Abstract
This article presents methods for measuring noise-vibration of light truck gearbox designed and made in Vietnam in laboratory. Process of measuring values carried out on gearbox designed and made in Vietnam is the product of the subject the scientific research with the code of KC.05.DA02/06-10. The 4-channel, 3-channel measuring devices are used to measure acceleration in 3-dimension space (xyz) and one channel for noise measuring 10 Cm away from secondary shaft measuring point. This 4-channel noise-vibration measuring device has the relation between the acceleration measuring three channels and one noise measuring channel. Particularly, it is to survey the impact of changes in loads (Nm) by adjusting MP-100S load creating and measuring equipment in the modes of: 0%, 25%, 50%, 75%, 100% and the overload mode of 115% applying on the secondary shaft of the gearbox. The engine rotations are maintained fixed in the two modes of: adjusting step nE = 1400 rpm, adjusting step nE = 2800 rpm and only changes in gear from 1 to 5 at the two low and high levels. Measuring result shall indicate negative value as per time domain as treated by the DasyLab 7.0 software. With such result, if by observation, it is difficult to identify the noise-vibration value of the gearbox as expected from the beginning. Therefore, from the negative value as per time domain, we shall carry out FFT (Fast Fourier Transform), Octave, Envelope and RMS (Root Mean Square) analyses. Finally, using the Excel software to put out numeric table and diagram for identification, inference of gearbox noise-vibration result in accordance with the changes in load values.
Keywords: Gearbox, Load (Nm), Noise-Vibration, Analyzer FFT, RMS, Excel, Octave, Envelope