4. Reducing noise of Shinkansen train disc brake application

Research was carried out into the reasons for and origins of braking noise (squealing) emitted from Shinkansen trains as they stop with a view to finding measures to reduce this phenomenon.

From analysis of the break assembly vibration mode, it was found that squealing occurred because of the divergence in self-induced vibrations emitted from very small frictional displacements on the braking surface.

A special measuring system was then developed to gain insight into the high frequency vibrations of discs rotating at high speed. This system was then integrated to a test bench and quantitative evaluations were made of the squealing (Fig.1).

Following on from this, a brake assembly was set up with low hardness disc, at low speed and low pressing force using a brake pad with a coefficient of friction of over 0.6, and it was found that the increasing divergence due to increasing coupling effect of pad and disc vibrations produced the squealing noise.

Based on these findings a series of fundamental countermeasures were made such as increasing the hardness of discs being fitted.