Salvage of Outer Planetary Carrier Pin Bores, Using Metal Spray and Machining Operations for 793 Off-Highway Trucks{4001, 4008, 4050} Caterpillar

Off-Highway Truck/Tractor:

793 (S/N: 3SJ1-UP)

793B (S/N: 1HL1-UP)

793C (S/N: CBR1-UP; 4AR1-UP; ATY1-UP; 4GZ1-UP)

793D (S/N: FDB1-UP)

793F (S/N: SND1-UP; SSP1-UP; RBT1-UP)

Introduction

© 2014 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. Information contained in this document is considered Caterpillar: Confidential Yellow.

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:

• Caterpillar Dealer Technical Communicator

• Dealer Solution Network

• Caterpillar Technical Representative

• Knowledge Network

Canceled Part Numbers and Replaced Part Numbers

This document may 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 pin bores of Planetary Carriers used in 793 Off Highway Trucks can be salvaged and reconditioned. The repair procedure in this guideline provides a method of salvaging carriers using the latest engineering design which will minimize owning and operating costs.

When used in the same application, carriers that meet the 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 condition 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.

Important Safety Information

Illustration 1	g02139237

Follow all safety warnings. Most accidents that involve product operation, maintenance, or repair are caused by failure to observe safety warnings. An accident can often be avoided by recognizing potentially hazardous situations before an accident occurs. Personnel must be properly trained in order to perform maintenance, repair, or operate any machine. Safety precautions and warnings are provided this instruction and on Caterpillar products. These warnings should be observed before performing any procedures. Caterpillar cannot anticipate every possible circumstance that might involve a potential hazard. The warnings in this publication and on the product are not all inclusive.

The hazards are identified by the "Safety Alert Symbol" which is followed by a "Signal Word" such as "DANGER", "WARNING" or "CAUTION". The "WARNING" Safety Alert Symbol is shown in Illustration 2.

Illustration 2	g00008666

This safety alert symbol means:

Pay Attention!

Become Alert!

Your Safety is Involved.

The message that appears under the safety alert symbol explains the hazard.

Operations that may cause product damage are identified by "NOTICE" labels on the product and in this publication.

Caterpillar cannot anticipate every possible circumstance that might involve a potential hazard. The safety information in this document and the safety information on the machine are not all inclusive. Determine that the tools, procedures, work methods, and operating techniques are safe. Determine that the operation, lubrication, maintenance, and repair procedures will not damage the machine. Also, determine that the operation, lubrication, maintenance, and repair procedures will not make the machine unsafe.

The information, the specifications, and the illustrations that exist in this guideline are based on information which was available at the time of publication. The specifications, torques, pressures, measurements, adjustments, illustrations, and other items can change at any time. These changes can affect the service that is given to the product. Obtain the complete, most current information before you start any job. Caterpillar dealers can supply the most current information.

Cleaning Procedure

All parts should be cleaned thoroughly before inspection. Use the below procedure for cleaning the parts.

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

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

3. Use compressed air to dry parts.

Inspection of Planetary Carrier

Determine if bores can be salvaged by measuring the wear (elongation) of the bore on the output side. Measure in various locations around the diameter of the bore (60 degrees apart). The bores cannot exceed 1.27 mm (0.050 inch) out-of-round.

The total run-out of diameter (C) cannot exceed 0.15 mm (0.006 inch). If the run-out of diameter (F) is greater than 0.15 mm (0.006 inch), the pin bores cannot be salvaged. Refer to Illustration 7.

Metal Spray Terminology and Techniques

For further information on the equipment needed to perform thermal spray processes, refer to the following publications:

• Special Instruction, SEBF9236, "Fundamentals of High Velocity Oxygen Fuel (HVOF) Spray for Reconditioning Components"

• Special Instruction, SEBF9238, "Fundamentals of Arc Spray for Reconditioning Components"

• Special Instruction, SEBF9240, "Fundamentals of Flame Spray for Reconditioning Components"

Masking Aids

Masking is required to protect critical surfaces and holes from the effects of grit blasting and spraying. Any type of material that can withstand the effects of either operation is considered a suitable masking material.

The mask can be a permanent sheet metal cover or use other temporary material.

Temporary-type masking materials are:

• Hard rubber

• High temperature silicon rubber

• Several layers of duct or masking tape

• High temperature fiber type materials

• Cloths and liquids

Grit Blasting

Grit blasting for metal spraying operations should be considered surface texturing. Clean, dry compressed air, and a sharp, coarse blasting abrasive that is free from contaminants must be used to avoid finishing problems.

