Repairing Track Roller Frames{4151} Caterpillar

Track-Type Loader:

973 (S/N: 66G1-UP; 86G1-UP; 90L1-UP; 91L1-UP; 26Z1-UP; 32Z1-UP)

973C (S/N: 3RZ1-UP)

Introduction

The 973 Track-Type Loaders that are used in severe applications may eventually show cracks on the track roller frame. This publication will show the two areas that the cracks may occur. This publication will also show the methods that are necessary in order to repair the cracks.

Note: A stronger track roller frame went into production on the 973C, that is effective with the following Track-Type Loader: BCP1. This loader does not require the addition of support plates.

This publication will be divided into two sections. Each section will cover a specific area of the frame and the fabricated parts that will be needed in order to repair that area.

Reference: Service Manual

Cracks between the Wrapper Plate and The Track Adjuster Access Casting

Illustration 1	g01089190

Crack (A) usually starts in the weld on the top of the track roller frame. Crack (A) usually continues to the wrapper plate.

Fabricated Parts

Illustration 2	g01089216

Fabricate one plate for each cracked roller frame with 8.0 mm (0.32 inch) thick high strength structural steel with a 289.4 MPa (4200 psi) yield strength.

Making the Repair

1. Use an air carbon arc torch, or similar tooling, in order to remove all cracks and the cracked weld bead.

   Note: It may be necessary to disassemble the recoil spring in order to protect the recoil spring from damage during the repair process. Refer to the Service Manual for instruction on removing the recoil spring.

2. Weld the wrapper plate and reweld the wrapper plate to the casting for the access plate.

3. Grind all repair welds flush with the wrapper plate.

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Illustration 3	g01089218

4. Position the fabricated plate, as shown.

5. Weld both sides (A) with an 8.0 mm (0.32 inch) fillet weld.

Cracks on the Rear of the Track Roller Frame

Illustration 4	g01089220
(1) Bead between the wrapper plate and the end plate (2) Crack (3) Wrapper plate (4) Vertical end plate

Making the Repair

Illustration 5	g01089231
Section view of cracked area

1. Remove bead (1) and all cracks (2) between wrapper plate (3) and end plate (4) .

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Illustration 6	g01089235
(A) Removed weld and crack

2. Minimize the gap at location (B) between the end plate and the wrapper plate. Use a torch to heat the wrapper plate and bend the wrapper plate toward the end plate.

3. Weld the end plate and the wrapper plate together at location (A) with a 6.4 mm (0.25 inch) bevel weld.

4. Allow the weld to cool. Inspect the weld in order to verify that the crack does not reappear.

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Illustration 7	g01089239

5. If the crack reappears, fabricate a reinforcing plate with 6.4 mm (0.25 inch) thick mild steel, as shown.

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Illustration 8	g01089241

6. Position reinforcement plate (5), as shown.

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Illustration 9	g01089242

7. Tack weld plate (5) in place.

8. Weld plate (5) with a 12.0 mm (0.47 inch) fillet weld at location (C) .

9. Weld plate (5) to wrapper plate (3) at location (D) with a 6.0 mm (0.24 inch) fillet weld.