- Articulated Truck
- All
- Integrated Toolcarrier
- All
- Landfill Compactor
- 816 (S/N: 57U1-UP)
- 816B (S/N: 15Z1-UP)
- 816F (S/N: 5FN1-UP; BMR1-UP)
- 816K (S/N: LT61-UP; SLL1-UP)
- 826B (S/N: 58U1-UP)
- 826C (S/N: 87X1-UP)
- 826G (S/N: 7LN1-UP)
- 826G Series II (S/N: AYH1-UP)
- 826K (S/N: 2L31-UP; 2T61-UP)
- 836G (S/N: BRL1-UP; 7MZ1-UP)
- 836K (S/N: T6X1-UP; L6Z1-UP)
- 816B (S/N: 15Z1-UP)
- Motor Grader
- All
- Soil Compactor
- 815 (S/N: 91P1-UP; 15R1-UP)
- 815B (S/N: 17Z1-UP)
- 815F (S/N: BKL1-UP; 1GN1-UP)
- 815K (S/N: SL91-UP; T1Y1-UP)
- 825B (S/N: 43N1-UP)
- 825G (S/N: 6RN1-UP)
- 825G Series II (S/N: AXB1-UP)
- 825K (S/N: 2L91-UP; 2T91-UP)
- 835 (S/N: 44N1-UP)
- 815B (S/N: 17Z1-UP)
- Wheel Dozer
- 814 (S/N: 90P1-UP; 14R1-UP)
- 814B (S/N: 16Z1-UP)
- 814F (S/N: BGF1-UP; 9DM1-UP)
- 814K (S/N: LW41-UP; T1Z1-UP)
- 824 (S/N: 29G1-UP)
- 824B (S/N: 36H1-UP)
- 824C (S/N: 85X1-UP)
- 824G (S/N: 4SN1-UP)
- 824G Series II (S/N: AWW1-UP)
- 824K (S/N: 2T21-UP; 2L41-UP)
- 834 (S/N: 43E1-UP)
- 834B (S/N: 7BR1-UP; 92Z1-UP)
- 834G (S/N: BPC1-UP; 6GZ1-UP)
- 834K (S/N: TW41-UP; L4Y1-UP)
- 844 (S/N: BBN1-UP; 2KZ1-UP)
- 844H (S/N: BTW1-UP)
- 844K (S/N: M4R1-UP; K4Y1-UP)
- 854G (S/N: AMP1-UP; A4W1-UP; 1JW1-UP)
- 854K (S/N: 2211-UP; KK61-UP; RM61-UP; H9K1-UP; H8M1-UP)
- 814B (S/N: 16Z1-UP)
- Wheel Loader
- All
- Wheel Tractor-Scraper
- All
Introduction
| Revision | Summary of Changes in SEBF8119 |
|---|---|
| 24 | Added new serial number prefixes for New Product Introduction (NPI). |
| 23 | Added new serial number prefixes for New Product Introduction (NPI).
Updated copyright date to 2018. Added 1 part number. |
| 22 | Removed sleeving verbiage. |
| 21 | Added 7 part numbers. |
| 20 | Added 8 part numbers. |
© 2018 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 NPR on SIS for information about canceled part numbers and replaced part numbers. NPR will provide the current part numbers for replaced parts.
Summary
The contents of this guideline discuss the reusability of components of the differential housing for differentials. The contents also provide dimensions of diameters to reuse bearing journals. Additional instructions for the salvage of repairable components will be contained in future individual guidelines. Differential housing assemblies can be salvaged by metal spraying pinion bores, bearing journals, axle bores, bearing shoulders, ring gear mounting faces, and split faces. Bolt hole damage and distortion in the flange half can be repaired by sleeving the bolt holes. The repair procedure in this guideline provides a method to salvage differential housings.
Several conditions can cause damage. For example, the differential housing bores can be damaged by foreign material or component failure. Damage to the differential housing can occur from bearing or gear failures. These failures can cause the bores of the housing to become elongated. Damage to the differential housing can also occur when subjected to extreme axial loads.
This guideline identifies the various areas that can be salvaged using the metal spray. The metal spray operation must be followed by precision machining and using dimensions provided in this guideline.
Differential housings that meet these salvage guidelines and specifications can be expected to perform normally in the same application. Never install a part that this guideline indicates cannot be used again. Before installing a used or reconditioned part, correct any condition that may have caused the original wear.
