ASTM D8165-24
(Test Method)Standard Test Method for Evaluation of Load-Carrying Capacity of Lubricants Used in Hypoid Final-Drive Axles Operated under Low-Speed and High-Torque Conditions
Standard Test Method for Evaluation of Load-Carrying Capacity of Lubricants Used in Hypoid Final-Drive Axles Operated under Low-Speed and High-Torque Conditions
SIGNIFICANCE AND USE
5.1 This test method measures a lubricant's ability to protect hypoid final drive axles from abrasive wear, adhesive wear, plastic deformation, and surface fatigue when subjected to low-speed, high-torque conditions. Lack of protection can lead to premature gear or bearing failure, or both.
5.2 This test method is used, or referred to, in specifications and classifications of rear-axle gear lubricants such as:
5.2.1 Specification D7450.
5.2.2 American Petroleum Institute (API) Publication 1560.
5.2.3 SAE J308.
5.2.4 SAE J2360.
SCOPE
1.1 This test method, commonly referred to as the L-37-1 test, describes a test procedure for evaluating the load-carrying capacity, wear performance, and extreme pressure properties of a gear lubricant in a hypoid axle under conditions of low-speed, high-torque operation.3
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.2.1 Exceptions—Where there is no direct SI equivalent such as National Pipe threads/diameters, tubing size, or where there is a sole source supply equipment specification.
1.2.1.1 The drawing in Annex A6 is in inch-pound units.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use. Specific warning statements are provided in 7.2 and 10.1.
1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
General Information
Buy Standard
Standards Content (Sample)
This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: D8165 − 24
Standard Test Method for
Evaluation of Load-Carrying Capacity of Lubricants Used in
Hypoid Final-Drive Axles Operated under Low-Speed and
High-Torque Conditions
This standard is issued under the fixed designation D8165; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
INTRODUCTION
Portions of this test method are written for use by laboratories that make use of ASTM Test
Monitoring Center (TMC) services (see Annex A1 – Annex A4).
The TMC provides reference oils, and engineering and statistical services to laboratories that desire
to produce test results that are statistically similar to those produced by laboratories previously
calibrated by the TMC.
In general, the test purchaser decides if a calibrated test stand is to be used. Organizations such as
the American Chemistry Council require that a laboratory utilize the TMC services as part of their test
registration process. In addition, the American Petroleum Institute and the Gear Lubricant Review
Committee of the Lubricant Review Institute (SAE International) require that a laboratory use the
TMC services in seeking qualification of oils against their specifications.
The advantage of using the TMC services to calibrate test stands is that the test laboratory (and
hence the test purchaser) has an assurance that the test stand was operating at the proper level of test
severity. It should also be borne in mind that results obtained in a non-calibrated test stand may not
be the same as those obtained in a test stand participating in the ASTM TMC services process.
Laboratories that choose not to use the TMC services may simply disregard these portions.
1. Scope* 1.2 The values stated in SI units are to be regarded as
standard. No other units of measurement are included in this
1.1 This test method, commonly referred to as the L-37-1
standard.
test, describes a test procedure for evaluating the load-carrying
capacity, wear performance, and extreme pressure properties of 1.2.1 Exceptions—Where there is no direct SI equivalent
a gear lubricant in a hypoid axle under conditions of low- such as National Pipe threads/diameters, tubing size, or where
speed, high-torque operation.
there is a sole source supply equipment specification.
1.2.1.1 The drawing in Annex A6 is in inch-pound units.
This test method is under the jurisdiction of ASTM Committee D02 on
1.3 This standard does not purport to address all of the
Petroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility of
safety concerns, if any, associated with its use. It is the
Subcommittee D02.B0.03 on Automotive Gear Lubricants & Fluids.
Current edition approved May 1, 2024. Published May 2024. Originally
responsibility of the user of this standard to establish appro-
approved in 2017. Last previous edition approved in 2022 as D8165 – 22. DOI:
priate safety, health, and environmental practices and deter-
10.1520/D8165-24.
mine the applicability of regulatory limitations prior to use.
