Inspection and Salvage of Front Wheel Spindles for Off-Highway Trucks {4201, 4205} Caterpillar

Inspection and Salvage of Front Wheel Spindles for Off-Highway Trucks {4201, 4205}

Usage:

769C 01X

Mining Truck: 794 AC (S/N: HRT1-UP)
Off-Highway Truck/Tractor: All

Introduction

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Table 1
Revision	Summary of Changes in SEBF9309
07	Updated the References Table 2 with more references. Updated Illustrations 25, 34, 37,39,40,41, and 42 with new Illustrations. Updated Tooling & Equipment Table 3. Added Carbon Fiber Snap Gages (outside micrometers) to the Tooling and Equipment Table.3. Added "Laser Heat Treated Areas Cracking (Bearing - Journals)" section. Updated "Crack Detection Methods" section. Updated boilerplate information.
06	Updated copyright date to 2018. Updated Repair Process Engineering (RPE) point of contacts. Added Special Instruction, SEBF9240, "Fundamentals of Flame Spray for Reconditioning Components" to the "References" table. Updated "Crack Detection Methods" section. Inserted wheel group column and part numbers in to Tables 6 and 7. Inserted contents from SEBF2169 Reuse and Salvage Guidelines , "Thermal Spray Procedures for OHT Front Spindles".
05	Corrected dimension in Table 6.
04	Corrected dimension in Table 6.
03	Added one part number.

© 2019 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 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 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 technical questions when using this document, work with your Dealer Technical Communicator (TC).

To report suspected errors, inaccuracies, or suggestions regarding the document, submit a form for feedback in the Service Information System (SIS web) interface.

Canceled Part Numbers and Replaced Part Numbers

This document may include canceled part numbers and replaced part numbers. Use the Numerical Part Record (NPR) on the Service Information System Website (SIS web) for information about canceled part numbers and replaced part numbers. NPR will provide the current part numbers for replaced parts.

Note: This document can be used for reuse and salvage procedures of the Front Wheel Spindles for Off-Highway Trucks.

Important Safety Information

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Illustration 1	g02139237

Work safely. Most accidents that involve product operation, maintenance, and repair are caused by failure to observe basic safety rules or precautions. An accident can often be avoided by recognizing potentially hazardous situations before an accident occurs. A person must be alert to potential hazards. This person should also have the necessary training, skills, and tools to perform these functions properly. Safety precautions and warnings are provided in this instruction and on the product. If these hazard warnings are not heeded, bodily injury or death could occur to you or to other persons. Caterpillar cannot anticipate every possible circumstance that might involve a potential hazard. Therefore, the warnings in this publication and the warnings that are on the product are not all inclusive. If a tool, a procedure, a work method, or operating technique that is not recommended by Caterpillar is used, ensure that it is safe for you and for other people to use. Ensure that the product will not be damaged or the product will not be made unsafe by the operation, lubrication, maintenance, or the repair procedures that are used.

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Improper operation, lubrication, maintenance or repair of this product can be dangerous and could result in injury or death.

Do not operate or perform any lubrication, maintenance or repair on this product, until you have read and understood the operation, lubrication, maintenance and repair information.

Safety precautions and warnings are provided in this manual and on the product. If these hazard warnings are not heeded, bodily injury or death could occur to you or to other persons.

The hazards are identified by the “Safety Alert Symbol” which is followed by a “Signal Word” such as “DANGER”, “WARNING” or “CAUTION”. Refer to Illustration 2 for an example of a “WARNING” Safety Alert Symbol.

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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.

Summary

This guideline provides the procedures that are necessary to determine the reusability for front spindles / front axles on Off-Highway Trucks. Life will vary depending on application, load, lubrication, and environment.

This guideline contains the latest standards of engineering, which will help minimize owning and operating costs. A part is expected to reach the next Planned Component Rebuild (PCR) if the part meets the specifications within this guideline and the part is intended for a similar application. Use this guideline to determine whether a part should be reused. Do not install a part that is not reusable. During reconditioning, correct any condition that might have caused the original failure.

The dimensions and tolerances provided are to return a part / component to specification. The dimensional information alone is not solely used to condemn a part from reuse. Follow the "Visual Surface Inspection" and "Crack Detection Methods" sections for further guidance.

References

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Table 2
References
Media Number	Publication Type & Title
Channel1	"Gear Tooth Inspection"
	https://channel1.mediaspace.kaltura.com/media/Gear+Tooth+Inspection/1_5ujdi5zp
	"Why Reuse and Salvage Parts"
	https://channel1.mediaspace.kaltura.com/media/Why+Reuse+and+Salvage+Parts/0_ae9rhu2z
PERJ1017	Special Publication "Dealer Service Tools Catalog"
SEBD0512	Reuse and Salvage Guidelines , "Caterpillar Service Welding Guide"
SEBF8187	Reuse and Salvage Guidelines , "Standardized Parts Marking Procedures"
SEBF8443	Reuse and Salvage Guidelines , "Procedure to Inspect and Repair Wheels Used on Off-Highway Trucks"
SEBF9236	Reuse and Salvage Guidelines , "Fundamentals of HVOF Spray for Reconditioning Components"
SEBF9238	Reuse and Salvage Guidelines , "Fundamentals of Arc Spray for Reconditioning Components"
SEBF9240	Reuse and Salvage Guidelines , "Fundamentals of Flame Spray for Reconditioning Components"

Service Letters and Technical Information Bulletins

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NOTICE

The most recent Service Advisories, Service Letters, and Technical Service Bulletins that are related to this component should be reviewed before beginning work. Often Service Advisories, Service Letters, and Technical Service Bulletins contain upgrades in repair procedures, parts, and safety information which pertain to the components being repaired.

Tooling and Equipment

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NOTICE

Failure to follow the recommended procedure or the specified tooling that is required for the procedure could result in damage to components. To avoid component damage, follow the recommended procedure using the recommended tools.

Note: The Tooling and Equipment in Table 3 is not an all inclusive list of Tooling required to perform every task within this document. Tooling needs may vary for the scope of work to be performed for each specific rebuild.

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Table 3
Tooling and Equipment
Part Number	Description	Designation
— ⁽¹⁾	Personal Protective Equipment (PPE)	Personal Protection
— ⁽¹⁾	Tool (Cribbing)	Component Repositioning and Movement
1P-3537	Dial Bore Gauge Kit	Internal Measurement Checks
1U-5516	Disc Coarse	Surface Preparation / De-burring
1U-5518	Threaded Shaft	Surface Preparation / De-burring
1U-5519	Holder (Disc Pad)	Surface Preparation / De-burring
1U-9918	Brush	General Cleaning
—	Penetrating Oil	Liquid Penetrant Testing (PT)
—	Developer	Liquid Penetrant Testing (PT)
4C-8514	Wheel (2 x 1 inch) (60 Grit)	Surface Preparation / De-burring
4C-8515	Flapper Wheel (2" x 1" 120 grit)	Surface Preparation / De-burring
4C-8516	Flapper Wheel (2" x 1" 180 grit)	Surface Preparation / De-burring
4C-8521	Wheel Adapter	Surface Preparation / De-burring
4C-9616	Blanket 183 cm (72 inch) x 183 cm (72 inch)	Post Welding Treatment
5P-1720	Seal Pick	Gear/ Shaft Step Inspection
6V-6035	Hardness Tester	Hardness Check
6V-6042	Indicator Point Group	Run-Out Checks
8S-2257	Magnifying Glass	Visual Surface Inspection (VT)
8T-5096	Tool Group Dial Indicator	Run-Out Checks
8T-7765	Surface Reconditioning Pad (180 Grit)	General Cleaning
9A-1593	Comparison Gauge (Surface Texture)	Surface Texture Tester
9U-6382	Grinding Wheel	Surface Preparation / De-burring
9U-6383	Grinding Wheel	Welding Preparation Weld Removal/ Crack Excavation
9U-7377 ⁽²⁾	Metal Marking Pen	Parts Marking
162-5791	Towel	General Cleaning
222-3074	Wheel Grinder Group	Welding Preparation Weld Removal/ Crack Excavation
222-3076	Die Grinder (Right Angle)	Surface Preparation / De-burring
236-8097	Carbide Bur	Welding Preparation Weld Removal/ Crack Excavation
251-0030	Infrared Thermometer	Temperature Checks
254-5314	Flap Brush Assembly 3" x 2" 120 grit	Surface Preparation / De-burring
254-5315	Flap Brush Assembly 3" x 2" 240 grit	Surface Preparation / De-burring
263-7184	Crack Detection Kit (Magnetic Particle)	Dry Magnetic Particle Testing (MPT)
288-2512	Grinder 4½ inch	Welding Preparation Weld Removal/ Crack Excavation
362-4253	Gauge Kit Electronic Depth 0.0 - 600 mm (0.0 - 24.0 inch)	Depth Measurement Checks
385-9422	Micrometer Internal Micrometer Set 2-24 inch	External Measurement Checks
386-3364	Straight Edge Ruler 1000.0 mm (39.37 inch)	Measurement Checks
448-3698	Indicator (Profilometer)	Surface Texture Tester
458-9587 ⁽³⁾	Paint Yellow	Touch Up
459-0184	Lamp Group Ultraviolet	Wet Magnetic Particle Testing (MPT)
467-0158	Abrasive Material (Roll)	General Cleaning
473-8688 or 473-8689	Instrument Group Micrometer, Inside 2.00 - 12.00 inch	Internal Measurement Checks
473-8688 or 473-8689	Instrument Group Micrometer, Inside 50 - 300 mm	Internal Measurement Checks
473-8690	Instrument Group Outside Micrometer Set 0.00 - 4.00 inch	External Measurement Checks
473-8691	Instrument Group Outside Micrometer Set 2-6 inch	External Measurement Checks
473-8692	Instrument Group Micrometer, Outside - Digital 152.4 - 304.8 mm (6.00 - 12.00 inch)	External Measurement Checks
90141-2 ⁽⁴⁾	Instrument Group Carbon Fiber Snap Gages Gage to Check 425.415 ± 0.025 mm (16.74859 ± 0.00098 inch)	External Measurement Checks
92268-2 ⁽⁴⁾	Instrument Group Carbon Fiber Snap Gages Gage to Check 288.895 ± 0.025 mm (11.37380 ± 0.00098 inch)	External Measurement Checks
92270-2 ⁽⁴⁾	Instrument Group Carbon Fiber Snap Gages Gage to Check 234.92 ± 0.025 mm (9.24880 ± 0.00098 inch)	External Measurement Checks
92531-2 ⁽⁴⁾	Instrument Group Carbon Fiber Snap Gages Gage to Check 317.457 ± 0.025 mm (12.49828 ± 0.00098 inch)	External Measurement Checks
92718-2 ⁽⁴⁾	Instrument Group Carbon Fiber Snap Gages Gage to Check 346.032 ± 0.025 mm (13.62328 ± 0.00098 inch)	External Measurement Checks
474-3709 or 474-3710	Instrument Group Micrometer, Inside (8.00 - 32.00 inch)	Internal Measurement Checks
474-3709 or 474-3710	Instrument Group Micrometer, Inside 200 - 800 mm	Internal Measurement Checks
479-5400 ⁽⁵⁾	Paint Yellow	Touch Up
549-3510	Pin Set 8.0 mm	Measurement Between / MOP Gear/ Spline Wear Inspection
549-3520	Tool (Magnet) ⁽⁶⁾	Gage Pin Magnetizer/ Demagnetizer
—	Arc Spray system or HVOF system	Metal spray
—	Adequate lathe	Machining

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⁽¹⁾	Refer to PERJ1017Special Publication, "Dealer Service Tools Catalog" for Personal Protective Equipment (PPE) part numbers suitable by geographic location and local safety standards.
⁽²⁾	Available in the United States only.
⁽³⁾	Available in North and South America (except Canada).
⁽⁴⁾	Dorsey Metrology International web address: https://www.dorseymetrology.com/
⁽⁵⁾	Available in Canada, APD, and EAME.
⁽⁶⁾	For use with precision gage pins.

Preparation Recommendations

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Personal injury can result when using cleaner solvents.

To help prevent personal injury, follow the instructions and warnings on the cleaner solvent container before using.

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Personal injury can result from air pressure.
Personal injury can result without following proper procedure. When using pressure air, wear a protective face shield and protective clothing.

