Repair Procedure for the Upper Hitch Assembly{7057, 7100} Caterpillar


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Repair Procedure for the Upper Hitch Assembly{7057, 7100} [REHS1611]
FRAME AND BODY
HITCH GP
Wheel Loader:
992G (S/N: 7HR1-UP; ADZ1-515)

This Special Instruction can be used to repair the upper hitch assembly.

------ WARNING! ------

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
----------------------

------ WARNING! ------

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.

----------------------

Table 1
Parts List    
Part Number     Part Description     Quantity    
234-2952     Hitch Assembly     1    
234-2983     Plate     1    
231-3518     Bracket As     1    

  1. Separate the loader frame and the rear frame. Refer to Disassembly and Assembly, SENR5893, "Loader Frame and Rear Frame - Separate" for the correct procedure.

  1. Establish the centerline of the upper hitch for boring after welding is complete.



    Illustration 1g01002357

    Dimensions are shown in millimeters.

  1. Mark lines for two cuts. The first line will be 365 mm (14.4 inch) from the center of the hitch. The second line will be 425 mm (16.7 inch) from the center of the hitch. This is also 253 mm (10.0 inch) from the front of the ROPS mounting bolts.

  1. Make the first cut (A) at 365 mm (14.4 inch) on the front edge of the vertical plate, as shown. Remove the upper hitch plate and the spreader plate (B) .

  1. Make the second cut at 253 mm (10.0 inch) from the ROPS mounting bolts. Use the ROPS mounting bolts as a reference point for the cut.

    Note: Remove only 60 mm (2.4 inch) of the upper hitch. The vertical straight plate between the hitch plates should not be removed.




    Illustration 2g00986680

    (C) 253 mm (10.0 inch) to ROPS bolts.

    (D) 425 mm (16.7 inch) to the hitch




    Illustration 3g01048015

    Typical view of the 992G (S/N: 7HR318-UP) Wheel Loader and the 992G (S/N: ADZ1-515) Wheel Loader

    Dimensions are shown in millimeters.

    (1) 234-2952 Hitch

  1. The edge of the cut should be beveled to a 30 degree angle. See Illustration 2.

    Note: The 992G (S/N: 7HR318-UP) Wheel Loader and the 992G (S/N: ADZ1-515) Wheel Loader have an existing 70 mm thick hitch plate. In this case, the rear surface of the new 231-2952 Hitch Assembly should also be beveled to a 30 degree angle. See Illustration 3.

  1. Install a backup strip (1) to the cut plate on the frame, as shown.

  1. Clean the area with a grinder and remove all debris.

  1. Some machines use a doubler plate on the lower hitch. The plate is similar to the 234-2983 Plate that is shown in illustration 7. If the doubler plate exists, the 234-2952 Hitch will need to be trimmed. The hitch needs to be trimmed in order to clear the plate before the new hitch assembly can be moved into the proper location. The 234-2983 Plate will need to be located on the top surface of the lower top hitch plate if the doubler plate is not present. See illustration 7. The 16 mm (.7 inch) weld that extends from location (H) to location (J) must be completed before the 234-2952 Hitch is installed.

  1. Position the new 234-2952 Hitch Assembly . Center the bore of the hitch with the centerline that was established in Step 2. Plate (3) may need to be trimmed in order to correctly locate the new hitch assembly. Plate (3) is located on the bottom side of the new hitch assembly. Keep the angle of the bevel consistent when you are trimming the plate in order to maintain the required size of the weld.

    Note: The new hitch assembly should be located vertically so that the front cab mounts are in line with the existing ROPS mounting pad.




    Illustration 4g01029073

    Dimensions are shown in millimeters.

  1. Use the above graphic as a reference in order to locate the correct location for the new hitch.



    Illustration 5g01029109

  1. Install tie bars (2) in order to control distortion during welding procedures.

    Note: Alternate welds in order to prevent warping of the hitch or the frame.




    Illustration 6g00991118

    Typical view of the 992G (S/N: 7HR1-317)

    Dimensions are shown in millimeters.

    (3) 234-2952 Hitch

  1. Create the 30 mm (1.2 inch) bevel groove weld and the 12 mm fillet weld by using one of the welding processes and filler metals that are listed in Table 2. Use a 70 mm bevel groove weld for the 992G (S/N: 7HR318-UP) Wheel Loader and the 992G(S/N: ADZ1-5151) Wheel Loader. See Illustration 6 and Illustration 3 for clarification. As you weld, be sure to observe the following at all times:

    • Maintain a minimum of 37.8 °C (100 °F) interpass temperature.

    • The weld passes should be blended smoothly with the other weld beads.

    • Each weld pass should be free of crater cracks, slag inclusions, undercuts, porosity, and any other visible discontinuities.

    • Clean the weld after each pass.




    Illustration 7g01002436

    Dimensions are shown in millimeters.

    Do not weld from location (J) to location (K) .

    Do not weld from location (M) to location (L) .

    Do not weld from location (K) to location (L) .

    (4) 234-2983 Plate .

  1. If the result is OK, weld a 12 mm (0.5 inch) fillet on top of the bevel groove weld.

    Table 2
    Recommended Welding Processes and Filler Metals    
    Welding Process     AWS Specification     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)    
    ( 1 ) This is used for horizontal welding.
    ( 2 ) This is used for all positions.

    Table 3
    Bore Dimensions for the Rear Frame
    Articulating Hitches    
    Bore     Diameter    
    E    
    184.25 ± .05 mm (7.254 ± .002 inch)    
    F    
    152.48 ± .05 mm (6.003 ± .002 inch)    
    G    
    133.40 ± .05 mm (5.252 ± .002 inch)    

    Note: Use Illustration 5 as a reference for the above table.

  1. After the welds cool, remove tie bars (1) that were installed in Step 12.



    Illustration 8g01002703

    Dimensions are shown in millimeters.




    Illustration 9g01002577

    Dimensions are shown in millimeters.

  1. Machine the bores from the centerline that was established in Step 2.

  1. Machine the upper face of the boss 442 mm (17.40 inch) above the counterbore. The counterbore is located at 1934 mm (76.14 inch) above the bottom surface of the lower plate.

  1. Check that the counterbore on the top surface of the lower plate is 90 mm (3.54 inch) above the lower surface. If the counterbore is not 90 mm (3.54 inch) above the lower surface, then the upper surface must be built up. The upper surface must then be machined in order to obtain the 2024 mm (79.69 inch) dimension.



    Illustration 10g01002442

    Dimensions are shown in millimeters.

  1. Drill 12 14.25 mm (.561 inch) holes to the upper hitch, as shown. Tap these holes by using a M16 x 2-6H tap. The threads should be 29 mm (1.142 inch) deep.



    Illustration 11g01002720

  1. Discard the old 126-3890 Plate Assembly for the steering neutralizer valve. Install a new 231-3518 Bracket Assembly (5). Reuse existing stops (6) and the existing hardware.

  1. Adjust the steering neutralizer valve. Refer to Testing and Adjusting, SENR1373, "Steering Neutralizer Valve - Check and Adjust" for the correct procedure.

  1. Connect the loader frame and the rear frame. Refer to Disassembly and Assembly, SENR5893, "Loader Frame and Rear Frame - Connect" for the correct procedure.

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