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.

Proposal to amend UN GTR 24 (Laboratory Measurement of Brake Emissions for Light-Duty Vehicles) by clarifying requirements for electromechanical brakes and dry brakes, modifying test procedures, updating definitions and technical specifications, revising cooling airflow adjustment methodologies, refining PM and PN measurement protocols, and adjusting calibration intervals and quality control procedures.

Task Force 4 addresses brake system development towards dry brakes, specifically electromechanical brakes. Current methods to determine friction brake torque available for hydraulic systems are not all applicable for dry systems. Task Force 4 targets defining a pressure-based equivalent method for electromechanical brake systems and reviewing document validity for electromechanical braking systems. Work Package B completed text document review with proposed changes due end of May 2026. Work Package A discusses two alternative approaches for c-factor calculation: clamping force based and recuperated energy based, with verification tests planned by end of June 2026.

At the 94th session of GRPE, CLEPA proposed a draft UN Regulation for approval of replacement brake parts. A dual pathway approach was proposed with two options depending on data availability: fully available data or minimal set of data with worst-case assumptions. PMP Task Force 3c was established to prepare a UN Regulation for approving replacement brake parts regarding particle emissions. The TF3c will define minimum information required under the simplified approach, assess variability within a family, and identify worst-case assumptions. CLEPA presented two approval concepts and requested support for Option A only. The next meeting is scheduled for 18 May 2026.

PMP Task Force 3b held kick-off on 07.05.2026 to address vehicles with legal limited speed, vehicles unable to follow cycle trace, and vehicles with capped speed by OEM decision. Proposals include adaptation of UN R179 cycle and procedure for vehicles with legal limited speed at 90 kph, with same duration for acceleration, cruise, and deceleration events, same acceleration and deceleration rates, and speed capped when needed. Introduction of such vehicles into brake corner emission families and vehicle types requires methodology to calculate adapted cycle and procedure, including c-factor measurement as alternative to fixed c-factor, and adaptation of Annex 5 procedure.

PMP TF 3a is consolidating and updating UN R179 and GTR 24 through weekly web-meetings organized by JRC with 30+ participants. Over 50 topics have been identified and categorized by priority. Key issues include aligning Type Approval and Conformity of Production testing procedures, harmonizing cooling air adjustment requirements, clarifying vehicle c-factor calculations, adding definitions for light-duty vehicles exceeding 3.5 tonnes, and addressing test wheel load per GRPE-94-15e. The task force is preparing track changes versions and supporting documentation for major changes.

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.