SYNACT and NEXTT: intelligent disc brakes for future generations.
Young project leaders and their teams were the driving force behind two next-generation disc brakes, SYNACT and NEXTT, that are set to serve as global platforms.
Michael Peschel is attending an in-house workshop in Hallbergmoos near Munich with disc brake experts from all the relevant business units and regions. They are discussing the requirements for a next-generation disc brake. The current SB7 and SN7 models for heavy-duty trucks and buses already represent the state of the art. Four teams present a wide range of ideas, with Peschel responsible for dimensioning. At the time, Peschel is responsible for the dimensioning, i. e. defining the basic measurements of the brakes during the design phase. “It wasn’t just a case of giving them a facelift – we completely rethought the systems from the ground up.” The most important goals for the redevelopment were that the new brakes should be easily capable of 30 kNm braking torque and should operate robustly even on extremely long downhill gradients. At the same time, they should be lighter and have a significantly longer service life. Finally, the wish-list also included easier maintenance. “We wanted a modular platform so that we could further harmonize the truck and bus models on the basis of individual modules”, says Dimitrij Habermann, who has now taken over Peschel’s role.
New megatrends are a challenge for disc brakes
In addition to being easily adaptable, the new disc brakes also had to reflect the major trends in the industry. A lower weight would reduce fuel consumption, thereby helping to cut CO2 emissions. Meanwhile, a smaller brake caliper would simplify the final assembly process, and the entire internal mechanics had to fit inside a single module, says overall leader of the SYNACT project, Jan Philipp Regul. “The internal mechanics could be described as the intelligence of the brake. Industrially manufacturing them in a single module means that we can produce them centrally, making it much easier to guarantee quality for our global production.”
New disc brakes for autonomous driving
Speaking of intelligence, the next-generation disc brakes are autonomous-driving ready. Additional sensor technology such as Brake Condition Monitoring (BCM) enables predictive and condition-based maintenance. Active Caliper Release (ACR) is another unique feature. When the driver releases the brake pedal, ACR actively separates the brake pads from the disc, thereby reducing brake drag. “This delivers additional fuel savings of around one percent over and above the savings achieved through the lighter design”, says Regul. The adjuster is also being redeveloped in order to extend its service life and ensure that it is robust enough to meet tougher market requirements. The mechanical adjuster automatically compensates for brake pad wear, ensuring that the distance between the pads and the disc is always virtually the same.
130 individual parts combined
In total, the SYNACT project involves the redesign, re-engineering, testing and approval of 130 individual parts. Andreas Haidukiewitz, who is in charge of the city bus version of SYNACT, is responsible for twelve of them. “The SYNACT project involved more than simply developing new technology. We suddenly had to put a huge number of new parts through our processes, which posed major challenges for all our departments”, says Haidukiewitz. However, the project leader and his team benefited greatly from the guidance provided by Knorr-Bremse’s clearly defined, automotive-oriented process structure Product Development and Commercialization (PDC).
The NEXTT disc brake is a global product
As overall project leader Markus Bartel explains, the second new disc brake involved a different approach. “We broke new ground not only as regards the technology but also in terms of its realization – NEXTT is a global product.” A total of seven sites in Europe and the US were involved in the development process. In North America, NEXTT is intended for light and medium-duty truck applications and trailers; in Europe, the brake is aimed solely at the trailer market. It thus merges the different Bendix and Knorr-Bremse system platforms – the previous ST7 and ADB 22X/ LT models had largely been developed separately in the two regions.
NEXTT: low weight, lower costs
Technical project leader Andreas Petschke explains what is special about NEXTT: “Above a braking torque of 19 kNm, you need a conventional two-piston brake like SYNACT.” However, NEXTT is suitable for anything up to 19 kNm, with the advantage that “NEXTT’s all-new single-piston design delivers weight and cost reductions.” However, before NEXTT could be developed it was necessary to define the requirements. “The development of this joint product was the key milestone”, says Bartel. “But there was a terrific global team spirit and common sense of purpose throughout the sites in Germany, Hungary, India and the US.”
Easier to adapt to local needs thanks to modular design
As part of a global production strategy, the NEXTT brakes are made at the Bowling Green facility in the US and Aldersbach in Germany. “NEXTT’s modular design means that it can be very easily adapted for the local markets”, says Andreas Petschke. The team was in regular contact with the SYNACT colleagues in order to share lessons learned regarding working methods and processes.
Successful project work in the SYNACT and NEXTT team
Clear and open communication within the team played a fundamental part in both projects, as did regular discussions with customers in order to meet and exceed their expectations. Haidukiewitz, Regul and Habermann brought the core SYNACT team together once a week for project days that alternated between Munich and Aldersbach. “We defined PDC-based project phases that allowed us to clearly track the project’s progress at all times so that we could take quick and focused decisions as necessary”, says Regul. Bartel and Petschke were also constantly in touch with the NEXTT project’s core team in the US and held regular meetings with them. “In keeping with a global governance approach, we constantly coordinated our decisions with each other, sharing all the data and facts.” The huge responsibility associated with these two major projects has made both teams stronger, and they are now in great shape to face future challenges.