- Articulated Truck
- Asphalt Paver
- Backhoe Loader
- Cold Planer
- Compact Track Loader
- Compact Wheel Loader
- Continuous Haulage
- FH330 (S/N: FHY1-UP)
- Electric Rope Shovel
- Forest Products
- Hydraulic Shovel
- Integrated Toolcarrier
- Landfill Compactor
- Motor Grader
- Off-Highway Truck/Tractor
- On-Highway Transmission
- Petroleum Transmission
- Road Reclaimer/Soil Stabilizer
- Track-Type Loader
- Track-Type Skidder
- Track-Type Tractor
- All OEM Transmissions
- TH55FT-E70 (S/N: PCJ1-UP)
- TH55FT-E90 (S/N: THE1-UP)
- TH55FT-E70 (S/N: PCJ1-UP)
- Underground Articulated Truck
- Wheel Dozer
- Wheel Loader
- Wheel Skidder
- Wheel Tractor-Scraper
|Revision||Summary of Changes in SEBF8091|
|13||Added new serial number prefixes for New Product Introduction (NPI).|
|12||Added new serial number prefixes for New Product Introduction (NPI).|
|11||Added serial number prefixes.|
|10||Added media to tables.|
|09||Added group effectivity for All OEM Transmissions.|
© 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).
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.
The contents of this guideline includes component reusability and some salvage procedures. Most of this guideline gives visual examples of parts that fall into the "Use again" or "Do not use again" categories. Subjects requiring more lengthy salvage procedures are contained in other published guidelines. These guidelines are listed in the "References" section.
Replacement of individual ring, planet, or sun gears in a planetary set is acceptable. It is recommended that all the planet gears be replaced together if the new gears have the same package date. Otherwise, individual gears can be replaced.
When used in the same application, parts that meet the "Use again" specifications in this and other guidelines can be expected to give normal performance until the next Planned Component Rebuild (PCR). Never install a part that this guideline shows cannot be used again. During reconditioning, correct any conditions that might have caused the original failure.
Prior to beginning the transmission repair, service personnel should also have on-hand the appropriate Service Manual and the following Reuse and Salvage Guidelines.
|Media Number||Publication Type & Title|
|SEBF8006||Reuse & Salvage Guidelines , "Clutch Housings and Clutch Pistons for Transmissions and Torque Dividers"|
|SEBF8013||Reuse & Salvage Guidelines , "Transmission Clutch Plates and Disc Assemblies with Sintered Bronze Friction Material"|
|SEBF8014||Reuse & Salvage Guidelines , "Identification and Applications of Transmission Clutch Plates and Specifications to Machine Reaction Faces for Power Shift Transmissions"|
|SEBF8017||Reuse & Salvage Guidelines , "Clutch Ring Gears For All Power Shift Transmissions"|
|SEBF8021||Reuse & Salvage Guidelines , "Transmission Bevel Pinion and Transfer Gear for D5, D6, D7, D8, and D9 Tractors with Oval Tracks"|
|SEBF8028||Reuse & Salvage Guidelines , "Salvage Case Assembly and Idler Shaft in Transmission Transfer Gear Groups for 621B, 623B, 627, 627B, 641, 641B, 650B, 651B, 651E, 657, 657B, 657E, 657G, 660B, 666, and 666B Tractor-Scrapers"|
|SEBF8031||Reuse & Salvage Guidelines Reuse & Salvage Guidelines , "Transmission Clutch Plates and Disc Assemblies with F37 and F37X Friction Material"|
|SEBF8048||Reuse & Salvage Guidelines , "Procedure to Machine Damaged Transmission and Differential Yokes"|
|SEBF8060||Reuse & Salvage Guidelines , "Repair of Transmission, Torque Converter and Torque Divider Shafts"|
|SEBF8070||Reuse & Salvage Guidelines , "Bearing Bores in Hydrostatic Transmission Cases"|
|SEBF8091||Reuse & Salvage Guidelines , "Reuse and Salvage of Transmission Components"|
