Wheel Squeal Noise in Rail Transport: The Effect of Friction Modifier Composition

This study aimed tofind an appropriate content of water-based friction modifier that will be able to reduce squeal noise without a significant impact on the coefficient of adhesion. A twin-disc machine was used, and the angle of attack of 4° simulates sharp curve conditions. The frictional behavior of nine water-based compositions was investigated for dry and wet films. During these experiments, the sound pressure level and the coefficient of adhesion were monitored. The results showed that the presence of solid lubricant in the composition is needed to achieve a long retentivity; however, its higher content can cause low adhesion. The composition with lower solid lubricant content and particles for friction modification with lower Mohs hardness was found to be suitable for further experiments. Moreover, comparison of recorded signals revealed that there is a bilinear dependence between the coefficient of adhesion and the sound pressure level.