Tech Briefs
Advanced stopping systems

Meritor WABCO Electronic Braking System (EBS) electronic control unit and modulator. Volvo's drop test rig. Volvo's dynamic test system used to simulate a pedestrian impact. A side-impact crash test. An offset crash test. Meritor SteelLite X30 brake drum and DaytonLite hub.

Technology can make it possible to stop (heavy) trucks more like cars," said Walter Frankiewicz, Vice President and General Manager, Worldwide Braking Systems for Meritor Automotive Heavy Vehicle Systems, during a technology and product overview at the company's Troy, MI, world headquarters. Meritor's Electronic Braking System (EBS) is a next-generation braking system for commercial trucks that the company says could significantly shorten tractor-trailer stopping distances.

"EBS will help resolve the tractor-trailer compatibility issue (of a disc-brake tractor and drum-braked trailer)," said Paul Johnston, Director of Engineering, Brake Products Engineering Worldwide Truck & Trailer Systems for Meritor Automotive. "It also will provide the ability to predict when the brakes need to be serviced, in effect going from diagnostics to prognostics by taking onboard diagnostics to the next level."

More than 200,000 EBS production applications exist today, mostly in Europe. "This is not a brand new technology," said Dennis Sandberg, Director of Electronic Products for Meritor WABCO Vehicle Control Systems. "Once EBS gets simpler and less expensive, it will evolve into the system of choice vs. pneumatic systems. But today, pneumatic (components) are a full back-up to EBS. It's fully 100% redundant." He also noted that Freightliner's Century Class offers EBS as a factory-installed option.

Meritor officials predict stopping systems eventually will channel to a multiplexed, all-electronic system. A fully orchestrated smart stopping system would essentially determine when to downshift a gear, modulate the engine or driveline retarder, reduce engine rpm, and apply foundation brakes.

"We are absolutely convinced through our own tests that we can significantly reduce tractor-trailer stopping distances through the combination of EBS technologies and drum and disc brakes vs. traditional drum brake and pneumatic logic controlled vehicles," said Dennis Kline, Vice President North American Sales for Meritor Heavy Vehicle Systems.

Meritor executives discussed other stopping technologies such as a new lightweight ductile iron drum brake hub, DaytonLite. It has 20% less mass than standard ductile iron hubs and is 50% stronger than aluminum hubs. Also discussed was a new concept in brake linings and pads referred to as a friction-coupling concept, which is a research project aimed at developing friction-pair materials that transfer energy with minimal wear of the two mating materials; and caliper part reduction.

"One of the issues with disc brakes today is the complexity of the caliper, which has a mass of about 18 kg (40 lb) and consists of some 100 mechanical components. Our goal is to reduce that number of components to only 12 or 15 and at the same time trim the size and weight of the caliper by as much as two-thirds," said Johnston.

According to Prakash Mulchandani, President of Meritor's Heavy Vehicle Systems, stopping-component sales content per vehicle are forecast to increase about 30%, while total sales revenues are expected to increase about 40% in North America by 2005.

Kami Buchholz