Salvage of Planetary Carrier Pin Bores Using Tapered Roller Bearings for 785 and 789 Trucks{0760, 0761, 4050} Caterpillar

Off-Highway Truck/Tractor:

785 (S/N: 8GB1-UP)

785B (S/N: 6HK1-UP)

785C (S/N: 1HW1-UP; APX1-UP; 5AZ1-UP)

785D (S/N: DMC1-UP; MSY1-UP)

789 (S/N: 9ZC1-UP; 1KT1-UP)

789B (S/N: 7EK1-UP)

789C (S/N: 2BW1-UP)

Introduction

© 2011 Caterpillar All Rights Reserved. This guideline is for the use of Cat dealers only. Unauthorized use of this document or the proprietary processes therein without permission may be violation of intellectual property law.

This Reuse and Salvage Guideline contains the necessary information in order to allow a dealer to establish a parts reusability program. Reuse and salvage information enables Caterpillar dealers and customers to benefit from cost reductions. Every effort has been made in order to provide the most current information that is known to Caterpillar. Continuing improvement and advancement of product design might have caused changes to your product which are not included in this publication. This Reuse and Salvage Guideline must be used with the latest technical information that is available from Caterpillar.

For questions or additional information concerning this guideline, submit a form for feedback in the Service Information System. In order to address an urgent issue, use the following resources in order to communicate your request to Caterpillar Repair Process Engineering:

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Canceled Part Numbers and Replaced Part Numbers

This document does not include Canceled part numbers and replaced part numbers. Use NPR on SIS for information about Canceled part numbers and replaced part numbers. NPR will provide the current part numbers for replaced parts.

Summary

The outer planetary carriers on 785 and 789 Trucks can be salvaged and reconditioned to accept new tapered roller bearings.

This procedure can be used on 8W-1365 Planetary Carriers in this Guideline provide a method of salvaging carriers using the latest engineering design which will minimize owning and operating costs.

Illustration 1	g02160625
Salvage of carrier bolt holes and pin bores.

When used in the same application, parts that meet the "Use again " specifications in this guideline can be expected to give normal performance until the next overhaul. Never install a part that this guideline shows cannot be used again. During reconditioning, correct any conditions that might have caused the original failure.

Equipment and Tooling

The following list of machines and tooling is a recommended list. The salvage procedure can also be completed using equivalent machinery.

Machining Threaded Insert Installation Tool

A special tool is required to install the threaded insert without damage. Machine this tool from SAE 1020steel to the dimensions given in Illustration 2 and Table B. The 2F-6869 Dowel Pins are 7.93750 mm (0.3125 inch) diameter by 25.40000 mm (1 inch) long.

Illustration 2	g02160861
Threaded insert installation tool.

Fabricating Machining Fixture

A holding fixture or other holding device should be fabricated or obtained prior to starting the Salvage Procedure. This fixture is only a suggested tool. If other means of retaining the carrier during machining are available, they may be used.

It is recommended that all machining is completed at the same time. If the locating fixture is removed from the boring mill, it will need to be relocated and checked for alignment and Total Indicator Run-out prior to machining.

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Illustration 3	g02160864
Planetary locating fixture. See table C. Locating Fixture Dimensions for reference items.

1. Fabricate a holding fixture as shown in Illustration 3. All side plates and fixture base are made from 50 mm (1.96850 inch) thick SAE 1020 steel. After welding, the fixture must be stress relieved to prevent any improper alignment or movement of the fixture.

2. Machine side faces and base of the fixture. Cut a key way into the base of the fixture which corresponds to the key ways on the boring mill.

3. Drill and bore/ream a 12.50 mm (0.500 inch) center hole which will be used for an absolute zero point.

4. Drill and tap holes in the side of the fixture for 5/8-11 or 3/4-10 bolts. Holes should be on 75 mm (3.00inch) to100 mm (4.00 inch) centers from the absolute zero point. Drill 25 mm (1.00 inch) holes on all sides of the fixture. These holes can be used for locator pins and help to lighten the fixture.

Safety and Personal Protection

Safety glasses should be worn during machining operations and application of solvents. Contact lenses should not be worn while performing Any machining operations. Protective clothing and plastic or rubber protective gloves are also recommended when using chemical cleaning solutions.

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Personal injury can result from improper handling of chemicals. Make sure you use all the necessary protective equipment required to do the job. Make sure that you read and understand all directions and hazards described on the labels and material safety data sheet of any chemical that is used. Observe all safety precautions recommended by the chemical manufacturer for handling, storage, and disposal of chemicals.

Cleaning Procedure

Before a part is inspected, clean the part thoroughly following these steps.

1. When lifting or moving parts to be cleaned, use proper lifting devices for operator safety and to prevent machined surfaces from damage.

2. Wash each carrier separately. When several parts are washed together, machined surfaces can be damaged.

3. Use pressure air to dry parts.

4. If inspection is not done immediately after cleaning, put hydraulic oil on each machined face to prevent rust or corrosion. Then place the parts into a clean container.

Visual inspection

Visually determine if the carrier can be salvaged. Check for web cracks or other damage that would prevent the carrier from being used again. Check pin bores and counter bores for correct size. Determine if the pin bore can be machined oversize to accept the threaded inserts.

Illustration 4	g02160905
Inspection of thrust faces (2) and bolt hole mounting surface (1) .

The wheel mounting surface may require metal spray to repair damage caused by wheel loosening. Restore the flange thickness to its original dimension of 22.00 ± 0.51 mm (0.866 ± 0.020 inch). Do not use carriers with cracked bolt holes.

