ASTM D7421-23

Standard Test Method for Determining Extreme Pressure Properties of Lubricating Oils Using High-Frequency, Linear-Oscillation (SRV) Test Machine

SIGNIFICANCE AND USE
5.1 This laboratory test method can be used to quickly determine extreme pressure properties of lubricating oils at selected temperatures specified for use in applications where not only high-speed vibrational or start-stop motions are present with high Hertzian point contact. This test method has found wide application in qualifying lubricating oils used in constant velocity joints of front-wheel-drive automobiles, gear-hydraulic circuit, rear axles, gears and engine components. Users of this test method should determine whether results correlate with field performance or other applications.
SCOPE
1.1 This test method covers a procedure for determining extreme pressure properties of lubricating oils for hydraulics, gears, and engines under high-frequency linear-oscillation motion using the SRV test machine.
Note 1: This test method was developed and the international round robin tests were jointly performed with the DIN 51834 working group. This procedure is based on the 2005 revision of Test Method D5706 for greases and differs regarding the stroke length and the cleaning solvent.  
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.3 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.  
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

• Status: Published
• Publication Date: 31-Oct-2023
• ICS: 75.100 - Lubricants, industrial oils and related products
• Technical Committee: D02 - Petroleum Products, Liquid Fuels, and Lubricants
• Drafting Committee: D02.L0.11 - Tribological Properties of Industrial Fluids and Lubricates

Relations

• Replaces: ASTM D7421-19 - Standard Test Method for Determining Extreme Pressure Properties of Lubricating Oils Using High-Frequency, Linear-Oscillation (SRV) Test Machine
• Effective Date: 01-Nov-2023
• Refers: ASTM D5706-16 - Standard Test Method for Determining Extreme Pressure Properties of Lubricating Greases Using a High-Frequency, Linear-Oscillation (SRV) Test Machine
• Effective Date: 15-Nov-2016
• Referred By: ASTM D8227-20 - Standard Test Method for Determining the Coefficient of Friction of Synchronizer Lubricated by Mechanical Transmission Fluids (MTF) Using a High-Frequency, Linear-Oscillation (SRV) Test Machine
• Effective Date: 01-Nov-2023
• Referred By: ASTM D8324-21 - Standard Guide for Selection of Environmentally Acceptable Lubricants for the U.S. Environmental Protection Agency (EPA) Vessel General Permit
• Effective Date: 01-Nov-2023
• Referred By: ASTM D8316-20a - Standard Test Method for Measuring Friction and Wear Properties of Extreme Pressure (EP) Lubricating Oils with the Roller-Disk Geometry Using SRV Test Machine
• Effective Date: 01-Nov-2023
• Referred By: ASTM D5706-23 - Standard Test Method for Determining Extreme Pressure Properties of Lubricating Greases Using a High-Frequency, Linear-Oscillation (SRV) Test Machine
• Effective Date: 01-Nov-2023
• Referred By: ASTM D7594-19 - Standard Test Method for Determining Fretting Wear Resistance of Lubricating Greases Under High Hertzian Contact Pressures Using a High-Frequency, Linear-Oscillation (SRV) Test Machine
• Effective Date: 01-Nov-2023
• Referred By: ASTM D7217-22 - Standard Test Method for Determining Extreme Pressure Properties of Solid Bonded Films Using a High-Frequency, Linear-Oscillation (SRV) Test Machine
• Effective Date: 01-Nov-2023

Overview

ASTM D7421-23 is the internationally recognized standard test method for determining extreme pressure (EP) properties of lubricating oils using a high-frequency, linear-oscillation (SRV) test machine. Developed by ASTM (American Society for Testing and Materials), this method is essential for qualifying the EP performance of lubricants under laboratory conditions that replicate high-stress, high-speed, and vibrational contact scenarios common in modern mechanical assemblies. Its wide adoption contributes to consistent product performance evaluations in applications like automotive constant velocity joints, gearsets, hydraulics, and engine components.