For surface preparation of a coating, a pressure type system is preferred. Pressure blast provides the surface texture and depth using steel grit. In grit blasting for surface preparation, a coarse grit of steel G25 should be used. Steel angular grit is recommended for use on softer steel materials, up to a hardness of Rc35 and cast material. The effective operational pressure for this grit is between to 620 to 680 kPa (90 to 99 psi). Steel angular grit must be kept free of any moisture contamination because it is an iron type of grit.

Note: Visually inspect to ensure grit sharpness. If dull or contaminated grit is found, replace the grit. Dull or contaminated grit will result in poor surface preparation and contaminants found in the grit are blasted in to the surface of the carrier itself.

Rotational/Transverse Equipment

Rotating cylindrical parts can be sprayed manually by hand or placed into a fixture on a transverse mechanism. Some type of rotational device dedicated solely to the metal spraying process, is recommended. Rotational equipment may be found to have limited capabilities, but equipment must have some type of variable rotational control to provide relatively high rpm capability. Specially designed rotating systems manufactured by Metco and other companies can withstand dusty spray environment, yet provide the parts rotational requirements.

Illustration 3	g02287753
8X-0603 Planetary Carrier positioned on rotational/transverse machine.

The following formulas can be used to calculate either rpm or Surface Feet Per Minute (SFPM) for a part:

(3.82 x SFPM) COATING AREA DIAMETER (inches) = Required rpm

0.262 x OPERATING RPM x COATING AREA DIAMETER (inches) = SFPM

For transverse motion of the metal spraying gun, the following guideline should be used to apply an even coating deposit.

For round/rotating work: Transverse the gun at 6.3 to12.6 mm (0.25 to 0.50 inch) per revolution.

Metal Spray Process

Metal spraying is a term used to describe a group of processes in which fine molten or semi-molten metallic or nonmetallic materials are deposited onto a prepared surface. Generally, metal spraying is considered to be a relatively "cold" method of part salvaging, when compared to welding or brazing. Metal spraying is considered a cold process because the surface temperature of the piece part is kept below 150 to 175 °C (302 to 315 °F) when a coating is being deposited. As a result, the part experiences no metallurgical or physical changes.

The Caterpillar salvage application and process orientation in this guideline are for the thermal (powder combustion) spray process. Applications detailed in this guideline assume the use of Metco 6P II spraying equipment and materials.

Illustration 4	g02289813
Cross section of a powder flame spray gun. (1) Oxygen (2) Fuel gas (3) Gun (4) Powder (5) Flame (6) Coating (7) Substrate (8) Spray stream (9) Nozzle (L) Length 102 to 254 mm (4.0 to 10.0 inch)

Pressure Feed

With a pressurized feeding system, the powder is transported and delivered to the gun by inert gas (pre-purified nitrogen or argon) at a constant rate, independent to the orientation or movement of the spray gun. In addition, the material feed rate (measured in pounds per hour) can easily be set, result, pressurized feeding offers more process control and deposit high quality, repeatable coating.

Coating

Since multiple particles are needed to create a coating, a number of transverse passes of the gun, applying 0.10 to 0.15 mm (0.004 to 0.006 inch) of coating material per pass, is required to produce the desired coating thickness. These multi-gun passes can be performed by hand holding the unit or mechanical (lathe) movement of the spray gun. In general, a coating can be applied greater than 2.54 mm (0.100 inch) per side thickness. The actual thickness of a coating depends on the amount of wear elongation of the part, plus an allowance for finishing. The finishing allowance is generally 0.51 to 0.64 mm (0.020 to 0.025 inch) on a side.

The coating will not provide any strength to a part. The function of coating is to add some desirable characteristics to the surface that is currently lacking in the worn piece part. Desirable metal spray characteristics include:

• Better wear characteristics

• Dimension restoration

• Corrosion protection

• Electrically conductive and resistive

Illustration 5	g02289933
Typical coating cross-section illustrates lamellar structure. (7) Substrate (10) Oxide inclusions (11) Pores/voids (12) Cohesive strength between particles (13) Particle (14) Substrate roughness (15) Adhesion to substrate (R) Substrate roughness

Preparation List for Planetary Carrier Salvage

Machining Dimensions

Illustration 6	g02291773
Bore location and finished dimensions.

Illustration 7	g02287633
Section M-M Salvage of 8X-0603, 200-6387, 200-6387 Planetary Carrier pin bores. (C) Flange diameter (D) Lower bore (E) Upper bore (F) Inside bore diameter

Refer to Table 4 or 5 for dimensions.

