Euro 7 has been getting a lot of attention recently because of its potential impact on the brake industry. So I decided to sit down with Stefan Guether, Global Product Manager Brake Test Systems for Horiba Europe, and Sebastian Granstat, Senior Expert, Development Foundation Brake for Audi AG, to learn more about this potential legislation and where things might be headed.
Can you provide some background on how we got to this point?
Sebastian Gramstat: We started this work back in 2014, let’s say officially, launching an informal working group, PMP, Informal Working Group on Non-Exhaust Emissions, as it is called under the UNECE umbrella. And this working group started in the beginning just to collect data, information, knowledge, and expertise in those called non-exhaust emissions. This includes brake particle emissions, such as those from tires, and the topic of resuspension.
However, brake emissions came into focus over the years. And that PMP working group was focused then later on preparing a test method that allows determining in a robust way, emission factors of brake systems, the foundation brake, better to say. And this is where we are right now. This method is now available in terms of the GTR, a global technical regulation. I guess we will stress this item a little bit later on in more detail. And yeah, this is in the outcome of that work of almost ten years now.
What has been the goal of collecting this data?
Sebastian Gramstat: It’s really a huge amount of work behind. And before I come to the details, perhaps I will highlight that the entire community worked very hard on that in a very transparent way and in a very impressive collaboration. I would like also to highlight here the support we got from the JRC, the Joint Research Center. This is the scientific division of the European Commission. And here we had really great support over the years, especially from Dr. Theodoros Grigoratos. Theo did an amazing job, not only in terms of the brakes but also in terms of the tires.
When it comes really to the details, we started with just a very trial literature review work. So this is what we did in the beginning. Theo prepared together with Giorgio Martini and a reference study, I would say, at this time. And then we started with experimental work, really gathering data, learning, where to measure, how to measure.
We have Stefan here today with us, Horiba did a great job, and together we started a collaboration, I think quite early in 2015. And so everybody in this community started to collect data, some knowledge and this is a very very impressive thing. We shared it. We shared it within the community but also outside the community. So this was really always a very transparent way to share data and to make it accessible to everybody who is interested, I would say.
Can you provide an overview of GTR and the role it plays?
Stefan Guether: So I think it’s important to understand that the GTR itself is a global technical requirement and not legislation itself. So as Sebastian said, the main task for the PMP working group was to define a methodology on how to measure brake particle emissions because there was nothing available at the very early beginning and the PMP started some kind of from scratch. Define a test cycle in the first step, which shall be run on a brake dynamometer to have a homogeneous methodology on how to do it. Because in the first approach, there were different ideas on how the test cycle shall look like. For example, the AK master as a standard brake test would be some approach or to find something which is closer to the exhaust emission test cycle, the WLTP for example. So this was one of the goals of the PMP and the content of the GTR, which is defined the test cycle itself. And of course the whole test setup on how to be conducted, how the setup of the dyno shall look like, which requirements need to be fulfilled, and which parameters need to be monitored.
So I think we will also talk about this later, the measurement of total particle number and solid particle number, things. And last but not least of course, the requirements on the measurement devices which shall be used for the methodology. And one topic we’re let’s say still working on is how to take into account the non-friction braking coefficients. So this is also very important to make a good judgment on the particle emissions.
Is GTR a global standard or only applicable in Europe?
Stefan Guether: No, it’s a global technical standard. I think also important is to know that for now, it’s mainly intended to be used for vehicles with a gross vehicle mass below 3.5 tons. So it’s not a standard yet for heavy-duty applications. And yes, of course, it’s a standard that shall be used to do the homologation test and the R&D testing sure we fulfill the Euro 7 requirements and legislation limits.
So What is Euro 7 exactly?
Sebastian Gramstat: So traditionally, Euro standards are focused on exhaust emissions. We have now a completely new situation since we have here several approaches, amongst others, also the brake emissions. So I think a really complete change in terms of the approach. This is upcoming, not agreed upon yet. So far, it is a draft or a proposal, published by the Commission in November last year, and now it is time really to define all the details to fix it to agree on that between the European Commission, the Council, and the Parliament and therefore also a certain let’s say the political process is required so it still takes some time till we will see all the details and by the way all the details that are necessary for the development phase and for the industrialization. So we as the industry are eager, we are keen to understand that we want to have it as soon as possible so that the boundary conditions for us as engineers are clear and that we can start our development even more precisely than we do already today. I think this is a very crucial point then.
Do we know exactly what types of tests or testing will be required?
