New technology against brake abrasion: out with the dust

 "When you brake, fine dust gets into the air. There is a lot of protective technology at hand. A French start-up, for example, wants to extract fine dust where it arises - directly on the brakes of trains, cars or buses.

 

Germany has not leased complaining environmental organizations for itself. The Netherlands knows them and France knows them too. The “Respire” association did not file a lawsuit against automobile or oil companies in the Paris court last spring, but against the RATP. The state-owned company operates the metro and light rail in Paris. So local public transport, which is actually an ally of green interests.

 

But Respire accuses the company of endangering the health of its customers because the air pollution at the train stations is too high. You don't want to stay long in the subway shaft, but the fine dust pollution is all the higher. In 2015, the French environmental authority measured precisely: With an average of 100 micrograms of particles per cubic meter, it was more than three times as high as outdoors on the streets of Paris.

 

The advance comes at the right time for the French company Tallano Technologie. After the foundation in 2012, the technology of "Tamic" was developed and ready for use. The system offers a technical solution to stop the fine dust where it mostly occurs: on the brakes. The state railway company SNCF is already cooperating with Tallano, the Île-de-France region has a stake in the company, and the waste giant Veolia recently got involved because the secondary use of the magnesium or copper particles collected can be lucrative. Reason enough to send a prototype onto the rails. One of the light rail trains, the RER, that runs across Paris is now equipped with the brake vacuum cleaner.

 

Filters also conceivable for commercial vehicles and cars

 

Tamic is an active anti-fine dust system. If the driver applies the brakes on his train, a turbine generates a vacuum. It sucks the fine particles into a filter, which are rubbed off on each wheel and each axle between the brake disc and brake shoes. Tamic reduces these emissions by 85 percent, says Bert Stegkemper, who has been on the start-up's supervisory board since 2014 and is now responsible for establishing the technology on the German market. 

 

The German GmbH is currently being founded, and talks are already being held with Deutsche Bahn, even if pilot projects like those in France have not yet been agreed.

 

However, the rail is not the only place where such a filter system can work. Tallano also has commercial vehicles, buses and trucks in mind, and cars. Because even if the car manufacturers themselves are hesitating, a lot is happening on the developers' side. 

 

The German filter specialist Mann + Hummel is competing with a similar product. Except that its system passively captures the fine dust on the brakes. For this purpose, a housing filled with metal fiber fleece sits above the brake caliper, into which the fine particles are thrown every time the brake is applied. According to the company, 80 percent of the particle mass can be collected.

 

The filter system of the French competition requires active electronic control, so the architecture of the disc brakes is almost indistinguishable from ordinary ones. The system has already been tested on a Parisian Renault Zoe, and Tallano has tested it on an RS 5 together with Audi. Mainly to find out whether the braking characteristics change. 

 

After all, approval can only be given if the safety-relevant technology works without restrictions. 

 

"The only thing we do on the brake pad is make a small groove," explains Stegkemper. "But that has no effect on the braking behavior." The vacuum generated by the turbine can pull the fine dust into a thin hose and finally into the filter via the groove. The heat dissipation does not change as a result, nor does the mechanical integrity of the brake pads. Neither water nor ice clogged or silted up the filter. 

 

The negative pressure is metered in such a way that it only absorbs the suspended matter.

 

Bosch offers coated brake discs

 

In order to prevent particles from getting loose at all, or at least none that are fine enough to carry their harmful effects to the lung tissue or the bloodstream, other developers work directly on the brake disc. Bosch offers one with a tungsten carbide coating, which is said to drastically reduce abrasion and prevent rust. In the premium segment, such as at Porsche, expensive brake discs made of ceramic or with a ceramic coating perform similarly. And specialist companies such as HPL Technologies have developed laser processes to apply a durable, thin metal layer to the classic cast discs in the most energy-efficient way possible to reach. For this purpose, the Aachen-based company has developed a process in which the coating and cast disk are melt-metallurgically bonded. This works with standard brake discs and reduces fine dust by up to 90 percent, according to the company.

 

"If you want to do it right, you take both," says Tallano's Germany boss, his active filter system and a coated brake disc. At least when the car industry is serious about its promises of “zero emissions”, or at least getting closer to it. Even electric cars still cause a lot of fine dust. On the one hand, they brake less actively, and whoever recuperates does not cause any brake dust. On the other hand, the batteries bring a lot of weight to the road. If the driver brakes mechanically, which happens often enough in city traffic, the brake wear can be higher than with most combustion engines.

 

"A system that car manufacturers don't really want"

 

In any case, the costs do not speak against the additional systems. "We're talking about a series price of 100 to 150 euros for a car," says Stegkemper. The filter cartridge can also be quickly exchanged for a new one via a bayonet mount, which is necessary after around 30,000 kilometers. Stegkemper considers retrofits to be unrealistic for cars, unlike for buses, trains and trucks, which offer more installation space. However, these questions can only be answered precisely when the French have brought their patented technology to the important suppliers. They should bring them into series production and thus to the customer.

 

"This is a system that the car manufacturers don't really want," Stegkemper believes, which he means in a completely neutral way, as he says. But also one that they may need to have soon. The exhaust gases of modern combustion engines are cleaner than ever. Only about twelve percent of the fine dust caused by the car can still be attributed to them. The rest is divided evenly between tire abrasion, road surface - and brake dust. 

 

Although in 2020 no measuring station in Germany even touched the permitted limit values ​​for fine dust, i.e. the particle sizes PM 2.5 and PM 10, the pressure on the automotive groups is likely to increase. Because the WHO is calling for a significant tightening of precisely these limit values. 

 

And with the Euro 7 standard, which is to come in 2025, fine dust that does not come from the combustion engine could also be regulated for the first time."