Comparative study of transient forces as a source of structure-borne noise on two and four-wheeler drum brakes

Drum brakes, being economical, are commonly used as rear brakes in both two-wheelers and four-wheelers. However, the transient forces developed in the drum brake during braking contribute to the vibration and hence the structure-borne noise in vehicles. The dynamic performance of an automotive drum brake during braking depends on several parameters such as initial conditions, braking force, contact parameters, etc., which are typically different for a two-wheeler as compared to a four-wheeler. This paper attempts to analytically estimate the effect of these parameters on the transient forces and hence the noise due to drum brake in two- and four-wheelers. The adopted methodology involves the development of a four degrees-of-freedom discrete system model of the drum brake with conformal contact to obtain the system response. The forces are then calculated by dynamic balancing and kinematic relationships. The different cases are simulated by modifying the corresponding parameters in the model. The effect of each parameter is systematically studied using the time and frequency domain results. The impact of variation in these parameters in two-wheelers was found to be qualitatively and quantitatively different from that of four-wheelers. It is expected that the dynamic analyses presented in this work will be helpful in the design of quieter drum brakes.