Key Topics

• Extreme Pressure Properties: The focus is to measure how lubricating oils withstand and perform under intensified stress, specifically at the point of potential metal-to-metal contact in dynamic applications.
• SRV Test Machine: Utilizes a test ball oscillating against a stationary test disk with a lubricant in between. The applied load is increased stepwise until seizure (a sudden rise in friction) is detected, and the maximum load prior to this point is recorded as the lubricant’s EP limit.
• Precision Test Parameters: The method specifies use of steel materials with controlled surface characteristics and standard solvents for cleaning, ensuring high repeatability and reproducibility across labs.
• Simulation of Field Conditions: The procedure allows for variations in temperature, load, stroke length, and frequency, making results more relevant to real-world use cases.

Applications

ASTM D7421-23 delivers practical value by enabling:

• Lubricant Qualification: Manufacturers and formulators can evaluate and compare the extreme pressure characteristics of lubricating oils intended for gear, hydraulic, and engine applications.
• Product Development: The method helps in optimizing formulations for high-load, high-speed environments, facilitating innovations in lubricant technologies.
• Quality Assurance: Suppliers and OEMs use this test to verify lubricant consistency and performance prior to deployment in critical components such as:
  • Constant velocity (CV) joints in automotive drivetrains
  • Gearboxes and rear axles in vehicles and industrial machinery
  • Hydraulic systems where high-frequency oscillating motion and rapid load changes occur
  • Engine parts prone to start-stop operations and high point contacts
• Performance Benchmarking: Oil performance can be benchmarked against international competitors, given the method’s harmonization with relevant DIN and ISO standards.

Related Standards

• ASTM D5706 - Test method for determining EP properties of lubricating greases using the SRV test machine (basis for D7421, with differences in specification).
• DIN 51834 - Parallel German standard, developed jointly and harmonized with ASTM D7421.
• ASTM A295/A295M - Specification for high-carbon anti-friction bearing steel, relevant for test components.
• ASTM D217 - Test methods for cone penetration of lubricating greases.
• ASTM D235 - Specification for mineral (petroleum) spirits, referenced as a cleaning solvent.
• ASTM D4175 and G40 - Terminology for petroleum products, lubricants, wear, and erosion.
• DIN EN ISO 683-17 - Heat-treated and alloy steel standards, covering ball and disk materials for testing.

Conclusion

ASTM D7421-23 provides a standardized, internationally accepted procedure for evaluating the extreme pressure properties of lubricating oils under conditions simulating high-frequency oscillation and point contacts. Its use supports improved product quality, accurate benchmarking, and enhanced confidence in oil performance for manufacturers and end-users in automotive, industrial, and mechanical engineering sectors. For those selecting, developing, or certifying lubricating oils in demanding applications, adherence to ASTM D7421-23 is essential for reliable results and global acceptance.

