Rationing the size of the irreducible reserve of locomotives at the turnover stations

Based on the model developed by the specialists of JSC “VNIIZhT” for determining the rational dimensions of the irreducible reserve of locomotives at the turnover stations (Мнр), mass calculations were performed to determine the size of the reserve depending on the influencing factors. The value of Мнр substantially depends not only on the size of the motion, but also on a number of other factors that are taken into account in this model. Using the model, it is possible to carry out calculations to establish the influence of various factors on the value of Мнр. The first question of this study is the analysis of the dependence of the magnitude of Мнр on various factors (multivariate analysis), determination of its significance and ranking of factors. The second question is the determination of the numerical values of Мнр in the form of practical recommendations for its use in determining the size of the minimum reserve of locomotives at the turnover stations, taking into account the various effects of the factors under consideration: average daily train flows and its fluctuations per day, oddness of operating trains, planning quality (deviation of planned train flows from actual), the level of fulfillment of the tasks of the plan for sending locomotives by a single follow-up at the turnover station.

In total, 1575 variants of the work of locomotive turnover stations were calculated, in each of which the sizes of the irreducible reserve of locomotives are determined by the results of work for 400 days. The total data set amounted to 630 thousand results. As the result, the significance of the factors is established, its ranking is made. Based on the results of modeling, a table of standard values of the irreducible reserve of locomotives at the turnover stations was developed, which can be used by the employees of the JSC “Russian Railways” for practical purposes. This will improve the quality of execution of the train schedule and reduce unproductive downtime of trains ready for departure at locomotive turnover stations.

The impact of deformation in the zone of welded joints on the force action of the rolling stock on the track

The causes of deformation in the zone of welded joints are considered. Authors experimentally studied changes in hardness on the rolling surface of the rail in the longitudinal and transverse profiles within the thermally affected zone of the welded joint. It is established that the hardness of the rolling surface of the rail in the longitudinal direction in the thermally affected zone of the joint is uneven and is determined by the structures arising from the effects of the thermal cycles of welding and the quality of the local heat treatment. In this case, two “low spots” are clearly traced with a decrease in hardness to 290 ... 300 HB and with a higher hardness up to 350 HB right in the welded joint. Experimentally investigated the change in the depth of the welded joint from the implemented tonnage. At the same time with strain gauge method, using the force method developed by N. N. Kudryavtsev, continuous changes in vertical forces when the wheels move along the welded joint zone were recorded. Average values of vertical forces from loaded cars were established. Experimental distributions of vertical forces were approximated by theoretical laws according to the Kolmogorov — Smirnov matching criterion. Recommendations are given on minimizing the harmful impact of rolling stock on the track in areas of lowering welded joints. The following conclusions were made.

1. Geometry of the joint irregularity is in the form of a W-shaped deformation with an influx of metal on the receiving rail and lowering on the directing rail. The width of the upper part of the deformation varies between 160 ... 200 mm along the axis of the rail.

2. Deformation zone of the welded joint is a source of increased dynamic impact from the wheels of the rolling stock on the elements of the upper track structure. According to the results of experimental studies it was found that the greatest increase in dynamic effects was observed from locomotive wheels up to 45 ...70 kN, maximum values reached 180 ... 210 kN, from the wheels of loaded freight cars the values of vertical forces increased by 35 ... 45 kN, from the wheels of empty cars increase dynamic impacts amounted to 14 ... 16 kN.

