Effect of Contact Geometry and Elastic Deformations on the Torque Characteristics of a Drum Brake

Abstract

Existing torque analyses of drum brakes, based on the assumption that the shoe and drum are rigid, fail to predict torques accurately, especially when the lining makes non-uniform contact with the drum. An analysis has been made therefore of a floating shoe brake in which the elastic deflections of the shoe and the drum have been included.

The analysis has been verified by measuring the torque developed by a standard two-leading shoe brake on an inertia dynamometer under different contact conditions. The agreement between the theoretical and observed torques was found to be better than ± 10 per cent even under extreme contact conditions and much better under more moderate conditions. Some consequences of the theory are discussed because of their practical importance.

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