Antilock Systems for Air-Braked Vehicles

When a heavy vehicle driver (or in fact a driver of any vehicle) makes a brake application that is too "hard" for conditions - especially when the vehicle is lightly loaded or empty and/or the road is wet or slippery - he is likely to lock some or all of his wheels. Under these conditions, the tractor can jackknife or the trailer can swing out of its lane (if it is a combination-unit vehicle) or the truck can spin out (if it is a single-unit vehicle). Incorporation of an antilock brake system addresses the wheel lock and resultant control loss. Using a well-maintained air-brake system of current design as the baseline, this paper identifies the potential benefits that can be accrued from the use of antilock technology; traces the evolution of antilock braking technology from the rail and air industries to application to highway vehicles, including the effect that U.S. regulatory and/or legal actions had on this development; and describes the status of current technology in terms of the components, system performance, reliability, and test procedures for quantifying the performance enhancement provided by antilock.