that they are not readily visible.

   If no cracks are found, using a sanding disc, blend any weld terminations located in the areas shown in Illustration 7. Take care not to gouge the weld or remove any excessive weld material. Also, take care not to gouge or remove any of the base, parent material. The final blended weld should look like a continuous, smooth weld with no discernable starts or stops.

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Illustration 9	g03664800
Inspection between centershift plates

4. Looking between the centershift plates on the right side of the machine, inspect for any signs of cracking at the intersections of the welds at the top and bottom corners of the centershift plates. Inspect the top and bottom plates near the welds to ensure that no cracking is present. The vertical welds between the centershift plates should also be inspected for any cracks. If any deficiencies are found, refer to Special Instruction, REHS4249, "Front Frame Inspection and Crack Repair For 16M Motor Graders". Again, steps 24 through 29 in the Section "Crack Repair in bottom Plate" should be omitted. An improved bottom plate and weld procedure will be referenced later in this Special Instruction.

   If any visible or abrupt weld starts or stops are present, using a sanding disc, blend any weld terminations located in the areas shown in Illustration 9. Take care not to gouge the weld or remove any excessive weld material. Also, take care not to gouge or remove any of the base, parent material. The final blended weld should look like a continuous, smooth weld with no discernable starts or stops.

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Illustration 10	g03664920
View of right front inspection

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Illustration 11	g03664938
View of right front inspection (old style fish plate)

5. On the right side of the machine, inspect the area in front of the centershift plate as shown in Illustration 10 and Illustration 11. Focus on the vertical weld seams and the four weld intersections. Look for any signs of cracking (cracked paint, visible rust seam, etc.). Magnetic particle or dye penetrant tests may be used to confirm a crack is present. Ensure that the frame top and bottom plates are inspected next to any of the weld intersections to ensure that no cracks are present. Pay particular attention to areas where weld terminations are present.

   Note: If your frame is equipped with the old style fish plates, see Illustration 11, replace fish plates with the improved square style fish plates shown in 10. Refer to Special Instruction, REHS4249, "Front Frame Inspection and Crack Repair For 16M Motor Graders"

   If a crack is found in the vicinity of either of the front weld intersections (locations (J) or (K), Illustration 10 or locations (L) or (M), Illustration 11), the front vertical weld seam (between locations (J ) and (K), Illustration 10), or bottom frame plates, refer to Special Instruction, REHS4249, "Front Frame Inspection and Crack Repair For 16M Motor Graders" to repair the cracks and replace the fish plates. Steps 24 through 29 in the Section "Crack Repair in bottom Plate" should be omitted. An improved bottom plate and weld procedure will be referenced later in this Special Instruction.

   If any cracking is present in the rear vertical weld seam and there is no cracking present in either the top or bottom frame plates, the damaged weld can be gouged out and rewelded. The crack must be fully excavated to find the root. Multiple weld passes may be required to complete the repair. The final repair should be blended into the adjacent material. The weld starts and stops must be blended into the adjacent weld such that they are not readily visible.

   If no cracks are found, using a sanding disc, blend any weld terminations located in the areas shown in Illustration 10. Take care not to gouge the weld or remove any excessive weld material. Also, take care not to gouge or remove any of the base, parent material. The final blended weld should look like a continuous, smooth weld with no discernable starts or stops.

6. Following the same procedure, inspect the left side of the frame in the centershift area. Working from the rear of the machine to the front, identify and repair any cracks.

Bottom Reinforcement Plate Installation

A bottom reinforcement plate has been designed to improve the weld fatigue life of the centershift welds. If a bottom reinforcement plate is already installed on the frame, removing the existing bottom plate and installing a new one will not improve the overall centershift life. Inspect the welds on the existing reinforcement plate and the adjacent base material to ensure that no cracking is present. Ensure that no weld discontinuities exist. Blend the existing weld starts and stops into the adjacent weld material. The finished weld should be smooth and uniform in appearance with no visible starts or stops. Once the existing bottom reinforcement plate welds are inspected, repaired, and blended properly, skip to ""TIG Dressing Procedure" " Section.

If the frame does not already have a bottom plate, refer to the following procedure to install the bottom reinforcement plate.

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Illustration 12	g03666251

1. Remove hardware from the bottom of the frame, see Illustration 12. Take care not to gouge the bottom plate. All weld material must be removed and area blend smooth and flush with the frame bottom plate of the frame.

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Illustration 13	g03666273

2. Remove all paint from the area where the bottom plate will be welded as shown in Illustration 13.

3. In order to position new reinforcement plate (2) on bottom of the frame, it has to be fed through the centershift bracket from the front side of the centershift bracket. The rear of plate (2) can be identified by the slots that are cut out. Use two people to position th plate, the weight of plate (2) is approximately 80 kg (175 lb).