Maximum air pressure at the nozzle must be less than 205 kPa (30 psi) for cleaning purposes.

Note: Clean exterior of the spindle prior to disassembly.

Before you inspect a part, clean the part thoroughly to ensure that all components are free from rust, oil, burrs, and debris prior to inspection. A surface irregularity can hide the indication of an unacceptable defect.
Use a proper lifting device to provide safety to the operator. Also, use a proper lifting device to prevent damage to the part when you lift the part.
During cleaning, do not damage machined surfaces.
Do not use pressurized air to dry internal components. Compressed air has moisture and contaminants that can cause premature failure of internal components.
Put hydraulic oil on all machined surfaces to prevent rust or corrosion if inspection is not done immediately after cleaning. Carefully store the parts in a clean container.
Inspect all flange mating surfaces for fretting. Ensure that flange mating surfaces are true and free from raised material resulting from rust, nicks, and dents.
Use appropriate thread taps to chase all threaded holes.

Standardized Parts Marking Procedure

Reference: SEBF8187Reuse and Salvage Guidelines, "Standardized Parts Marking Procedures".

The code is a Cat standard and is used to record the history of a component. The code will identify the number of rebuilds and hours at the time of each rebuild. This information is important and should be considered for any decision to reuse a component.

Ensure that the mark is not covered by a mating part.

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NOTICE

Do not use numbering stamp punches to mark internal components. The impact from striking the stamp will cause an abnormal stress riser. The added stress riser may cause premature part failure.

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Illustration 3	g06124077
DO NOT use numbering stamp punches to mark internal components.

The procedure for marking components is a Cat standard. This code is helpful when the machine is sold into a different territory after the first rebuild. During an overhaul, the previous code of a part should never be removed.

Example 1

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Illustration 4	g03856853
Typical Example

Illustration 4 shows code (1-15). The first number (1) indicates that the gear had been rebuilt once. The second number (15) indicates that there were 15,000 hours on the gear at the time of rebuild.

Example 2

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Illustration 5	g03856857
Typical Example

Illustration 5 shows code (1-12) and code (2-10). Code (2-10) represents the information from the second rebuild. The first number (2) indicates that the gear had been rebuilt twice. The second number (10) indicates that 10,000 hours accumulated on the gear between the first and second rebuild.

Note: Add the first and second rebuild hours to obtain the total number of hours for the gear in Illustration 5. In this example, the gear has a total of 22,000 hours.

Checklist for Inspection and Salvage of Front Wheel Spindles / Front Axles

Reuse Inspection

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Table 4
Critical Features	Type of Check
Entire spindle / front axle	Magnetic particle testing and dye penetrating oil for cracks.
Splines	Measurement Over Pins (MOP)
Bearing journals	The hardness for each journal must be at a Rockwell rating of at least 30N 64. (Rockwell C 45) The tolerance of the OD for each journal is + 0.025 - 0.050 mm (+ 0.0010 - 0.0020 inch). The alignment of each journal must be measured to a tolerance of ± 0.025 mm (± 0.0010 inch).

Salvage

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Table 5
Critical Features	Operation
Bearing journals	Repair with Arc Spray or HVOF Refer to Table 3 for the hardness. Machine the journals to size. Alignment must be measured to the value in Table 4.

Identification of Spindle / Front Axle Type

Illustrations 6, 7 show the typical configuration of front wheels on Off-Highway Trucks

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Illustration 6	g03694131
Typical front spindle/ front axle.

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Illustration 7	g03694133
Typical front spindle / front axle.

Identification of Areas that Wear

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Illustration 8	g03694136
The area between the bearing and the spindle / front axle (arrows) may encounter wear.

Prepare the Area for Inspection & Welding

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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 product used to clean the components.

Observe all safety precautions recommended by the chemical manufacturer for handling, storage, and disposal of cleaning agents.

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Personal injury can result from air pressure.
Personal injury can result without following proper procedure. When using pressure air, wear a protective face shield and protective clothing.

Maximum air pressure at the nozzle must be less than 205 kPa (30 psi) for cleaning purposes.

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Illustration 9	g03794147
Typical burr removal Tooling. (A) Die Grinder, Right Angle (B) Wheel Grinder, Group (C) Conditioning Discs, Disc pad Holder, and Threaded Shaft (D) Flapper Wheel

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Illustration 10	g06396825
(E) Before cleaning with pad. (F) After cleaning with pad.

Before you inspect a part, clean the part thoroughly to ensure that all components are free from rust, oil, burrs, and debris prior to inspection. A surface irregularity can hide the indication of an unacceptable defect.
When you move parts that require cleaning, always use a proper lifting device. This device must protect the part from damage. For the safety of the operator, all lifting devices must be inspected before use.
During cleaning, do not damage machined surfaces.
Use pressurized air to dry parts.
If the component cannot be inspected immediately after cleaning, put hydraulic oil on all machined surfaces to prevent rust or corrosion. Carefully store the parts in a clean container.
Inspect all flange mating surfaces. Ensure that flange mating surfaces are true and free from raised material resulting from rust, nicks, and dents.
Use appropriate thread taps to chase all threaded holes.

Clean the area that will be welded. Ensure that the substances that follow are removed from the area that will be welded.

Oil
Grease
Paint
Dirt

General Guidelines

Inspect the spindle / front axle before the salvage procedure. The spindle / front axle should be inspected immediately after disassembly and cleaning. To prevent a failure, inspect each of the following critical areas of a spindle / front axle.

Entire Spindle / Front Axle - Inspect the spindle / front axle for cracks. Use either a magnetic particle or a liquid penetrant testing processes. An internal crack that is not detected or fully removed before salvage can lead to failure.
Splines - A cracked spline is not to be salvaged. A spline that does not meet the dimensional requirement cannot be salvaged. Because splines transfer high loads, thoroughly inspect each spline for cracks. Measure the average dimension over pins to determine wear.
Bearing Journals - Measure the surface hardness and the outside diameter for each journal. Bearing journals may be salvaged by using Arc Spray or by using High Velocity Oxygen Fuel (HVOF).
Mounting Flange Bolt Holes - These bolt holes may experience damage if bolts are loose during operation. Inspect each bolt hole for deformation. You may salvage a deformed bolt hole by welding the bore and machining the bore.

Always use proper lifting devices for the safety of the operator. Prevent damage to machined surfaces by using the correct lifting equipment.

Visual Surface Inspection

Wheel Bearing Journals

A wheel bearing journal can be visually inspected with the unaided eye. During an inspection, the best results can be achieved with the use of a magnifying glass and a strong light source. Sunlight is the best light source. If difficult to distinguish small scratches from cracks, use either a Liquid Penetrant Testing (PT), Dry / Wet Magnetic Particle Testing (MPT).

Note: To recondition the surface of a bearing journal, Refer to "Thermal Spray Procedures for OHT Front Spindles".

Normal Wear

The following photos show both inner wheel bearing journal and outer wheel bearing journal. However, the criteria for reusing either wheel bearing journal is identical.

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Illustration 11	g03680466
The outer journal surface in this illustration has been laser hardened. The shiny area (A) has been buffed slightly to check the hardness. OK TO USE THIS PART AGAIN

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Illustration 12	g03680470
Illustration 12 is a laser hardened inner journal that exhibits normal wear. Once the corrosion has been removed from the surface, this part may be reused. OK TO USE THIS PART AGAIN

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Illustration 13	g03680472
Illustration 13 is an inner journal that exhibits normal wear. OK TO USE THIS PART AGAIN

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Illustration 14	g03680474
Illustration 14 inner journal exhibits light wear and light pitting (B). OK TO USE THIS PART AGAIN

Surface Damage

To recondition the surface of a bearing journal, Refer to "Thermal Spray Procedures for OHT Front Spindles" section.

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Illustration 15	g03680477
The bearing journal surface exhibits smearing damage (C). Before you reuse the spindle / front axle, buff the surface and verify the dimensions. Refer to Table 6. OK TO USE THIS PART AGAIN

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Illustration 16	g03680480
Illustration 16 is a magnified view of Illustration 15. Before you reuse the spindle / front axle, buff the surface and verify the dimensions. Refer to Table 6. OK TO USE THIS PART AGAIN

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Illustration 17	g03680485
Illustration 17 is an outer journal that exhibits bruising (D). A band of corrosion (E) is shown below the journal. DO NOT USE THIS PART AGAIN This journal may be salvaged, Refer to "Thermal Spray Procedures for OHT Front Spindles" section.

Note: If corroded (E) is the only damage, the spindle / front axle may be reused after you buff the corrosive area.

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Illustration 18	g03680490
The outer journal exhibits scratching and spalling damage. DO NOT USE THIS PART AGAIN This journal may be salvaged, Refer to "Thermal Spray Procedures for OHT Front Spindles" section.

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Illustration 19	g03680493
Illustration 19 is an outer journal that exhibits heavy damage from spalling. DO NOT USE THIS PART AGAIN This journal may be salvaged, Refer to "Thermal Spray Procedures for OHT Front Spindles" section.

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Illustration 20	g03680502
The outer journal has a layer of thermal spray material that is mostly gone. DO NOT USE THIS PART AGAIN This journal may be salvaged, Refer to "Thermal Spray Procedures for OHT Front Spindles" section.

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Illustration 21	g03680509
Illustration 21 is an inner journal that exhibits scratching and spalling damage. DO NOT USE THIS PART AGAIN This journal may be salvaged, Refer to "Thermal Spray Procedures for OHT Front Spindles" section.

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Illustration 22	g03680513
The inner journal has a layer of thermal spray material that has started to flake off. The bond between the journal and the thermal spray material failed. DO NOT USE THIS PART AGAIN This journal may be salvaged, Refer to "Thermal Spray Procedures for OHT Front Spindles" section.

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Illustration 23	g03680517
The scalloped edge on the wheel has caused the inner bearing journal to wear a round groove into the spindle / front axle. OK TO USE THIS PART AGAIN The depth of the groove must not exceed 2.00 mm (0.0787 inch). Buff the surface to eliminate sharp edges or grooves.

Hardness Checks

Hardness should be measured using a suitable type hardness tester. Persons should be qualified or properly trained in how to use the hardness tester to ensure good results.

Note: A minimum hardness reading of 45 Rockwell "C" (RC) or 430 Brinell (10 mm steel ball) is required.

Directions for using a Detroit Hardness Tester

Follow Steps 1 through 8 for using a Detroit Hardness Tester:

Locate area to be tested.
Use a non-metallic synthetic buffing wheel to clean bottom of grooves in area to be hardness tested.
Turn tester upside down allowing the ball to seat in the cap.
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Illustration 24 g03727170

Typical example of performing a hardness test using 6V-6035 Hardness Tester.
Turn tester right side up and place on area that has been cleaned. Refer to Step 2.
Hold tester vertically and steady.
Slowly depress trigger, do not strike or you will get an inaccurate reading.
Read the top of the ball at the highest point of the ball's bounce.
Repeat Steps 3 through 7 for each test location three times to obtain an accurate reading.

Repair for Front Spindle / Front Axle Assembly

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Illustration 25	g06397810
Typical view of a front spindle / front axle dimensions. (P) Chamfer. Refer to Table 6 for the dimensions.

If diameter (A) and diameter (B) are worn, a Thermal Spray operation may be used to restore the diameter of the bearing race to the original dimension. If you have questions concerning equipment, recommendations for powder, machine settings, or procedures for the application, Refer to "Thermal Spray Procedures for OHT Front Spindles" section. Each step in the procedure is critical to achieve the desired bond coating and the desired surface texture. Preparation of the spindle / front axle is critical to achieve the desired bond and the desired surface texture of the coating. After the spindle / front axle has been sprayed, mount the spindle / front axle assembly on a lathe. Zero the part on diameter (X) and face (Y). Machine the spindle / front axle to the dimensions that are shown in Table 6. Diameter (A) and diameter (B) must be within 0.038 mm (0.0015 inch). Both diameters must be within the maximum total indicator reading of each other and face (Y). Refer to Illustration 25 for the dimension locations.