If you need dimensional information for a component that is not yet available or to report suspected errors, inaccuracies, or suggestions regarding the document, submit a form for feedback in the Service Information System (SIS Web) interface. Examples of gear wear are provided in this publication, but much more detailed description and information for analysis can be found in publication Reuse and Salvage Guideline, SEBF8193, "Reusability of Drive Train Gears".
This guideline contains the latest standards of engineering, which will help minimize owning and operating costs. A part can be expected to reach the next Planned Component Repair if the part meets the specifications in this guideline and if the part is used in the same application.
Do not operate or perform any lubrication, maintenance, or repair on this product until you have understood the operation, lubrication, maintenance, and repair information. If a part has met the specification in this guideline, the part can be expected to give normal performance until the next overhaul. The conditions apply when the part is used in the same application.
If this guideline shows a part that is not reusable, do not install the part. During reconditioning, correct any conditions that might have caused the original failure.
Important Safety Information
| |
| 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.
 |
|
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. The “WARNING” safety alert symbol is shown below.
| |
| 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.
Service Letters and Technical Information Bulletins
| NOTICE |
|---|
|
The most recent Service Letters and Technical Information Bulletins that are related to this component shall be reviewed before beginning work. Often Service Letters and Technical Information Bulletins contain upgrades in repair procedures, parts, and safety information that pertain to the parts or components being repaired. |
References
| References | |
| Media Number | Publication Type & Title |
| SEBF8187 | Reuse and Salvage Guideline , "Standardized Parts Marking Procedures" |
| SEBF8193 | Reuse and Salvage Guideline , "Reusability of Drive Train Gears" |
| SEBF8227 | Reuse and Salvage Guideline , "Salvage of Differential Housing Assembly used on 785, 789, and 793 Off-Highway Trucks" |
| SEBF8728 | Reuse and Salvage Guideline , "Specifications for Inspection of Drive-line Fasteners" |
| SEBF9236 | Reuse and Salvage Guideline , "Fundamentals of HVOF Spray for Reconditioning Components" |
| SEBF9238 | Reuse and Salvage Guideline, SEBF9238, "Fundamentals of Arc Spray for Reconditioning Components" |
| SEBF9240 | Reuse and Salvage Guideline , "Fundamentals of Flame Spray for Reconditioning Components" |
Tooling and Equipment
| 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. |
Table 3 contains the items that are needed to complete the repair procedures in this guideline.
| Tooling and Equipment | |
|---|---|
| Part Number | Description |
| Polishing Cloth / Emery Cloth | |
| Disc Pad Holder | |
| Discs (Coarse) | |
| Wire Brush | |
| Dial Bore Gauge Kit | |
| Penetrant | |
| Developer | |
| Flapper Wheel (2" x 1" 120 grit) |
|
| Wheel Adapter | |
| Seal Pick | |
| Bearing Mount Compound | |
| Eye Loupe | |
| Surface Reconditioning Pad | |
| Surface Texture Comparison Gauge | |
| Metal Marking Pen | |
| Gear Inspection Stand | |
| Die Grinder | |
| Right Angle Die Grinder | |
| White LED Pen Light | |
| Crack Detection Kit | |
| Blue LED Pen Light | |
| Paper Towel | |
| Digital Caliper 6 Inch | |
| Inside Micrometer Set
2-24 inch |
|
or |
Profilometer
Bluetooth Feature |
| Profilometer
Non-Bluetooth Feature |
|
| UV Light Kit | |
or |
Inside Micrometer Set
2-12 inch |
| Inside Micrometer Set
50-300 mm |
|
| Outside Electronic Micrometer Set
0-4 inch |
|
| Outside Electronic Micrometer Set
2-6 inch |
|
Preparation Before Inspection
|
|
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. |
|
|
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 |
| |
| Illustration 3 | g03721203 |
|
Typical burr removal tooling. (A) Right Angle Die Grinder (B) Die Grinder (C) ( D) ( E) Conditioning Discs, Disc Pad Holder, and Threaded Shaft (F) ( G) Flapper Wheels | |
- Clean all surfaces for inspection before you inspect the part. Make sure that you remove all debris, paint, and oil.
- 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 bore 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.
- Use appropriate thread taps to chase all threaded holes.
Preheat the base metal to a minimum of
Clean the area that will be welded. Make sure that the substances that follow are removed from the area that will be welded.