|SEBF8096||Reuse & Salvage Guidelines , "Transmission Governor Salvage for Seven and Eight Speed Powershift Transmissions"|
|SEBF8098||Reuse & Salvage Guidelines , "Transmission Clutch Plates and Disc Assemblies with Rayflex Friction Material"|
|SEBF8099||Reuse & Salvage Guidelines , "Repair of Reaction Dowel Holes in Transmission Clutch Housings"|
|SEBF8114||Reuse & Salvage Guidelines , "Identification of Non-Metallic Discs that are Used in Power Shift Transmissions"|
|SEBF8115||Reuse & Salvage Guidelines , "Transmission Clutch Plates and Disc Assemblies with Cellulose Friction Material"|
|SEBF8116||Reuse & Salvage Guidelines , ""White Layer Flaking" of Transfer Gears in Off-Highway Trucks and Tractors"|
|SEBF8134||Reuse & Salvage Guidelines , "Individual Clutch Modulation (ICM) Control Valves"|
|SEBF8163||Reuse & Salvage Guidelines , "Procedures to Salvage Thrust Faces on Planetary Carriers"|
|SEBF8173||Reuse & Salvage Guidelines , "Salvage of Transmission Transfer Gear Case and Cover for Articulated Trucks, Compactors, Load Haul Dump, Wheel Loaders, Wheel Tractors, and Motor Graders"|
|SEBF8178||Reuse & Salvage Guidelines , "Procedure to Salvage Tang Slots on Transmission and Brake Pistons."|
|SEBF8195||Reuse & Salvage Guidelines , "Salvage Procedure for 8E-2155, 6I-9430, 6I-9678 Transmission Covers"|
|SEBF8257||Reuse & Salvage Guidelines , "Procedure to Salvage the Slots for the Pin and Holes for the Reaction Dowel in Transmission Clutch Plates, Pistons, and Housings"|
|SEBF8332||Reuse & Salvage Guidelines , "Transmission Transfer Gear and Torque Converter Updates for 994 Wheel Loaders"|
|SMHS8079||Reuse & Salvage Guidelines , "Installation of 6T-1995 Housing As And 6T-2483 Transfer Gear Case Assembly"|
|SEBF9241||Reuse & Salvage Guidelines , "Inspection of Synchronizer Assemblies for Continuously Variable Transmissions"|
|SEBF9324||Reuse & Salvage Guidelines , "Inspection of Clutch Reaction Splines in Aluminum Transmission Cases"|
|SEHS9420||Reuse & Salvage Guidelines , "Output Transfer Shaft and Case Rework"|
For information concerning Planetary Final Drives, Non-Planetary Final Drives and/or gear failure, see the following Reuse and Salvage Guidelines.
|Media Number||Publication Type & Title|
|SEBF8078||Reuse & Salvage Guidelines , "Non-Planetary Final Drives (TTT)"|
|SEBF8079||Reuse & Salvage Guidelines , "Planetary Final Drives for Track-Type Tractors"|
|SEBF8084||Reuse & Salvage Guidelines , "Procedure to Repair Damaged Sprocket Hubs for D8L, D8N, D9L, D9N, D10N, and D11N Tractors"|
|SEBF8093||Reuse & Salvage Guidelines , "Planetary Final Drives for Wheel Loaders, Wheel Tractors, Compactors, Underground Articulated Trucks"|
|SEBF8132||Reuse & Salvage Guidelines , "Salvage of Final Drive Sprocket Hubs For Pipelayers, Track Loaders, and Track-Type Tractors"|
|SEBF8135||Reuse & Salvage Guidelines , "Repair of Web Cracks In Final Drive Planetary Carriers"|
|SEBF8168||Reuse & Salvage Guidelines , "Salvage of Final Drive Carrier Plate for Track-Type Loaders"|
|SEBF8182||Reuse & Salvage Guidelines , "Salvage and Reuse of Final Drive Axle Bearings Used in Off-Highway Trucks/Tractors and 990, 992, and 994 Wheel Loaders"|
|SEBF8183||Reuse & Salvage Guidelines , "Salvage of Final Drive and Differential Thrust Washer Used in Off-Highway Trucks, Tractors, and Wheel Loaders"|
|SEBF8185||Reuse & Salvage Guidelines , "Salvage Procedure for Final Drive Planet Gear Used in Off-Highway Trucks"|
|SEBF8221||Reuse & Salvage Guidelines , "Salvage of Planetary Carrier (Outer Pin Bore) Using Pressed In Sleeves for 785 and 789 Trucks"|
|SEBF8222||Reuse & Salvage Guidelines , "Salvage of Planetary Carrier Pin Bores Using Tapered Roller Bearings for 785 and 789 Trucks"|