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Table 6
Dimensions for Front Spindles / Front Axles
Spindle / Front Axle	Wheel Group	Diameter (A) ⁽¹⁾	Diameter (B) ⁽¹⁾	Length (L)	Chamfer Angle (P)
5D-8203	9M-1353	Ø 77.77 ± 0.013 mm (3.062 ± 0.0005 inch)	Ø 129.982 ± 0.013 mm (5.1174 ± 0.0005 inch)	150.42 mm (5.922 inch)	30°
5T-2098 9D-1388 183-7417	6G-7877 8X-6474 9D-2750 243-5552 243-5549 261-2356	Ø 152.370 ± 0.025 mm (5.9988 ± 0.0010 inch)⁽²⁾	Ø 199.944 ± 0.025 mm (7.8718 ± 0.0010 inch)	130.0 + 20.0 - 0.0 mm (5.12 + 0.79 - 0.0 inch)	30°
5T-6063 8W-5599 8X-8950 183-7418	6G-9270 8W-5599 8X-9487 183-7418 309-9597	Ø 231.745 ± 0.025 mm (9.1238 ± 0.0010 inch)	Ø 269.845 ± 0.025 mm (10.6238 ± 0.0010 inch)	111.0 + 20.0 - 0.0 mm (4.37 + 0.79 - 0.0 inch)	30°
5T-6116 8X-9561 183-7419	5T-1023 183-7419	Ø 231.745 ± 0.025 mm (9.1238 ± 0.0010 inch)⁽²⁾	Ø 269.845 ± 0.025 mm (10.6238 ± 0.0010 inch)	111.0 + 20.0 - 0.0 mm (4.37 + 0.79 - 0.0 inch)	30°
6D-0093	6G-8240 270-5384 308-3174	Ø 120.620 ± 0.025 mm (4.7488 ± 0.0010 inch)⁽²⁾	Ø 139.670 ± 0.0254 mm (5.4988 ± 0.0010 inch)	109.50 mm (4.311 inch)	30°
6G-6430 205-9071 205-9072	6G-8240 270-5384 308-3174	Ø 120.620 ± 0.025 mm (4.7488 ± 0.0010 inch)	Ø 139.670 ± 0.025 mm (5.4988 ± 0.0010 inch)	109.50 ± 0.5 mm (4.311 ± 0.02 inch)	30°
6G-6440 133-4727	6G-8241 247-5532 308-3240	Ø 133.320 ± 0.025 mm (5.2488 ± 0.0010 inch)⁽²⁾	Ø 152.370 ± 0.025 mm (5.9988 ± 0.0010 inch)	128.5 ± 0.5 mm (5.06 ± 0.02 inch)	30°
7D-2834	7D-2834 7D-2820	Ø 133.320 ± 0.025 mm (5.2488 ± 0.0010 inch)⁽²⁾	Ø 152.370 ± 0.025 mm (5.9988 ± 0.0010 inch)	128.50 mm (5.059 inch)	30°
8X-1468	8X-0870 280-2056 353-7174	Ø 231.745 ± 0.025 mm (9.1238 ± 0.0010 inch)⁽²⁾	Ø 317.470 ± 0.025 mm (12.4988 ± 0.0010 inch)	124.0 + 20.0 - 0.0 mm (4.88 + 0.79 - 0.0 inch)	30°
9M-1683	9M-1353	Ø 77.77 ± 0.013 mm (3.062 ± 0.0005 inch)	Ø 129.982 ± 0.013 mm (5.1174 ± 0.0005 inch)	150.42 mm (5.922 inch)	30°
144-0804	278-8797	Ø 346.032 ± 0.025 mm (13.6233 ± 0.0010 inch)⁽²⁾	Ø 415.874 ± 0.025 mm (16.3730 ± 0.0010 inch)	161.0 + 20.0 - 0.0 mm (6.34 + 0.79 - 0.0 inch)	30°
174-7530	216-1716	Ø 260.3 ± 0.025 mm (10.24801 ± 0.0010 inch)	Ø 330.0 ± 2.0 mm (13.00 ± 0.10 inch)	124.0 + 20.0 - 0.0 mm (4.88 + 0.79 - 0.0 inch)	30°
205-9073	6G-8241	Ø 133.320 ± 0.025 mm (5.2488 ± 0.0010 inch)	Ø 152.370 ± 0.025 mm (5.9988 ± 0.0010 inch)	128.50 mm (5.059 inch)	30°
205-9074	6G-8241	Ø 133.320 ± 0.025 mm (5.2488 ± 0.0010 inch)	Ø 152.370 ± 0.025 mm (5.9988 ± 0.0010 inch)	128.50 mm (5.059 inch)	30°
244-7765	247-0895 309-4133 216-1716 280-7765	Ø 260.3 ± 0.025 mm (10.24801 ± 0.0010 inch)	Ø 317.45 ± 0.025 mm (12.49801 ± 0.0010 inch)	160.0 ± 0.5 mm (6.30 ± 0.02 inch)	6°
252-7959 252-7960 261-0650	252-7957 252-7958 261-0649 308-3196	Ø 120.620 ± 0.025 mm (4.7488 ± 0.0010 inch)	Ø 139.670 ± 0.025 mm (5.4988 ± 0.0010 inch)	109.50 ± 0.5 mm (4.311 ± 0.02 inch)	30°
278-8809	280-4253 292-2173 309-4031 292-2172 309-4131	Ø 346.032 ± 0.025 mm (13.6233± 0.0010 inch)⁽²⁾	Ø 457.15 ± 0.025 mm (17.9980 ± 0.0010 inch)	167.97 + 20.0 - 0.0 mm (6.613 + 0.79 - 0.0 inch)	30°
375-0114	380-6955	Ø 346.032 ± 0.025 mm (13.6233± 0.0010 inch)⁽²⁾	Ø 457.15 ± 0.025 mm (17.9980 ± 0.0010 inch)	167.97 + 20.0 - 0.0 mm (6.613 + 0.79 - 0.0 inch)	30°
386-5921	337-7940	Ø 231.745 ± 0.025 mm (9.1238 ± 0.0010 inch)	Ø 317.470 ± 0.025 mm (12.4988 ± 0.0010 inch)	124.0 + 20.0 - 0.0 mm (4.88 + 0.79 - 0.0 inch)	30°
389-3912	309-4133 216-1716 280-2057	Ø 260.3 ± 0.025 mm (10.24801 ± 0.00098 inch)	Ø 317.45 ± 0.025 mm (12.49801 ± 0.0010 inch)	160.0 ± 0.5 mm (6.30 ± 0.02 inch)	6°

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⁽¹⁾	The surface texture is 1.6 µm (63 µinch) for the Laser Heat Treated Areas (Bearing - Journals).
⁽²⁾	The tolerance for reusability is + 0.025 /- 0.050 mm (+ 0.0010 /- 0.0020 inch).

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Table 7
Mounting Flange Hole Dimensions for Front Spindles / Front Axles
Spindle / Front Axle Part Number	Wheel Group	Hole Diameter	(+) Hole Tolerance	(-) Hole Tolerance
5D-8203	9M-1353	Ø 22.631 mm (0.891 inch)	0.5 mm (0.020 inch)	0.150 mm (0.006 inch)
5T-2098 9D-1388 183-7417	6G-7877 8X-6474 9D-2750 243-5549 243-5552 261-2356	Ø 24.0 mm (0.945 inch)	0.5 mm (0.020 inch)	0.150 mm (0.006 inch)
5T-6063 8W-5599 8X-8950 183-7418	5T-6063 6G-9270 8X-9487 183-7418 309-9597	Ø 24.0 mm (0.945 inch)	0.5 mm (0.020 inch)	0.150 mm (0.006 inch)
5T-6116 8X-9561 183-7419	5T-1023 8X-0270 8X-9561 183-7419 328-8492	Ø 24.0 mm (0.945 inch)	0.5 mm (0.020 inch)	0.150 mm (0.006 inch)
6D-0093	6G-8240 270-5384 308-3174	Ø 24.0 mm (0.945 inch)	0.5 mm (0.020 inch)	0.150 mm (0.006 inch)
6G-6430 205-9071 205-9072	6G-8240 270-5384 308-3174	Ø 24.0 mm (0.945 inch)	0.5 mm (0.020 inch)	0.150 mm (0.006 inch)
6G-6440 133-4727	6G-8241 247-5532 308-3240	Ø 19.750 mm (0.778 inch)	0.250 mm (0.010 inch)	0.250 mm (0.010 inch)
7D-2834	7D-2820	Ø 19.750 mm (0.778 inch)	0.250 mm (0.010 inch)	0.250 mm (0.010 inch)
8X-1468	8X-0870 280-2056 252-7174	Ø 24.0 mm (0.945 inch)	0.5 mm (0.020 inch)	0.150 mm (0.006 inch)
9M-1683	9M-1353	Ø 22.631 mm (0.891 inch)	0.5 mm (0.020 inch)	0.150 mm (0.006 inch)
144-0804	250-3930	Ø 26.0 mm (1.0236 inch)	0.5 mm (0.020 inch)	0.250 mm (0.010 inch)
174-7530	216-1716	Ø 21.5 mm (0.846 inch)	0.5 mm (0.020 inch)	0.150 mm (0.006 inch)
205-9073	6G-8241	Ø 19.750 mm (0.778 inch)	0.250 mm (0.010 inch)	0.250 mm (0.010 inch)
205-9074	6G-8241	Ø 19.750 mm (0.778 inch)	0.250 mm (0.010 inch)	0.250 mm (0.010 inch)
244-7765	216-1716 247-0895 280-2057 309-4133	Ø 21.5 mm (0.846 inch)	0.5 mm (0.020 inch)	0.150 mm (0.006 inch)
252-7959 252-7960 261-0650	252-7957 252-7958 261-0649 308-3196	Ø 24.0 mm (0.945 inch)	0.5 mm (0.020 inch)	0.150 mm (0.006 inch)
278-8809	280-4253 292-2173 309-4031	Ø 33.0 mm (1.300 inch)	0.5 mm (0.020 inch)	0.250 mm (0.010 inch)
375-0114	380-6955 309-4131	Ø 33.0 mm (1.300 inch)	0.5 mm (0.020 inch)	0.250 mm (0.010 inch)
386-5921	337-7940	Ø 24.0 mm (0.945 inch)	0.5 mm (0.020 inch)	0.150 mm (0.006 inch)
389-3912	280-2057 309-4133	Ø 21.5 mm (0.846 inch)	0.5 mm (0.020 inch)	0.150 mm (0.006 inch)

Checklist for Inspection and Salvage of Front Wheel Spindles / Front Axles

Reuse Inspection

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Table 8
Critical Features	Type of Check	Available Procedures for Salvage
Entire spindle / front axle	Magnetic Particle Testing (preferred) or Liquid Penetrant Testing l(optional) for cracks	Magnetic Particle Testing of Front Spindles / Front Axles
Bearing journals	The hardness for each journal must be at a Rockwell rating of at least 30N 64. (Rockwell C 45) The tolerance of the OD for each journal is + 0.025 - 0.050 mm (+ 0.0010 - 0.0020 inch). The alignment of each journal must be measured to a tolerance of ± 0.025 mm (± 0.0010 inch).	Refer to Table 5

Laser Heat Treated Areas Cracking (Bearing - Journals)

Note: An Ultrasonic Testing (UT) inspection method has not been established for the laser heat treated bearing journal cracks. Follow the inspection criteria with in this section for reuse criteria.

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Illustration 26	g06415716
Laser heat treating start and stop locations. The laser heat treating overlaps in this area. (A) Laser heat treating start location. (B) Cracking induced from the laser heat treating process. (C) Laser heat treating stop location.

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Illustration 27	g06397115
Located at the start and stop of laser heat treat. Located in the neutral zone of the spindle. Magnified view of cracks on the bearing journal. OK TO USE THIS PART AGAIN (D) Laser heat treated bearing journals. (E) Neutral Zone

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Illustration 28	g06397406
Located at the start and stop of laser heat treat. Located in the neutral zone of the spindle. Magnified view of cracks on the bearing journal. OK TO USE THIS PART AGAIN (D) Laser heat treated bearing journals. (E) Neutral zone.

Note: Located at the start and stop of laser heat treat. Located in the neutral zone of the spindle.

Some spindles typically exhibit cracking parallel to the axis in the Laser Heat Treated portions of the bearing journals on the neutral axis. This may appear as cracks in individual bands, multiple bands, or in every band of the Laser Heat Treated regions. Refer to Illustrations 27 and 28.

Note: Multiple crack criteria does not apply to these locations.

The cracks may be present at any time during the life of the spindle.

