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Comparative bench tests of acoustic emission occurring during the interaction of the brake pad with a brake disc for the brake unit with a stationary brake pad and a brake unit with a floating brake pad are carried out. The floating brake pad, depending on the braking conditions, occupies an optimum position on the surface of the brake disc, while making movements of an oscillating nature around the turning axis that does not pass through its center of mass and parallel to the axis of rotation of the brake disc. The frequency range is determined in which there are noticeable differences in the acoustic emission of a brake unit with a floating brake pad and a stationary brake pad. The theory of fuzzy sets is used to analyze the acoustic emission perceived by the human hearing organs, which accompanies the interaction of the surfaces of a friction pair in the investigated frequency region. The results of a comparative analysis of the noise characteristics of the brake blocks under investigation are discussed. The spectra of the acoustic emission power are compared according to the obtained base of the expert evaluation of the noise power perceived by man.

To increase the speed of the cargo delivery, freight wagons are being developed, intended for the design speed of 140 km/h. One of the important parts of a freight wagon is the bogie, the design of which determines the wagon dynamic behaviour. The bogie of such wagons uses a frame of a rigid design, which is susceptible to antisymmetric loads. The analysis of standards has shown that the strength test during designing a rigid bogie frame under the impact of maximum antisymmetric forces that may occur in operation when a wheel derails is not required, which can lead to a residual antysymmetric deformation of the bogie frame. Theoretical research is performed to estimate the impact of the residual antisymmetric deformation on traffic safety using the wheelset safety factor against derailment. The research results have shown that the bogie frame residual deformation leads to a load redistribution on the wheelset axle journal, which, in terms of the impact on the wheelset safety factor against derailment, is similar to the wagon rolling motion. The wagon rolling motion affects the reduction of the wheelset safety factor against derailment to a greater extent than oscillations during pitching and bouncing. Thus, the permission to operate wagons with the antisymmetric residual deformation of the bogie frame without its non-destructive testing can lead to traffic safety violation. In order to ensure the traffic safety of wagons with bogies having rigid frames and reduce economic losses at the design stage, bogies strength depending on the action of antisymmetric forces should be estimated.