- Oil
- Grease
- Paint
- Dirt
All components need thoroughly cleaned prior to inspection to be sure that no damage is hidden by oil or dirt. Use a wash tank or a coarse bristle brush with a mild petroleum-based solvent. Be sure that the solvent does not have any water contamination. Also, never use a chlorinated solvent. Water or chlorine can cause corrosion on the surface from pitting. Pits cause areas of highly concentrated stress that are called stress raisers to occur. These areas are more likely to result in component failure.
The 8S-2257 Eye Loupe As and 5P-1720 Seal Pick are useful in the close inspection of irregularities on the surface of the component. Use a dye penetrant or other suitable equipment to check all components for cracks, and scrap any cracked parts. Emery cloth or abrasive sheets are used to remove surface rust, light fretting, or nicks from handling. When inspection is completed, be sure to maintain the cleanliness of all acceptable differential components and protect the components from moisture. If necessary, clean the parts again before reassembly.
Standardized Parts Marking Procedure
Reference: Refer to Reuse And Salvage Guideline, SEBF8187, "Standardized Parts Marking Procedures" for additional information regarding marking procedures.
The code is a Cat standard and is used to record the history of a gear. The code will identify the number of rebuilds and hours at the time of each rebuild. This information is important for any decision to reuse a gear. The information should be considered when deciding whether to reuse a gear. The information should be utilized for locating the cause of a failure.
The mark should be on the sides of planetary gears and sun gears. The mark should not be covered by a mating part. Use a Metal Marking Pen to mark the code onto the gear.
| NOTICE |
|---|
|
Do not use a numbering stamp punches set to mark internal parts. The impact from striking the stamp will cause an abnormal stress riser. The added stress riser may cause the part to fail prematurely. |
The procedure for marking gears 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
| |
| Illustration 4 | g03649157 |
Illustration 4 shows code (1-15). The first number (1) indicates that the component had been rebuilt once. The second number (15) indicates that there were 15,000 hours on the component at the time of rebuild.
Example 2
| |
| Illustration 5 | g03649151 |
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 component had been rebuilt twice. The second number (10) indicates that 10,000 hours accumulated on the component between the first and second rebuild.
Note: To obtain the total number of hours for the component in Illustration 5, add first and second rebuild hours. In this example the component has a total of 22,000 hours.
Metal Spray
Metal spray is an acceptable method of restoring a surface to the original size. Each step in the procedure is critical in achieving the desired coating, bond, and surface finish. Refer to Reuse and Salvage Guideline, SEBF9236, "Fundamentals of HVOF Spray for Reconditioning Components", Reuse and Salvage Guideline, SEBF9238, "Fundamentals of Arc Spray for Reconditioning Components" and Reuse and Salvage Guideline, SEBF9240, "Fundamentals of Flame Spray for Reconditioning Components" for metal spray repair procedures.
Ring Gear and Pinion
On most machines, the ring and the pinion are serviced separately. However, if the ring and the pinion are a matched set, damage to either gear requires the installation of a new set.
Start of Active Profile
If pitting of the teeth occurs on the ring gear and the pinion, the result is normally a line of small pits at the SAP (Start of Active Profile). The pitting starts first on the pinion, and then on the ring gear. See Illustration 7 through Illustration 9.
| |
| Illustration 6 | g03782670 |
|
Profile of gear tooth (1) Start of Active Profile (SAP) (2) Pitch line | |
| |
| Illustration 7 | g01363842 |
|
Slight indication of pitting at the SAP. | |
USE THE GEAR AGAIN
| |
| Illustration 8 | g01367967 |
|
Slight indication of pitting at the SAP. | |
USE THE GEAR AGAIN
| |
| Illustration 9 | g03782673 |
|
Slight indication of pitting at the SAP. | |
Pitch Line
Do not reuse gears with any pitting around the pitch line.
Sensor Gear
| |
| Illustration 10 | g03782675 |
Differential Spider Gears, Side Gears, and Pinions
Surfaces of the thrust face must be free of smearing, grooves, corrosion from pitting and any other mechanical damage that could act as a cutting edge against the bearing.
| |
| Illustration 11 | g01234759 |
|
The thrust face has shallow grooves. | |
DO NOT USE THE GEAR AGAIN
| |
| Illustration 12 | g01234768 |
|
Stains from rusting. | |
USE THE GEAR AGAIN
Part can be reused after removing the rust with a fine abrasive cloth.
| |
| Illustration 13 | g01234825 |
|
The thrust face has been grooved by abrasive particles. | |
DO NOT USE THE GEAR AGAIN
| |
| Illustration 14 | g01234832 |
|
The thrust face has been pitted by corrosion. | |
Spider Shaft
No wear is permitted on spider shafts.