ASTM Test Monitoring Center, 203 Armstrong Drive, Freeport, PA 16229.
www.astmtmc.org.
Specific warning statements are provided in 7.2 and 10.1.
Until the next revision of this test method, the ASTM Test Monitoring Center
1.4 This international standard was developed in accor-
(TMC) will update changes in this test method by means of Information Letters.
This edition includes all Information Letters through No. 24-1. Information Letters dance with internationally recognized principles on standard-
may be obtained from the ASTM Test Monitoring Center, 203 Armstrong Drive,
ization established in the Decision on Principles for the
Freeport, PA 16229, Attn: Director. The TMC is also the source of reference oils.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D8165 − 24
Development of International Standards, Guides and Recom- 3.1.5 non-reference oil, n—any oil other than a reference oil,
mendations issued by the World Trade Organization Technical such as a research formulation, commercial oil or candidate oil.
Barriers to Trade (TBT) Committee. D4175
3.1.6 reference oil, n—an oil of known performance
2. Referenced Documents
characteristics, used as a basis for comparison.
2.1 ASTM Standards:
3.1.6.1 Discussion—Reference oils are used to calibrate
D235 Specification for Mineral Spirits (Petroleum Spirits)
testing facilities, to compare the performance of other oils, or
(Hydrocarbon Dry Cleaning Solvent)
to evaluate other materials (such as seals) that interact with
D4175 Terminology Relating to Petroleum Products, Liquid
oils. D4175
Fuels, and Lubricants
3.1.7 test oil, n—any oil subjected to evaluation in an
D6121 Test Method for Evaluation of Load-Carrying Capac-
established procedure. D4175
ity of Lubricants Under Conditions of Low Speed and
3.2 Definitions of Terms Specific to This Standard:
High Torque Used for Final Hypoid Drive Axles
D7450 Specification for Performance of Rear Axle Gear 3.2.1 abrasive wear, n—on ring and pinion gears, removal
Lubricants Intended for API Category GL-5 Service
of material from the operating surface of the gear caused by
E29 Practice for Using Significant Digits in Test Data to lapping of mating surfaces by fine particles suspended in
Determine Conformance with Specifications
lubricant, fuel, or air or imbedded in a surface.
ASTM Distress Rating Manual No. 21
2.2 Other ASTM Publications:
ASTM Distress Rating Manual 21 (Formerly CRC Manual
3.2.2 adhesive wear, n—on ring and pinion gears, removal
21)
of material from the operating surface of the gear caused by
ASTM TMC L-37 Information Letter 15-1, March 17, 2015
shearing of junctions formed between operating surfaces in
2.3 AGMA National Standard:
direct metal-to-metal contact; sheared-off particles either re-
AGMA 1010 Appearance of Gear Teeth—Terminology of
main affixed to the harder of the mating surfaces or act as wear
Wear and Failure
particles between the surfaces.
2.4 SAE Standards:
ASTM Distress Rating Manual No. 21
SAE J308 Information Report on Axle and Manual Trans-
3.2.3 broken gear tooth, n—a gear tooth where a portion of
mission Lubricants
the tooth face is missing and the missing material includes
SAE J2360 Automotive Gear Lubricants for Commercial
some part of the top land, toe, heel, or coast side of the tooth.
and Military Use
3.2.3.1 Discussion—This condition is distinct from and
2.5 API Standard:
more extensive than “chipping,” which is defined in 3.2.5.
