Comparative analysis of pin-on-disc and inertia-dynamometer sliding tests on a friction material

The development of modern brake systems requires the assessment of multiple aspects. Among these, parameters related to the tribological behaviour, vibration, and particulate matter emission are typically evaluated using inertia dynamometers and tribometers. While these two testing systems have been previously compared regarding emissions and tribological behaviours, vibrations were not compared, nor have all these aspects been examined simultaneously. This study investigates the scale effects between a pin-on-disc tribometer and a reduced-scale dynamometer operating under dragging conditions with two levels of pressure and velocity, and a disc temperature not exceeding 260 °C. Regarding the vibration, the pin-on-disc exhibited higher and broader values in the normal direction, 1.3–15.5 m/s2, than the reduced-scale dynamometer, 0.37–0.42 m/s2, while the tangential vibrations exceeded those in the normal direction in both systems. The wear rates in the two systems were overall similar, in the range of 1–4 e−14 m2/N. During the tests the disc temperature in the dynamometer increased at a higher rate compared to the pin-on-disc, affecting the tribological and emission behaviours: steady state values were obtained only in the pin-on-disc tests. The particulate concentration values observed during dynamometer tests better correlated with the peak values from pin-on-disc tests rather than with the steady-state values. This study highlights the importance of including transient values in the evaluation of pin-on-disc testing.