|SEBF8223||Reuse & Salvage Guidelines , "Salvage of Inner Planetary Carrier Pin Bores using Tapered Roller Bearings for 785, 789, and 793 Off-Highway Trucks"|
|SEBF8225||Reuse & Salvage Guidelines , "Reusability of Final Drive Splines on 785, 789, 793, and 797 Off-Highway Trucks"|
|SEBF8285||Reuse & Salvage Guidelines , "Salvage of Outer Planetary Carrier Pin Bores, Using Metal Spray and Machining Operations for 793 Off-Highway Trucks"|
|SEBF8419||Reuse & Salvage Guidelines , "Axle Housing and Final Drive Hub Salvage Procedure for 24H Motor Graders"|
|SEBF8752||Reuse & Salvage Guidelines , "Off-Highway Truck Final Drive Planetary Carrier"|
|SEBF8759||Reuse & Salvage Guidelines , "Reusability of Rear Final Drive Splines on 769 to 784 Off-Highway Trucks"|
|SEBF8841||Reuse & Salvage Guidelines , "Planetary Final Drives for Small and Medium Wheel Loaders and Small Integrated Tool Carriers"|
Planet Shaft Bores
Planet Shaft Retention Ball Pocket
The bottom or sides of the pocket must not be worn more than
Planet Gear Thrust Faces
A thrust face showing light circumferential scratches and/or small nicks can be used again after the scratches are removed and the thrust face is polished. Remove the nicks and scratches with a file and polish with 240 grit emery paper.
Wear steps, up to
Wear steps on splines.|
Use again if wear steps do not exceed
Top view of spline. Use a straight edge and feeler gauge to measure wear step on both sides of the spline.|
Carrier Deck Cracks
Only 8S-0005 Carriers with deck cracks that meet the following criteria can be used again. Other carriers cannot be used again if any cracks are visible anywhere on the carrier deck. 8S-0005 Carriers with cracks visible on the outside edge of the decks, can be used again (see Illustration 4). If cracks are visible on the flat surface of the decks, do not use again (see Illustrations 5 and 6). use a penetrant or magnetic particle procedure to identify cracks.
8S-0005 Carrier deck with crack visible only on edge.|
Use again if cracks are not visible on the flat deck surfaces of an 8S-0005 Carrier.
8S-0005 Carrier deck with crack on flat surface.|
Do not use again if crack extends onto the flat surface.
8S-0005 Carrier with crack extending onto flat surface.|
Shaft Support Diameters
Wear steps on the diameters of the shaft support are not acceptable. If there are no wear steps, but only light fretting, the shaft may be used again. See Illustration 7.
Shaft support diameter with light fretting.|
Pitting, spalling, or wear steps that can be felt with a fingernail are not acceptable. Light scratches may be acceptable, but only if scratches do not catch a piece of tag wire or paper passed across the top of the scratched surface.
Crown: Slight convex outline of a gear tooth viewed from the top (see Illustration 8). The slightly rounded shape of the tooth crown compensates for minor gear tooth misalignment by avoiding load concentration on the ends of the teeth.
Profile: Shape or outline of the tooth as seen from the side of the tooth.
HPSTC: Highest point of single tooth contact.
LPSTC: Lowest point of single tooth contact.
Pitch Line: The tooth location between the HPSTC and the LPSTC where there is no sliding action between the two mating gear teeth surfaces.
Rolling/Sliding Action: When two mating gears rotate, the teeth go through a combined rolling/sliding action (see Illustration 9).
The rolling/sliding action takes place when two teeth begin to make contact. As the teeth engage, the sliding action stops at the operating pitch line. The rolling action continues until the tip of the drive gear tooth and the root of the driven gear begin to make contact. Currently, sliding/rolling action resumes and the cycle begins again (see Illustration 9).