Sebastian Gramstat: That’s a very relevant, very crucial question, very important, of course. In the past, as I said, we were focused on exhaust emissions. Here it is quite simple. You have a vehicle, so the vehicle manufacturer is responsible for that. They have to take care of the homologation process.
With the brake system then, as a component, but that is included in the vehicle, it might be a little bit more complicated. In addition to that, we have a component test. So we do not test it within the vehicle, but on the test bench, on the brake dynamometer test bench. So things are a little bit different. In any case, it is part of the whole vehicle homologation. So we as an OEM are in the end responsible for that. This is one essential and relevant item. Additionally, the Commission has already stated that the replacement of the aftermarket parts will play a certain role. And that means that not only OEM business or OE parts, also as replacement parts, but also the non-OE parts, will be somehow and someday a part of this Euro 7. Further details, still have to be discussed, so this is still, let’s say, in progress.
Is the industry prepared or capable of conducting the required tests?
Stefan Guether: That’s a very good question and one of our big challenges, not only for us as a supplier for the test systems and the measurement devices, also of course for our customers, the OEMs and tier one suppliers, component suppliers. Since we have now, let’s say, some kind of final draft of the GTR, since the beginning of this year, we can start seriously to prepare and to upgrade our test systems and provide them and start manufacturing. So of course we have some systems available, some dynos we can already run some tests on, but I think we all need to spend some more effort to come to a system and a test setup which can be used for homologation testing, to really fulfill all the details of the GTR. And of course there might be some minor changes, but yes, we are under pressure to speed up to provide testing capacities and test systems the latest at the beginning of next year, to have a chance to do homologation testing and some kind of development, if necessary, to meet the introduction of the Euro 7 on the 1st of July 2025.
What is the timeline for Euro 7?
Sebastian Gramstat: I guess there’s a certain hope or I would say huge hope, at least from side of the industry, that we have the necessary time available. So far, according to the proposal, we have to consider really July 2025 as the date. So that means that at this point of time, all vehicles have to be prepared. They have to fulfill Euro 7 requirements. This is tomorrow, in terms of our preparations.
And it is even more concerning since we must not forget the homologation process. So to be ready on July 2025 to offer a product means that the homologation process has to take place a little bit earlier. And when I say a little bit, I mean more or less, or roughly a year. So that means we have to be ready with our products summer of next year, which is, honestly speaking, not very realistic. So we really have a strong hope and we fight for that, that we get sufficient time in terms of A, the development phase, and B, the industrialization. Because we must not forget that certain measures are necessary to be compliant with the requirements, to fulfill those thresholds then.
And that means not only a certain refinement of a brake lining, in composition or the composition of a gray-cast iron alloy, that means some crucial measures, crucial measures that have been part of the advanced or pre-development phase till today. And now we have to move it very quickly to serial development. And yeah, again, that means we have to hurry up, we have to speed up. And of course, some additional time is more than welcome, more than helpful.
Do we know what the impact is going to be outside of Europe?
Stefan Guether: So at least if you plan to sell any cars in the European community, you have to fulfill the Euro 7 legislation. And that means not only German OEMs are affected by this legislation. So the whole brake and automotive industry has to take care of this topic. We already see that other customers are also very interested in Europe. I’m pretty sure that there is a very high chance that other countries might follow also with maybe not the same but similar legislation approach.
Sebastian Gramstat: Totally agree with that. We have global markets, right? So that means that everybody is focused on that. Everybody has to be compliant in the end with Euro 7. This is I think the first answer to this question. And the second one of course we have seen huge interest in the past from US colleagues from US side. So we know that the California Air Resources Board (CARB) that I mentioned earlier. CARB has also launched in the meantime several research projects. So they are eager in getting information, getting data, increasing their knowledge and expertise.
And I’m pretty sure they did that. So they are experts. They know what to do. They follow this Euro 7 approach here very closely. So they are really aware of that, so to say, and we also know from our Japanese friends, for instance, they had already a standard. defined a couple of years ago. Say, even before the GTR was available, they have internally already defined the standard. They did also create work in the past, gathering data and understanding what happens, how to determine particle emissions. So we see around the globe there is a huge interest and it is not only restricted and limited to the European market.
Will regenerative braking play a significant role in meeting Euro 7 requirements?
Stefan Guther: I think it’s of course, one piece of the puzzle. I’m not sure if this is the final solution. So in case we can rely on regenerative braking, we do not need to think about brake particle emissions. I think this is not the case. Because due to not using the friction brake, there also come up some additional requirements for the brake.