API 1560 Lubricant Service Designations for Automotive
3.2.4 burnish, n—on ring and pinion gears, an alteration of
Manual Transmissions, Manual Transaxles, and Axles
the original manufactured surface to a dull or brightly polished
condition. ASTM Distress Rating Manual No. 21
3. Terminology
3.1 Definitions: 3.2.5 chipping, n—on ring and pinion gears, a condition
caused in the manufacturing process in which a small irregular
3.1.1 blind reference oil, n—a reference oil, the identity of
cavity is present only at the face/crown edge interface. The
which is unknown by the test facility.
edge-chipping phenomenon occurs when sufficient fatigue
3.1.1.1 Discussion—This is a coded reference oil that is
cycles accumulate after tooth surface wear relieves the com-
submitted by a source independent from the test facility. D4175
pressive residual stress on the tooth profile side of the
3.1.2 calibrate, v—to determine the indication or output of a
profile-to-topland interface. Chipping within 1 mm of the
device (for example, thermometer, manometer, engine) with
face/crown edge interface is to be called chipping, not pitting/
respect to that of a standard. D4175
spalling. ASTM Distress Rating Manual No. 21
3.1.3 candidate oil, n—an oil that is intended to have the
3.2.6 corrosion, n—in final drive axles, a general alteration
performance characteristics necessary to satisfy a specification
of the finished surfaces of bearings or gears by discoloration,
and is to be tested against that specification. D4175
accompanied by roughening not attributable to mechanical
3.1.4 cracked gear tooth, n—a gear tooth exhibiting a linear
action. ASTM Distress Rating Manual No. 21
fracture of the tooth surface. D6121
3.2.7 deposits, n—in final drive axles, material of pasty,
gummy, or brittle nature adhering to or collecting around any
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
of the working parts. ASTM Distress Rating Manual No. 21
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
3.2.8 discoloration, n—on ring and pinion gears, any al-
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website.
teration in the normal color of finished steel surfaces.
Available from the ASTM website, www.astm.org (Stock #: TMCMNL21).
ASTM Distress Rating Manual No. 21
Available from American Gear Manufacturers Association (AGMA), 1001 N.
Fairfax St., Suite 500, Alexandria, VA 22314-1587, http://www.agma.org.
3.2.9 pitting, n—on ring and pinion gears, small irregular
Available from SAE International (SAE), 400 Commonwealth Dr., Warrendale,
cavities in the tooth surface, resulting from the breaking out of
PA 15096, http://www.sae.org.
small areas of surface metal.
Available from American Petroleum Institute (API), 1220 L. St., NW,
Washington, DC 20005-4070, http://www.api.org. ASTM Distress Rating Manual No. 21
D8165 − 24
3.2.10 ridging, n—on ring and pinion gears, an alteration of 3.4.3 M —the magnitude of test parameter out from speci-
i
the tooth surface to give a series of parallel raised and polished fication limit at occurrence, i (A9.3.2)
ridges running diagonally in the direction of sliding motion, 3.4.4 P —the test parameter specification range (A9.3.2)
R
either partially or completely across the tooth surfaces of gears. 3.4.5 R—reproducibility limit (14.1.2.1)
ASTM Distress Rating Manual No. 21 3.4.6 S—estimated standard deviation (Table 2, Section 14)
3.4.7 S —intermediate precision standard deviation
ip
3.2.11 rippling, n—on ring and pinion gears, an alteration
(Table 2, Section 14)
of the tooth surface to give an appearance of a more or less
3.4.8 S —the reproducibility standard deviation (Table 2,
R
regular pattern resembling ripples on water or fish scales.
Section 14)
ASTM Distress Rating Manual No. 21
3.4.9 T —the length of time the test parameter is outside the
i
3.2.12 scoring, n—on ring and pinion gears, the rapid
specification range at occurrence, i, (A9.3.2)
removal of metal from the tooth surfaces caused by the tearing
3.4.10 t—test or test phase duration in the same units as T
i
out of small contacting particles that have welded together as
(A9.3.2)
a result of metal-to-metal contact. The scored surface is
characterized by a matte or dull finish. 4. Summary of Test Method
ASTM Distress Rating Manual No. 21
4.1 An axle ring and pinion gearset is mounted in an axle
3.2.13 scratching, n—on ring and pinion gears, an altera- housing, which is installed on a test stand equipped with the
tion of the tooth surface in the form of irregular scratches, of appropriate controls for speed, torque, lubricant temperature,
random length, across the tooth surface in the direction of
axle cooling, and various other operating parameters. The axle
sliding of the surfaces. assembly is driven by an electric motor.