Energy efficiency assessment of the 3ES5K electric locomotives when using interval regulation technology in the form of “virtual coupling”

One of the promising ways to increase the capacity of railways is the way to reduce the interval between trains and its packet-mode handling. This method is implemented through the introduction of technology for interval regulation of train traffic. More advanced at present is the technology of interval regulation of train operation according to the “virtual coupling” type, which organizes the operation of trains with a minimum interval between them, which is safe for motion at and between stations. This technology removes the problem of extending the receiving

and departure tracks, reduces peak loads on the traction power supply system and the formation time of the virtual coupling structure, and increases the train speed to the yellow traffic signal with safety guaranteed. The technology is implemented due to the presence of an interval control system for train operation, the introduction of on-board automatic locomotive signaling devices ALS-EN and ALS-R, on-board complexes BLOK and KLUB-U (safety devices (auto-driving system for coupled trains) and radio modems for data transmission. The use of these devices in packet mode traffic schedule will reduce the time interval along the sections of the railway and reduce the loss of time when the train runs to the yellow traffic signal. The set of tasks to increase the energy efficiency of applying the technology of interval regulation of train operation according to the “virtual coupling” type should also include the tasks of developing modern rectifier-inverter converters VIP4000-M on AC electric locomotives together with the reactive current block developed in the Railway Implementing Center of the Krasnoyarsk Railway. These developments provide a high power factor of the electric locomotive in the traction and regenerative braking modes (up to 0.96), which will reduce the specific electric energy consumption by electric locomotives for train traction, which will increase the efficiency of the application of the technology of interval regulation of train operation according to the “virtual coupling” type. In July 2019 pilot operational tests of this technology were carried out on the Far Eastern Railway, which showed generally positive results. The paper also presents an analysis of the results on the specific consumption of electric energy for traction and its return to the contact network during regenerative braking by 3ES5K electric locomotives participating in the technology of interval regulation of train operation of the “virtual coupling” type in the sections Khabarovsk-2-Ruzhino and Ruzhino-Khabarovsk-2 of the Far Eastern Railway. These results show an increase in the energy efficiency of electric locomotives using this technology.

Managing the effectiveness of strategic decisions to rationalize the system of maintenance and repair of passenger cars

Reducing the cost of maintaining a fleet of passenger cars is one of the key objectives of the operating company as part of its strategic management. The article describes the criteria by which can be evaluated the effectiveness of strategic decisions in the field of rationalization of the system of maintenance and repair of passenger cars. The process of rationalization of this system is presented in accordance with the Deming — Schuhart cycle (PDCA) with feedback. This process provides for monitoring the effectiveness of the implemented changes in the system on the basis of IT-technologies and processing “Big Data” on three conditions: efficiency of use (C-criterion), integrated reliability availability) (K-criterion) and functional safety of passenger cars (λ-criterion). The C-criterion characterizes the savings from reducing the costs of maintenance and repair of cars by introducing appropriate changes to the system of maintenance and repair of passenger cars. At the same time, the savings will be expressed as a reduction in the cost of the life cycle of cars in terms of technical content when introducing changes to this system. The K-criterion characterizes the change in the working time fund of cars and, as a result, determines the amount of profit (lost profit) from the increase (decrease) in the working time of cars after introducing changes to the system of maintenance and repair of passenger cars. Within the K-criterion, comprehensive reliability indicators are used — the availability factor and the technical availability coefficient. λ-criterion characterizes the current safety state of trains in terms of passenger facilities on the basis of functional performance of cars safety. A negative indicator was adopted as a similar indicator — the intensity of dangerous railway failures that led to a violation of the safety of train traffic.

The given approach was developed in the tradition of the process control methodology according to the ISO system of standards and the IRIS standard of the railway industry. Currently, there are methodological developments and hardware/software that allow to move towards practical implementation of the described approach to effective management in the field of rationalizing the maintenance and repair of passenger cars by the operating company as part of the overall strategic management.