Laser heat treated cracking will not extend outside of the laser heat treated bearing journals.

Refer to Illustrations 27 and 28 as a guide for laser heat treated areas of certain models.

Multiple Crack Criteria

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Illustration 29	g03681149
Collinear if less than 45° angle. (A) 45° angle.

Two cracks close together are considered to be collinear (along the same line) if the angle between the two cracks is less than 45°.

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Illustration 30	g03681152
Multiple Crack Criteria. (1) Collinear within 25.0 mm (0.984 inch) diameter circle, treat as one crack. (2) Collinear outside 25.0 mm (0.984 inch)diameter circle, treat as two cracks. (3) Non-Collinear within 25.0 mm (0.984 inch) diameter circle, treat as two cracks. (4) Mixture of Collinear and Non-Collinear within 25.0 mm (0.984 inch) diameter. Treat the two collinear cracks as one crack. Treat the one non-collinear crack as one crack.

After grinding is complete determine if multiple cracks are still present. Measure the area to determine if the cracks fall within a 25.0 mm (0.984 inch) diameter circle.
If multiple cracks are within the 25.0 mm (0.984 inch), they are considered as a single crack.
If the effective crack length is greater than the allowable criteria for each zone, the spindle / front axle must be sent to Cat Reman for salvage process.
The spindle / front axle can be used again if the effective crack length is less than allowable criteria for each zone. This is applicable to Zones (A), (B), (F), (H), (K), (R), (S), and (T).

Note: Refer to "Spindle / Front Axle Zones, Crack Inspection, and Repair of 793 & 797 Front Spindles / Front Axles" for spindle / front axle zones and crack criteria for each zone.

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Illustration 31	g03694182
Example of Crack Separation.

Note: Circles represent 25.0 mm (0.984 inch) area.

Example (5) is considered two separate cracks. The cracks are separated by a 25.0 mm (0.984 inch) area.
Example (6) is considered one continuous crack. The cracks are within a 25.0 mm (0.984 inch) area.
Example (7) is considered one continuous crack. The two cracks span within a 25.0 mm (0.984 inch) area.

Splines

Perform a complete inspection of the spline before you proceed with the repair procedure. During an inspection, the best results can be achieved with the use of a magnifying glass and a strong light source. Sunlight is the best light source. If it is difficult to distinguish small scratches from cracks, use either a liquid dye penetrating oil or a magnetic particle testing.

Inspect every spline on each spindle / front axle. If a damaged spline is found, recheck the spline on mating parts. Then, inspect the teeth that are 180° from the damaged splined tooth for possible bending fatigue.

Crack Inspection for Splines

Thoroughly clean the splines before inspection occurs.

Typical Sequence in the Failure of a Spline

When you inspect a spline, determine whether the damage will progress into a failure before the next Planned Component Rebuild (PCR). Analyze the application and spline size for each truck when you make this determination.

There are two typical sequences for a failure:

Misalignment will cause spline wear. Spline wear can lead to a fracture.
A fatigue crack can cause a fracture.

Wear and Misalignment

There is normally a small amount of relative motion between meshing spline teeth. Uneven contact patterns on the spline teeth are the result of misalignment of one or both of the meshing splines. Splines that are misaligned do not fully engage. Spline misalignment will cause only a portion of each tooth to carry the full load. If the brake hub and the spindle / front axle are not aligned, the spline teeth will not mesh correctly. This situation can place high contact pressures on a portion of the teeth. Misalignment can cause high contact pressure and relative movement. Eventually, spline wear and fretting corrosion will appear as damage on the surface. Misalignment can be identified by the uneven contact pattern on the spline teeth.

If any spline displays uneven contact patterns, be sure to check for misalignment and correct the cause of the problem. The spline could be misaligned, if any of the following are worn or damaged.

Do not reuse a spline with damage from misalignment. Even if you correct the cause of misalignment, the previous abnormal wear will not permit full tooth contact. Correct the cause of misalignment. Then install a new spline.

Normal Wear

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Illustration 32	g03680781
The spline shows signs of even loading and full contact. OK TO USE THIS PART AGAIN

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Illustration 33	g01240365
The spline has an external wear step, but the spline meets specifications for reusability. Corrosion from fretting is also apparent. This corrosion is due to lack of lubrication, OK TO USE THIS PART AGAIN.

Damage of Spline/ Teeth

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Illustration 34	g06324678
Typical example of spline damage from poor handling, but no signs of cracking. Use a polishing stone to smooth any raised material from indentation. OK TO USE THIS PART AGAIN

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Illustration 35	g03680793
A tooth on this spline is missing and the adjacent teeth are heavily damaged. DO NOT USE THIS PART AGAIN

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Illustration 36	g03680795
This spline has a crack which began in the root. The crack has progressed into the adjacent splines. DO NOT USE THIS PART AGAIN

Corrosion and Pitting

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Illustration 37	g06324680
Typical example of corrosion from poor storage techniques, clean, inspect for pitting. If excessive pitting, then DO NOT USE THIS PART AGAIN.

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Illustration 38	g03680798
This spline has heavy fretting corrosion. DO NOT USE THIS PART AGAIN

Reusability of Splines

This section provides the procedures that are necessary for you to measure external splines. This section will help you to calculate these measurements. These results can be used to determine reusability of external splines.

Measuring Procedure

For the measurement of an external spline, take three measurements over pins. For each of the three dimensions, measure the highest external point over two pins that are 180° opposite of each other.
Average the three dimensions to produce the average dimension over pins.
Compare these measurements to Table 9 to determine the spline wear.

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Illustration 39	g06321303
Typical wear step on an external spline.

For this procedure, the spline will require the use of a specific pin set. There are three-pin sets for the measurement of splines. Each pin set consists of six pins. Each pin is machined to a specific dimension. Care must be taken to precisely machine these pins to the specification due to the close tolerances of the splines.

Make the pins out of SAE 1020 steel. Use the dimension for the pin diameter in Table 9 to precisely machine each pin for the specific pin set. Magnetize each pin so that the pins will stay in place during the process of measurement. You may also use a rubber band to secure the pins. Refer to Illustration 40.

To measure an external spline, calculate the average for the three measurements over pins. Use the following procedure to determine the maximum allowable spline wear.

Use an outside micrometer to measure external splines. To obtain accurate results, you must have a thorough working knowledge of the use of outside micrometers.

Pins must be 60° from other pins. Refer to Illustration 41.

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Illustration 40	g06075262
Typical example of MOP. (N) Rubber Band (P) Gage Pins

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Illustration 41	g06181327
(L)¹, (L)₂, and (L)₃ Measurement Locations

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Illustration 42	g06075290
Typical example of taking a Measurement Over Pins (MOP).

Verify that the spline is not out of round. This can be done by taking the maximum difference between the high pin and the low pin. The next section provides examples for obtaining this measurement. This measurement is a critical measurement which must be calculated to ensure that the spline can evenly transfer a load.

Measurement Examples

External Spline

The location of gage pins at 60° intervals is critical to the formula. These three locations will provide information about the wear of the part. Refer to Illustration 41.

Note: For odd splines take measurement as close to 180° from each gage pin as possible.

Place gage pins at 60° intervals on the spline. Take the measurements over gage pins that are located approximately 180° away from each other.

A micrometer must be positioned to measure the highest external points on the gage pins. This procedure will provide the measurement of the wear of the spline. The gage pin diameter for each individual part is determined by the size and pitch of the spline. Calculate the average from the values taken. The difference between the measurements will determine if there is an out of round condition caused by poor load distribution on the splines.

Steps 1 through 5 demonstrate an example of the process to calculate external spline roundness. Provided is an example of performing spline reusability calculations of a spindle.

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NOTICE

The spline must pass the roundness tests by meeting the reusability specification measurement over gage pins and the maximum difference between the high and low measurements to be reused again.

The following steps show the calculations that are required to check the measurements for an external spline.

Take the measurements at location (L)₁, (L)₂, and (L)₃ over gage pins. The measurements in the following list are provided as an example.
- Dimension (L)₁ is 416.250 mm (16.3878 inch).
- Dimension (L)₂ is 416.500 mm (16.3976 inch).
- Dimension (L)₃ is 416.750 mm (16.4074 inch).
Once measurements (L)₁, (L)₂, and (L)₃ are obtained, add the measurements together.
- Sum dimensions (L)₁ + (L)₂ + (L)₃ = 1249.500 mm (49.1928 inch)
Divide this sum by 3 to obtain the average. The result is 416.500 mm (16.3976 inch).
Because this average is greater than 416.035 mm (16.3793 inch) (the inspection for the minimum reuses dimension over pins), the spline wear is acceptable.
Calculate the difference between the high measurement 416.750 mm (16.4074 inch) and the low measurement 416.250 mm (16.3878 inch)
- 416.750 mm (16.4074 inch) - 416.250 mm (16.3878 inch) = 0.500 mm (0.0197 inch)

The difference between the high dimension and the low dimension indicates whether the splines are out of round. Never install a warped spline. A load cannot be distributed evenly on a spline that is out of round. Teeth on a warped spline can crack due to excessive stress. The excessive stress is caused from an uneven load distribution on the splines. The difference between the high measurement and the low measurement will help to determine if the part can be used again.

The maximum dimension between the high dimension and the low dimension is 0.416 mm (0.0164 inch). Refer to Table 9 for this dimension. Because the actual difference 0.500 mm (0.0197 inch) is greater than the allowable maximum, this spline is elliptical. DO NOT USE PART AGAIN.

If the spline does not meet both specifications, then DO NOT REUSE the spindle/ front axle. An external spline must pass both of the following tests to be used again.

Minimum dimension over pins
Maximum difference between the high dimension and the low dimension

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Table 9
Reuse Dimensions for Splines on Spindles / Front Axles
Spindle / Front Axle Part Number	Cat Reman Service Part Number	Pin Diameter	Minimum Print Dimension Over Pins	Minimum Reuse Dimension Over Pins
244-7765 389-3912	10R-6185 N/A	Ø 8.000 mm (0.31496 inch)	Ø 557.190 mm (21.93657 inch)	Ø 556.643 mm (21.91503 inch)
278-8809	10R-9958	Ø 8.000 mm (0.31496 inch)	Ø 638.115 mm (25.12259 inch)	Ø 637.560 mm (25.10074 inch)
375-0114	20R-1696	Ø 8.000 mm (0.31496 inch)	Ø 638.115 mm (25.12259 inch)	Ø 637.560 mm (25.10074 inch)

Methods of Securing Gage Pins

Note: Rubber band, bungee strap, or magnetizing of the gage pins can be used to secure gage pins in place when taking measurements of external splines. Refer to Illustrations 40 through 43.

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Illustration 43	g06124082
Typical example of a magnetizer/ demagnetizer.

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NOTICE

If gage pins are magnetized, then demagnetize after use. When a gage pin is magnetized, cuttings and iron powder will easily stick to the surface, thus precipitating wear.

Gage pins can be magnetized to aid in taking measurements between or over gage pins. Ensure that gage pins are demagnetized after use and stored properly.

Spindle / Front Axle Zones, Crack Inspection, and Repair of 793 & 797 Front Spindles / Front Axles

The following instruction explains the spindle / front axle zones and crack criteria for the 793 & 797 Front Spindles / Front Axles only.

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Illustration 44	g03694186
View of 793 standard spindle / front axle and 797 spindle / front axle. (A) Spindle / Front Axle Zone A and View of Threaded Holes. (A2) 32.0 mm (1.260 inch) Elliptical Radius and Seal Surfaces for 793 standard spindles / front axles only. (A2) 40.0 mm (1.575 inch) Elliptical Radius and Seal Surfaces for 797 spindles / front axles only. (B) Spindle / Front Axle Zone B. (B2) 60.0 mm (2.362 inch) Radius and Pilot Diameter for 793 standard spindles / front axles. (B2) 75.0 mm (2.953 inch) Radius and Pilot Diameter for 797 spindles / front axles. (F) Spindle / Front Axle Zone F (brake flange). (K) Spindle / Front Axle Zone K (R) Spindle / Front Axle Zone R.

