In this paper, a digital computer model for studying the braking performance of an articulated vehicle equipped with anti-lock devices is presented. Using this computer model, the braking characteristics of a tractor-semitrailer fitted with a commercially available system (System A) is compared with that of the same vehicle equipped with a proposed system (system B). The deficiencies of system A are identified. The merits and disadvantages of system B are also examined. Based on the results of the simulation study, guiding principles for the development of the control logic of anti-lock brake systems are suggested.