Physical Address
304 North Cardinal St.
Dorchester Center, MA 02124
SAE J2487: A Complete Guide to the 3600 rpm Stepped Power Test for Wet Friction Systems
SAE J2487_2019 is the latest revision of the recommended practice for evaluating automatic transmission plate clutch friction characteristics using the SAE No. 2 Friction Test Machine. The test defines a 3600 rpm stepped power procedure to measure performance variation as a function of power level. It is intended for common use by both suppliers and end users, standardizing evaluation while allowing only three user-selected variables: friction material, fluid, and reaction plates.
Test Equipment and Data Acquisition Requirements
The SAE No. 2 Friction Test Machine must be equipped with a breakaway accessory or inertia simulation capability. Flywheels or inertia simulation must deliver the specific kinetic energy steps as defined in Tables 1A and 1B of the standard. Data acquisition must meet minimum performance thresholds to capture transient torque, pressure, speed, and temperature accurately.
| Parameter | Requirement |
|---|---|
| Sampling Rate | ≥ 1000 samples per second, all channels |
| Torque Channel Bandwidth | 500 Hz |
| Apply Pressure Channel Bandwidth | 500 Hz |
| Speed Channel Bandwidth | 500 Hz |
| Fluid Temperature Channel Bandwidth | 3 Hz |
| Calibration Accuracy | ±2% over 10% to full scale |
🛠️ Engineering Design Insight: The only variables allowed are friction material, fluid, and reaction plates. Changing any other test parameter — for example, system hardware, inertia values, or data acquisition settings — means results cannot be reported as being obtained using SAE J2487. This strict scoping ensures repeatable, comparable results across different labs and applications.
Key Variables and Reporting Standards
When reporting test results, the three selected variables must be clearly identified. The standard is not intended to evaluate initial coefficient or break-in characteristics; those are covered in SAE J2490. The test uses an initial engagement speed of 3600 rpm with specific inertia steps (see Table 1A for details). The total inertia ranges from 0.213 kg·m² (Step 1) to 0.538 kg·m² (Step 9) using incremental flywheels labeled A, B, C, D.
⚠️ Common Mistake: Using the test to assess initial coefficient or break-in behavior. Refer to SAE J2490 for those evaluations. Also, never deviate from the specified hardware or procedure without noting the results are not compliant with this document.
Frequently Asked Questions
What are the allowable tolerances for test parameters?
All channels must be calibrated to maintain ±2% accuracy from 10% of full scale to full scale. Bandwidth and sampling rate must meet the minimums shown in the table above.
How should results be reported?
Test reports must identify the friction material, fluid, and reaction plates used. If any other parameters are changed, the data cannot be reported as having been obtained using this document.
How is the inertia of the system set?
Inertia is set using flywheels or inertia simulation that deliver the kinetic energy steps specified in Tables 1A and 1B. The standard provides exact combinations for each step level.
How does this test differ from other SAE friction tests?
SAE J2487 focuses on performance variation as a function of power level at 3600 rpm initial speed. SAE J2488 uses 6000 rpm, SAE J2490 evaluates μ-Pv-t (initial coefficient and break-in), and SAE J2489 covers durability testing.
🔍 For a deeper dive into the complete test procedure, equipment specifications, and inertia tables, refer to the full SAE J2487_2019 document available from SAE International.