16.0 mm (0.630 inch) of surface cracks are allowed in Zone (A). No cracks are allowed in the threaded holes of Zone (A) that meet the Multiple Crack Criteria.
If cracks exceed 16.0 mm (0.630 inch) the spindle / front axle must be sent to Reman for the salvage process.
No surface cracks are allowed in the (A2) 32.0 mm (1.260 inch) for 793 spindles / front axles and 40.0 mm (1.575 inch) for 797 spindles / front axles of Zone (A).
16.0 mm (0.630 inch) of surface cracks are allowed in Zone (B) that meet the Multiple Crack Criteria in Illustration 30.
Grind cracks in Zone (B) to a depth of 5.0 mm (0.197 inch) and blend to a smooth radius of 12.0 mm (0.472 inch). No cracks are allowed in Zone (B2) and Pilot Diameter.

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Illustration 45	g03720228
View of 793 XLP spindle / front axle. (A) Spindle / Front Axle Zone A and View of Threaded Holes. (B) Spindle / Front Axle Zone B. (F) Spindle / Front Axle Zone F (splined brake flange). (K) Spindle / Front Axle Zone K (R) Spindle / Front Axle Zone R.

No surface cracks are allowed in Zone A or Zone B. If cracks are present, the spindle / front axle must be sent to Reman for salvage process.

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Illustration 46	g03698412
View of 793 standard spindle / front axle and 797 spindle / front axle. (T) Top and Bottom View of Spindle / Front Axle Zone T.

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Illustration 47	g03720660
View of 793 XLP spindle / front axle. (T) Top and Bottom View of Spindle / Front Axle Zone T.

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Illustration 48	g03698424
View of 793 standard spindle / front axle and 797 spindle / front axle. (S) Spindle / Front Axle Zone S

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Illustration 49	g03720708
View of 793 XLP spindle / front axle. (S) Spindle / Front Axle Zone S

Zone T Crack Inspection

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Illustration 50	g03694200
View of 793 standard spindle / front axle and 797 spindle / front axle. (T) Zone T Bottom Side. (T1) 430.0 mm (16.929 inch) Diameter on the Mounting Face for 793 standard spindles / front axles only. (T1) 500.0 mm (19.685 inch) Diameter on the Mounting Face for 797 spindles / front axles only.

The mounting face should not be repaired if cracks on the (T1) are within 430.0 mm (16.929 inch) for 793 standard spindles / front axles and 500.0 mm (19.685 inch) for 797 spindles / front axles. If cracks are visible submit the information to the Dealer Solution Network (DSN) for instructions.
Cracks can be excavated by grinding to a maximum depth of 7.0 mm (0.275 inch) outside of the mounting face in Zone (T). The spindle / front axle may be reused after grinding if the crack lengths are less than 25.0 mm (0.984 inch) and meet the Multiple Crack Criteria listed in Illustration 30.
Blend the surrounding surface with a smooth radius of 12.0 mm (0.472 inch) minimum.

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Illustration 51	g03720732
View of 793 XLP spindle / front axle. (T) Zone T Bottom Side. (T1) 495.0 mm (19.4881 inch) Diameter on the Mounting Face for 793 XLP spindles / front axles only.

Cracks on the mounting face should not be repaired. If cracks are found, submit Dealer Solution Network (DSN) for Engineering feedback.

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Illustration 52	g03694210
View of 793 standard spindle / front axle and 797 spindle / front axle. (T) Zone T Top Side. (H) Zone H Tapered Bore.

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Illustration 53	g03720792
View of 793 XLP spindle / front axle. (T) Zone T Top Side. (H) Zone H Tapered Bore.

Cracks that appear in the top side machined surface of Zone (T) are allowed if the crack length is less than 25.0 mm (0.984 inch) and meet the Multiple Crack Criteria listed in Illustration 30.
Grind cracks to a depth of 7.0 mm (0.275 inch) to remove the cracks and blend the surrounding areas to a smooth radius of R12 mm minimum.
Grind 10.0 mm (0.393 inch) deep in rough cast areas of Zone (T) to remove cracks and blend the surrounding areas to a smooth radius of R12 mm minimum.
Grind cracks in Tapered Bore Zone (H) that are greater than 16.0 mm (0.629 inch) in length to a depth of 7.0 mm (0.276 inch) maximum.
Cracks that are less than 16.0 mm (0.629 inch) in length are allowed in Zone (H) if they meet the Multiple Crack Criteria. Blend the surrounding surface with a smooth radius of R12 mm minimum.
The entire area of Zone (H) should be cleaned and free of debris after repair.

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Illustration 54	g03694212
View of 793 standard spindle / front axle and 797 spindle / front axle. Zone (R1) Top view.

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Illustration 55	g03720804
View of 793 XLP spindle / front axle. Zone (R1) Top view.

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Illustration 56	g03694217
View of 793 standard spindle / front axle and 797 spindle / front axle. Zone (R2) Side View. (R3) 260.0 mm (10.236 inch) for 793 standard spindles / front axles only. (R3) 300.0 mm (11.811 inch) for 797 spindles / front axles only.

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Illustration 57	g03720813
View of 793 XLP spindle / front axle. Zone (R2) Side View. (R3) 200.0 mm (7.874 inch) Zone (R4) Side View.

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Illustration 58	g03720826
View of 793 XLP spindle / front axle. Zone (R2) Side View. (R3) 200.0 mm (7.874 inch) Zone (R4) Side View.

Grind cracks in Zone (R1) to a depth of 12.0 mm (0.472 inch) maximum in the top areas.
Grind cracks in Zone (R2) to a depth of 12.0 mm (0.472 inch) within the side area of (R3) 260.0 mm (10.236 inch) for 793 standard spindles / front axles, 200.0 mm (7.874 inch) for 793 XLP spindles / front axles and 300.0 mm (11.811 inch) for 797 spindles / front axles.
Grind cracks on previously ground surfaces to a depth of 3.0 mm (0.1181 inch) max.
Use the same procedure for the opposite side. Blend the surrounding surface with a smooth radius of 12.0 mm (0.472 inch) minimum.
After grinding is complete, the spindle / front axle can be used again if the lengths of the cracks are less than 25.0 mm (0.984 inch) and meet the Multiple Crack Criteria listed in Illustration 30.
Craze or cluster cracking is allowed if they fall within the Multiple Crack Criteria.

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Illustration 59	g03694223
View of 793 standard spindle / front axle and 797 spindle / front axle. Zone (R4) Bottom View.

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Illustration 60	g03720844
View of 793 XLP spindle / front axle. Zone (R4) Bottom View.

Grind cracks on the bottom side of Zone (R4) to a depth of 3.0 mm (0.118 inch) maximum on the cast surface.
Blend ground areas with surrounding surfaces to a radius of 12.0 mm (0.472 inch) minimum. No cracks are allowed in this area after grinding.
If cracks or indications are still present submit Dealer Solution Network (DSN) for Engineering feedback.

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Illustration 61	g03694228
View of 793 standard spindle / front axle and 797 spindle / front axle. Zone (F) Brake Flange.

Do not grind any cracks on Zone (F) Brake Flange surface.
Cracks or indications are allowed on the outside diameter of Zone (F) if they are less than 25.0 mm (0.984 inch) in length and do not extend through either of the adjacent surfaces.
If cracks are found a Dealer Solution Network (DSN) must be submitted with the following information: (1) The length and depth of the crack/s as per multiple crack criteria. (2) The location of the crack/s and the distance from the mounting holes.

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Illustration 62	g03694230
View of 793 standard spindle / front axle and 797 spindle / front axle. Zone (S)

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Illustration 63	g03720854
View of 793 XLP spindle / front axle. Zone (S)

Grind cracks in Zone (S) to a depth of 7.0 mm (0.275 inch) maximum.
Blend ground areas with surrounding surfaces to a radius of 12.0 mm (0.472 inch) minimum.
After grinding, the spindle / front axle is allowed to be used if the length of the crack/s is less than 25.0 mm (0.984 inch) and meet the Multiple Crack Criteria listed in Illustration 30.
Craze or cluster cracking is allowed if they fall within the Multiple Crack Criteria.

Zone K Crack Inspection and Grinding Procedure

Note: Zone K does not apply on 793 XLP spindles / front axles.

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Illustration 64	g03694234
View of 793 standard spindle / front axle and 797 spindle / front axle. Zone (K1)

Cracks in Zone (K1) are allowed if the length of the cracks is less than 25.0 mm (0.984 inch) and meet the Multiple Crack Criteria listed in Illustration 30.
Cracks in Zone (K1) can be excavated by grinding to a depth of 7.0 mm (0.275 inch) maximum.
Blend the surrounding surface with a smooth radius of 12.0 mm (0.472 inch) minimum.
After grinding the spindle/ front axle can be used again if the length of the crack/ cracks is less than 25.0 mm (0.984 inch) and meet the Multiple Crack Criteria.

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Illustration 65	g03694239
View of 793 standard spindle / front axle and 797 spindle / front axle. (K2) Machined Face. (K3) Machined Face. (K4) Crack in corner of Keyway. (K5) Crack in corner of Keyway.

Do not grind on Machine Faces (K2) and (K3). If cracks are present in these areas a DSN must be submitted for Engineering Feedback.

Note: Before grinding on the Keyway determine if previous grinding has been performed. If grinding has been performed proceed with the welding process. Refer to Section "Weld Procedure for Zone K".

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Illustration 66	g03694242
Depth of grind in corners of Zones (K4) and (K5). (L) 5.0 mm (0.1969 inch)

Grind cracks at the corners (K4) and (K5) to a depth of (L) 5.0 mm (0.197 inch) maximum. If cracks still appear, proceed with the welding process. Refer to Section "Weld Procedure for Zone K".

Additional Crack Grinding in Zone K

If cracks are still present after initial grinding to a depth of 5.0 mm (0.197 inch) grind an extra 5 mm (0.197 inch) without affecting the slot width.

The following conditions must be met to continue with the weld procedure. Use the Magnetic Particle Testing procedure to verify the cracks.

Maximum length of the crack must be less than 108.0 mm (4.251 inch).
The depth of the crack must be less than (M) 10.0 mm (0.394 inch) total depth.

If the crack is still present beyond 10.0 mm (0.394 inch) or 108.0 mm (4.251 inch) in length the spindle / front axle cannot be used again. Refer to Illustration 67 to determine crack depth and crack length.

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Illustration 67	g03694250
(L) 5.0 mm (0.197 inch) (M) 10.0 mm (0.394 inch)

Weld Procedure for Zone K

Note: The weld procedure and weld parameters in this section are used to repair deep cracks in the corner of the key way in Zone (K.)

Welder Qualifications

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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 kill.
Read and understand the manufacturer's instruction and your employer's safety practices. Keep your head out of the fumes. Use ventilation, exhaust at the arc, or both, to keep fumes and gases from your breathing zone and the general area. Wear correct eye, ear and body protection. Do not touch live electric parts.

Refer to the American National Standard Z49.1, "Safety in Welding and Cutting" published by the American Welding Society, 2501 N.W. 7th Street, Miami, Florida 33125: OSHA Safety and Health Standards, 29 CFR 1910, available from U.S. Dept. of Labor, Washington D.C. 20210.

Note: Personal breathing protection should be worn by the personnel that are welding. Personal breathing protection will prevent fumes from entering the lungs of the person that is welding. Refer to PERJ1017Special Instruction, "Dealer Service Tools Catalog" for Personal Protective Equipment (PPE).

Welders must be qualified for the appropriate type of weld that is being performed:

Shielded Metal Arc Welding (SMAW)
Flux Cored Arc Welding (FCAW)
Gas Metal Arc Welding (GMAW)
Gas Tungsten Arc Welding (GTAW)/ Tungsten Inert Gas (TIG)

Welders must be qualified for the appropriate position of weld that is being performed. Refer to AWS Specifications D1.1 and D14.3 or comparable standards for information that regards qualification requirements. The welders must have used the process at some time within the last 6 months. The welders must complete the process of certification if the welders have not used the welding processes for 6 months. The welding operator must hold a current certification for this process. The operator must wear the appropriate equipment. The operator must also install all appropriate equipment. All equipment must maintain the amount of fumes, heat, and ultraviolet radiation at a safe limit.

References:

, SEBD0512Reuse and Salvage Guidelines, "Caterpillar Service Welding Guide"
ANSI/ AWS D1.1, D14.3
Caterpillar Manufacturing Practice MC1000-105

Weld Parameters

Use the direct current electrode positive polarity (DC reverse polarity) setting and remove the slag after every pass. The weld width must not exceed two times the electrode diameter.