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: D7421 − 23
Standard Test Method for
Determining Extreme Pressure Properties of Lubricating
Oils Using High-Frequency, Linear-Oscillation (SRV) Test
Machine
This standard is issued under the fixed designation D7421; 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.
1. Scope* D235 Specification for Mineral Spirits (Petroleum Spirits)
(Hydrocarbon Dry Cleaning Solvent)
1.1 This test method covers a procedure for determining
D4175 Terminology Relating to Petroleum Products, Liquid
extreme pressure properties of lubricating oils for hydraulics,
Fuels, and Lubricants
gears, and engines under high-frequency linear-oscillation
D5706 Test Method for Determining Extreme Pressure
motion using the SRV test machine.
Properties of Lubricating Greases Using a High-
NOTE 1—This test method was developed and the international round
Frequency, Linear-Oscillation (SRV) Test Machine
robin tests were jointly performed with the DIN 51834 working group.
This procedure is based on the 2005 revision of Test Method D5706 for
E45 Test Methods for Determining the Inclusion Content of
greases and differs regarding the stroke length and the cleaning solvent.
Steel
1.2 The values stated in SI units are to be regarded as G40 Terminology Relating to Wear and Erosion
standard. No other units of measurement are included in this
2.2 DIN Standards:
standard.
DIN 51631:1999–04 Mineral spirits; special boiling point
spirits; requirements
1.3 This standard does not purport to address all of the
DIN EN ISO 683-17 Heat-treated Steels, alloy steels and
safety concerns, if any, associated with its use. It is the
free-cutting steels—Part 17 : Ball and roller bearing steels
responsibility of the user of this standard to establish appro-
[Replaces DIN 17230-1980]
priate safety, health, and environmental practices and deter-
DIN EN ISO 13565-2:1998 Geometrical Product Specifica-
mine the applicability of regulatory limitations prior to use.
tions (GPS)—Surface texture: Profile method; Surfaces
1.4 This international standard was developed in accor-
having stratified functional properties—Part 2: Height
dance with internationally recognized principles on standard-
characterization using linear material ratio curve [Re-
ization established in the Decision on Principles for the
placement of DIN 4776:1990: Measurement of surface
Development of International Standards, Guides and Recom-
roughness; parameters R , R , R , M , M for the
mendations issued by the World Trade Organization Technical
K PK VK r1 r2
description of the material portion]
Barriers to Trade (TBT) Committee.
3. Terminology
2. Referenced Documents
3.1 Definitions:
2.1 ASTM Standards:
3.1.1 break-in, n—in tribology, an initial transition process
A295/A295M Specification for High-Carbon Anti-Friction
occurring in newly established wearing contacts, often accom-
Bearing Steel
panied by transients in coefficient of friction or wear rate, or
D217 Test Methods for Cone Penetration of Lubricating
both, which are uncharacteristic of the given tribological
Grease
system’s long-term behavior. G40
3.1.2 coeffıcient of friction, μ or f, n—in tribology, the
dimensionless ratio of the friction force (F) between two
This test method is under the jurisdiction of ASTM Committee D02 on
Petroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility of
bodies to the normal force (N) pressing these bodies together.
Subcommittee D02.L0.11 on Tribological Properties of Industrial Fluids and
G40
Lubricates.
Current edition approved Nov. 1, 2023. Published January 2024. Originally
3.1.3 Hertzian contact area, n—apparent area of contact
