A new brake system is in the works - one that promises to completely change the nature and feel of truck braking.
The components involved are electronic controlled braking systems (ECBS) and air disc brakes. Combined, they may bring the curtain down on the S-cam brake in the North American truck market.
During a one-day session arranged by The Maintenance Council of the American Trucking Assns. last month, leading proponents of ECBS and air disc brake technology talked about the advantages, and limitations, of this approach.
Dick Radlinski, a former engineer for the National Highway Traffic Safety Administration and president of consulting firm Radlinski & Assoc., explained that the primary advantage of ECBS is faster brake actuation. "With ECBS, electronic controls replace pneumatic or air controls," he said. "That's critical because pneumatic signals travel at the speed of sound, while electronic signals travel at the speed of light."
However, truckers won't experience significantly faster brake times unless ECBS and air disc brakes are used on both the tractor and trailer.
Meritor WABCO illustrated this by publishing the results of stopping distance tests it conducted. At 60 mph, fully loaded, a tractor-trailer equipped with all-drum brakes needed 330 ft. to stop completely. With air disc brakes on just the tractor, the vehicle stopped in 234 ft.
However, with ECBS and air disc brakes on both tractor and trailer, the vehicle stopped in 189 ft., a shorter distance than the average passenger car, which requires 194 ft. to stop.
There are potential economic advantages to ECBS as well, according to Radlinski. Electronic control would allow the brakes to conduct self-diagnostics, making maintenance easier. Electronic controls may also balance the brakes better, allowing for more even wear and longer brake life.
ECBS could also help truck drivers get a better "feel" for the brake pedal, so there would be no need to use the brakes differently when pulling loaded and unloaded trailers, Radlinski said.
However, he pointed out that there is a downside. Adding ECBS may mean more complex technical work for the mechanic, and the combination of air discs and ECBS weighs more than S-cam brakes.
