In late 2022, SAE International published a new, revised version of the SAE J2521_200306. The procedure provides a laboratory test method for high-frequency squeal type noise evaluation on passenger cars and light duty truck type vehicles. The revision is broken into five different schedules defined as Schedules A, B, C, D, and E. These schedules provide extended climate conditions, more brake events with emphasis on low pressures, low speeds, and colder temperatures as well as extended temperature soaks.
SAE J2521:2013 provided three Schedules, defined as:
- Schedule A – Mild temps with 1430 brake events
- Schedule B – Cold with 460 brake events
- Schedule C – Post-Fade with 487 brake events
While the SAE J2521:2022 provides five Schedules, defined as:
- Schedule A – Mild temps with 2018 brake events
- A.1 🡪 20 ºC / 50 % RH
- A.2 🡪 10 ºC / 30 % RH
- A.3 🡪 -5 ºC / 30 % RH
- Schedule B – Cold with 472 brake events
- B.1 🡪 -20 ºC / n.a. % RH
- B.2 🡪 -25 ºC / n.a. % RH
- Schedule C – High Humidity with 654 brake events
- C.1 🡪 20 ºC / 80 % RH
- Schedule D – Post-Fade with 687 brake events
- D.1 🡪 20 ºC / 50 % RH
- Schedule E – Could & Humid with 168 brake events
- E.1 🡪 0 ºC / 80 % RH
- E.2 🡪 5 ºC / >75 % RH
- E.3 🡪 -5 ºC / 80 % RH
In addition, the protocol has an extended environmental spectrum of requirements, proving challenging for CCU 1 and 2, especially under parts A.3 and E.3 where subzero temperatures and high humidity is required. These sections lead to the need of a CCU 3 to correctly perform the SAE J2521.
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