Effect of pin finite width on instability of pin-on-disc systems

Many previous theoretical studies of the vibration properties of the pin-on-disc rigs used to study the phenomena encountered in disc brake dynamics, e.g. Earles and Hamabe, have shown that the instability phenomenon of brake squeal occurs only when the pin is in digging-in positions. However, experiments have indicated that squeal can also be generated when the pin is in a leaning position as well as in a digging-in position. In this paper, the discrepancy between earlier theoretical predictions and measurements has now been shown to be due to the effect of the finite width of the pin and a suitably revised mathematical model is presented showing a much better correlation with test data.