Performance Comparison between ABS 4S/4M and ABS 4S/3M

After the anti-skid brake system (ABS) introduction, mandatory for all vehicles in the Brazilian market, manufacturers have given increasing attention to optimized systems which meet legal and safety requirements. For commercial vehicles, an alternative for the ABS, which presents feasibility, is the configuration 4S/3M (4 wheel-speed sensors and 3 modulator valves) in substitution to the configuration 4S/4M. In other words, application of just one modulator valve to control the brakes of the same axle, front or rear, instead of independent control per each brake of the vehicle. The aim of this paper is to present a performance comparison between a brake system fitted with ABS configuration 4S/3M and an ABS configuration 4S/4M. To this end, both configurations were tested on the same vehicle application in accordance with the Brazilian legislation, CONTRAN 519/15. In addition, a test on which the vehicle was prepared with an unusual load distribution was performed in order to verify if the proposed system would be capable to keep its performance. A discussion regarding feasibility of ABS 4S/3M on 6x2 or 6x4 trucks is also presented.