The new and further development of vehicle brake systems today mainly takes place on flywheel brake test rigs. In these test benches, the brake disc is accelerated to the desired test speed by means of an electric motor. The vehicle mass is simulated using rotating flywheel masses that are integrated in the drive train of the test rig and are thus mechanically coupled to the brake disc to be tested. Different vehicle masses are usually implemented with several inertia masses, which can be coupled and decoupled as required. An exact setting to the vehicle mass to be simulated can then be made via the drive motor, which acts as a generator/motor during the test run and thus can represent an additional positive or negative inertia. In principle, a very simple and realistic simulation of the vehicle masses can be achieved using the flywheels, but the structurally complex implementation of such a solution ultimately means a not inconsiderable cost item in the total price of such a test system. The great advances that have been made in recent years with high-torque motors and their control accuracy make it possible today to ask whether the standard centrifugal masses can be replaced by a mass inertia simulation of large motors. For this purpose, extensive investigations and calculations are currently being carried out at RENK Test System GmbH using the example of a full-scale flywheel brake test bench for brake systems in rail traffic. The results of this work will be presented with the proposed technical paper: Estimation of the limits and control accuracy of the electrical inertia simulation by testing it on the real test bench Examination of the essential assemblies (base frame, basic flywheel, floating bearing (test specimen holder), test station) with regard to the necessary function, design and costs Presentation of the advantages and disadvantages of the "classic flywheel brake test bench" compared to the "brake test bench with electrical mass simulation" We would expressly welcome a following discussion of the presented study results (also regarding the partly personal preferences of the operators).

An upcoming fine dust regulation is recently the most challenging issue in the brake development of ICE vehicles. In regards of countermeasures to improve the fine dust behaviour the hard-metal-coated brake disc is one of the most promising ways to reduce the mass and number of brake fine dust particles. According to the current publications of the PMP-group, todays foundation brake systems emit more the 10 mg per km fine dust in the size of PM10. Since an expected regulation reduces this amount significantly, the VW group is developing and monitoring the most promising approaches to fulfil the expected legislation. Our preferred idea is to prevent the production of fine dust. To face this issue, high-speed laser gladded coatings on the brake disc friction surface is one of the mainstream technologies. Since we have a change in the tribology of the foundation brake system on the disc side, we are also developing with our partners adjusted brake pad materials. This work focuses the influence of the mechanical and chemical properties of the brake disc coating on the fine dust emission behaviour. Therefore, we performed a test sequence with different tribological systems.

In the context of the PMP Inter-Laboratory Study (ILS), several brake systems were circulated at different laboratories to characterize their brake-wear particulate emissions following the recently developed PMP measurement methodology. Each laboratory is required to employ its own dynamometer, sampling system and measurement instrumentation, including PM2.5, PM10, 10 nm total particle number (PN) and optionally 10 nm solid particle number. The absence of reference measurement instrumentation circulated to the participating laboratories was mainly due to time constraints. Given the challenges associated with the characterization of brake-wear particles and the limited experience with the application of the new methodology, it is important to also assess the contribution of the measurement instrumentation on the repeatability and reproducibility of the novel methodology. To this end, a set of measurement instrumentation was circulated in three laboratories participating in the ILS. The instrumentation included two AVL PM samplers and the associated cyclones for PM2.5 and PM10 quantification, as well as two AVL Particle Counters (APCs). One APC was unmodified and fully compliant with the Global Technical Regulation (GTR) 15 as recently updated for 10 nm measurements. This includes the use of a full-flow CPC with a cut-off size at 10 nm, and a catalytic stripper at 350ºC. The second APC was a modified 10 nm version operating with its heaters deactivated, and the catalytic stripper removed. Both the APCs and the internal CPCs were calibrated in an iso-certified calibration line before the start of the campaign. Their calibration was also validated at the end of the measurement campaign. All three laboratories performed measurements with the two reference brake systems, one of which was tested with two different types of brake-pads. Some additional investigations were performed at each lab. These included testing of two different brake systems, one of which used drum-brakes, as well as investigations of an alternative bedding-in procedure. In this talk an overview of the measured particulate emissions including both mass and number, is presented. The reference brake systems allowed for the assessment of the repeatability and the reproducibility of the measurement results for each metric. These figures when compared to the official statistics of the entire ILS will help assess the contribution of measurement instrumentation on the overall accuracy or the measurement methodology. The talk will also address the robustness as well as improvement potential in the methodology, based on the results with the additional brake systems and the alternative bedding-in procedure.