6. Apparatus
6.1 Four-Ball Extreme-Pressure Tester, illustratedin Figs.2 and 3.

NOTE 1 - It is important to distinguish between the four-ball EP tester and the four-ball wear tester. The four-ball EP tester is designed for testing under more severe conditions and lacks the sensitivity necessary for the four-ball wear test.

6.2 Microscope, equipped with a calibrated measuring scale and readable to an accuracy of 0.01mm.
6.3 Timer, graduated in tenths of a second.

NOTE 2 - Optional equipment with four-ball apparatus consists of a friction-measuring device electrically driven and conveniently graduated in 10-s markings.

7. Materials
7.1 Cleaning Solvent, safe, non-film forming, nonchlorinated. (Warning - Flammable. Harmful if inhaled. See A1.1.)

NOTE 3 - Certain petroleum distillates, formerly used as solvents, have been eliminated due to possible toxic effects. Each user should select a solvent that can meet applicable safety requirements and thoroughly clean machine parts. Reagent Grade Stoddard solvent is an example of a solvent that has been found suitable.

7.2 Rinse Solvent, same as in 7.1, but with higher volatility. ASTM n-Heptane is an example of one such rinse solvent that has been found suitable. (Warning - Flammable. Harmful if inhaled. See A1.2.)
7.3 Test Balls - Test balls shall be chrome alloy steel, made from AISI standard steel No.E-52100, with diameter of 12.7mm (0.5 in.), Grade 25 EP (Extra Polish). Such balls are described in ANSI Specifications B 3.12, for Metal Balls. The Extra-Polish finish is not described in that specification. The Rockwell C hardness shall be 64 to 66, a closer limit than is found in the ANSI requirement.

8. Preparation of Apparatus
8.1 Thoroughly clean four new test balls, test-lubricant cup, and chuck assemblies by first washing with cleaning solvent (see 7.1) and then rinse solvent (see 7.2).

NOTE 4 - Do not use solvents such as carbon tetrachloride or other solvents that may inherently possess load-carrying properties which may affect the results.

8.2 Lower the crosshead by raising the lever arm. Lock the lever arm in the raised position by means of a locking arrangement for that purpose.