ASTM D5706 Standard Test Method for Determining Extreme Pressure Properties of Lubricating Greases Using a High-Frequency, Linear-Oscillation (SRV) Test Machine
1. Scope
1.1 This test method covers a procedure for determining extreme pressure properties of lubricating greases under high-frequency linear-oscillation motion using the SRV test machine. This test method can also be used for evaluating extreme pressure properties of lubricating fluid.

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 and health practices and determine the applicability of regulatory limitations prior to use.

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
D4175 Terminology Relating to Petroleum Products, Liquid Fuels, and Lubricants
D6425 Test Method for Measuring Friction and Wear Properties of Extreme Pressure (EP) Lubricating Oils Using SRV Test Machine
D7421 Test Method for Determining Extreme Pressure Properties of Lubricating Oils Using 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 Other Standards:
DIN EN ISO 683-17 Heat-treated Steels, alloy steels and free-cutting steels - Part 17 : Ball and roller bearing steels
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 [Replaces DIN 4776:1990: Measurement of surface roughness; parameters RK, RPK, RVK, Mr1, Mr2 for the description of the material portion]

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.

3.1.2 coefficient 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.

3.1.3 Hertzian contact area, n - the apparent area of contact between two nonconforming solid bodies pressed against each other, as calculated from Hertz's equations of elastic deformation.

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 Pmax in the centre of the contact or as Paverage as average over the total contact area.

3.1.5 lubricant, n - any material interposed between two surfaces that reduces the friction or wear, or both, between them.

3.1.6 lubricating grease, n - a semi-fluid to solid product of a dispersion of a thickener in a liquid lubricant.
3.1.6.1 Discussion - The dispersion of the thickener forms a two-phase system and immobilizes the liquid lubricant by surface tension and other physical forces. Other ingredients are commonly included to impart special properties.

3.1.7 thickener, n - in lubricating grease, a substance composed of finely divided solid particles dispersed in a liquid lubricant to form the grease structure.
3.1.7.1 Discussion - The thickener can be fibers (such as various metallic soaps) or plates or spheres (such as certain non-soap thickeners) which are insoluble or, at most, only very slightly soluble in the liquid lubricant. The general requirements are that the solid particles be extremely small, uniformly dispersed, and capable of forming a relatively stable, gel-like structure with the liquid lubricant.

3.1.8 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.
3.1.8.1 Discussion - C.L.A. means center line average, and it is a synonym for Ra.

3.1.9 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.

3.1.10 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.

3.1.11 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.

3.2.2 seizure, n - localized fusion of metal between the rubbing surfaces of the test pieces.
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 greater than 0.2 for over 20 s. In severe cases, a stoppage in the motor will occur.

3.3 Abbreviations:
3.3.1 SRV, n - Schwingung, Reibung, Verschleiss (German); oscillating, friction, wear (English translation).