approved in 2008. Last previous edition approved in 2019 as D7421 – 19. DOI:
between two nonconforming solid bodies pressed against each
10.1520/D7421-23.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on Available from Beuth Verlag GmbH (DIN, Deutsches Institut fur Normung
the ASTM website. e.V.), Burggrafenstrasse 6, 10787, Berlin, Germany, http://www.en.din.de.
*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
D7421 − 23
other, as calculated from Hertz’s equations of elastic deforma-
tion published in 1881. G40
3.1.4 Hertzian contact pressure, n—magnitude of the pres-
sure at any specified location in a Hertzian contact area, as
calculated from Hertz’s equations of elastic deformation. The
Hertzian contact pressure can also be calculated and reported
as maximum value P in the centre of the contact or as
max
P as average over the total contact area. D4175
average
3.1.5 lubricant, n—any material interposed between two
surfaces that reduces the friction or wear, or both between
them. D217
3.1.6 Ra (C.L.A.), n—in measuring surface finish, the arith-
metic average of the absolute distances of all profile points
from the mean line for a given distance.
3.1.6.1 Discussion—C.L.A. means center line average, and
it is the synonym to Ra.
FIG. 1 SRV Test Machine (Model III)
3.1.7 Rpk, n—Reduced peak height according to DIN EN
ISO 13565-2:1998. Rpk is the mean height of the peak sticking
out above the core profile section.
SRV models III, IV, and V are identical. However, the SRV IV and V allow
to incline the axis of movement. Both models are fully computer
3.1.8 Rvk,, n—Reduced valley height according to DIN EN
controlled. In SRV IV and V models, the test described here is run
ISO 13565-2:1998. Rvk is the mean depth of the valley
horizontally and without inclination. SRV I and II models can also
reaching into the material below the core profile section.
perform this test, but they are limited with regard to maximum load and
stroke. As modern and high performance oils may exceed an O.K.-load of
3.1.9 Rz (DIN), n—in measuring surface finish, the average
1200 N, seizure may not be reached. Optimol Instruments supplies an
of all Ry values (peak to valley heights) in the assessment
upgrade kit to allow for SRV I and SRV II models to be operated at
length.
1600 N, if needed. SRV III test machines after 1995 reach 2000 N. SRV
IV and SRV V models can be equipped with a maximum test load unit of
3.2 Definitions of Terms Specific to This Standard:
2500 N.
3.2.1 extreme pressure, adj—in lubrication, characterized
by metal surfaces in contact under high-stress rubbing condi-
5. Significance and Use
tions. It is not limited to metallic materials.
5.1 This laboratory test method can be used to quickly
3.2.2 seizure, n—localized fusion of metal between the
determine extreme pressure properties of lubricating oils at
rubbing surfaces of the test pieces. D5706
selected temperatures specified for use in applications where
3.2.2.1 Discussion—In this test method, seizure is indicated
not only high-speed vibrational or start-stop motions are
by a sharp rise in the coefficient of friction, over steady state,
present with high Hertzian point contact. This test method has
of >0.2 for over 20 s. In severe cases, a stoppage in the motor
found wide application in qualifying lubricating oils used in
will occur. (These criteria were believed to be right, because
constant velocity joints of front-wheel-drive automobiles, gear-
this test method is related to liquid lubricants.)
hydraulic circuit, rear axles, gears and engine components.
Users of this test method should determine whether results