Differential Housing
Visually determine if the differential housing can be salvaged. Damage to machined bolt holes in the flange area may be repaired by enlarging the hole and installing a sleeve.
| |
| Illustration 15 | g03704110 |
|
Inspect all areas indicated by arrows for wear, dents, nicks, and other types of damage. | |
- Check bolt hole depth using the bolt without the washer. The bolt must go completely through both parts with sufficient clearance for locknut, washer, and nut.
- Check the housing for cracks.Do Not Use Again, If the housing is cracked.
- Check housing for heat damage and distortion.
- Check bore and outside diameter bearing surfaces for wear. If worn beyond recommended specification, repair the damage before using again.
Mounting Faces
Movement between the halves of the differential housing and between the ring gear and the housing causes the pieces to fret. Fretting refers to the wearing and transferring of metal between the pieces. Any parts that show fretting up to the amount in Illustration 16 can be reused after all high spots are removed. Face off the surface and build up the surface by thermal spray if the damage is deeper. Contact dealer support for dimensions for given parts.
| |
| Illustration 16 | g01234839 |
|
The damage from fretting on the mounting surface is not excessive. The damage from fretting on the mounting surface must not be more than the amount of damage that is shown here. | |
Use the differential housing again.
Bore of the Spider Shaft
Some fretting is permitted in this bore. See Illustration 17 for a typical example of acceptable fretting. The bores which are machined in the mounting face of the case may show fretting or wear beyond this point. The bores may then be built up using thermal spray and re-bored. This is done together with the mounting faces. Call Dealer Support to obtain this dimension for given housings.
| |
| Illustration 17 | g01234842 |
|
Typical example of acceptable fretting. | |
Use the differential housing again.
Side Gear and Pinion Thrust Faces
Do not reuse a housing if the thrust bearing has worn into the housing more than
| |
| Illustration 18 | g03782677 |
|
The thrust face does not have more than | |
Use the differential housing again.
The component is acceptable to be reused if the thrust face does not have more than
Locating Dowel for the Thrust Bearing
Do not reuse a housing if the locating dowel is loose. See Illustration 19. Loose dowels will break during operation, which will permit the thrust bearing to turn. Housings with worn dowel holes can be salvaged by drilling a new hole in the other half of the housing or by boring the worn hole, plugging the hole with a steel rod, and drilling a new hole in the original location.
| |
| Illustration 19 | g01234855 |
|
Housing with loose locating dowel. | |
Use the differential housing again.
The hole for the locating dowel must be relocated or repaired to be reused.
Support Bearing Journals
The maximum amount of wear that is permitted on the outside diameter of the bearing journals that support the differential housing is shown in Table 4. Journals that are worn beyond this amount can be salvaged with metal spray. Bearings that will be used on journals that are smaller than the new diameter must be installed using 7M-7456 Bearing Mount Compound. Wear on the thrust face up to
| |
| Illustration 20 | g01234859 |
|
Excessive wear on the bearing journal that supports the differential housing. | |
Use the differential housing again.
The bearing journal that supports the differential housing must be repaired.