ASTM Distress Rating Manual No. 21
4.2 Prior to each test run, the axle assembly is built, cleaned,
3.2.14 spalling, n—on ring and pinion gears, the breaking inspected, and build specifications are measured and recorded,
out of flakes of irregular area of the tooth surface, a condition
and the gears conditioned under specified operating conditions.
more extensive than pitting.
4.3 The test method consists of running the axle unit for
ASTM Distress Rating Manual No. 21
24 h at 80 wheel r/min and 2359 N·m wheel torque. There are
3.2.15 surface fatigue, n—on ring and pinion gears, the
two variants of the test—the standard test, for which the
failure of the ring gear and pinion material as a result of
lubricant temperature in the axle is 135 °C, and the Canadian
repeated surface or subsurface stresses that are beyond the
test, for which the lubricant temperature is 93 °C.
endurance limit of the material. It is characterized by the
4.4 The ring gear and pinion gear are removed and rated for
removal of metal and the formation of cavities.
various forms of distress.
AGMA National Standard
5. Significance and Use
3.2.16 wear, n—on ring and pinion gears, the removal of
metal, without evidence of surface fatigue or adhesive wear,
5.1 This test method measures a lubricant’s ability to protect
resulting in partial or complete elimination of tool or grinding
hypoid final drive axles from abrasive wear, adhesive wear,
marks or development of a discernible shoulder ridge at the
plastic deformation, and surface fatigue when subjected to
bottom of the contact area near the root or at the toe or heel end
low-speed, high-torque conditions. Lack of protection can lead
of pinion tooth contact area (abrasive wear).
to premature gear or bearing failure, or both.
ASTM Distress Rating Manual No. 21
5.2 This test method is used, or referred to, in specifications
3.3 Acronyms:
and classifications of rear-axle gear lubricants such as:
3.3.1 AGMA—American Gear Manufacturers Association
5.2.1 Specification D7450.
5.2.2 American Petroleum Institute (API) Publication 1560.
3.3.2 API—American Petroleum Institute
5.2.3 SAE J308.
3.3.3 ASTM—American Society for Testing Materials
5.2.4 SAE J2360.
3.3.4 LTMS—Lubricant Test Monitoring System
6. Apparatus
3.3.5 n/a—not available
6.1 General—The apparatus for the standard test is de-
3.3.6 NIST—National Institute of Standards and Technol-
scribed in 6.2 to 6.3 and that for the nonmandatory Canadian
ogy
test in Appendix X1.
3.3.7 P/N—Part number
6.2 Test Unit—These tests units are suitable for tests:
9,10
3.3.8 RCMS—Rater Calibration Monitoring System
6.2.1 A Gleason Works test axle part number 1758276
(Uncoated) or test axle part number 1559643 (Manganese
3.3.9 SAE—Society of Automotive Engineers
3.3.10 TMC—Test Monitoring Center
The sole source of supply of the apparatus known to the committee at this time
3.4 Quantity Symbols: is The Gleason Works, Gleason Sales
...
This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: D8165 − 22 D8165 − 24
Standard Test Method for
Evaluation of Load-Carrying Capacity of Lubricants Used in
Hypoid Final-Drive Axles Operated under Low-Speed and
High-Torque Conditions
This standard is issued under the fixed designation D8165; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
INTRODUCTION
Portions of this test method are written for use by laboratories that make use of ASTM Test
Monitoring Center (TMC) services (see Annex A1 – Annex A4).
The TMC provides reference oils, and engineering and statistical services to laboratories that desire
to produce test results that are statistically similar to those produced by laboratories previously
calibrated by the TMC.