Sliding action, plus the load placed between two teeth, is the basic operational cause of surface damage, such as scoring, on gear teeth. Sliding action is greatest near the tooth tip and root. These areas must be inspected for scoring and other types of surface damage.
Sliding under a high load can also cause pitting. The areas of greatest stress caused by sliding are the LPSTC of the sun gear and the HPSTC of the planet and ring gears. These areas need careful inspection for pitting.
Pitting And Spalling
Pitting is a type of surface or subsurface fatigue failure of a gear tooth. Pitting is usually the result of high contact stresses and the rolling/sliding action of two gear teeth. A pit begins as a minute crack, less the
Destructive pitting usually occurs after a long period of operation and high contact stresses. Inadequate lubrication can also cause destructive pitting. Destructive pitting can progress rapidly into either spalling, or complete disintegration of the tooth. Each pit acts as a point of stress concentration which accelerates pit formation until the tooth fractures.
If ridges or high spots are present in high load areas, surface cracks and surface pits may begin to develop. Such pits are less than
Magnified view of initial pitting on gear tooth.|
Initial pitting in the fillet section of the tooth. Pitting is localized into one area.|
Magnification of Illustration 12.|
Initial pitting in the fillet section on a different tooth of the same gear. Again, pitting is localized into one area.|
Magnification of Illustration 14.|
Initial pitting with larger single pits covering more of the tooth face.|
Magnification of Illustration 16.|
Initial pitting with larger single pits covering more of the tooth face and extending into the root of the gear.|
Magnification of Illustration 18.|
Note: Illustrations 10,12,14,16, and 18 Use again after lightly polishing the tooth profiles with a 6V-2010 Stone and oil.
Destructive pitting usually occurs after a long period of operation and high contact stresses. Inadequate lubrication can also cause destructive pitting. Destructive pitting can progress rapidly into either spalling or complete disintegration of the tooth. Each pit acts as a point of stress which accelerates pit formation until the tooth fractures. Illustrations 20 through 26 show the progression of a typical gear tooth failure from destructive pitting through spalling.
Early stage of destructive pitting.|
Early stage of destructive pitting (magnification x 20).|
Cross sectional view of destructive pitting (magnification x 100).|
Stage two of destructive pitting. Damage has progressed across the tooth.|
Stage three of destructive pitting. Damage has progressed vertically on the tooth face.|
Stage four of destructive pitting. Damage has progressed from pitting to spalling.|
Cross section view of a gear tooth showing pitting damage which has progressed to spalling.|
Early stage destructive pitting|
Do not use again sun and planet gears. Use again ring gears.
Appearance of pitting. What appears to be pits are really machining marks. A dark appearance on the edges of the teeth and in the machining marks is caused by the extreme pressure gear oil used in the final drive.|
Early stage of destructive pitting.|
Illustrations 29 & 30 Do not use again sun and planet gears. Use again ring gears.
Start of destructive pitting in the ring gear.|
Pitting between the pitch line and fillet.|
Magnified photo of pitting shown in Illustration 32.|
Illustrations 31 & 32 Do not use again.
Advanced stage of destructive pitting.|
Crack in tooth initiated from destructive pitting.|
Spalling is a type of subsurface fatigue failure. Spalling usually begins with a small fatigue crack under the surface of the gear tooth. The tooth surface is then weakened and metal flakes away from the tooth face. Once spalling begins, the damage can progress quickly to gear tooth fracture.
Abrasive wear on gear teeth is caused by small foreign particles, such as dirt or metal, in the lubrication system. These small particles act as a lapping compound during machine operation and wear down the gear tooth surface.
During the early stage of abrasive wear, the gear teeth will have a satiny, not shiny, appearance. The next stage of abrasive wear results in the appearance of flat spots on the gear tooth profile and a reduction of the tooth crown. The advanced stage of abrasive wear results in deep grooves appearing on both sides of the gear tooth pitch line. Abrasive wear of the gear teeth is accompanied by wear on all transmission components, including bearing needles, cages, and races.
Note: If abrasive wear is found in the gear train, correct the source of contamination.