The FCAW process will be used with the E90T-1 D-3 (ANSI/AWS A5.29) welding electrode such as the ESAB Dual Shield 150. The weld deposited by these electrodes must have the following mechanical properties listed in Table 10.

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Table 10
Tensile Strength	620 MPa (90 KSI)
Yield Strength	540 MPa (78 KSI)
Elongation	17%
Impact Toughness	20 FT LBF @-20F (27J @- 30C)

Welding parameters will vary due to weld position and operator preference but may not vary more than 10%.
Refer to Table 11 for 1.6 mm (1/16 inch) diameter electrode welding parameters.

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Table 11
Wire Feed Speed	Voltage	Approximate Amps
Min 150 IMP	27	190
OPT 250 IMP	30	300
Max 300 IMP	33	365

Note: Use welding grade 100% Carbon-Dioxide Shielding Gas. 45-55 cfh flow rate. 20-25 mm ID gas nozzle.

Welding Cracks in Zone K

Pre-heat the area to be welded to 204.4° C (400° F).
Weld the area to be repaired using a pass width of no greater than 8.0 mm (0.315 inch).
The final weld pass must be no greater than 3.0 mm (0.118 inch) above any finished surface. Refer to Illustration 68.

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Illustration 68	g03694256
Multiple weld pass pattern

After welding is complete, grind, polish, and, needle peen the repaired area.
The repaired area must be finished to the original specifications. This area has critical functionality for the mounting of the steering arm

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Illustration 69	g03700380
View of 793 standard spindle / front axle.

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Table 12
793
(N) Slot Width	152.76 ± 0.08 mm (6.014 ± 0.003 inch)
(P) Slot Corner Chamfer	1.1 ± 0.5 mm (0.043 ± 0.02 inch) X 45°
(R) Slot Fillet Radius	1.2 ± 0.5 mm (0.047 ± 0.02 inch) X 45°
(S) Slot Depth	7.37 ± 0.25 mm (0.290 ± 0.010 inch)

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Illustration 70	g03700399
View of 797 spindle / front axle.

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Table 13
797
(T) Slot Width	342.0 ± 0.02 mm (13.464 ± 0.0008 inch)
(U) Slot Corner Chamfer	1.1 ± 0.2 mm (0.043 ± 0.008 inch) X 45°
(V) Slot Fillet Radius	R1.2 ± 0.3 mm (0.047 ± 0.012 inch)
(W) Slot Depth	7.37 ± 0.25 mm (0.290 ± 0.010 inch)

It is important to restore the repaired area to the specifications listed in Table 12 and 13, and Illustrations 69 and 70.
Use the"Checklist for Inspection and Salvage of Front Wheel Spindles / Front Axles"to verify the repair.

Thermal Spray Procedures for OHT Front Spindles

Part Description

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Table 14
Base Metal	41B45 Modular or 4140 Steel Alloy
Hardness	28-34 rc

Arc Spray Equipment and Procedure

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Table 15
Maximum Surface Texture	1.6 µm (63.00 µinch)
Reason for Spraying	Wear or grooving
Mating Part Contact Area & Material	Bearing
Arc Spray Equipment Type	SmartArc by Oerlikon Metco,TAFA 8830 MHU, or TAFA 8835 MHU
Wire	TAFA 90MXC Wire Top Coat, TAFA 75B Bond Coat
Finish Thickness	As Required
Spray Angle	90°
Substrate Pre-Heat Temperature	66° C (150° F) Do not direct arc on area to be sprayed
Substrate Temperature During Spraying Not to Exceed	148° C (300° F)
Auxiliary Cooling	Filtered shop air
Rotation/Traverse Device	Lathe
Rotation Speed	92.0 SMPM (300.00 SFPM)
Surface Preparation Method	Undercut and Grit blast if necessary
Equipment Required	Turn Vertical Lathe
Recommended Cutting Tool	ISCAR DNMG 432TFIC507
Blast Media Recommendation	Pressure Type Only (Aluminum Oxide Grit)

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Table 16
Arc Spray		Procedure		Check List
Clean Part		Degrease in hot caustic solution
Undercut		To "tru-up" surface
Chamfer		If required - 1.0 mm (0.039 inch) x 45°
Remove Oxide		Use fiber flap brush or Clean/strip disc
Clean Spray Area		Commercial degreaser
Mask for Grit Blaster		Duct Tape
Grit Blast Equipment		Pressure type only
Grit Type and Size		20 mesh aluminum oxide
Blast Air Pressure		690 kPa (100.0 psi)
Blast Nozzle to Work Distance		51 to 150 mm (2.0 to 6.0 inch)
Remove Blast Mask		Make sure that surface is clean
Mask for Metal Spray		Antibond or Blue Layout Dye
Metal Spray Equipment Type		Smart Arc byOerlikon Metco	TAFA
	Consumable (Bondcoat)	TAFA 75B	TAFA 75B
	Clamp Pressure	275 kPa (40 psi)
	Air Jets/Pressure	415 kPa (60 psi)	415 kPa (60 psi)
	Arc Load Volts	30V	30V
	Amps	125 Amps	150 Amps
	Gun to Work Distance (Standoff)	128 mm (5.0 inch)	128 mm (5.0 inch)
	Spray Rate/Bond Pass	0.038 mm (0.0015 inch)/pass	0.038 mm (0.0015 inch)/pass
	Consumable (Topcoat)	TAFA 90 MXC	TAFA 90 MXC
	Clamp Pressure	275 kPa (40 psi)
	Air Jets/Pressure	415 kPa (60 psi)	415 kPa (60 psi)
	Arc Load Volts	32V	32V
	Amps	125 Amps	150 Amps
	Gun to Work Distance (Standoff)	102 mm (4.0 inch)	102 mm (4.0 inch)
	Spray Rate/Build Up	0.038 mm (0.0015 inch)/pass	0.038 mm (0.0015 inch)/pass
	Rotation Speed of Part (RPM)	RPM varies depending on diameter (70 to 374 RPM)
	Rotation Speed of Part	92.0 SMPM (300.00 SFPM)
	Traverse Rate of Gun	11.0 SMPM (40.00 SFPM)
Gun Fixturing Method		Machine mount or hand held
Finishing Equipment		Lathe
Part/Cutter Rotation		Roughing 12.0 SMPM (40.00 SFPM) Finishing 15.0 SMPM (50.00 SFPM)
Coolant		Oil base synthetic - 40:1 ratio
Traverse Speed		0.30 mm (0.012 inch) per revolution
Depth of Rough Cut		0.38 mm (0.015 inch) per side max.
Depth of Finish Cut		0.25 mm (0.010 inch) per side max.

Flame Spray Equipment and Procedure

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Table 17
Maximum Surface Texture	1.6 µm (63.00 µinch)
Reason for Spraying	Wear or grooving
Mating Part Contact Area & Material	Tapered Roller Bearing
Metco Equipment Type	6P-II by Oerlikon Metco
Metco Material	Metco 453
Finish Thickness	As Required
Finishing Allowance	0.51 to 0.64 mm (0.020 to 0.025 inch) per side
Spray Angle	90°
Substrate Pre-Heat Temperature	66° C (150° F) Do not direct flame on area to be sprayed
Substrate Temperature During Spraying Not to Exceed	148° C (300° F)
Auxiliary Cooling	Filtered shop air
Rotation/Traverse Device	Lathe
Rotation/Traverse Speed	91.4 SMPM (300.00 SFPM)
Surface Preparation Method	Undercut and Grit Blast if necessary
Finishing Method	Machine
Machining Equipment Type	Vertical Lathe
Recommended Cutter Grade	C-2, 883 Carboloy or equivalent

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Table 18
Thermo Spray Process (6P)	Procedure	Check List
Clean Part	Degrease in hot caustic solution
Undercut	To "tru-up" surface
Remove Oxide	Use fiber flap brush, Clean/strip disc
Clean Spray Area	Metco cleaning solvent or equivalent
Mask for Blast	Duct Tape
Blast Equipment	Pressure type only
Grit Type and Size	Aluminum Oxide 20 mesh
Blast Air Pressure	690 kPa (100.0 psi)
Blast Nozzle to Work Distance	51 to 150 mm (2.0 to 6.0 inch)
Remove Blast Mask	Remove mask, make sure that surface is clean
Mask for Spray	Metco Antibond or Blue Layout Dye
Spray Equipment Type	6P-II Hand Held Thermo Spray System by Oerlikon Metco
Auxiliary Cooling	If desired
Nozzle	6P-C7A-K "K" Nozzle
Air Capacity/Pressure	6P-3/Cooling Air 140 - 170 kPa (20.0 - 25.0 psi)
Oxygen Pressure	210 kPa (30.0 psi)
Oxygen Flow	1190 L/h (42.0 cfh)
Fuel Gas Pressure	100 kPa (15.0 psi)
Fuel Gas Flow	1415 L/h (50.0 cfh)
Carrier Gas Pressure	380 kPa (55.0 psi)
Carrier Gas Flow	1050 L/h (37.0 cfh)
Spray Rate/Build Up	5.5 kg (12 lb) per hour or 90 g (3.2 oz) per min
Gun to Work Distance	230 mm (9.0 inch)
Rotation Speed Of Part (RPM)	RPM varies depending on diameter
Rotation Speed Of Part	91.4 SMPM (300.00 SFPM)
Traverse Rate of Gun	15.24 SMPM (50.000 SFPM)
Gun Fixturing Method	Machine mount or hand held
Top Coat/Thickness	0.10 to 0.15 mm (0.004 to 0.006 inch) per pass
Finishing Equipment	Lathe
Part/Cutter Rotation	91.4 SMPM (300.00 SFPM)
Traverse Speed	0.05 to 0.10 mm (0.002 to 0.004 inch) per revolution
Depth of Rough Cut	0.38 to 0.51 mm (0.015 to 0.020 inch) per side
Depth of Finish Cut	0.25 to 0.38 mm (0.010 to 0.015 inch) per side
Optional Finish Method	Emery cloth for desired surface texture

HVOF Spray Equipment and Procedure

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Table 19
Maximum Surface Texture	ɥ 1.6 µm (63.00 µinch) Ra, 40 Rz (40 Micron maximum peak to valley distance)
Reason for Spraying	Wear
Mating Part Contact Area & Material	Bearing
Oerlikon Metco Equipment Type	Diamond Jet Hybrid Spray System
Metco Material	Metco 1008
Finish Thickness	As Required
Finishing Allowance	0.127 to 0.38 mm (0.005 to 0.015 inch) per side, as required
Spray Angle	90°
Spraying Not to Exceed	148° C (300° F)
Auxiliary Cooling	Filtered shop air
Rotation/Traverse Device	Lathe or headstock/tailstock arrangement, rotary turntable
Rotation/Traverse Speed	45.7 SMPM (150.00 SFPM) Traverse rate of 5.00 mm (0.197 inch) per revolution
Surface Preparation Method	Machine to "tru-up" surfaces and Grit blast
Machining Method	Turn or Grind
Equipment Required	Turn (Lathe) / Grind (Finishers Tech)
Recommended Cutting Tool	Kennametal DNMP, Grade K313 or equivalent
Blast Media Recommendations	Pressure type Only (20 Mesh Aluminum Oxide Grit) Blast Profile: 6 Micrometer (250 Microinch) profile minimum
Finishing and Superfinishing Equipment Type	Diamond Belt Grinding
Grinding Equipment	Finishers Tech Super G-6 Belt Grinder or equivalent
Recommended Abrasive	3M^TM Trizact^TM Diamond Cloth Belts 663FC (70 micron)
Superfinishing Equipment	Supfina 210, IMPCO, GEM, or equivalent
Recommended Abrasive	3M^TM Diamond Microfinishing Film 675L (20 micron)
Remarks	If at anytime during spraying oil evolves from the casting, metal spraying must stop. Remove the coating and start the preparation procedure over from the beginning. If this is not done, the coating will fail during machining or during service.

