Abstract
KEYWORDS - disc thickness variation (DTV), test bench, low load μ, brake torque variation, cold judder
ABSTRACT
Disc thickness variation (DTV) generated during off-brake phases due to non parallel brake discs and pads or manufacturing tolerances of the brake disc can lead to undesirable effects for example; brake force variation or judder in the brake system. Where many ECE friction materials with a higher disc wear are able to recover from DTV, usually NAO’s don’t possess this ability or not to a sufficiently high degree. Thus, it is crucial that DTV is not generated in the first place.
As long as residual drag reduced calipers or actively retracting calipers don’t represent the state of the art, DTV - especially in the NAO material development - it is and remains a reoccurring issue. Different friction material concepts and friction materials show a different degree of inclination towards producing DTV. To be able to predict and investigate the susceptibility of friction materials for DTV generation a simple and also very effective test procedure is proposed. On a special test rig, the Low Pressure Wear Tester, under different load cycles the DTV inclination of a friction material can be measured and assessed to predict DTV generation probability, to develop DTV optimized materials and to improve existing material formulations.