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

This paper evaluates statistically the variability of braking efficiency obtained with new, original equipment(OE) 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 (due to differences in materials, machining, and assembling); and 2) measuring errors (pertaining to the braking measurement methods and measuring personnel).

The data were obtained using three different methods: torque wheels, a low speed roller dynamometer, and “Road Transducer Plates” (RTP). The data were taken after burnishing each new brake set according to the Federal Motor Vehicle Safety Standard No. 105.

The most accurate results were provided by the torque wheel measurements conducted simultaneously on the four wheels. With this type of measurement, the variability of braking efficiency was due more to brake set differences than to measuring errors. The converse occurred for the low speed roller dynamometer and the RTP methods.