PRODUCT SUPPORT PROGRAM FOR INSPECTING AND REWORKING TAIL CASTINGS ON CERTAIN 777G AND 777G OEM OFF-HIGHWAY TRUCKS Caterpillar

PRODUCT SUPPORT PROGRAM FOR INSPECTING AND REWORKING TAIL CASTINGS ON CERTAIN 777G AND 777G OEM OFF-HIGHWAY TRUCKS

Usage:

TEBE5412-03

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27Oct2016

(Revised 05Jul2017)

R120
R12Z
U062
U066
U067
U068
U069
U135
U245
Z800

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Before/After (Limited distribution)	PRODUCT SUPPORT PROGRAM FOR INSPECTING AND REWORKING TAIL CASTINGS ON CERTAIN 777G AND 777G OEM OFF-HIGHWAY TRUCKS
7051 0679		PS45264

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NOTE:

Caterpillar’s obligations under this Service Letter are subject to, and shall not apply in contravention of, the laws, rules, regulations, directives, ordinances, orders, or statutes of the United States, or of any other applicable jurisdiction, without recourse or liability with respect to Caterpillar.

NOTE:

This Program must be administered either before or after failure. In either case the decision whether to apply the Program is made by the dealer. When reporting the repair, use "PS45264" as the Part Number and "7755" as the Group Number. If administered before failure, use "56" as the Warranty Claim Description Code and "T" as the SIMS Description code. If administered after failure, use "96" as the Warranty Claim Description Code, and "Z" as the SIMS Description Code.

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NOTE:

The information supplied in this service letter may not be valid after the termination date of this program. Do not perform the work outlined in this Service Letter after the termination date without first contacting your Caterpillar product analyst.

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NOTE:	This Revised Service Letter replaces the 27Oct2016 (Revised 07Jun2017) Service Letter. Changes have been made to the Affected Product.

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TERMINATION DATE

31Oct2018

PROBLEM

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The existing tail casting can crack due to thin wall thickness on certain 777G and 777G OEM Off-Highway Trucks in rough operating conditions. If the existing tail casting cracks, it can cause a more extensive repair to be needed.

AFFECTED PRODUCT

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Model	Identification Number
777G	TNM00104-00109, 121, 123, 125, 127, 143-145, 147, 149, 151-152, 167, 169, 171, 173, 226, 237, 239-240, 292, 294, 296, 298, 315, 320, 322-327, 337, 362-364, 381, 383, 388, 413, 432, 438-440, 448, 454-455, 487, 489-490, 492, 495, 497, 514, 516, 518, 520, 532, 534-540, 552, 554, 556, 558, 566, 568, 570-571, 576-577, 580-581, 601-602, 612, 614, 617-618, 622-624, 629-633, 644, 676-677, 682, 703-716
777G OEM	T4Y00100-00101, 126, 130, 153-155, 163, 177-178, 181

PARTS NEEDED

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No parts needed for this program

ACTION REQUIRED

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Measure tail casting thickness and build up wall thickness if less than minimum required. Refer to the attached Rework Procedure.

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SERVICE CLAIM ALLOWANCES

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Product smu/age whichever comes first	Caterpillar		Dealer Suggested		Customer Suggested
Product smu/age whichever comes first	Parts %	Labor Hrs%	Parts %	Labor Hrs%	Parts %	Labor Hrs%
0-25000 hrs, 0-60 mo	100.0%	100.0%	0.0%	0.0%	0.0%	0.0%

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NOTE: This is a 1.0-hour job
If the wall thickness is less than the minimum, it is considered a failure and 10 additional hours will be allowed for building up the wall thickness and blending with the tail casting.

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PARTS DISPOSITION

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Handle the parts in accordance with your Warranty Bulletin on warranty parts handling.

Rework Procedure

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If a crack is found, the Ultrasonic Thickness Inspection can be preformed to identify areas of casting not meeting minimum wall thickness. However, the cracks must be repaired prior to preforming the procedure to build up the wall thickness in areas not meeting minimum wall thickness.

