Bendix Commercial Vehicle Systems will introduce an air disc brake for the North American market in the fourth quarter of 2002.
The new system known as the ADB 225 is a major change from air disc brakes already in use in Europe, weighing 30 pounds less per wheel than its European counterpart. The weight reduction comes from eliminating component mass associated with compounding, a European brake standard that mandates separate systems to apply the service brakes and the emergency brake. Compounding is not required in North America, allowing Bendix to reduce total system weight.
Air disc brakes have improved dramatically from earlier versions where weight, cost, and system balance issues made them less than attractive to fleets, says Ron Bailey, Bendix technical sales manager. Most important, however, is improved performance. Compared to conventional S-cam drum brakes, air disc brakes offer a 26% shorter stopping distance and exceed the federal standards for stopping a 10-wheel tractor by 39%, he says.
Tests of the air disc brake system were performed in October 2001 on a stretch of I-70 just below the Eisenhower Tunnel west of Denver. The test course used eight miles of 7% downgrade. In tests of brake fade during prolonged used, the disc brakes required only 4% additional air pressure to maintain braking performance as brake temperature rose compared to 25% more pressure required for drum brakes.
The ADB 225 system is designed for use with 22.5-inch wheels. It is compatible for use in combinations with drum brakes and works with ABS.
At present, Bendix air disc brakes are manufactured in Europe through a relationship with Knorr-Bremese, parent company of Bendix. The company is investigating options for manufacturing the systems in North America.