3.3 Abbreviations:
correlate with field performance or other applications.
3.3.1 SRV, n—Schwingung, Reibung, Verschleiß (German);
oscillating, friction, wear (English translation).
6. Apparatus
4. Summary of Test Method
6.1 SRV Test Machine, illustrated in Figs. 1-4.
4.1 This test method is performed on an SRV test machine
6.2 Test Balls, 52100 steel, 60 HRC 6 2 HRC hardness,
using a steel test ball oscillating against a stationary steel test
0.025 μm 6 0.005 μm Ra surface finish, 10 mm diameter.
disk with lubricant between them. Test load is increased in
6.3 Lower Test Disk, vacuum arc remelted (VAR) AISI
100 N increments until seizure occurs. The load, immediately
52100 steel with a inclusion rating using Method D, Type A,
prior to the load at which seizure occurs, is measured and
and a severity level number of 0.5 according to Specification
reported as O.K.-load, which can be converted in Hertzian
A295/A295M or Test Methods E45 or an inclusion sum value
contact pressures.
K1 ≤ 10 in accordance with DIN EN ISO 683-17 and
NOTE 2—Test frequency, stroke length, temperature, and ball and disk
spherodized annealed to obtain globular carbide, 60 HRC 6
material can be varied to simulate field conditions. The test ball yields
2 HRC hardness, with the surfaces of the disk being lapped and
point-contact geometry. To obtain line or area contact, test pieces of
differing configurations can be substituted for the test balls.
NOTE 3—With regard to the test chamber and the operating conditions, 5
The sole source of supply of the apparatus known to the committee at this time
is Optimol Instruments GmbH, Flößergasse 3, D-81369 Munich, Germany. If you
are aware of alternative suppliers, please provide this information to ASTM
Amstutz, Hu, “Surface Texture: The Parameters,” Bulletin MI-TP-003-0785, International Headquarters. Your comments will receive careful consideration at a
Sheffield Measurement Division, Warner and Swasey, 1985. meeting of the responsible technical committee, which you may attend.
D7421 − 23
1. Oscillation drive rod 6. Electrical Resistance Thermometer
2. Test Ball Holder 7. Resistance Thermometer
3. Load Rod 8. Test Disk Holder
4. Test Ball 9. Piezoelectric Measuring Device
5. Test Disk 10. Receiving Block
FIG. 2 Test Chamber Elements of SRV III
be determined by four values, 24 mm 6 0.5 mm diameter by
7.85 mm 6 0.1 mm thick:
0.500 μm < Rz (DIN) < 0.650 μm
0.035 μm < C.L.A. (Ra) < 0.050 μm
0.020 μm < Rpk < 0.035 μm
0.050 μm < Rvk < 0.075 μm
7. Reagents and Materials
7.1 Cleaning Solvent—single boiling point spirit type 2-A
according to DIN 51631:1999 (published in English).
(Warning—Flammable. Health hazard.)
NOTE 4—In the case of unavailability, please refer to Specification
D235 regarding Type I, Class C (with less than 2 % by volume of
aromatics), mineral spirits.
8. Preparation of Apparatus
Preparation of SRV III, SRV IV, and SRV V Models
8.1 When using SRV III, SRV IV, and SRV V models, clean
and install the specimens as specified under 9.1 to 9.7. Turn on
the test machine and the PC and allow to warm up for 15 min
prior to running tests.
8.2 Create a set point profile in the SRV control software
FIG. 3 SRV Test Machine (Model IV) with the following parameters:
NOTE 5—Depending on the software version, names and availability of
the parameters can vary.
free of lapping raw materials. The topography of the disk will 8.2.1 Start conditions:
D7421 − 23
1. Base of the Receiving Block 7. Upper Specimen Holder
2. Piezo Force Measurement Elements 8. Drive Rods of the Load Unit
3. Supporting Surface (Head Plate) of the Receiving Block 9. Test Disk
4. Lower
...