Illustration 5	g02161971
Inspect the carrier for cracks, elongation of bores, damaged thrust faces, and web area damage.

Illustration 6	g02161977
Carrier with cracked flange.

Do not use again

Web Cracks

Inspect the carrier for cracks in the web area. Refer to Reuse and Salvage Guidelines, SEBF8135, "Repair of Web Cracks in Final Drive Planetary Carriers" for additional information.

Illustration 7	g02161984
Typical location of web crack.

Preparation for Salvage and Machining the Threaded Insert

Before starting the salvage procedure, threaded inserts should be machined and ready to install.

Illustration 8	g02162179
Machining dimensions for threaded inserts. Refer to Table E for dimensions.

1. Machine the insert from SAE 1020 steel to the dimensions listed in Table E.

2. The inside diameter of the insert must be finish bored after installation into the carrier.

General Preparation

1. The carrier should be cleaned to remove all oil, grease, and debris prior to performing the savage procedure. See Cleaning Procedure.

2. Metal spray is an acceptable method of restoring a surface to its original size. Each step in the metal spray process is critical in achieving the desired coating, bond, and surface finish. Refer to Reuse and Salvage Guide, SERF8799, "Thermal Spray General Information Guide" for additional information about metal spray repair procedures.

   Note: Outer pin bores should not be metal sprayed. Evaluation of over-spray contamination is a major concern.

Salvage of Bolt Hole Face

Minor damage to bolt hole faces in the flange area of the carrier may be repaired with metal spray. More severe damage can be repaired using 6K-6351 Washers as spacers when the thrust faces are damaged more than 1.5 mm (0.060 inch) deep with a maximum of 3.05 mm (0.120 inch) with two washers.

To use the washer method of repair, counter bore the bolt hole to accept the washer. The counterbore diameter should be large enough that the washer slips into place. The depth should allow the washer to remain flush with the top of the flange surface.

Illustration 9	g02162203
Bolt hole salvage.

Note: When using this method of repair, use a maximum of two to three washers per hole. Do not exceed the maximum depth. Make sure that the face height of the washer is flush with the flange surface. When more than five bolt holes are damaged repair the surface using metal spray.

Salvage of Pin Bores

Illustration 10	g02162208
Fixture with locating blocks to position the carrier.

Illustration 11	g02162215
Carrier mounted on the fixture.

Illustration 12	g02162319

1. Correctly locate the carrier onto the fixture for machining. Establish the X and Y axes for machining. Establish the X and Y axes in relation to the four pin bores and absolute zero point. Refer to Illustrations 11 and 12. Locate carrier with pin bores aligned in vertical and horizontal directions. Refer to Illustration 11. Secure carrier to the holding fixture.

2. Check the center line of all four bores. Make sure the line of true position to each other does not exceed 0.01 mm (0.0004 inch). Outside diameter (Z) of 8W-1365 Carrier measures 1054.00 ± 0.08 mm (41.496 ± 0.003 inch). Distance (AA) measures 575.152 mm (22.643 inch). Radius (BB) measures 287.576 mm (11.3219 inch). Distance (CC) measures 406.694 mm (16.0116 inch) between adjacent bores.

3. Install a dial indicator into the spindle of the vertical mill and zero (center) the pin bore. Refer to Illustration 13.

   1. Place the spindle directly in line with one pin bore.
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   Illustration 13	g02162324
   Zeroing the center pin bore.

   2. Position the dial indicator into the pin bore hole and zero (center) to within 0.03 mm (0.001 inch) total indicator runout (TIR).

4. After the pin bore is centered, lock the vertical and horizontal axes to prevent movement of the table.

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Illustration 14	g02162332
Install the boring bar. Machining the pin bore and counterbore.

5. Remove the dial indicator and install the boring bar into the spindle. Refer to Illustration 14.

6. Rough machine the pin bore to 102.87 mm (4.050 inch) and finish machine to 105.156 ± 0.013 mm (4.140 ± 0.0005 inch) or size to fit threaded insert.

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Illustration 15	g02162336
Thread cutting tool.

7. Remove the boring bar and install thread cutting tool. Cut threads in the pin bore. Install the threaded insert to ensure a proper fit and remove the threaded insert.

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Illustration 16	g02162337
Installation of threaded insert.

8. Prior to final installation, the insert and the pin bore must be cleaned with 6V-1541 Quick Cure Primer to remove all contaminants. Inspect both pin bore and insert thoroughly.

9. The insert must be threaded into the pin bore to check the fit, eliminate burrs, and establish a permanent seat. The threaded insert must then be removed and inspected.

10. Coat the threaded insert with 9S-3263 Thread Lock Compound to promote thermal conduction of heat inside the bore and to prevent rotation of the threaded insert. Install insert to establish a permanent seat.

11. Finish bore the threaded insert to the finish dimensions shown in Table F and IIlustration 17.
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    Table 6

    Finish Machining Dimensions for Threaded Inserts Table F
    Item	Dimension
    DD	112.0 ± 0.5 mm (4.409 ± 0.020 inch)
    EE	85.013 ± 0.013 mm (3.3470 ± 0.0005 inch)
    FF	4.34 mm (0.171 inch)
    GG	134 mm (5.28 inch)
    HH	31 mm (1.220 inch)
    II	103.961 mm (4.093 inch)

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Illustration 17	g02166514
Finish bore the insert after installation into the 8W-1365 Planetary Carrier. See Table F for the dimensions.

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Illustration 18	g02166536
Automatic facing tool used to back-face the threaded insert.

12. use and automatic facing tool or back-facing tool to back-face the threaded insert if necessary.

13. Repeat Steps 2 through 11 on the remaining three bores.