Statistical Analysis of the Variability of the Braking Efficiency of New, Original Equipment Brake Sets Installed in the Same Vehicle

摘要

The report evaluates statistically the variability of braking efficiency obtained with new, original equipment brake sets, installed successively in the same vehicle. The analysis separates the components of braking efficiency variability caused by: (1) production variability among brake sets; and (2) measuring errors. The data were obtained using three different methods: torque wheels, a low speed roller dynamometer, and 'Road Transducer Plates' (RTP). The most accurate results were provided by the torque wheel measurements conducted simultaneously on the four wheels. With this type of measurements the variability of braking efficiency was due more to brake set differences than to measuring errors. Conversely, with the low speed roller dynamometer, and with the RTP method, braking efficiency variability was due more to measuring errors than to brake set differences. Because the measuring errors were randomly distributed, the braking efficiency means yielded by the three measuring methods were not statistically different. However, due to the larger measuring errors of the low speed roller dynamometer and the RTP methods, the 95% confidence limits of the individual braking efficiencies for these methods were wider than for the torque wheel method.