Estudo da influência do levantamento de eixos em veículos comerciais no desempenho na frenagem e na estabilidade direcional / Study of commercial vehicles elevated axle influence on braking performance and on directional stability

AUTOR(ES)

Eduardo Piquera Vianna

DATA DE PUBLICAÇÃO

2006

RESUMO

The systems that elevate the axles of the commercial vehicles were initially developed with the objective of saving tires. The use of these systems was restricted, not causing a notable statistical effect in the vehicle safety. Due to an agreement between road concessionaires and the government, the commercial vehicles pay toll value according to the number of axles in contact with the soil on that moment, minimizing the taxes of the vehicles using this system. This practice was diffused quickly and few technical studies were accomplished focusing its influence in the vehicle safety. The elevated axles alters in a significant way the vehicle static margin of stability and the ideal distribution of the braking forces, increasing the accident risks. This work consist in deepened studies of the commercial vehicles with these systems of elevation of axles, of the technical and operational point of view, focusing the vehicle safety. For this is used as methodology mathematical models developed already in the scientific literature in vehicles examples. Parameters as the margin of stability, steer gradient, braking efficiency and others are analyzed. Likewise, the effects in the directional response during the transient maneuvers and in the initial instants of the braking. The influences of the elevation of the axes are analyzed according to norms and established requirements for ABNT and ECE R13, including annex 10, because the practice of the elevation of the axes can be infringing requirements imposed by these norms. As main conclusion these systems are prejudicial to vehicle dynamics and handling and its use could be anticipated in conceptual and design phase and in brazilian transport laws.

ASSUNTO(S)

estabilidade direcional directional stability desempenho na frenagem braking performance veículos comerciais commercial vehicles sistema de levantamento de eixos system of rising of axes

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