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Table 20
HVOF Spray Process (Hybrid Gun)			Salvage Procedure	Check List
Straighten Part			Step 1
	Equipment Necessary
	Maximum Runout Allowed
"Tru-up" Coating Surface			Step 2
	Rotational and Positioner Equipment
	Coolant
	Grinding Requirements
		Grinding Equipment	Finishers Tech Super G-6 Belt Grinding Machine or equivalent
		Contact Wheel	406 mm (16.0 inch) Diameter, 1:2 ratio Scoop Wheel 45° serration, 90 Shore A hardness, 6.4 mm (0.25 inch) wider than belt
		Contact Wheel vs. Rod Rotational Direction	Opposing Directions (Rotate towards the contact area)
		Abrasive	3M^TM Cubitron^TM Cloth Belts 966F 24 grit
		Idler Force	70 - 100 lbs idler force per inch of belt width
		Belt Speed	1830.0 SMPM (6000.00 SFPM)
		Part Rotational Speed	25.0 SMPM (100.00 SFPM)
		Rotation Speed Of Part (RPM)	RPM varies depending on diameter
		Traverse Speed	6.0 mm (0.25 inch) per revolution
	Turning Requirements
		Recommended Cutter Grade	Kennametal DNMP, Grade K313 or equivalent
		Part/Cutter Rotation (SFPM)	67 SMPM (220.00 SFPM)
		Traverse Speed	0.2108 mm (0.00830 inch) per revolution
		Depth Of Cut	0.38 to 0.51 mm (0.015 to 0.020 inch) per side, are required to "Tru-up"
		Rotation Speed Of Part (RPM)	RPM varies depending on diameter
Clean the Spray Area			Step 3 A) Degrease in hot caustic solution or wipe with a degreasing agent B) Vapor de-grease or set on a turntable and use a torch to heat to 120° C (248° F) to remove all oil from the castings pores. C) Drench bearing areas in Zep I.D. Red or equivalent
Surface Preparation (Grit Blaster)			Step 4
	Mask For Blast		A) Mask off areas, leave 6.0 mm (0.25 inch) area of the spline exposed B) The bearing surfaces must be grit blasted to a roughness of 7.5 micrometer (300.00 microinch)
	Blast Equipment		Pressure Type Only
	Grit Type And Size		20 mesh Aluminum Oxide
	Blast Profile		6 micrometer (250.0 microinch) profile minimum
	Blast Air Pressure		689 kPa (100.0 psi)
	Blast Nozzle to Work Piece Distance		51 to 127 mm (2.0 to 5.0 inch)
	Remove Blast Masking		Remove blast-masking material and make sure that the surfaces are clean, but leave graphite plug in place
HVOF Coating			Step 5
HVOF Application of Coating			A) Install spindle into lathe or headstock/tailstock arrangement. Set up shadow masks in front of spline area and at turnaround point. The shadow masks block heat transfer prevent overheating. Grit blast the shadow mask so that coating will adhere to the mask. Turn the shadow masks at a slight angle (20°) to prevent overspray from hitting the sprayed bearing surface. B) Perform a final degrease with trichloroethylene or Zep I.D. Red. Rotate the spindle during the degreasing operation. C) Monitor coating surface temperature with an optical pyrometer. Do not allow the spindle to reach 150° C (300° F). D) Every 10 passes stop spraying to allow cool down and check lathe chuck for tightness. E) Overspray the diameter to allow for cleanup and shrinkage upon cooling.
Refer to SEBF9236 for HVOF spray parameters
HVOF Grinding Or Turning			Step 6
	Rotational and Positioner Equipment		Lathe or headstock/tailstock arrangement
	Coolant		Use flood coolant of water with 5% Synthetic coolant such as Milicron 46C or equivalent.
	Turning Requirements
		Recommended Cutter Grade	Kennametal DNMP, Grade K313 or equivalent
		Part/Cutter Rotation - Rough Cut	67 SMPM (220.00 SFPM)
		Traverse Speed - Rough Cut	0.2108 mm (0.00830 inch) per revolution
		Depth Of Cut - Rough Cut	0.076 mm (0.003 inch)
		Rotation Speed Of Part (RPM) - Rough Cut	RPM varies depending on diameter
		Final Pass Depth Of Cut For Finishing	0.0381 mm (0.00150 inch)
	Turning Instructions
	1) Start cutting 6.35 mm (0.250 inch) from the edge of the coating and move the tool towards the end of the coating. Do not start at the end of the coating or the coating may lift. 2) Once a 6.35 mm (0.250 inch) wide band is cut, change directions and machine the remainder of the coating. 3) The machining can be performed dry, but a thin film of oil will increase insert life and provide a better surface texture.
	HVOF Grinding Requirements
		Grinding Equipment	Finishers Tech Super G-6 Belt Grinding Machine
		Contact Wheel	Plain face, Incompressible (Aluminum, steel or other), 6.4 mm (0.25 inch) wider than belt
		Abrasive	3M^TM Trizact^TM Diamond Cloth Belts 663FC (70 micron)
		Contact Wheel Vs. Rod Rotational Direction	Opposing Directions (Rotate towards the contact area)
		Belt Speed	1830.0 SMPM (6000.00 SFPM)
		Idler Force	70 - 100 lbs idler force per inch of belt width
		Part Rotational Speed	23.0 SMPM (75.00 SFPM)
		Rotation Speed Of Part (RPM)	RPM varies depending on diameter
		Traverse Speed	6.0 mm (0.25 inch) per revolution
		Infeed Per Pass (inches on diameter)	0.0025 inches
	HVOF Superfinishing Requirements
		Superfinishing Equipment	Supfina 210, IMPCO, GEM, or equivalent
		Contact Wheel	Plain face, 60 Shore A hardness
		Abrasive - HVOF Superfinishing	3M^TM Diamond Microfinishing Film 675L (20 micron)
		Contact Force	20-40 lbs
		Abrasive Feed Rate	8.4 mm (0.33 inch) per minute
		Belt Oscillation (Machine Setting)	Optional
		Spindle Speed	92.0 SMPM (300.00 SFPM)
		Rotation Speed Of Part (RPM)	RPM varies depending on diameter
		Traverse Speed	1.5 mm (0.06 inch) per revolution

Note: Contact wheels are to be 6.0 mm (0.25 inch) wider than the belt to ensure that the belt width is supported evenly from edge-to-edge. Depth of cut for 3M^TM Trizact^TM Diamond Cloth Belts 663FC by grade (Depth of cut on the diameter per pass):

70 micron - 0.064 mm (0.0025 inch)

40 micron - 0.041 mm (0.0016 inch)

20 micron - 0.020 mm (0.0008 inch)

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Table 21
Belt Roll Grinding Recommended Operating Parameters
Belt Roll Grinding Recommended Operating Parameters
Abrasive	3M^TM Trizact^TM Diamond Cloth Belts 663FC
Contact Wheel	Smooth Faced / Incompressible (Aluminum, 65 Shore D, Steel)
Belt Width	2 inches*
Belt Speed	6,000 SFPM
End of Roll Dwell	1/2 Overlap - 2 Revolutions
	Shoulder Grind - 5 revolutions
	* Wider belt allows faster traverse
	** Higher in-feed traverse combinations have been achieved using cylindrical roll grinders

			Chrome Carbide (CAT)
	=75 SFPM	=0.25 inch/rev.	Grinding Infeeds
Rod Diameter	RPM	Traverse Rate	Infeed Per Pass (on diameter)
(inches)	(Workpiece)	(inch/min)	663FC 70-micron	663FC 40-micron	663FC 20-micron
Ø 1.50	191.0	47.7	0.0025	0.0017	0.0008
Ø 2.00	143.2	35.8	0.0025	0.0017	0.0008
Ø 2.50	114.6	28.6	0.0025	0.0017	0.0008
Ø 3.00	95.5	23.9	0.0025	0.0017	0.0008
Ø 3.50	81.9	20.5	0.0025	0.0017	0.0008
Ø 4.00	71.6	17.9	0.0025	0.0017	0.0008
Ø 4.50	63.7	15.9	0.0025	0.0017	0.0008
Ø 5.00	57.3	14.3	0.0025	0.0017	0.0008
Ø 5.50	52.1	13.0	0.0025	0.0017	0.0008
Ø 6.00	47.7	11.9	0.0025	0.0017	0.0008
Ø 6.50	44.1	11.0	0.0025	0.0017	0.0008
Ø 7.00	40.9	10.2	0.0025	0.0017	0.0008
Ø 7.50	38.2	9.5	0.0025	0.0017	0.0008
Ø 8.00	35.8	9.0	0.0025	0.0017	0.0008
Ø 8.50	33.7	8.4	0.0025	0.0017	0.0008
Ø 9.00	31.8	8.0	0.0025	0.0017	0.0008
Ø 9.50	30.2	7.5	0.0025	0.0017	0.0008
Ø 10.00	28.6	7.2	0.0025	0.0017	0.0008
Ø 10.50	27.3	6.8	0.0025	0.0017	0.0008
Ø 11.00	26.0	6.5	0.0025	0.0017	0.0008
Ø 11.50	24.9	6.2	0.0025	0.0017	0.0008
Ø 12.00	23.9	6.0	0.0025	0.0017	0.0008
Ø 12.50	22.9	5.7	0.0025	0.0017	0.0008
Ø 13.00	22.0	5.5	0.0025	0.0017	0.0008
Ø 13.50	21.2	5.3	0.0025	0.0017	0.0008
Ø 14.00	20.5	5.1	0.0025	0.0017	0.0008
Ø 14.50	19.8	4.9	0.0025	0.0017	0.0008
Ø 15.00	19.1	4.8	0.0025	0.0017	0.0008

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Table 22
Rod Diameter	RPM	Traverse Rate
Superfinishing Chrome Carbide Recommended Operating Parameters

Abrasive	3M^TM Diamond Microfinishing Film 675L (20 micron)
Film Feed Rate	0.33 inch/min
Applied Force	25 lb/inch
Oscillation	Low (Low/None: final pass)
Film Width	2 inch*
# of Passes	1 - 2 passes with a 25 - 35 Ra input surface texture**
Obtainable Surface Texture	3 - 6 µinch Ra
	* Wider film allows faster traverse
	** Finish obtained with 3M^TM 663FC 70 micron

		=300 SFPM	=0.0625 inch/rev.
(inches)	(Workpiece)	(inch/min)
Ø 1.50	764.0	47.7
Ø 2.00	573.0	35.8
Ø 2.50	458.4	28.6
Ø 3.00	382.0	23.9
Ø 3.50	327.4	20.5
Ø 4.00	286.5	17.9
Ø 4.50	254.7	15.9
Ø 5.00	229.2	14.3
Ø 5.50	208.4	13.0
Ø 6.00	191.0	11.9
Ø 6.50	176.3	11.0
Ø 7.00	163.7	10.2
Ø 7.50	152.8	9.5
Ø 8.00	143.2	9.0
Ø 8.50	134.8	8.4
Ø 9.00	127.3	8.0
Ø 9.50	120.6	7.5
Ø 10.00	114.6	7.2
Ø 10.50	109.1	6.8
Ø 11.00	104.2	6.5
Ø 11.50	99.6	6.2
Ø 12.00	95.5	6.0
Ø 12.50	91.7	5.7
Ø 13.00	88.1	5.5
Ø 13.50	84.9	5.3
Ø 14.00	81.9	5.1
Ø 14.50	79.0	4.9
Ø 15.00	76.4	4.8

Crack Detection Methods

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NOTICE

Regardless of which crack detection method is used, it is important that the instructions furnished with the detection equipment are followed closely when checking any component. Failure to do so may cause inaccurate results or may cause injury to the operator and/or surroundings.

There are five major crack detection methods or Non-Destructive Testing (NDT) listed in this section: Visual Surface Inspection (VT), Liquid Penetrant Testing (PT), Dry / Wet Magnetic Particle Testing (MPT), and Ultrasonic Testing (UT).

Crack detection methods or NDT is methods for testing components for cracks without damaging the component. VT, PT, Dry/ Wet MPT, and UT are methods recommended. There may be more than one acceptable crack detection method for the testing of a given part, although PT is the most versatile. For example, the PT method can be used when testing smooth machined components such as shafts, gear teeth, and splines, but using the Wet MPT is more accurate. Refer to Table 23 for advantages and disadvantages and Table 24 for standards and requirements for these NDT methods.

