Scientific paper ID 1946 : 2020/3

The report presents a project for Renovation and modernization of a stand for brake systems of freight cars, which is implemented in the laboratory ”Brake systems of transport equipment”. The laboratory provides a compressed air supply system from an air compressor, purchased under the project ”Laboratory equipment for testing brake systems and braking processes in high-speed rolling stock and subway”, funded by the research project program from the budget of VTU ”Todor Kableshkov “For 2019. The stand has been restored to the level of a working facility, equipped with modern recording and recording equipment, with which both laboratory exercises can be performed, and specific practical problems can be solved. Pneumatic sensors are placed in specific places in the stand, which measure the air pressure in the respective space or apparatus, converting the air pressure into an electrical signal. At the places where the mechanical force for actuation of the lever braking system is realized, strain gauges are placed, which measure the force of pressure of the pads on the wheels. The listed elements send the signals to an analog-to-digital converter (ADC), which converts the signals and sends them to a computer. Along with the above elements, electropneumatic valves are connected to the ADC, the purpose of which is to open and close nozzles of a certain diameter and thus to simulate air leaks from pneumatic devices of different intensity. All data digitized by the ADC is submitted to a computer, which with appropriate software processes them, illustrates them in the form of graphs and records. The data obtained can be applied in various documents.