The disc brake: from rail to truck
It’s the mid-1980s and Knorr-Bremse is carrying out a major research project. A development team is testing brake discs, calipers and brake pads to their limits on the friction dynamometer. So far, so unremarkable. What is unusual, though, is that even all those years ago colleagues from Knorr-Bremse’s Rail Vehicle Systems and Commercial Vehicle Systems divisions were working side by side on the test rig. 30 years ago, the engineers were tasked with developing a Knorr-Bremse disc brake for commercial vehicles that would ideally become just as successful as its rail vehicle counterpart.
The ultimate example of technology transfer
Rail vehicles were using disc brakes as long ago as the 1950s. They proved themselves as the standard technology in trains and cars over a long period, with benefits including excellent braking force control, short braking distances and ease of maintenance. At this time, commercial vehicles used drum brakes exclusively.
How disc brakes work
When Knorr-Bremse started systematically developing disc brakes for commercial vehicles in the 1980s, the company was able to draw on its experience in the rail vehicles sector. Ultimately, all disc brakes are based on the same operating principle: Brake pads press against the disc, converting kinetic energy into heat. Effective heat dissipation to prevent the brake from overheating is one of the key challenges in developing disc brakes.
Drum brake vs. disc brake
Knorr Bremse’s engineers knew that disc brakes produce a more even braking force than drum brakes. As trucks got ever faster and heavier, this would help to improve handling and steering while braking. In addition, drum brakes require shorter maintenance intervals. In today’s parlance, disc brakes offer lower total costs of ownership (TCO). Knorr-Bremse therefore decided to develop its own disc brakes for commercial vehicles and began marketing and mass-producing them in the 1980s.
Harnessing synergies: Two divisions, one development center
The sharing of existing test rigs between the two divisions was a key factor in the disc brake success story and a sign of things to come. Since 2016, some 650 highly specialized engineers and technicians from both sides of the business have been working together across disciplines on the 100 state-of-the-art test systems in Knorr-Bremse’s new Munich Development Center.
The disc brake today
Back to the present: The next-generation disc brakes are called SYNACT for heavy-duty trucks and NEXTT for light and medium-duty trucks and trailers . They stand for the development of a digital and networked brake system and related components. As such, they are a key technology on the path towards a largely accident-free future for road traffic.