Image1.1.1

Image1.1.2

Image1.1.3

Ultrasonic Thickness Inspection

Equipment ? Cat 168-7720 Ultrasonic Wear Indicator III Group (168-7721 UT Wear Indicator, 168-7722 UT Probe, and 9U-7981 UT Couplant)

Equipment Setup ? Ensure the UT probe is connected and the indicator is on by pressing the ON/OFF Key. The measured value needs to be displayed in MM to change press the MM/INCH key until MM is displayed. To calibrate the indicator apply a small amount of UT couplant on the face of the UT probe and place the probe on the Calibration Disk(6.3mm), then press the Probe Cal key, (Probe) will be displayed, continue to press the transducer to the calibration disk until the measured value display shows 6.3mm. If the thickness shown is not 6.3mm repeat the calibration process. Reference Image 1.2.1.

Image1.2.1

Inspection Procedure ? Couplant should be applied to the specific highlighted areas in Image 1.3.1. The areas should be scanned to get complete coverage of the entire area highlighted. Care should be taken to ensure proper thickness readings are observed. The measured value on the indicator will blink while scanning and denotes the indicator is getting readings. Not all areas will have parallel back walls and obtaining readings may be difficult in some areas. Reference Image 1.3.1 Section A-A and B-B for thickness profiles through the cross section.

Marking Areas for Repair ? If a thin wall condition is found, below minimum wall thickness, it is required to record the area and minimum thickness on the parts surface. The thin area should be mapped by placing the UT probe in the thin area and scanning outward until the thickness is found above nominal. At this point a mark should be made at the center of the transducer, repeat this action to provide an outline of the thin area on the part. The minimum thickness shall be recorded on the parts surface to help establish the thickness of weld repair. A picture of the thin area under the minimum thickness should be saved for future reference and documentation by truck serial number.

Inspection after Repair ? After the weld repair is finished per Image 1.8.1 the area of repair shall be inspected to ensure adequate buildup of weld material thickness equal to or greater than the nominal thickness requirements in Image 1.3.1. Follow initial inspection procedure for repair inspection.

Image1.3.1

If the area does not meet the ?minimum? wall thickness as depicted, then build up the appropriate area by welding to the "nominal" wall thickness shown in Image 1.3.1.

If a crack exists in one of the areas, repair the crack and then restore the area to the "nominal" wall thickness as depicted.

For those situations requiring build up:
Image 1.4.1 depicts an approximation of the cross section for a thin wall casting condition that is inspected to be below the ?minimum? wall thickness and requires the addition of weld metal. X represents the amount of material below the "nominal" wall thickness. X also represents the amount of material that will be needed to be added by welding to bring that area up to the "nominal" wall thickness.

Image1.4.1

Remove all the paint and contaminants from the surface to be welded. Preheat area if required.

Weld one layer of surfacing welds as depicted in Image 1.5.1. Utilizing a proper stacking technique, one layer of surfacing welds will add approximately 3 mm +/- 1 mm.

Note: Extend the first layer of surfacing welds at least 4 times the amount of X beyond the point where the wall is at minimum wall thickness.

Image1.5.1

Depending on the amount of material that is needed, a second layer may need to be added.

Prior to sanding, you will need approximately 2 mm more material.

Image 1.6.1 depicts what the second layer of surfacing welds should look like.

Image1.6.1

Note: The final layer should be approximately 2 mm higher (prior to sanding) than what is needed (X).

If a third layer is needed, continue the same sequence. Otherwise, sand approximately as shown in Image 1.7.1.

Image 1.7.1 depicts what the finished profile should look like.

Image1.7.1

Note: After completion of welding, blend sand the surfacing welds flush in the middle and taper the edges into the surrounding plate profile. There should be a seamless transition into the surrounding base material with no sharp notches at the interface. A 36 grit sanding disc should be used for the bulk of material removal and then finish sand with an 80 grit sanding disc.