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: D7421 − 19 D7421 − 23
Standard Test Method for
Determining Extreme Pressure Properties of Lubricating
Oils Using High-Frequency, Linear-Oscillation (SRV) Test
Machine
This standard is issued under the fixed designation D7421; 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.
1. Scope*
1.1 This test method covers a procedure for determining extreme pressure properties of lubricating oils for hydraulics, gears, and
engines under high-frequency linear-oscillation motion using the SRV test machine.
NOTE 1—This test method was developed and the international round robin tests were jointly performed with the DIN 51834 working group. This
procedure is based on the 2005 revision of Test Method D5706 for greases and differs regarding the stroke length and the cleaning solvent.
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.3 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.
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:
A295/A295M Specification for High-Carbon Anti-Friction Bearing Steel
D217 Test Methods for Cone Penetration of Lubricating Grease
D235 Specification for Mineral Spirits (Petroleum Spirits) (Hydrocarbon Dry Cleaning Solvent)
D4175 Terminology Relating to Petroleum Products, Liquid Fuels, and Lubricants
D5706 Test Method for Determining Extreme Pressure Properties of Lubricating Greases Using a High-Frequency, Linear-
Oscillation (SRV) Test Machine
E45 Test Methods for Determining the Inclusion Content of Steel
G40 Terminology Relating to Wear and Erosion
2.2 DIN Standards:
DIN 51631:1999–04 Mineral spirits; special boiling point spirits; requirements
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.L0.11 on Tribological Properties of Industrial Fluids and Lubricates.
Current edition approved Dec. 1, 2019Nov. 1, 2023. Published January 2020January 2024. Originally approved in 2008. Last previous edition approved in 20162019 as
D7421 – 16.D7421 – 19. DOI: 10.1520/D7421-19.10.1520/D7421-23.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Available from Beuth Verlag GmbH (DIN, Deutsches Institut fur Normung e.V.), Burggrafenstrasse 6, 10787, Berlin, Germany, http://www.en.din.de.
*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
D7421 − 23
DIN EN ISO 683-17 Heat-treated Steels, alloy steels and free-cutting steels—Part 17 : Ball and roller bearing steels [Replaces
DIN 17230-1980]
DIN EN ISO 13565-2:1998 Geometrical Product Specifications (GPS)—Surface texture: Profile method; Surfaces having
stratified functional properties—Part 2: Height characterization using linear material ratio curve [Replacement of DIN
4776:1990: Measurement of surface roughness; parameters R , R , R , M , M for the description of the material portion]
K PK VK r1 r2
3. Terminology
3.1 Definitions:
3.1.1 break-in, n—in tribology, an initial transition process occurring in newly established wearing contacts, often accompanied
by transients in coefficient of friction or wear rate, or both, which are uncharacteristic of the given tribological system’s long-term
behavior. G40
3.1.2 coeffıcient of friction, μ or f,n—in tribology, the dimensionless ratio of the friction force (F) between two bodies to the
normal force (N) pressing these bodies together. G40
3.1.3 Hertzian contact area, n—apparent area of contact between two nonconforming solid bodies pressed against each other, as
calculated from Hertz’s equations of elastic deformation published in 1881. G40
3.1.4 Hertzian contact pressure, n—magnitude of the pressure at any specified location in a Hertzian contact area, as calculated
from Hertz’s equations of elastic deformation. The Hertzian contact pressure can also be calculated and reported as maximum
value P in the centre of the contact or as P as average over the total contact area. D4175
max average
3.1.5 lubricant, n—any material interposed between two surfaces that reduces the friction or wear, or both between them. D217
3.1.6 Ra (C.L.A.), n—in measuring surface finish, the arithmetic average of the absolute distances of all profile points from the
mean line for a given distance.
3.1.6.1 Discussion—
C.L.A. means center line average, and it is the synonym to Ra.
3.1.7 Rpk, n—Reduced peak height according to DIN EN ISO 13565-2:1998. Rpk is the mean height of the peak sticking out
above the core profile section.
3.1.8 Rvk,, n—Reduced valley height according to DIN EN ISO 13565-2:1998. Rvk is the mean depth of the valley reaching into
the material below the core profile section.
3.1.9 Rz (DIN), n—in measuring surface finish, the average of all Ry values (peak to valley heights) in the assessment length.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 extreme pressure, adj—in lubrication, characterized by metal surfaces in contact under high-stress rubbing conditions. It is
not limited to metallic materials.
3.2.2 seizure, n—localized fusion of metal between the rubbing surfaces of the test pieces. D5706
3.2.2.1 Discussion—
In this test method, seizure is indicated by a sharp rise in the coefficient of friction, over steady state, of >0.2 for over 20 s. In severe
