Measurement of Interlace Temperatures During Braking

This paper describes analytical and experimental attempts to determine the temperatures at the interface between the brake lining and brake drum of a transit coach bus during braking. A simple transient heat flow analysis was conducted assuming the drum to be a semi-infinite solid. A time-dependent heat input was used to simulate frictional heat generation during braking. Using this model, an interface temperature rise of 42 F was predicted for a loaded bus braking from 24 mph in 8 seconds.

Measurements of the temperature distribution in a bus brake drum during passenger service were made to confirm the analytical results. Three thermocouples were placed at three radial positions in the drum thickness and the interface temperature was extrapolated from the data using an error function curve fit routine.

Under conditions similar to those used in the analytical model, the interface temperature was found to increase approximately 36 F during braking. This correlated fairly well with the estimates provided by the model.