Ways to improve characteristics of the climate systems of passenger rolling stock

Passenger rolling stock is operated in various climatic conditions, calculated outside temperature can vary from –40 to +40 °С. The microclimate parameters permissible for a long stay of people (the longest route is about 6 days) are achieved by installing ventilation, air conditioning and heating systems. Currently, more and more attention is being paid to the safety and comfort of passengers, and the urgent task is to create a climate system that ensures that the air environment in the premises of passenger rolling stock is up to date with all requirements. To ensure safe parameters of the car air environment, it is necessary to increase the influx of outdoor air to 20 – 35 m3/h per person, which allows achieving a CO2 content of 1000 ppm. It should be taken into account that an increase in the flow of external air and its conditioning leads to an increase in the cost of electricity (in order to fulfill the requirement for the content of CO2, an increase in the power of the heaters by 1.5 – 2 times is required), and therefore, the cost of transportation. Comparison of sources of additional energy, the use of which can increase the flow of external air into the car with minimal additional loads on the power supply system, showed the greatest efficiency of the installation with a heat pump that uses the heat of the exhaust air to heat the supply air in combination with maintaining air back-up for protection against dust. Proposed technical solution allows to increase the level of comfort in passenger cars with minimal energy costs for air processing and equipment dimensions. The problem of increased hydraulic resistance of the installation is solved by using a beam of transversely streamlined pipes with longitudinal turbulators of a hydraulic boundary layer as the heat exchange surface of the evaporator of the heat pump. This surface will allow to develop a heat exchanger with minimal resistance and thereby get away from the need for forced traction, limiting to a minimum back pressure of 15 Pa.

On the issue of improving the reliability of the cylinder head of the diesel engine

Cylinder head in a modern diesel engine is one of the most complex structurally loaded parts of its cylinder-piston group. The cylinder head is one of the most damaged units that determine the terms of scheduled repairs of the entire engine and, ultimately, the level of costs to maintain its performance.

Article gives a review of studies on the cylinder head refinement of a diesel engine 5D49 (ChN26/26), and especially its main part which is the bottom of the combustion chamber. Design disadvantage of the bottom is the close location of the holes of the exhaust and intake valves, the inclined location of the nozzle. Depending on the heating and on the degree of constraint of the deformation of the head element, i. e. the absence of its free expansion, during heat exchange the process of destruction of the bottom elements proceeds, which is characterized by the accumulation of fatigue damage in the material and plastic deformations. Studies have shown that under stationary loading conditions with the same scale of alternation of heating and cooling, the head should provide failure-free and durable operation. The occurrence of cracks due to the accumulation of residual stress should be attributed to the share of random “bursts” of temperature and temperature stresses arising during transient processes. These processes occupy approximately 20 % of the total engine operating time. One of the main reserves for improving the reliability of heads is to prevent exceeding thermal loads in operation by optimizing transient processes and increasing the uniformity of cylinder loading. The cylinder head of the 5D49 (ChN26/26) diesel engine type, apparently, has outlive the possibilities for a significant increase in reliability and service life and bringing it into line with operational requirements. For use on new engines, a new head must be developed — symmetrical with a central vertical arrangement of the nozzle, and with a well-thought-out cooling circuit.

Calculation of heat transfer during the manufacture of railway wheels of increased hardness

The article is devoted to the study of temperature conditions in the tread of a railway wheel during the production of wheels with increased hardness of the rolling surface. It is shown that obtaining a metal structure on the wheel surface without martensite and with hardness of 360–390 HB required by technical conditions at a depth of 30 mm from the rolling surface is difficult to realize by varying technological parameters: the number of sprayers, changing the water supply to the rolling surface due to the switch on/off the sprayers. To achieve the highest cooling speeds in the mass of the wheel tread, including at a depth of 30 mm, it is necessary to use the largest possible rolling surface in the heat removal process. It is advisable to remove heat from the rolling surface according to a predetermined dependence of the specific heat flux on time. It was established by experimental studies that the required hardness at a depth of 30 mm was achieved with an increased carbon content in steel and with an increase in the temperature of heating of the wheel before cooling with water spayers of more than 900 °C. To optimize the cooling process, it is advisable to carry out additional theoretical studies with more correctly specified boundary conditions of heat transfer on the tread surface and with refinement of the boundaries of phase transformations. It is advisable to carry out experimental studies on cooling the wheel surface with the possibility of varying the heat removal when using a gas-liquid flow as a cooling agent.