Note: Center of both bores (E) and (D) must be within 0.040 mm (0.0016 inch) of each other. Make sure that the line of true position is within 0.05 mm (0.002 inch) Total Indicator Reading (TIR) of the other bores and within 0.10 mm (0.004 inch) of the center bore.

Salvage Procedure

1. Correctly locate and secure the cleaned and inspected carrier onto the bed of a vertical boring machine or fabricated fixture.

2. Establish the (X) axis and (Y) axis in relation to the four bores, using the dimensions in Illustration 6.

3. Install a dial indicator into spindle on vertical boring machine and zero (center) the pin bore to within 0.25 mm (0.001 inch).

4. When the pin bore is centered, lock the vertical axis and horizontal axis to prevent table movement.

5. Remove the dial indicator and place boring bar into the spindle.

6. Rough machine the pin bores to the size specified below.

   Note: The center of the upper bore (E) must be within 0.040 mm (0.0016 inch) of the lower bore (D) centerline.

Show/hide table



Illustration 8	g02291793
Section N-N Rough machine all bores to the following dimensions and chamfer 45 degrees × 1.0 mm (0.04 inch). (G) 133 ± 1.0 mm (5.2 ± 0.04 inch). (H) 30.00 ± 0.05 mm (1.181 ± 0.002 inch) (E) 102.870 ± 0.03 mm (4.0499 ± 0.001 inch) (D) 132.334 ± 0.03 mm (5.2099 ± 0.001 inch)

7. Repeat Step 2 to Step 6 on the remaining three bores.

8. Remove carrier from machine or fixture and prepare the carrier for "Metal Spray".

9. Clean the surfaces to be sprayed with acetone.

10. Pre-heat carrier bores to 107 to 121 °C (225 to 250 °F) with an even heat from a rose bud and check carrier frequently with a thermometer so temperature is not exceeded.

11. Mask off all critical areas that are not to be grit blasted.

12. Grit blast areas to be metal sprayed on the side (E) of the planetary carrier only. Grit blast material is G25 steel angular grit, at a pressure of 620 kPa (90 psi).

13. Mask all surrounding bore areas not to be metal sprayed.

14. Cover all bores that are not being metal sprayed with a rubber cover plate, or other material.

15. Make sure that metal spray equipment is set up for the correct gas pressure and gas flows refer to Table 3.

16. Position gun and establish the rotational speed of carrier part at 91.4 SMPM (300 SFPM).

17. Metal spray one bore. Bring the part to a complete stop and use inside micrometer to measure bore at 60 degree intervals. If all dimensions are less than 100.571 mm (3.9595 inch) on face (E), proceed to the next bore. However, cover this bore prior to metal spraying the next bore (uncover only the bore to be sprayed).

18. Proceed to remaining bores following Step 15 to Step 17 on side (D) .

19. Cover all bores on side (E) of carrier.

20. Rotate carrier to side (D) and follow Step 5 to Step 16 on this side.

21. Metal spray one bore. Bring the part to a complete stop and use inside micrometer to measure bore at 60 degree intervals. If all dimensions in the bore are less than 130.000 mm (5.1181 inch) on face (D), proceed to the next bore. However, cover this bore prior to metal spraying the next bore (uncover only the bore to be sprayed).

22. When all bores are complete, glass bead the carrier to remove all masking material and overspray using BT-10 Round Glass bead at 620 kPa (90 psi) air pressure.

23. Thoroughly blow out all bolt holes and dead areas. Pay special attention to assure all grit and glass beads are removed prior to machining.

24. Correctly locate and secure the cleaned carrier on to the bed of the vertical boring machine or fabricated fixture.

25. Establish the (X) axis and (Y) axis in relation to the four bores, using the dimensions in Illustration 6 and Table 4.

26. Install a dial indicator into spindle on vertical machine and zero (center) the pin bore.

27. When the pin bore is centered to less than 0.03 mm (0.001 inch), lock the vertical axis and horizontal axis to prevent table movement.

28. Remove the dial indicator and place boring bar into spindle.

29. Finish machine the pin bores to the size specified in the Table 4 and Illustration 6.

Note: The center of the upper bore (E) must be within 0.040 mm (0.0016 inch) of lower bore (D). Make sure that the line of true position is within 0.05 mm (0.002 inch) and the Total Indicator Reading (TIR) of the bores are within 0.10 mm (0.004 inch) of the center bore.