NHTSA\u2019s Heavy Duty Vehicle Brake Research Program Report Number 11: Evaluation of Stopping Performance of Trailer Antilock Brake Systems

007445121997PDFResearch PaperDOT HS 808 568TrailersTrucksAntilock brake systemsStopping distancesPneumatic equipmentBraking performanceABSheavy duty vehicle brakesstopping performancetrailer antilock brakesUnited StatesUnited States. Department of Transportation. National Highway Traffic Safety AdministrationFlick, Mark A.NTL-FREIGHT-Trucking IndustryUS Transportation CollectionIn order to better understand the functioning of antilock brake systems on pneumatically braked trailers, a series of tests were conducted to evaluate different ABS control strategies, performance variations among systems supplied by different manufacturers, and the operation of ABS on double and triple trailer combinations. The testing showed that there was relatively little difference in the stopping capability of the vehicle with the various control strategies and with the various manufacturers' systems. The only exception to this was in the case of a split coefficient surface of a maneuver where there was significant weight transfer from one side of the vehicle to the other. In these two situations, the systems which use axle control strategies had longer stopping distances than those using individual wheel or side-by-side control. These results held true for the doubles and triples combinations as well. Additionally, it was found that the stopping capability of doubles and triples combinations was particularly enhanced with ABS on the trailers and dollies compared to having ABS on just the tractor in the case of mixed loads, where some of the trailers in the combination are loaded and some are not.83