In general, the test purchaser decides if a calibrated test stand is to be used. Organizations such as
the American Chemistry Council require that a laboratory utilize the TMC services as part of their test
registration process. In addition, the American Petroleum Institute and the Gear Lubricant Review
Committee of the Lubricant Review Institute (SAE International) require that a laboratory use the
TMC services in seeking qualification of oils against their specifications.
The advantage of using the TMC services to calibrate test stands is that the test laboratory (and
hence the test purchaser) has an assurance that the test stand was operating at the proper level of test
severity. It should also be borne in mind that results obtained in a non-calibrated test stand may not
be the same as those obtained in a test stand participating in the ASTM TMC services process.
Laboratories that choose not to use the TMC services may simply disregard these portions.
1. Scope*
1.1 This test method, commonly referred to as the L-37-1 test, describes a test procedure for evaluating the load-carrying capacity,
wear performance, and extreme pressure properties of a gear lubricant in a hypoid axle under conditions of low-speed, high-torque
operation.
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.2.1 Exceptions—Where there is no direct SI equivalent such as National Pipe threads/diameters, tubing size, or where there is
a sole source supply equipment specification.
This test method is under the jurisdiction of ASTM Committee D02 on Petroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility of Subcommittee
D02.B0.03 on Automotive Gear Lubricants & Fluids.
Current edition approved July 1, 2022May 1, 2024. Published July 2022May 2024. Originally approved in 2017. Last previous edition approved in 20212022 as
ɛ1
D8165 – 21D8165 – 22. . DOI: 10.1520/D8165-22.10.1520/D8165-24.
ASTM Test Monitoring Center, 203 Armstrong Drive, Freeport, PA 16229. www.astmtmc.org.
Until the next revision of this test method, the ASTM Test Monitoring Center (TMC) will update changes in this test method by means of Information Letters. This edition
includes all Information Letters through No. 22-1.24-1. Information Letters may be obtained from the ASTM Test Monitoring Center, 203 Armstrong Drive, Freeport, PA
16229, Attn: Director. The TMC is also the source of reference oils.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D8165 − 24
1.2.1.1 The drawing in Annex A6 is in inch-pound units.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of
regulatory limitations prior to use. Specific warning statements are provided in 7.2 and 10.1.
1.4 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
2.1 ASTM Standards:
D235 Specification for Mineral Spirits (Petroleum Spirits) (Hydrocarbon Dry Cleaning Solvent)
D4175 Terminology Relating to Petroleum Products, Liquid Fuels, and Lubricants
D6121 Test Method for Evaluation of Load-Carrying Capacity of Lubricants Under Conditions of Low Speed and High Torque
Used for Final Hypoid Drive Axles
D7450 Specification for Performance of Rear Axle Gear Lubricants Intended for API Category GL-5 Service
E29 Practice for Using Significant Digits in Test Data to Determine Conformance with Specifications
2.2 Other ASTM Publications:
ASTM Distress Rating Manual 21 (Formerly CRC Manual 21)
ASTM TMC L-37 Information Letter 15-1, March 17, 2015
2.3 AGMA National Standard:
AGMA 1010 Appearance of Gear Teeth—Terminology of Wear and Failure
2.4 SAE Standards:
SAE J308 Information Report on Axle and Manual Transmission Lubricants
SAE J2360 Automotive Gear Lubricants for Commercial and Military Use
2.5 API Standard:
API 1560 Lubricant Service Designations for Automotive Manual Transmissions, Manual Transaxles, and Axles
3. Terminology
3.1 Definitions:
3.1.1 blind reference oil, n—a reference oil, the identity of which is unknown by the test facility.
3.1.1.1 Discussion—
This is a coded reference oil that is submitted by a source independent from the test facility. D4175
3.1.2 calibrate, v—to determine the indication or output of a device (for example, thermometer, manometer, engine) with respect
to that of a standard. D4175
3.1.3 candidate oil, n—an oil that is intended to have the performance characteristics necessary to satisfy a specification and is
to be tested against that specification. D4175
3.1.4 cracked gear tooth, n—a gear tooth exhibiting a linear fracture of the tooth surface. D6121
3.1.5 non-reference oil, n—any oil other than a reference oil, such as a research formulation, commercial oil or candidate oil.