| |
| Illustration 21 | g03782678 |
|
Typical group for the differential housing. (3) Flange (4) Bearing journal on the plain end (5) Bearing journal on the flange end | |
| Diameter of the Bearing Journal that Supports the Differential Housing | ||
|---|---|---|
| Part Number | Part Description | Dimension |
| differential case | |
|
| differential housing | |
|
| differential case | |
|
| differential case | |
|
| differential case | |
|
| housing | |
|
| differential housing | ||
| flange half of the differential case | |
|
| plain half of the differential case | |
|
| flange half of the differential case | |
|
| plain half of the differential case | |
|
| flange half of the differential case | |
|
| plain half of the differential case | |
|
| flange half of the differential case | |
|
| plain half of the differential case | |
|
| flange half of the differential case | |
|
| plain half of the differential case | ||
| flange half of the differential case | |
|
| plain half of the differential case | ||
| flange half of the differential case | |
|
| plain half of the differential case | |
|
| flange half of the differential case | |
|
| plain half of the differential case | |
|
| gear half of the differential case | |
|
| reaction half of the differential case | |
|
| gear half of the differential case | |
|
| reaction half of the differential case | |
|
| differential housing | |
|
| cover for differential housing | |
|
| flange half of the differential case | |
|
| plain half of the differential case | |
|
| flange half of the differential case | |
|
| plain half of the differential case | |
|
| flange half of the differential case | |
|
| plain half of the differential case | |
|
| flange half of the differential case | |
|
| plain half of the differential case | |
|
| flange half of the differential case | |
|
| plain half of the differential case | ||
| flange half of the differential case | |
|
| plain half of the differential case | ||
| flange half of the differential case | |
|
| plain half of the differential case | |
|
| flange half of the differential case | |
|
| plain half of the differential case | ||
| flange half of the differential case | |
|
| plain half of the differential case | ||
| flange half of the differential case | |
|
| plain half of the differential case | ||
| differential case | |
|
| large diameter of differential case | |
|
| small diameter of differential case | |
|
| differential housing | |
|
| cover for differential housing | |
|
| cover for differential housing | |
|
| half with the gear of the differential case | |
|
| plain half of the differential case | |
|
| half with the gear of the differential case | |
|
| plain half of the differential case | |
|
| half with the gear of the differential case | |
|
| plain half of the differential case | |
|
| half with the gear of the differential case | |
|
| plain half of the differential case | |
|
| flange half of the differential case | |
|
| plain half of the differential case | ||
| flange half of the differential case | |
|
| plain half of the differential case | |
|
| cover for differential housing | |
|
| plain half of the differential case | |
|
| half with the gear of the differential case | |
|
| plain half of the differential case | |
|
| half with the gear of the differential case | |
|
| plain half of the differential case | |
|
| half with the gear of the differential case | |
|
| plain half of the differential case | |
|
| half with the gear of the differential case | |
|
| plain half of the differential case | |
|
| half with the gear of the differential case | |
|
| half with the gear of the differential case | |
|
| plain half of the differential case | |
|
| flange half of the differential case | |
|
| plain half of the differential case | |
|
| cover for differential housing | |
|
| cover for differential housing | |
|
| flange half of the differential case | |
|
| plain half of the differential case | ||
| flange half of the differential case | |
|
| plain half of the differential case | |
|
| gear half of the differential case | |
|
| plain half of the differential case | |
|
| flange half of the differential case | |
|
| plain half of the differential case | |
|
| flange half of the differential case | |
|
| plain half of the differential case | |
|
| flange half of the differential case | |
|
| plain half of the differential case | |
|
| flange half of the differential case | |
|
| plain half of the differential case | |
|
| flange half of the differential case | |
|
| plain half of the differential case | |
|
| flange half of the differential case | |
|
| plain half of the differential case | |
|
| flange half of the differential case | |
|
| plain half of the differential case | |
|
| flange half of the differential case | |
|
| plain half of the differential case | |
|
| plain half of the differential case | |
|
| flange half of the differential case | |
|
| flange half of the differential case | |
|
| plain half of the differential case | |
|
| cover for differential housing | |
|
| flange half of the differential case | |
|
| plain half of the differential case | |
|
| flange half of the differential case | |
|
| plain half of the differential case | |
|
| flange half of the differential case | |
|
| plain half of the differential case | |
|
| flange half of the differential case | |
|
| plain half of the differential case | |
|
| plain half of the differential case | |
|
| flange half of the differential case | |
|
| flange half of the differential case | |
|
| plain half of the differential case | |
|
| flange half of the differential case | |
|
| plain half of the differential case | |
|
| plain half of the differential case | |
|
| flange half of the differential case | |
|
| plain half of the differential case | |
|
| half with the gear of the differential case | |
|
| plain half of the differential case | |
|
| flange half of the differential case | |
|
| plain half of the differential case | |
|
| flange half of the differential case | |
|
| half with the gear of the differential case | |
|
| plain half of the differential case | |
|
| half with the gear of the differential case | |
|
| plain half of the differential case | |
|
| plain half of the differential case | |
|
| flange half of the differential case | |
|
| plain half of the differential case | |
|
| flange half of the differential case | |
|
| reaction half of the differential case | |
|
| gear half of the differential case | |
|
| lock half of the differential case | |
|
| gear half of the differential case | |
|
Crack Detection Methods
Crack detection methods or Non-Destructive Testing (NDT) are utilized for examining components for cracks without damaging the component. Visual inspection, Liquid Penetrant Testing (PT), Magnetic Particle Testing (MT), Ultrasonic Testing (UT), Radiographic Testing and Eddy Current Testing are recommended methods. There may be more than one acceptable crack detection method for the inspection of a given part, though the liquid penetrant is the most versatile. For example, the liquid penetrant method can be used when inspecting smooth machined components such as shafts, gear teeth, and splines, but using the Wet Magnetic Particle Inspection is more accurate. Refer to Table 5 for advantages and disadvantages and Table 6 for standards and requirements for these NDT methods.
