An Investigation of the Pad/Disc Dynamic Centre of Pressure using a 12 Piston Opposed Caliper

Pressure sensitive film embedded into the body of a pad friction compound is a unique technique used to measure the dynamic centre of pressure at the pad/disc interface during a normal braking operation. This paper uses of a modified 12 piston opposed caliper where the initial centre of pressure may be varied both along the pad and radially. Results show a very definite movement of the centre of pressure towards the centre of the pad as the brake pressure is increased. In addition it is seen that a leading centre of pressure (CoP) will result in noise whereas a trailing CoP gives a quiet brake. Equally a CoP towards the inner edge of the pad increases noise propensity whereas towards the outer edge a quiet brake. The results also show little influence on the CoP with disc speed.