This SAE Recommended Practice is intended as the definition of a standard test, but may be subject to frequent change to keep pace with experience and technical advances. This should be kept in mind when considering its use. The SAE No. 2 Friction Test Machine is used to evaluate the friction characteristics of automatic transmission plate clutches with automotive transmission fluids. It can also be used to conduct durability tests on wet friction systems. The specific purpose of this document is to define a 3600 r/min Stepped Power Test for the evaluation of wet friction system performance variation as a function of power level. This procedure uses an initial engagement speed of 3600 r/min and is intended as a standard procedure for common use by both suppliers and end users. The only variables selected by the supplier or user of the friction system are: a. Friction Material b. Fluid c. Reaction Plates These three variables must be clearly identified when reporting the results of using this test. If any of the test parameters or system hardware as described in this document are changed, other than the friction material, test fluid, or reaction plates, the data may not be reported as having been obtained using this document. This procedure is not intended to evaluate the initial coefficient or break-in characteristics. For this information, refer to SAE J2490 SAE No. 2 Friction Test Machine PVT Test.
There were no units for the energy level in Table 1. It could be inferred but this is not appropriate. A discrepancy of this nature was noted on SAE J2490 by Matt Leite and needed later resolution. Since this document will be considered stable technology in the future it should be as complete as possible. There were several typo’s corrected per the last ballot, and the pressure plate drawing was updated to reflect current practice.