| Crack Inspection Method Advantages vs. Disadvantages | ||
|---|---|---|
| Inspection 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 NDT |
| Liquid Penetrant (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 (MT) | - Portable - Fast/Immediate Results - Detects surface and subsurface discontinuities |
- Works on magnetic material only - Less sensitive than Wet Magnetic Particle |
| Wet Magnetic Particle (MT) | - More sensitive than Liquid Penetrant - Detects subsurface as much as |
- Requires Power for Light - Works on magnetic parts 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 |
| Eddy Current Testing (ET) | - Surface and near surface flaws detectable -Moderate speed/Immediate results -Sensitive too small discontinuities |
- Difficult to interpret - Only for metals -Rough surfaces interfere with test - Surface must be accessible to probe |
| Radiographic Testing (RT) | -Detects surface and internal flaws - Minimum part preparation - Can inspect hidden areas |
- Not for porous materials - Radiation protection needed - Defect able to be detected is limited to 2% of thickness |
| Applicable Crack Detection Standards | |||
| Type | Standard | Acceptance
Criteria |
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 - Level 2
ANSI-ASNT SNT-TC-1A Level 2 |
| Liquid Penetrant Testing (PT) | EN-ISO 3452
ASTM E165 |
EN-ISO 23277
AWS - D1.1 |
EN-ISO 9712 - Level 2
ANSI-ASNT SNT-TC-1A Level 2 |
| Magnetic Particle Testing (MT) | EN-ISO 17638
ASTM E709 |
EN-ISO 23278 - Level 1
AWS D1.1 - Table 6.1 |
EN-ISO 9712 - Level 2
ANSI-ASNT SNT-TC-1A Level 2 |
| 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 - Level 2
ANSI-ASNT SNT-TC-1A Level 2 |
| Eddy Current Testing (ET) | EN-ISO 15549
ASTM E426 |
EN-ISO 20807 | EN-ISO 9712 - Level 2
ANSI-ASNT SNT-TC-1A Level 2 |
| Radiographic Testing (RT) | EN-ISO 5579
ASTM E94 |
EN-ISO 10657-1 | EN-ISO 9712 - Level 2
ANSI-ASNT SNT-TC-1A Level 2 |
| 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. |
Visual Surface Inspection (VT)
| |
| Illustration 22 | g06085008 |
|
Example of Visual Inspection Tools (A) Flashlight or adequate light source (B) Magnifying eye loupe (C) Tape measure or other measuring device (D) Inspection mirror (E) Weld size inspection gauges | |
Components and welds that are to be inspected using PT, MT, or UT shall first be subject to visual inspection (VT). Visual Inspection is often the most cost-effective inspection method and requires little equipment as seen in Illustration 22. It is suggested that at a minimum personnel performing Visual Inspection are either trained to a company standard or have sufficient experience and knowledge about the components being inspected. It is also suggested that personnel performing visual inspections take some type of eyesight test regularly.
Liquid Penetrant Testing (PT)
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|
Personal injury can result from improper handling of chemicals. Make sure you use all the necessary protective equipment required to do the job. Make sure that you read and understand all directions and hazards described on the labels and material safety data sheet of any chemical that is used. Observe all safety precautions recommended by the chemical manufacturer for handling, storage, and disposal of chemicals. |
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.
- Penetrant: 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 penetrant indications.
- Wire Brush: Removes dirt and paint.
- Cloth or Wipes: Use with cleaner and for other miscellaneous uses.
Procedure
- Preclean inspection area. Spray on cleaner / remover to loosen any scale, dirt, or any oil. Wipe the area to inspect with a solvent dampened cloth to remove remaining dirt and allow the area to dry. If there is visible crack remove paint using paint remover or wire brush.
