Suppliers scramble to cut vehicle stopping distances

A demand from automakers and consumers for safer vehicles is driving brake system engineers harder these days.

Brake suppliers such as Continental AG, TRW Inc., Robert Bosch GmbH and Delphi Automotive Systems Corp. are reducing vehicle stopping distances by treating the brakes, tires and suspension as a single design package.

'It's part of the whole `Safety sells' atmosphere of the last few years,' explains Philip Headley, chief engineer for Continental's Continental Teves Inc. unit.

DEVELOPING STANDARDS

Two factors are leading the push. In the United States, the National Highway Traffic Safety Administration is developing standards to measure stopping distance as part of its expanded new-car assessment program.

And in Europe, the popular German enthusiast magazine Auto Motor Und Sport has raised interest by regularly publishing comparative tests of stopping distances.

The advantages are clear. German safety researcher TUV Rheinland reports that reducing stopping distances by 20 percent would cut traffic deaths and serious injuries by 15 percent.

This trend presents an opportunity for Continental. The German supplier has developed the 30-meter car, a specially equipped VW Golf that can decelerate from 100 kilometers per hour to a stop within 30 meters. A conventional Golf requires 38 meters to stop. The vehicle showcases electrohydraulic brakes, high-friction tires and electronic suspension components.

Together, systems could reduce stopping distance as much as 25 percent. Not all of Continental's systems are ready for production. But the company says it can introduce these devices gradually over the next few years.

Continental unveiled its 30-meter project last winter, and automakers are responding. 'We are seeing interest coming from many areas,' says Wolfgang Ziebart, CEO of Continental's automotive systems business.

Good candidates

European sports cars would be good candidates for such a system, Ziebart says. In the United States, the brakes might prove useful on sport-utilities.

Elements of the prototype system will be featured next year on the next-generation Ford Expedition and Lincoln Navigator. Continental will supply rear corner modules, front brake components, air springs and tires.

Meanwhile, Bosch is supplying electrohydraulic brakes for the 2002 Mercedes SL roadster.

Delphi demonstrated advanced brakes on the EV1 electric car. And TRW will launch its electrohydraulic brakes on two 2003 model vehicles, says Phil Cunningham, product business director for chassis systems.

TRW also is tweaking suspension systems to improve weight distribution between a vehicle's front and rear axles. TRW has demonstrated up to 20 percent reductions in stopping distance on loose gravel or packed snow, Cunningham says.

Unlike Continental, Cunningham downplays the need for in-house tire design. 'There are incremental improvements we can make by linking existing systems, without any radical changes to tire technology,' Cunningham says.

better tires

But Headley of Continental says it is not possible to deliver big improvements unless brake suppliers integrate the tire into the complete brake system from the beginning.

For instance, an upgraded suspension can keep tires on the road during braking. And sensors in the sidewalls of tires can send data on tire friction to the antilock brake computer. In turn, the computer can calculate the maximum possible braking force for each wheel.

'Competitors have been working with the tire companies for years, but they haven't been able to pull together a program that actually does tie in the whole system,' he says.

'The auto companies buy the tires. They may be able to work with the tire company, but they don't really get that close to the tire people.'

Not all of Continental's innovations are ready, Headley says. One major goal: Improve tire durability. Eventually, the 30-meter car could be a precursor to a fully electronic chassis, Headley says.

'If we can use our expertise in tires, brakes and suspension on the same car to improve stopping distance, how much could we do to optimize the entire chassis system?'

E-mail writer Amy Wilson at awilson@crain.com

You can reach Amy Wilson at awilson@crain.com

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