A STUDY ON THE SQUEAL OF A DRUM BRAKE WHICH HAS SHOES OF NON-UNIFORM CROSS-SECTION

A stability analysis of a drum brake, which has shoes of non-uniform cross-section, is performed to find a simple and effective method of reducing the squeal of the drum brake by partially changing the shapes of the shoes. The squeal is considered as a noise induced by the self-excited vibration of the drum brake which makes the brake unstable. Shoes of non-uniform cross-section are often used for the drum brake of current passenger cars to reduce the squeal. However, the influence of this non-uniformity upon the squeal has not been analyzed theoretically. In this study, the drum and the shoes are assumed as a uniform ring and non-uniform arches, respectively, for modelling the brake. For a reasonable method of modelling, the vibration characteristics of the brake and their relations to the squeal are discussed based on the results of modal tests. The influences of brake design parameters upon the squeal are investigated, and a minor change of the cross-section is proposed to reduce the squeal. The effect of the minor change is verified through noise dynamometer tests. In addition, the effect of asymmetry of the drum, which can be built by mass addition, is presented.