In the heavy-duty application safety and reliability is always a key factor - especially while designing brakes. There are a lot of legal regulations regarding the performance of the brakes in the commercial vehicles. Although mass reduction is rather a secondary topic, there is a lot of potential to exploit within the legally specified framework.

The maximum brake torques reach values that are a few times higher than those known from the passenger car industry. This implies application of more material - larger diameter of the friction ring, higher overall thickness of the disc and thicker hub. Exactly at these points a composite disk rotor could give effective answers. Special attention has to be paid to the connection area between hub and rotor - it has to withstand the extreme load cases determined by the extraordinary high total mass of the vehicle. Due to harder thermal conditions than in the passenger car industry, steel has been considered as the most appropriate material for the hub.

The plug-in concept of the brake disc comprises a scalable design applicable from small city cars up to heavy-duty commercial vehicles. It has already been tested on mid-class cars and received an approval for the spare part aftermarket. After scaling up, this concept appeared to be viable also for the hardest test and work conditions. An appropriate number of connecting points - called locking pins - and corresponding thickness of sheet metal applied in the hub lead to a robust form scalable for any kind of commercial vehicles.

Thanks to a unique cooperation between the members of different industries: sheet metal forming, casting and commercial vehicle manufacturing - a universal concept for heavy-duty applications can be presented. The first test provided reasonable results - the main values were same level or even better than those known from the discs mounted in today's series trucks.

The concept is going to be optimized regarding mass and performance in order to assure that all the legal and technical requirements are met.

Dr. Matthias Muller, Erdrich Umformtechnik GmbH; Mr. Kamil Zawalich, ERDRICH Umformtechnik GmbH; Mr. Ulrich Lorenz, ERDRICH Umformtechnik GmbH; Mr. Wilfried Strauß, Fritz Winter Eisengießerei GmbH & Co. KG; Mr. Tobias Müller, Fritz Winter Eisengießerei GmbH & Co. KG