Advanced abrasive wear around the gear tooth pitch line. Notice that the tooth profile is altered because of the advanced wear.|
Gear Cleaning and Inspection
Note: Gears must be cleaned prior to inspection. After removing the gears from the transmission, clean and ensure that all are free of dirt, water, and oil. If the gears are to be stored after inspection, coat with a thin layer of oil and store in a clean, dry place.
After cleaning the gear, carefully inspect every tooth completely for cracks, pitting, spalling, or any surface damage. This inspection may be accomplished using a magnifying glass and a strong light source (sunlight is best). It may be difficult to distinguish between small scratches and cracks. Magnetic particle, or dye penetrant may be also used to ensure that the gear is reusable.
It is important to inspect every tooth of each gear. It is possible for only one tooth to be damaged. If a gear is used again after falling within the "Do not use again" criteria, failure may result in damage to other transmission components.
Some planet gears may have wear or damage on only one side (face) of the teeth. Do not turn the gears around to present new wear surface if the gear does not meet "Use again" criteria. Planet gears are idler gears. During each revolution there is equal tooth loading in both directions on every tooth. This tooth loading causes a planet gear to be unusable if wear or damage on only one side (face) of the teeth meets the "Do not use again" criteria.
No cracks or any amount of pitting and/or spalling are acceptable on planet gear teeth. If any evidence of cracks, pitting or spalling is visible, do not use again.
Note: What appear to be small cracks may only be hob (gear cutter) marks. Inspect the gear carefully using Illustrations 37 and 38 for reference.
It is common for shaving marks or machining marks to polish away without development of surface pits. Load carrying surfaces may become polished until they are mirror-like as seen in Illustration 39.
Machining marks may appear to be cracks.|
What appears to be several cracks on the planet gear tooth are actually hob marks.|
Surfaces of planet gear teeth have become frosted. Small pits are forming in the frosted area.|
Do not use again.
Frosting can also appear as thin surface layers of the tooth missing in bigger areas. This condition occurs when a rough surface or tiny projections from the surface make contact and microweld. The surface metal then either pulls out or fractures on a small scale. This results in a gray matte appearance which is not detrimental at this stage. However, if the conditions causing "frosting" are not corrected, destructive pitting may begin. See Illustration 40.
Frosting. If pitting has started, do not use the gear again.|
Planet gear tooth edge with a small nick.|
Use again only after removing the nick with a 6V-2010 Polishing Stone.
Planet gear tooth surface shows an indentation.|
Do not use again.
Surface blemishes, resulting from foreign material, are acceptable only if the material did not cause indentations on the faces of planet gear teeth.
Planet gear teeth with small nicks may be reusable, but only if the nick can be removed with a 6V-2010 Polishing Stone.
Excessive wear can cause an increased noise level and accelerates the tendency for tooth surface pitting and spalling.
To test for excessive wear on planet gears, except those that are listed below, place a straight edge across a gear tooth. If there is not excessive wear, the straight edge can be rocked against the tooth crown as shown in Illustration 43. Do not use gears that show excessive wear.
Note: The amount of crown is small, only
The following gears do not have crowned teeth.
Gears Without Crowned Teeth
Place a straight edge along the pitch line of a crowned gear tooth. If the straight edge can be rocked, the amount of wear if NOT excessive.|
Bearing bores with excessive wear will not adequately guide the bearing cage and could result in premature bearing failure.
The length of the bearing needles is not precisely controlled. If a bearing with long needles is installed in a gear with a wear step created by shorter needles, this could result in premature bearing failure.
To determine the amount of wear on the bearing bore, use a dial bore gauge to measure both a portion of the bore showing the most wear, and an unworn portion of the bore. Subtract the two measurements. No more than
Note: Note: Gears with bore wear exceeding the maximum amount permitted may be sectioned and used as a guide to compare with wear on other gears.
Use the following illustrations as aids to determine whether planet gear bearing bores fall within the "Do not use again" criteria.
Shallow pits have developed in the bearing bore due to rust and foreign material.|
Pitting in the bearing bore has progressed to spalling.|
Illustrations 44 & 45- Do not use again.