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Illustration 14	g03666398

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Illustration 15	g03666387

4. Use a crane or C-clamps to secure plate (2) in position. The plate should follow the contour of the frame. Try to locate the new plate by minimizing gap between reinforcement plate and bottom of frame. Illustration 14 shows a crane and strap used to hold plate in position. Illustration 15 shows clamps on rear section of plate to hold in position. With the cab and hydraulic and electrical components installed on the machine, clamps may need to be positioned on the lower flange of the frame and a bar used across the bottom to provide clamping force on the reinforcement plate.

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Illustration 16	g03666779
Centering of bottom plate

5. Center plate (2) on the bottom of the frame. Measure from the outside of the frame to the edge of the plate, there should be approximately 62 mm (2.44 inch) (A) on either side of the plate.

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Illustration 17	g03666828
View of gap inspection area

6. Inspect the fit-up of the plate. Pay particular attention to the area shown in Illustration 17. All gaps should be 5 mm (0.20 inch) or less. If any gaps exist that exceed 2 mm (0.08 inch), the weld must be oversized to compensate. The leg length of the fillet weld must be oversized by the amount of the gap; for example, if the nominal weld is 14 mm (0.55 inch) and a 4 mm (0.16 inch) gap exists, the leg length of the fillet weld in that area must be increased to 18 mm (0.71 inch).

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Illustration 18	g03666854
View of tack welded plate

7. Once plate (2) is properly located for best fit-up and centered, tack into position starting at the rear. Tack welds should be 15 mm (0.59 inch) to 20 mm (0.79 inch) in length and spaced out approximately every 150 mm (5.90 inch).

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Illustration 19	g03666860
View of weld locations on the bottom of the frame (2) Reinforcement plate (B) 1060 mm (41.73 inch) (C) 1010 mm (39.76 inch) (D) 450 mm (17.72 inch) (E) 500 mm (19.69 inch) (F) 825 mm (32.48 inch) (G) 875 mm (34.45 inch) (H) 75 mm (2.95 inch) (W1) 14 mm (0.55 inch) fillet weld (W2) 5 mm (0.20 inch) fillet weld

8. Mark out the perimeter weld as shown in Illustration 19. Once plate (2) is marked, finish weld the plate. Blend all starts and stops. Ensure transitions between the two sizes of fillet welds are smooth.

   W2 - 5 mm (0.20 inch) fillet weld

   • (AR) to (AS)

   • (AT) to (AU)

   • (AV) to (AX)

   • (AZ) to (AY)

   W1 - 14 mm (0.55 inch) fillet weld

   • (AY) to (AR)

   • (AX) to (AZ)

   • (AU) to (AV)

   • (AS) to (AT)

   Note: The 14 mm (0.55 inch) fillet weld (W1) should be made in a minimum of three stringer passes.

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Illustration 20	g03667364
(2) Reinforcement plate (W3) 12 mm (0.47 inch) fillet weld

9. Weld (W3) the three slots at the rear of plate (2). Blend welds as needed to ensure a smooth and uniform final weld.

After completing all the welds, inspect the welds according to ""Weld Quality Criteria" ".

TIG Dressing Procedure

Note: The fatigue performance is controlled by the profile of the weld toe. This applies to fabricated structures that have fillet welded attachments to highly stressed members. The fatigue performance can be improved by altering the original welded toe profile. This can be achieved by using several post weld treatment options. This procedure describes a method of using an electric arc to reduce adverse profiles and stress risers. This creates a seamless transition from one component to the next component.

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Illustration 21	g03667539
2.4 mm (0.09 inch) Tungsten Electrode Preparation (A) Serrations or Grinding Marks

1. Cleanliness and tungsten electrode preparation are the first steps in order to ensure that a proper TIG dressing is achieved. All contaminants must be removed from the fillet weld and the surrounding base metal. All rust, dirt, oil, scale, and silicate islands must be removed. This can be accomplished quickly via a grinder with a carbon steel wire attachment.

2. Prepare a 2.4 mm (0.09 inch) tungsten electrode. Refer to the dimensions that are shown in Illustration 21. The serrations should run parallel to each other.

3. Adjust the shielding gas flow rate to 15 CFH. Adjust the current control to approximately 200 amps. If a ramp down control is present on the power source, utilize the ramp down control to ensure that proper crater fill control is achieved.

4. A number of different techniques exist for TIG dressing. This is due to the variation of the contour of the fillet weld toe. The contour of the fillet weld toe must be reshaped. Use a stringer or weave manipulation of the torch in order to achieve a smooth radius of the weld. A minimum radius of 5.0 mm (0.20 inch) must exist between the base material and the weld metal.