D4175
3.1.6 reference oil, n—an oil of known performance characteristics, used as a basis for comparison.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Available from the ASTM website, www.astm.org (Stock #: TMCMNL21).
Available from American Gear Manufacturers Association (AGMA), 1001 N. Fairfax St., Suite 500, Alexandria, VA 22314-1587, http://www.agma.org.
Available from SAE International (SAE), 400 Commonwealth Dr., Warrendale, PA 15096, http://www.sae.org.
Available from American Petroleum Institute (API), 1220 L. St., NW, Washington, DC 20005-4070, http://www.api.org.
D8165 − 24
3.1.6.1 Discussion—
Reference oils are used to calibrate testing facilities, to compare the performance of other oils, or to evaluate other materials (such
as seals) that interact with oils. D4175
3.1.7 test oil, n—any oil subjected to evaluation in an established procedure. D4175
3.2 Definitions of Terms Specific to This Standard:
3.2.1 abrasive wear, n—on ring and pinion gears, removal of material from the operating surface of the gear caused by lapping
of mating surfaces by fine particles suspended in lubricant, fuel, or air or imbedded in a surface.
ASTM Distress Rating Manual No. 21
3.2.2 adhesive wear, n—on ring and pinion gears, removal of material from the operating surface of the gear caused by shearing
of junctions formed between operating surfaces in direct metal-to-metal contact; sheared-off particles either remain affixed to the
harder of the mating surfaces or act as wear particles between the surfaces.
ASTM Distress Rating Manual No. 21
3.2.3 broken gear tooth, n—a gear tooth where a portion of the tooth face is missing and the missing material includes some part
of the top land, toe, heel, or coast side of the tooth.
3.2.3.1 Discussion—
This condition is distinct from and more extensive than “chipping,” which is defined in 3.2.5.
3.2.4 burnish, n—on ring and pinion gears, an alteration of the original manufactured surface to a dull or brightly polished
condition. ASTM Distress Rating Manual No. 21
3.2.5 chipping, n—on ring and pinion gears, a condition caused in the manufacturing process in which a small irregular cavity
is present only at the face/crown edge interface. The edge-chipping phenomenon occurs when sufficient fatigue cycles accumulate
after tooth surface wear relieves the compressive residual stress on the tooth profile side of the profile-to-topland interface.
Chipping within 1 mm of the face/crown edge interface is to be called chipping, not pitting/spalling. ASTM Distress Rating
Manual No. 21
3.2.6 corrosion, n—in final drive axles, a general alteration of the finished surfaces of bearings or gears by discoloration,
accompanied by roughening not attributable to mechanical action. ASTM Distress Rating Manual No. 21
3.2.7 deposits, n—in final drive axles, material of pasty, gummy, or brittle nature adhering to or collecting around any of the
working parts. ASTM Distress Rating Manual No. 21
3.2.8 discoloration, n—on ring and pinion gears, any alteration in the normal color of finished steel surfaces.
ASTM Distress Rating Manual No. 21
3.2.9 pitting, n—on ring and pinion gears, small irregular cavities in the tooth surface, resulting from the breaking out of small
areas of surface metal.
ASTM Distress Rating Manual No. 21
3.2.10 ridging, n—on ring and pinion gears, an alteration of the tooth surface to give a series of parallel raised and polished ridges
running diagonally in the direction of sliding motion, either partially or completely across the tooth surfaces of gears. ASTM
Distress Rating Manual No. 21
3.2.11 rippling, n—on ring and pinion gears, an alteration of the tooth surface to give an appearance of a more or less regular
pattern resembling ripples on water or fish scales. ASTM Distress Rating Manual No. 21
3.2.12 scoring, n—on ring and pinion gears, the rapid removal of metal from the tooth surfaces caused by the tearing out of small
contacting particles that have welded together as a result of metal-to-metal contact. The scored surface is characterized by a matte
or dull finish.
