An instrument for measuring the vibration of vehicle brake pads (squeal)

The friction material is only one of many factors which determine how badly a vehicle brake squeals, if at all. An instrument has been built for use on a brake-testing dynamometer to measure the potential squeal of a material. It measures the vibration of the brake pad and conditions the signal in accordance with the frequency response of the human ear. Three outputs are available: (1) analogue of loudness; (2) digital measure of the time integral of loudness in each brake application; (3) digital measure of the time integral of loudness from the start of the test.