Brake testing: what faults can be found? An investigation of the ability of various brake testing methods to detect mechanical or hydraulic brake faults on light vehicles

Brakes can be considered the most important safety feature on a vehicle and must be maintained to ensure optimal performance. Brake testing machines provide a rapid method of investigating the performance of a vehicle’s brakes and assessing whether they meet roadworthiness criteria. However, it is important for vehicle owners and roads authorities to understand the differences between brake testing methods, their advantages, their limitations, and to have confidence in the results they provide. This study presents an investigation of the ability of four brake testing methods to detect mechanical or hydraulic faults on light vehicles. A test vehicle, representative of a common passenger vehicle, was professionally fitted with equipment to enable the control and measurement of the brake pressure applied to individual wheels. A brake pedal robot that could supply a repeatable and consistent brake application force was also installed. Data was collected during a series of tests performed over two days at a private airstrip. In each test, a brake fault condition in the test vehicle was simulated by reducing the maximum brake pressures at individual wheels. The vehicle was then tested three times with a plate brake tester, a roller brake tester, a portable decelerometer, and during a high-speed stopping distance test (from 80 km/h).