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Currently, in the brake system of operated cars, there is a problem of lack of brake pressure on the wheel, which is necessary for the movement of the train at a set speed in accordance with the regulatory documentation. This is due to the tendency to increase the mass of trains and the maximum load of cars with a constant tare weight, which requires an extended range of pressure control in the brake cylinder by an air distributor or auto mode, depending on the load of the car. To solve this problem, calculations were made of the braking coefficient of cars equipped with air distributors № 483, which showed that the freight car was not equipped with brakes to run as part of a train at a set speed. In the course of engineering studies, it turned out that increasing the spring rate of loaded and medium modes can increase the adjusting range of the air distributor and partially solve the problem of lack of brake pressure. Thus, it is proposed to recalculate the stiffness of the adjusting spring. Calculations of the rigidity of regular and proposed springs were made. The braking coefficient has been recalculated, taking into account the increased spring constant. As a result, this coefficient has increased, which makes it possible to remove speed limits. The proposed method for upgrading the air distributor can be carried out on all types of repairs, which facilitates the implementation process.

The article considers the issue of providing protection for the contact network when removing 3.3 kV traction substations from the Nazivoye direction of the Omsk power supply distance of the West Siberian Railway. When the 3.3 kV switchgear is brought out to repair, the protection zone for connection of the contact network of adjacent traction power supply system objects (traction substations, sectionalizing stations, parallel connection points) increases. To ensure the protection of the DC contact network, lowered settings for the operation of high-speed circuit breakers are introduced, which inevitably limit the capacity of the section for the passage of freight trains. Considered the existing order of withdrawal of equipment for repair with the inclusion of a traction substation post section. The limitations of skipping freight trains during the implementation of the existing scheme are estimated. Short circuit currents are also calculated and the settings for the protection of high-speed circuit breakers are selected when the sectioning station is switched off and the sectional disconnectors of the station are switched on. It was found that the condition for selecting the protection settings is not fulfilled when detaching from the minimum value of the short-circuit current. To reduce the limitations, a prototype of a short-circuit contactor of a direct current 3.3 kV grid has been developed. The use of a short-circuit-breaker allowed the protection of the contact network, for the time of the withdrawal of the switchgear equipment for repair, without transferring to lower settings for the operation of circuit breakers. Also in the article are given the technical characteristics and features of the proposed device design. The results of a test of a short-circuit of a 3.3 kV direct current contact network in the Dragunskaya-Novokievskaya-Lubinskaya section are presented. The main directions for further work are determined.