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Illustration 24 g06087912 Typical example of checking for cracks in the welded areas. - Apply penetrant by spraying to the entire area to be examined. Allow 10 to 15 minutes for penetrant to soak. After the penetrant has been allowed to soak, remove the excess penetrant with clean, dry wipe.
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Illustration 25 g06087914 - The last traces of penetrant should be removed with the cleaner solvent dampened cloth or wipe. Allow the area to dry thoroughly.
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Illustration 26 g06087916 - Before using Developer, ensure that it is mixed thoroughly by shaking can. Hold can approximately 8-12 inches away from part, apply an even, thin layer of developer over the area being inspected. A few thin layers are a better application method than one thick layer.
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Illustration 27 g06084042 Typical example of cracks found during a liquid penetrant examination. - Allow the developer to dry completely for 10–15 minutes before inspecting for cracks. Defects will show as red lines in white developer background, refer to Illustration 27. Clean the area of application of the developer with solvent cleaner.
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| Illustration 23 | g06087907 |
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Typical example of checking for cracks in the welded areas. | |
Dry Magnetic Particle Testing (MT)
Materials and Equipment Required
Refer to Tooling and Equipment Table 3 for part numbers.
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| Illustration 28 | g06085930 |
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(A) Indications shown by magnetic particle testing.
(B) Typical 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 (MT)
Materials and Equipment
Refer to Tooling and Equipment Table 3 for part numbers.
| |
| Illustration 29 | g06085937 |
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(A) Indications shown by magnetic particle testing.
(B) Typical electromagnetic yoke. (D) UV Lamp used in wet magnetic particle inspection process. | |
| |
| Illustration 30 | 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:
- The concentration of the suspended magnetic particles shall be as specified by the manufacturer and be checked by settling volume measurements.
- Concentrations are determined by measuring the settling volume by using an ASTM pear shaped centrifuge tube with a
1 mL (0.034 oz) stem with0.05 mL (0.0017 oz) 1.0 mL (0.034 oz) divisions, refer to Illustration 30. Before sampling, the suspension shall be thoroughly mixed to assure suspension of all particles, which could have settled. A100 mL (3.40 oz) sample of the suspension shall be taken and allowed to settle for 30 minutes. The settling volume should be between0.1 mL (0.0034 oz) and0.25 mL (0.0085 oz) in a100 mL (3.40 oz) sample. - Wet magnetic particles may be suspended in a low viscosity oil or conditioned water.
- The oil shall have the following characteristics:
- Low viscosity not to exceed 50 mSt (5.0 cSt) at any temperature at which the vehicle is to be used.
- Low inherent fluorescence and be non-reactive.
- 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 50 mSt (5.0 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 31 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 31 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)
Refer to Tooling and Equipment Table 3 for part numbers.
| NOTICE |
|---|
|
All personnel involved in ultrasonic examinations shall be qualified to Level 2 in accordance to standards stated in Table 6. |
- 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.
a. 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.
b. 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.
Eddy Current Testing
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| Illustration 32 | g06090873 |
|
Eddy Current testing | |
| NOTICE |
|---|
|
All personnel involved in Eddy Current examinations shall be qualified to Level 2 in accordance to standards stated in Table 6. |
Eddy Current testing (ET) is a Non-Destructive Testing (NDT) method in which eddy-current flow is induced in the test object. Changes in the flow caused by variations in the specimen are reflected in to a nearby coil or coils for subsequent analysis by suitable instrumentation and techniques. Major applications of eddy-current testing are surface inspection and tubing inspections.
Radiographic Testing
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| Illustration 33 | g06090892 |
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Radiographic Testing | |
All personnel involved in radiographic examinations shall be qualified to Level 2 in accordance to standards stated in Table 6.
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| Illustration 34 | g00008666 |
This process is dangerous. Only qualified personnel and test equipment should be appointed to perform this type of testing.
Radiographic testing (RT) is a Non-Destructive Testing (NDT) method in which short wavelength of electromagnetic radiation is used to penetrate materials to find hidden discontinuities such as cracks. In radiographic testing, the test object is placed between the radiation source and the film, or x-ray detector. The electromagnetic radiation will penetrate the thickness of the test object and, when all the way through, will project onto the film any indications that have been in the path of the radiation waves.