ASTM Distress Rating Manual No. 21
D8165 − 24
3.2.13 scratching, n—on ring and pinion gears, an alteration of the tooth surface in the form of irregular scratches, of random
length, across the tooth surface in the direction of sliding of the surfaces.
ASTM Distress Rating Manual No. 21
3.2.14 spalling, n—on ring and pinion gears, the breaking out of flakes of irregular area of the tooth surface, a condition more
extensive than pitting.
ASTM Distress Rating Manual No. 21
3.2.15 surface fatigue, n—on ring and pinion gears, the failure of the ring gear and pinion material as a result of repeated surface
or subsurface stresses that are beyond the endurance limit of the material. It is characterized by the removal of metal and the
formation of cavities.
AGMA National Standard
3.2.16 wear, n—on ring and pinion gears, the removal of metal, without evidence of surface fatigue or adhesive wear, resulting
in partial or complete elimination of tool or grinding marks or development of a discernible shoulder ridge at the bottom of the
contact area near the root or at the toe or heel end of pinion tooth contact area (abrasive wear).
ASTM Distress Rating Manual No. 21
3.3 Acronyms:
3.3.1 AGMA—American Gear Manufacturers Association
3.3.2 API—American Petroleum Institute
3.3.3 ASTM—American Society for Testing Materials
3.3.4 LTMS—Lubricant Test Monitoring System
3.3.5 n/a—not available
3.3.6 NIST—National Institute of Standards and Technology
3.3.7 P/N—Part number
3.3.8 RCMS—Rater Calibration Monitoring System
3.3.9 SAE—Society of Automotive Engineers
3.3.10 TMC—Test Monitoring Center
3.4 Quantity Symbols:
3.4.1 D—percent deviation from test operating conditions (A9.3.2)
3.4.2 ip—intermediate precision limit (14.1.1.1)
3.4.3 M —the magnitude of test parameter out from specification limit at occurrence, i (A9.3.2)
i
3.4.4 P —the test parameter specification range (A9.3.2)
R
3.4.5 R—reproducibility limit (14.1.2.1)
3.4.6 S—estimated standard deviation (Table 2, Section 14)
D8165 − 24
3.4.7 S —intermediate precision standard deviation (Table 2, Section 14)
ip
3.4.8 S —the reproducibility standard deviation (Table 2, Section 14)
R
3.4.9 T —the length of time the test parameter is outside the specification range at occurrence, i, (A9.3.2)
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3.4.10 t—test or test phase duration in the same units as T (A9.3.2)
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4. Summary of Test Method
4.1 An axle ring and pinion gearset is mounted in an axle housing, which is installed on a test stand equipped with the appropriate
controls for speed, torque, lubricant temperature, axle cooling, and various other operating parameters. The axle assembly is driven
by an electric motor.
4.2 Prior to each test run, the axle assembly is built, cleaned, inspected, and build specifications are measured and recorded, and
the gears conditioned under specified operating conditions.
4.3 The test method consists of running the axle unit for 24 h at 80 wheel r/min and 2359 N·m wheel torque. There are two variants
of the test—the standard test, for which the lubricant temperature in the axle is 135 °C, and the Canadian test, for which the
lubricant temperature is 93 °C.
4.4 The ring gear and pinion gear are removed and rated for various forms of distress.
5. Significance and Use
5.1 This test method measures a lubricant’s ability to protect hypoid final drive axles from abrasive wear, adhesive wear, plastic
deformation, and surface fatigue when subjected to low-speed, high-torque conditions. Lack of protection can lead to premature
gear or bearing failure, or both.
5.2 This test method is used, or referred to, in specifications and classifications of rear-axle gear lubricants such as:
5.2.1 Specification D7450.
5.2.2 American Petroleum Institute (API) Publication 1560.
5.2.3 SAE J308.
5.2.4 SAE J2360.
6. Appa
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