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Table 23
Crack Detection Methods Advantages vs. Disadvantages
Detection Method	Advantages	Disadvantages
Visual Surface Inspection (VT)	- Least Expensive - Detects most damaging defects. - Immediate Results - Minimum part preparation	- Limited to surface-only defects. - Requires inspectors to have broad knowledge of welding and fabrication in addition to Non-Destructive Testing (NDT).
Liquid Penetrant Testing (PT)	- Inexpensive - Minimal Training - Portable - Works on nonmagnetic material.	- Least Sensitive - Detects surface cracks only. - Rough or porous surfaces interfere with test
Dry Magnetic Particle (MPT)	- Portable - Fast/Immediate Results - Detects surface and subsurface discontinuities	- Works on magnetic material only. - Less sensitive than Wet Magnetic Particle Testing (MPT).
Wet Magnetic Particle (MPT)	- More sensitive than Liquid Penetrant Testing (PT). - Detects subsurface as much as 0.13 mm (0.005 inch).	- Requires power for light. - Works on magnetic material only. - Liquid composition and agitation must be monitored.
Ultrasonic Testing (UT)	- Most Sensitive - Detects deep material defects. - Immediate Results - Wide range of materials and thickness can be inspected	- Most Expensive - Requires operator training and certification. - Surface must be accessible to probe

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Table 24
Applicable Crack Detection Standards
Detection Method	Standard	Acceptance Criteria	Minimum Required Personnel Qualifications
Visual Surface Inspection (VT)	EN-ISO 5817 AWS D1.1	EN-ISO 5817 - Level B AWS D1.1 - Table 6.1	EN-ISO 9712 ANSI-ASNT SNT-TC-1A
Liquid Penetrant Testing (PT)	EN-ISO 3452 ASTM E165	EN-ISO 23277 AWS - D1.1	EN-ISO 9712 ANSI-ASNT SNT-TC-1A
Magnetic Particle Testing (MPT)	EN-ISO 17638 ASTM E709	EN-ISO 23278 - Level 1 AWS D1.1 - Table 6.1	EN-ISO 9712 ANSI-ASNT SNT-TC-1A
Ultrasonic Testing (UT)	EN-ISO 17640 - Level B AWS D1.1	EN-ISO 11666 Technique 2 - Level 2 AWS D1.1 - Class A - Table 6.3	EN-ISO 9712 ANSI-ASNT SNT-TC-1A

Visual Surface Inspection (VT)

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Illustration 71	g06085008
Example of Visual Surface Inspection (VT) Tooling (A) Flashlight (or adequate light source) (B) Magnifying Glass (C) Tape Measure (or other measuring device) (D) Inspection Mirror (E) Weld Size Inspection Gauges

Refer to Tooling and Equipment Table 3 for part numbers.

Components and welds that are to be tested using PT, MPT, or UT shall first be subject to a Visual Surface Inspection (VT). VT is often the most cost-effective inspection method and requires little equipment as seen in Illustration 71. Personnel performing VT shall either be trained to a company standard or have sufficient experience and knowledge regarding the components being inspected. Personnel performing VT shall take routine eye exams.

Liquid Penetrant Testing (PT)

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Observe all safety precautions recommended by the chemical manufacturer for handling, storage, and disposal of chemicals.

Materials and Equipment Required

Refer to Tooling and Equipment Table 3 for part numbers.

Cleaner: Removes dirt before dye application and dissolves the penetrant making possible to wipe the surface clean.
Penetration Oil: This solution is highly visible, and will seep into openings at the surface of a part with capillary action.
Developer: Provides a blotting action, bringing the penetrant out of the discontinuities and providing a contrasting background to increase the visibility of the penetrating oil indications.
Wire Brush: Removes dirt and paint.
Cloth or Wipes: Use with cleaner and for other miscellaneous uses.

Procedure

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Illustration 72	g06084048
Typical example of pre-cleaning the testing area.

Preclean the area to be tested. Spray on cleaner/ remover to loosen any scale, dirt, or any oil. Wipe the area to be tested with a solvent dampened cloth to remove remaining dirt and allow the area to dry. Remove paint where there are visible cracks using paint remover or a wire brush.
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Illustration 73 g06084053

Typical example of applying penetrating oil to areas to be tested.
Apply penetrating oil by spraying to the entire area to be tested. Allow 10 to 15 minutes for penetrating oil to soak. After the penetrating oil has been allowed to soak, remove the excess penetrating oil with clean, dry wipe.
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Illustration 74 g06084060

Typical example of removing penetrating oil with a cloth.
The last traces of penetrating oil should be removed with the cleaner solvent dampened cloth or wipe. Allow the area to dry thoroughly.
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Illustration 75 g06084070

Typical example of applying the developer.
Before using developer, ensure that the developer is mixed thoroughly by shaking the container. Hold the container approximately 203 - 305 mm (8 - 12 inch) away from part. Apply an even, thin layer of developer over the area being tested. A few thin layers are a better application method than one thick layer.
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Illustration 76 g03773759

Typical example of cracks found during Liquid Penetrant Testing (PT).
Allow the developer to dry completely for 10 to 15 minutes before inspecting for cracks. Defects will show as red lines in white developer background, refer to Illustration 76. Clean the area of application of the developer with solvent cleaner.

Liquid Penetrant Testing (PT)

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Observe all safety precautions recommended by the chemical manufacturer for handling, storage, and disposal of chemicals.

Materials and Equipment Required

Refer to Tooling and Equipment Table 3 for part numbers.

Cleaner: Removes dirt before dye application and dissolves the penetrant making possible to wipe the surface clean.
Penetrating Oil: This solution is highly visible, and will seep into openings at the surface of a part with capillary action.
Developer: Provides a blotting action, bringing the penetrant out of the discontinuities and providing a contrasting background to increase the visibility of the penetrating oil indications.
Wire Brush: Removes dirt and paint.
Cloth or Wipes: Use with cleaner and for other miscellaneous uses.

Dry Magnetic Particle Testing (MPT)

Materials and Equipment Required

Refer to Tooling and Equipment Table 3 for part numbers.

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Illustration 77	g06085930
(A) Indications shown by Dry Magnetic Particle Testing (MPT). (B) Electromagnetic Yoke (C) Dry Powder Bulb

Dry magnetic powder shall be of high permeability and low retentively and of suitable sizes and shapes to produce magnetic particle indications. The powder shall be of a color that will provide adequate contrast with the background of the surface being inspected.
Dry magnetic particles shall be stored in suitable containers to resist contamination such as moisture, grease, oil, non-magnetic particles such as sand, and excessive heat. Contaminants will manifest in the form of particle color change and particle agglomeration. The degree of contamination will determine further use of the powder.
Dry magnetic powder shall be tested in accordance with ASTM E709 Section 18 (Evaluation of System Performance/Sensitivity) when not performing.
Equipment should include a "U" shaped electromagnetic yoke made from highly permeable magnetic material, which has a coil wound around the yoke. This coil carries a magnetizing current to impose a localized longitudinal magnetic field into the part. The magnetizing force of the yoke is related to the electromagnetic strength and can be tested by determining the lifting power of a steel plate. The yoke shall have a lifting force of at least 4.5 kg (10 lbs).
Check dry powder blower routinely to ensure that the spray is a light, uniform, dust-like coating of the dry magnetic particles. Blower should also have sufficient force to remove excess particles without disturbing those particles that are evidence of indications.
All equipment shall be inspected at a minimum of once a year or when accuracy is questionable.

Procedure

Ensure surface to be inspected is dry and free from oil, grease, sand, loose rust, mil scale, paint, and other contaminants.
Apply the magnetic field using the yoke against the faces and inside diameter of each bore.
Simultaneously apply the dry powder using the dry powder blower.
Remove excess powder by lightly blowing away the dry particles.
Continue around the entire circumference of each bore. Position the yoke twice in each area at 1.57 rad (90°) to ensure that multiple directions of the magnetic field are created.
Observe particles and note if any clusters of particles appear revealing an indication.
Record the size and shape of any discontinuities or indications found.

Wet Magnetic Particle Testing (MPT)

Materials and Equipment

Refer to Tooling and Equipment Table 3 for part numbers.

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Illustration 78	g06085937
(A) Indications shown by Wet Magnetic Particle Testing (MPT). (B) Electromagnetic Yoke (D) Ultraviolet Lamp

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Illustration 79	g06003178
Pear Shaped Centrifuge Tube

Wet magnetic particles are fluorescent and are suspended in a vehicle in a given concentration that will allow application to the test surface by spraying.
Concentration:
1. The concentration of the suspended magnetic particles shall be as specified by the manufacturer and be checked by settling volume measurements.
2. Concentrations are determined by measuring the settling volume by using an ASTM pear shaped centrifuge tube with a 1 mL (0.034 oz) stem with 0.05 mL (0.0017 oz) divisions, refer to Illustration 79. Before sampling, the suspension shall be thoroughly mixed to assure suspension of all particles, which could have settled. A 100 mL (3.40 oz) sample of the suspension shall be taken and allowed to settle for 30 minutes. The settling volume should be between 0.1 mL (0.0034 oz) and 0.25 mL (0.0085 oz) in a 100 mL (3.40 oz) sample.
3. Wet magnetic particles may be suspended in a low viscosity oil or conditioned water.
4. The oil shall have the following characteristics:
  - Low viscosity not to exceed 5 mm²/_s (5 cSt) at any temperature at which the vehicle is to be used.
  - Low inherent fluorescence and be non-reactive.
5. The conditioning agents used in the conditioned water shall have the following characteristics:
  - Impart good wetting characteristics and good dispersion.
  - Minimize foaming and be non-corrosive.
  - Low viscosity shall not exceed a maximum viscosity of 5 mm²/_s (5 cSt) at 38° C (100° F).
  - Non-fluorescent, non-reactive, and odorless.
  - Alkalinity shall not exceed a pH of 10.5.
Equipment should include a "U" shaped electromagnetic yoke made from highly permeable magnetic material, which has a coil wound around the yoke. This coil carries a magnetizing current to impose a localized longitudinal magnetic field into the part. The magnetizing force of the yoke is related to the electromagnetic strength and can be tested by determining the lifting power of a steel plate. The yoke shall have a lifting force of at least 4.5 kg (10 lbs).

Procedure

Ensure surface to be inspected is dry and free from oil, grease, sand, loose rust, mil scale, paint, and any other contaminants.
Apply the magnetic field using the yoke against the surface in the area to be inspected.
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Illustration 80 g03536210
For case hardened and ground surfaces:
- Due to the sensitivity required to locate the grinding cracks, inspection of case hardened and ground surfaces require that the yoke is applied so that the magnetic field is 1.57 rad (90°) to the expected direction of the indications. Also, due to the increased sensitivity resulting when the yoke is energized, the yoke is not moved until the evaluation is completed in the first direction. An AC yoke shall be used. See Illustration 80 for an example of yoke placement.
Visually inspect for indications of discontinuities using the proper illumination.
Record the size and shape of any discontinuities found.

Ultrasonic Testing (UT)

Note: Crack depth cannot be accurately determined by UT, only full depth cracking can be consistently determined. For cracks that are not full depth, an indication of a partial depth cracks can be detected by an experienced technician. Refer to Table 24 for crack detection standards.

Refer to Tooling and Equipment Table 3 for part numbers.

Ultrasonic Testing (UT) is a method of Non-Destructive Testing (NDT) using short ultrasonic pulse waves (with frequencies from 0.1-15 MHz up to 50 MHz) to detect the thickness of the object. Ultrasonic testing consists of an ultrasound transducer connected to a diagnostic machine and passed over the object being inspected.
There are two methods of receiving the ultrasound waveform from the transducer: reflection and attenuation.
1. Reflection - Ultrasonic pulses exit the transducer and travel throughout the thickness of the material. When the sound waves propagate into an object being tested, the waves return to the transducer when a discontinuity is discovered along the sonic path. These waves continue and reflect from the back surface of the material to project the thickness of the material.
2. Attenuation - A transmitter sends ultrasound through one surface, and a separate receiver detects the amount that has reached it on another surface after traveling through the medium. Any discontinuities or other conditions within the medium will reduce the amount of sound transmitted, revealing the presence of the imperfections.

Caterpillar Information System:

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Illustration 24	g03727170
Typical example of performing a hardness test using 6V-6035 Hardness Tester.




Illustration 73	g06084053
Typical example of applying penetrating oil to areas to be tested.




Illustration 74	g06084060
Typical example of removing penetrating oil with a cloth.




Illustration 75	g06084070
Typical example of applying the developer.




Illustration 76	g03773759
Typical example of cracks found during Liquid Penetrant Testing (PT).