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Illustration 22	g02585257
Stringer Technique

Note: Use a 10 to 15 degree push angle for the stringer technique.

5. Illustration 22 represents the stringer technique of welding. The center of the arc needs to be 0.0 - 2.0 mm (0.0 - 0.08 inch) from the weld toe into the base material.

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Illustration 23	g02585296
Weave Technique

Note: Use a 10 to 15 degree push angle for the weave technique.

6. Illustration 23 represents the weave technique of welding.

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Illustration 24	g02585300

7. Illustration 24 represents a cross section view of a proper TIG dressed fillet weld.

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Illustration 25	g02585301

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Illustration 26	g02585303

8. Illustration 25 and Illustration 26 are examples of expected results.

9. Once TIG dressing is completed, the area needs to be cleaned and painted in order to prevent pitting due to corrosion.

   Note: Poorly shaped fillet welds with 70 degree to 90 degree transition angles will require several overlapping TIG dressing runs. Overlapping of the TIG dressing runs is required in order to stabilize the weld toe transition area.

   Note: TIG dressing can be conducted in the vertical position as long as the TIG dressing is performed in a downhill progression.

   Note: Some undercuts will require the addition of filler metal. This can be accomplished by hand feeding ER70S-2 1.5 mm (0.06 inch diameter) into the weld pool. You then repeat the TIG dressing in order to achieve the desired toe radius and the desired profile. Inspect using a radius gage to ensure a 5 mm (0.20 inch) minimum radius.

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Illustration 27	g03667512
(B) 75 mm (2.95 inch)

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Illustration 28	g03667708
Detailed view of TIG toe dressing

10. TIG dressing needs to be applied to the front and rear ends of plate (2) as shown in Illustration 27. It must extend 75 mm (2.95 inch) (B) past the radii. The TIG dressing is to be applied at the weld toe on the main bottom plate of the frame as shown in Illustration 28.

    Note: If the frame had a previous bottom plate installed, perform a similar TIG dress procedure on that plate concentrating on the radii at the front and rear edges of the plate.

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Illustration 29	g03667556
(B) 75 mm (2.95 inch)

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Illustration 30	g03667722
(L) Fish plate

11. Apply a TIG dressing to the toe of the vertical fish plate weld and extend the TIG dressing 75 mm (2.95 inch) along the side plate to frame top plate and side plate to frame bottom plate welds, see Illustration 29, TIG dressing should be applied continuously from location (C) to (D), (D) to (E), and (E) to (F). Then (G) to (H), (H) to (J), and (J) to (K). Also, see Illustration 30 for detailed location of the TIG dressing. Ensure prior to TIG dressing that the weld start and stops in this area are adequately blend ground; the weld should look uniform in appearance with no visible starts or stops. The TIG dressing should be continuous to provide a maximum benefit to the fatigue resistance of the weld. Both the right and left sides of the frame should be TIG dressed in these areas for a total of four locations.

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Illustration 31	g03667735
TIG dress on rear vertical seam of rear centershift plate

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Illustration 32	g03667747
Details of Rear Centershift Plate TIG Dressing (B) 75 mm (2.95 inch)

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Illustration 33	g03667748
Details of Rear Centershift Plate TIG Dressing

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Illustration 34	g03667749
Front Centershift Plate TIG Dressing

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Illustration 35	g03667750
Details of Front Centershift Plate TIG Dressing

12. Apply a TIG dressing to the welds on the front and rear of the centershift plates. Ensure that all weld starts and stops are blended prior to TIG dressing. Properly blended welds should be uniform in appearance without readily visible starts or stops. For the rear centershift plate, the TIG dressing should extend the entire length of the rear vertical seam. It will wrap around the top and bottom of the centershift plate and 75 mm (2.95 inch) down the other side on both ends. The front centershift plate is similar except that the vertical weld on the forward side of the plate will receive the TIG dressing for the entire length of the weld and it will wrap around to the rear side of the plate.

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Illustration 36	g03667429
(1) Boss (L) 40 ± 5 mm (1.57 ± 0.20 inch) (M) 316 ± 5 mm (12.44 ± 0.20 inch) (N) 477.5 mm ± 5 mm (18.799 inch ± 0.20 inch) (P) 852 mm ± 5 mm (33.54 inch ± 0.20 inch) (R) 1032.5 mm ± 5 mm (40.649 inch ± 0.20 inch) (W4) 3 mm (0.12 inch) fillet weld

13. Weld four bosses (4) as shown in Illustration 36.

14. After final inspection of all welds, paint frame as required for corrosion protection. Reinstall lift arms, reassemble electrical and hydraulic components as required and reinstall front covers. Refer to Disassembly and Assembly, KENR6018.

Weld Quality Criteria