Calculation of Deceleration Rates for S-Cam Air-Braked Heavy Trucks Equipped with Anti-Lock Brake Systems 2007-01-0714

Evaluating the deceleration rate of air-braked heavy trucks based on brake components and their adjustment has been well documented for vehicles not equipped with anti-lock brake systems (ABS). Though there are many non-ABS trucks still on the road, ABS is becoming more common, having been required by NHTSA on all heavy trucks manufactured since March 1998. It has been found that the stopping-capabilities of ABS-equipped trucks are often not well modeled by the traditional Heusser technique. This paper will present an expansion of that method to accommodate ABS-equipped trucks, a means of characterizing air brake chambers to obviate the need for lookup tables, and discuss some sources of uncertainty in the analysis. A comparison of predicted stopping characteristics to test results for one truck is presented.