Abstract
KEYWORDS:
driving axle, sound power, test bench, spectrum, pass-by noise.
ABSTRACT:
Reducing the pass-by noise of the ROMAN vehicles is imposed by the international regulations in force, namely the UN/ECE 51 Regulation, Amendment 02, which states that, in order to be certified, the exterior noise of the vehicles powered by engines rated more than 150 kW should be less than 80 dB(A).
This study presents the results obtained for the vehicle type AB 19.410 FLS, equipped with MAN 410 HP EURO 3 engine. As a consequence of the results obtained, the vehicle was certified by the Romanian Automotive Register (RAR) in December 2003.
The noise reduction measures have been firstly applied to the most intense individual noise sources, to those presenting the highest noise level, respectively. Thus, knowing the contribution of the various individual noise sources to the vehicle global noise was decisive for the application of efficient measures for reducing the vehicle noise.
The preliminary exterior noise level measurements led to the conclusion that the driving axle represents one of the most important noise sources. As a consequence, the sound power level of the PS13S driving axle, which equips the vehicle, was measured on the test bench. In order to decide on a more silenced driving axle, the central reduction gear and the final transmission have been changed and the results have been compared in terms of sound power values and spectra.