So, in case you do not use your friction brake, you might come to the point of corrosion and so on. You need to protect your brake system, and this might lead to the development of new brake systems as Sebastian already introduced or explained. For example, new modifications of the brake pads or coated discs, for example. So this is also part of the challenge to face these new developments, to include them into the brake development phase and all together facing the goal to meet the Euro 7 and to handle all these requirements and challenges at one time.
Will this cause automakers to evaluate solutions such as filters to capture particles?
Sebastian Gramstat: Yes. We have to. Of course, regen braking is a great thing. And especially when you look at pure electric vehicles, I guess that’s the solution in the end, right? At least in terms of the particle emissions. So here we see very huge potential. And I think there is no doubt. And the European Commission itself already confirmed that in the future, probably with all-electric vehicles, this won’t be an issue anymore. The time between, we also have other solutions as the customers require and need for sure. So we will have, or see hybrid vehicles, plug-in hybrids, etc. So we need here, even if we have region braking also there on board, but we need here additional measures.
And most probably, it will be then, in the end something like a measure in terms of the tribo partners. This can be then the case. Of course, filter systems are also discussed. I think that in the end is required that we provide sustainable solutions. This is important. So not only something that survives the emission test and then it is gone.
So I believe sustainability plays a huge role here. Of course, we have to address the costs, is probably out of the equation. And we have to ensure that such a new solution does not affect the requirements we have so far. So everything that deals with safety, for instance, but also with comfort and performance, this is something where we have to keep our high requirements and expectations. So I think it is not a good way to accept certain or lower requirements in terms of stopping distance, for instance. This is, of course, a no-go, so we have to continue with those requirements, be a little bit better in terms of emissions, and as I said, those measures, as I mentioned, can lead then to the fulfillment of Euro seven requirements.
Will heavier EVs cause more tire wear and ad challenges in meeting the Euro 7 requirements?
Sebastian Gramstat: Yes, but tire wear depends on the vehicle application in the end. Also in terms of the driving style, this has also a huge impact. There’s no doubt, I believe, but I have to state that we will always have, let’s say, some heavier applications. So people carrier, this is something you cannot expect with a vehicle weighing a tonne, for instance. So it always depends on the vehicle application and I’m pretty sure we will also see in the future the requirements for heavier vehicle let’s say. You mentioned of course also the increased weight of battery electric vehicles. I think this is also something that we have to deal with. Therefore, I think it is only fair to find a certain compromise in terms of a possible threshold in the end.
The current Euro7 proposal foresees certain units and you can download this from their official page there. But of course, as an industry, we really would like to see here a standardized value in the end, that refers also to the vehicle weight. I think this is more convenient, more practicable. And in the end, this is only fair that what we see on the road and when it come to requirements.
How is Horiba preparing for Euro 7 from a testing perspective?
Stefan Guether: First of all, we try to support and consult in some way our customers on what is the content of the Euro 7, what is the GTR, what needs to be done to enable them to do the testing appropriately, and what is necessary to be prepared for homologation testing. Light-duty vehicles and the passenger cars for the moment as the Euro 7 limits are introduced for these types of cars. But we also see a very high interest as we talked about heavier vehicles, so heavy-duty applications.
Some customers already started to do some activities on this and to transfer available methodology and measurement devices. Now, of course, we cannot just adopt the GTR content and to do truck applications. So one obvious thing is a truck brake does not fit in the brake enclosure for the GTR. So this is one example on what topics we try to adopt and to modify things we already know and the requirements that make sense, and to bring it to other applications and to make the first steps.
Is there anything else you all would like to share on the topic of Euro 7 and its impact?
Sebastian Gramstat: If you don’t mind, I would really highlight that item that Stefan just mentioned, that we need dedicated solutions. Dedicated solutions in terms of the testing method, so the GTR as well as the legislation in the end, so to say Euro 7. What do I mean with dedicated? So dedicated to the different vehicle classes, so that we really differ between the passenger cars side, the light commercial cars on the other side, and then the heavy duties.
And also in terms of heavy duties, we have to differ between different applications, right? There are differences between long haul trucks and trucks you see in the city or city buses, for instance. So I think that this is a very crucial point. Perhaps we did not focus on that in the past in detail on this, but I’m pretty sure we have to. And this is also a wish of mine for the future, that we will get the opportunity really to find the sophisticated solution for each single application where it is worthwhile and where it makes sense.
Stefan Guether: So I think this is a very important point. It’s very sure that we won’t get bored in the brake development industry. So many new applications will come up for heavy duty for trains and so on. So lots of things we have to take care of in the future.
