This SAE Recommended Practice is intended as the definition of a standard test, which 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 is used to evaluate the friction characteristics of automatic transmission plate clutches with automotive transmission fluid combinations.

The specific purpose of this document is to define a μPVT test for the evaluation of the variation of wet friction system low speed slip characteristics as a function of speed, temperature, and pressure. This procedure is intended as a suggested method for both suppliers and end users.

The only variables selected by the supplier or user of the friction system are:

Friction material

Fluid

Reaction plates

Oil flow (optional)

These four variables must be clearly identified when reporting the results of 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 being obtained using this document.

This procedure is intended to evaluate ramped speed friction characteristics, also called sweeps, and can be used to demonstrate capacity changes that occur between the different levels of slip speed, applied pressure, and fluid temperature. The level of coefficient of friction, as well as the trends in torque capacity with speed, can be used to compare candidate materials or fluids.