The paper gives the results of mathematical modeling of movement of a loaded wagon with elastic suspension under viscous friction force equivalent to the dry friction force. Parameters of vertical relative forced vibrations have been found, which are stipulated by the wave of road irregularity.

To ensure effective aeration of the biological wastewater treatment process, easy-to-operate and not too energy-intensive units are needed. Jet aerators have such capabilities. In this study, the authors searched for the best hole shape for the aeration nozzles. It was determined that a nozzle with an elongated hole has the largest size of the actively aerated zone. Experimental studies of nozzles of a diameter of 56 mm with nozzles of elongated shape showed that the best characteristics of mass transfer are provided by nozzles with a total area of holes of 356 mm2 at a flow rate of 10 … 12 m/s. For practical calculations, an equation was obtained for the dependence of the oxygen transfer coefficient KLa(20) on the complex criterion vn, and a method for calculating aeration units was developed, which is applicable for aerators with elongated holes.

No abstract

This article explores issues related to the friction of the brake pads of a freight car. The coefficients of friction of composite and cast-iron pads of a new type, calculated for a range of different speeds, and the specific braking force during emergency braking are given. A sectional brake block for a freight car and a locomotive has been developed. The advantages of sectional brake pads have been scientifically substantiated. The obtained calculations allow us to recommend them for further study and implementation in operation on the railways.

Transportation of perishable goods is a special type of transportation that has great social significance and has an impact on the health of the population. The correct choice of transportation technology and vehicle ensures the preservation of the quality of the transported perishable cargo due to compliance with the required temperature conditions, which in turn ensures compliance with food safety requirements. This article is devoted to the development of scientifically sound recommendations for the selection of new cooling systems for perishable goods by rail and technology parameters, including requirements for specialized vehicles, compliance with which will provide conditions for maintaining the quality of cargo throughout the entire transportation. The subject of research is to ensure the possibility of changing the composition of the gas environment of vehicles for the transportation of perishable goods due to re-equipment. The aim of the work is to develop the principles of technology for autonomous transportation of perishable foodstuffs, namely, ensuring high thermal parameters of vehicle enclosing structures; autonomous operation of installations during PG transportation with the simplest and most reliable implementation; achieving maximum efficiency of the equipment used in terms of generating thermal energy or energy spent on cooling when using non-energy-intensive methods organization of mass exchange of air inside the cargo area. Through analysis and theoretical studies, the possibility of joint operation of the gasifier and the heater was confirmed, the single-line nitrogen supply scheme was adjusted. Due to the use of modern methods and devices for cooling (heating), a reduction in costs for the transportation of products is guaranteed. The result of the work is confirmation of the possibility of joint operation of the gasifier and the heater under real conditions of transportation of fruit and vegetable products by rail.