The 56th PMP session convened online on 7 May 2026 with approximately 70 participants. Meeting minutes from 13 March 2026 were accepted. PMP agreed on a joint neutral template for all task forces. TF3a discussed cooling air adjustment, temperature criteria, and vehicle emission factors, with proposals requested by end of May 2026. TF3b will discuss family building and speed-limited vehicles. TF3c presented brake replacement parts activities. TF4 prepared work package B on electromechanical brakes and requested feedback by end of May 2026. TF5 reported progress on GTR on HD brake particle emissions with test campaigns planned. The next meeting is expected end of June or beginning of July 2026.

Task Force 5 is progressing on GTR development with tests on endurance braking ending 07/2026 and potential GTR adoption at GRPE 95th session 10/2026. Draft revisions to Sections 7 and 8 are agreed and incorporated, addressing caliper orientation, fixed airflow, and additional loading factor. Nominal test parameters for brake groups are under revision, with tables from R90 defining disc and drum brake specifications. A small Round Robin Exercise with five volunteers is underway to assess enclosure and duct diameter impacts, with results due first week of June. Auxiliary Braking Systems testing requires significant immediate effort.

The PMP webex meeting scheduled for 7 May 2026, 12:00-14:30 CET will review meeting minutes from 13.03.2026, provide an overview of amendments to Brakes GTR 24 and UN R179 covering layout and testing topics, vehicle limited speed, brake replacement parts, and electromechanical brakes, discuss GTR HD brakes, and address any other business.

The PMP session discussed revisions to the group’s terms of reference to address overlapping technical issues with GTR 24, UN R179, and replacement parts regulations. Three task forces were proposed: TF3a on layout and testing, TF3b on speed-limited vehicles, and TF4 on electromechanical brakes. Topics included non-original brake parts regulations, UN R179 amendments for new vehicle categories, and GTR heavy-duty brake particle emissions standards. The next meeting was scheduled for end of April 2026.

Proposal to establish a UN Global Technical Regulation for measuring brake particulate matter and particle number emissions from heavy-duty vehicles. The regulation defines laboratory test procedures using a brake dynamometer and the Worldwide Harmonized Heavy-Duty Vehicles Brake Cycle (WHBC), encompassing 20,353 seconds with 246 brake events across three driving segments. Tests require brake bedding with six WHBC repetitions, followed by emissions measurement. Laboratories must measure PM10 and PM2.5 mass gravimetrically and total and solid particle numbers (TPN10, SPN10) using particle counters. Technical specifications cover brake enclosure design, sampling tunnel configuration, climatic control, instrumentation calibration, and data reporting requirements to ensure reproducible and comparable brake emissions testing across regions.