cases, a stoppage in the motor will occur. (These criteria were believed to be right, because this test method is related to liquid
lubricants.)
3.3 Abbreviations:
3.3.1 SRV, n—Schwingung, Reibung, Verschleiß (German); oscillating, friction, wear (English translation).
4. Summary of Test Method
4.1 This test method is performed on an SRV test machine using a steel test ball oscillating against a stationary steel test disk with
Amstutz, Hu, “Surface Texture: The Parameters,” Bulletin MI-TP-003-0785, Sheffield Measurement Division, Warner and Swasey, 1985.
D7421 − 23
FIG. 1 SRV Test Machine (Model III)
lubricant between them. Test load is increased in 100 N increments until seizure occurs. The load, immediately prior to the load
at which seizure occurs, is measured and reported as O.K.-load, which can be converted in Hertzian contact pressures.
NOTE 2—Test frequency, stroke length, temperature, and ball and disk material can be varied to simulate field conditions. The test ball yields point-contact
geometry. To obtain line or area contact, test pieces of differing configurations can be substituted for the test balls.
NOTE 3—With regard to the test chamber and the operating conditions, SRV models III, IV, and V are identical. However, the SRV IV and V allow to
incline the axis of movement. Both models are fully computer controlled. In SRV IV and V models, the test described here is run horizontally and without
inclination. SRV I and II models can also perform this test, but they are limited with regard to maximum load and stroke. As modern and high performance
oils may exceed an O.K.-load of 1200 N, seizure may not be reached. Optimol Instruments supplies an upgrade kit to allow for SRV I and SRV II models
to be operated at 1600 N, if needed. SRV III test machines after 1995 reach 2000 N. SRV IV and SRV V models can be equipped with a maximum test
load unit of 2500 N.
5. Significance and Use
5.1 This laboratory test method can be used to quickly determine extreme pressure properties of lubricating oils at selected
temperatures specified for use in applications where not only high-speed vibrational or start-stop motions are present with high
Hertzian point contact. This test method has found wide application in qualifying lubricating oils used in constant velocity joints
of front-wheel-drive automobiles, gear-hydraulic circuit, rear axles, gears and engine components. Users of this test method should
determine whether results correlate with field performance or other applications.
6. Apparatus
6.1 SRV Test Machine, illustrated in Figs. 1-4.
6.2 Test Balls, 52100 steel, 60 HRC 6 2 HRC hardness, 0.025 μm 6 0.005 μm Ra surface finish, 10 mm diameter.
6.3 Lower Test Disk, vacuum arc remelted (VAR) AISI 52100 steel with a inclusion rating using Method D, Type A, and a severity
level number of 0.5 according to Specification A295/A295M or Test Methods E45 or an inclusion sum value K1 ≤ 10 in accordance
with DIN EN ISO 683-17 and spherodized annealed to obtain globular carbide, 60 HRC 6 2 HRC hardness, with the surfaces of
the disk being lapped and free of lapping raw materials. The topography of the disk will be determined by four values, 24 mm 6
0.5 mm diameter by 7.85 mm 6 0.1 mm thick:
0.500 μm < Rz (DIN) < 0.650 μm
0.035 μm < C.L.A. (Ra) < 0.050 μm
0.020 μm < Rpk < 0.035 μm
0.050 μm < Rvk < 0.075 μm
The sole source of supply of the apparatus known to the committee at this time is Optimol Instruments GmbH, Flößergasse 3, D-81369 Munich, Germany. If you are
aware of alternative suppliers, please provide this information to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of the
responsible technical committee, which you may attend.
D7421 − 23
1. Oscillation drive rod 6. Electrical Resistance Thermometer
2. Test Ball Holder 7. Resistance Thermometer
3. Load Rod 8. Test Disk Holder
4. Test Ball 9. Piezoelectric Measuring Device
5. Test Disk 10. Receiving Block
FIG. 2 Test Chamber Elements of SRV III
FIG. 3 SRV Test Machine (Model IV)
D7421 − 23
1. Base of the Receiving Block 7. Upper Specimen Holder
2. Piezo Force Measurement Elements 8. Drive Rods of the Load Unit
3. Supporting Surface (Head Plate) of the Receiving Block 9. Test Disk
4. Lower Specimen Holder 10. Test Ball
5. Position of the Electrical Resistance Heating Resistance Thermometer F Normal Force (Test Load)
n
6. Oscillation Drive Rods F Friction Force
f
FIG. 4 Test Chamber Elements of SRV Models IV and V
7. Reagents and Materials
7.1 Cleaning Solvent—single boiling point spirit type 2-A according to DIN 51631:1999 (published in English). (Warning—
Flammable. Health hazard.)
NOTE 4—In the case of unavailability, please refer to Specification D235 regarding Type I, Class C (with less than 2 % by volume of aromatics), mineral
spirits.
8. Preparation of Apparatus
Preparation of SRV III, SRV IV, and SRV V Models
8.1 When using SRV III, SRV IV, and SRV V models, clean and install the specimens as specified under 9.1 to 9.7. Turn on the
test machine an
...