Excessive wear in the bearing path caused by cage contact with the bore.|
Severe wear to bearing bore caused by bearing cage. Wear will not allow the bearing bore to guide a new bearing correctly and will cause premature failure.|
Gears with light rust on the bearing bore can be used again if the rust can be removed by light polishing with crocus cloth and oil. Gears showing heavy rust cannot be used again because the rust will create pits.
Water inside the transmission caused excessive rust on the planet gear bearing bore.|
Foreign material, usually the result of another failure, can result in bearing bore indentations and pitting. Dents in the bearing bore can greatly reduce the bearing contact area and/or create cracks in the surface, resulting in substantially shortened bearing life.
Excessive amount of damage to the planet gear bearing bore due to foreign material.|
Light, circumferential scratches may be acceptable, but only if they do not catch a piece of tag wire or paper passed across the top of the scratched surface. Use a 6V-2010 Polishing Stone to remove any radial scratches or small nicks.
Gears with more than
Planet gear thrust face.|
Planet Gear Thrust Washers
No pitting, spalling, or cracks are acceptable.
Frosting is a condition caused by inadequate oil film between mating gear teeth surfaces. It appears as a cloudy area on the gear contact surface and is sometimes accompanied by small surface pits.
Gears with frosting can be used again provided any surface pits are small enough that they do not catch a piece of tag wire passed along the frosted surface. Frosting accompanied by any pit that does catch a tag wire is unacceptable and the gear should not be used again.
Frosting is different in appearance than abrasive wear or light surface rust. Abrasive wear, due to foreign material, usually covers the entire tooth face contact surface and has a more satiny, shiny appearance.
Abrasive wear will usually appear on all gears and other transmission components. Light surface rust or corrosion can produce a mottled appearance, which has an irregular outline.
Note: If abrasive wear is found in the gear train, correct the source of contamination. Light surface rust or corrosion can produce a frosted appearance, but usually is of irregular shape. Gears with this type of condition can be reused if there are no pits or other defects.
Surfaces of the sun gear teeth have become frosted and small pits have formed in the frosted area.|
Reusability of ring gears depends on the amount of damage or wear. Some damaged clutch ring gears obviously cannot be used again. Other gears, with certain limitations, can be used again. Some clutch ring gears can be reused without limitations, depending upon the location and degree of damage.
Common types of damage which do not necessarily effect on reuse are:
- Wear of the ring gear side face
- Wear on crown of outer teeth
- Notches on face of outer teeth
- Damage caused by debris
Reuse bearings with less than 2,000 hours of use if there is no visible damage caused by other failures.
Clutch Friction Material
For complete information concerning the reusability of main shafts, see Reuse and Salvage Guidelines, SEBF8013, "Transmission Clutch Plates and Disc Assemblies with Sintered Bronze Friction Material", Reuse and Salvage Guidelines, SEBF8031, "Transmission Clutch Plates and Disc Assemblies with F37 Clutch Friction Material", and Reuse and Salvage Guidelines, SEBF8098, "Transmission Clutch Plates and Disc Assemblies with RAYFLEX® Friction Material".
Clutch Pistons and Housings
Ensure that there are no burrs, nicks, or scratches on housing faces that form a metal-to-metal oil seal. See Reuse and Salvage Guidelines, SEBF8006, "Clutch Housings and Clutch Pistons for Transmissions and Torque Dividers (with Cast Iron Seal Rings)" and Reuse and Salvage Guidelines, SEBF8014, "Identification and Applications of Transmission Clutch Plates and Specifications to Machine Reaction Faces for Power Shift Transmissions" for additional salvage information.
Selector and Pressure Control Valves
No scratches, nicks, or dents are acceptable on valve spools. If spools appear to have a satiny surface, it is an indication of abrasive wear.
Check spool and bore for excessive wear, such as spalling, pitting, and cracking. If excessive wear is present, do not use again. No scratches are acceptable in the bores. The metering edges of spools and bodies must be sharp and not rounded by erosion.
Check for cracks and blocked oil passages. Check pilot diameters and mounting faces for excessive wear or fretting. Check dowel pin bores for wear and cracks. If any of the above conditions are found, do not use again.