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The paper considers a drum brake mounted on a ½ vehicle test rig including suspension, cross beam and transmission differential. It is a continuation of earlier work (1) and so reviews the characteristics of a drum brake when generating noise on a ¼ vehicle test rig and compares them to those found on the ½ vehicle rig. Frequencies of 960, 850, 1400 and 4600Hz are examined in some detail using the technique of holographic interferometry. It is seen that the modes of vibration of the component parts vary notably over the frequency range considered. This observation allows the significance of each part to be evaluated for each frequency range. With the accumulated information it was possible to predict other possible unstable frequencies and although these were not observed within this series of test the predicted instability frequencies have been observed on earlier work.

This paper discusses the analysis and measurement of the dynamic centre of pressure of a brake pad during a normal braking event. The technique is unique in its design and implementation. The process is progressive whereby the interface static measurements are first taken and then dynamic testing is carried out under braking. Two different measurement systems are considered during the analysis with one used to measure the center of pressure. Both the in-board and out-board pads are measured for wear but the piston pad was selected for pressure measurements. Validation of the spragging process is undertaken on both test rigs and vehicle trials. Pad wear measurements complement the collective information. The results show the position of the centre of pressure to vary considerably during a braking event, both radially and axially along the pad.