Running gears of sets of freight wagons coupled with diesel or electric traction vehicle

W artykule przedstawiono przegląd rozwiązań konstrukcyjnych układów biegowych wagonów towarowych wynikających z wymagań zawartych w krajowych jak i europejskich przepisach. Przedstawiono krótką charakterystykę pojazdów trakcyjnych poruszających się w trakcji towarowej. Opisano główne typy wózków stosowanych w Polsce i Europie przede wszystkim rodzinę wózków typu Y25. Zawarto krótki rys historyczny układów biegowych wagonów towarowych. Przedstawiono wymagania zamienności układu biegowego jako układu standardowego. Omówiono główne zagadnienia związane z projektowaniem układów biegowych, wymaganiami, kryteriami, specyfikacją techniczną.

PROCEDURE AND ALGORITHM FOR DETERMINING THE COEFFICIENT OF THE FREIGHT WAGON STABILITY IN COMPLIANCE WITH CURRENT REQUIREMENTS

Improving the reliability of test results is achieved by applying more advanced methods of recording and processing the results. Therefore, an important part of the study of the strength of freight wagons is the choice of methods for obtaining, processing and analyzing experimental data. The article outlines the procedure and algorithms for determining the equivalent stresses under longitudinal and dynamic loads acting during operation. It is shown that algorithms for determining stresses generated by dynamic longitudinal and vertical forces are significantly different due to various load application schemes. Thus, the testing of freight wagons under dynamic longitudinal loads is carried out by the impact against an experimental wagon, and testing under dynamic vertical forces is performed during the wagon motion in the composition of the experimental train on the characteristic, pre-selected (planned) sections of the railway track at specified speeds. To estimate the level of loading of the freight wagon structureunder vertical dynamic loads, a method based on the replacement of a real random process is used by some schematized process, which in terms of the fatigue damage accumulation should be equivalent to a real process. From the whole variety of schematic methods, two methods stand out, i.e., the full cycle method and the rainflow method, which most fully represent the real process.The advantage of the rainflow method is the ability to process the process in real time. However, the algorithm of the rainflow method is quite complicated and does not allow processing large amounts of information. In this regard, a method of maximum discharge was proposed, which is a kind of full cycles method and allows you to process an unlimited amount of information online. An example specified in GOST 25.101 was used for a comparative analysis of the rainflow and maximum discharge methods. Analysis showed a satisfactory matching of both methods. Based on the procedure outlined, the block structure of the computational process is proposed to determine the equivalent reduced voltage amplitude. Each block displays the impact of the forces depending on the loading condition, that is, longitudinal impact force and dynamic forces when the wagon is moving on straight track sections, curves and switches of the railway track. Key words: wagon car, process, dynamic load, longitudinal load, voltage, amplitude, algorithm, equivalent stress, safety margin, strength.

ASPECTS OF BRAKING EFFICIENCY CRITERIA FOR FREIGHT WAGONS UNDER THE LATEST RULES OF HOST 34434-18

The paper deals with the analysis of the braking efficiency criteria for freight trains formed with wagons that have increased axle load up to 294.3 kN (30 ts) when moving at speeds up to 120 km/h inclusive. Increasing the efficiency of freight trains by increasing the technical and economic performance of cars by increasing the axial load to 294.3 kN (30 ts) and train speeds up to 160 km/h led to the development of technical requirements and rules for braking systems set out in HOST 34434-18. According to the new rules and requirements, the following are accepted as criteria for the braking efficiency of freight wagons, that is, up to the maximum values of the braking distances of the freight train on the site in the specified intervals of speeds of axial loads; calculated coefficients of force of pressing of composite blocks on wheels at braking; the pressing force of the composite pads on the axis in terms of cast iron pads. The calculation of the maximum allowable value of the braking distance of the freight train is performed based on the actual pressing forces and the actual friction coefficients. The paper shows that the specific braking forces obtained using the actual pressing forces exceed the calculated specific braking forces using the calculated coefficients. Based on the above-mentioned, it is concluded that the braking efficiency criteria with reference to the maximum allowable values of the braking distances and the calculated coefficients of the pressing force have a significant discrepancy between each other. It is proposed to use the actual pressure force coefficients instead of the calculated coefficients to assess the braking efficiency of the freight train. The paper presents the permissible values of the actual force values of pressing the pads on the wheels for wagons with axial load (230.5 - 294.3) kN at speeds up to 120 km/h inclusive, for which the braking distance criterion of the freight train is observed. Key words: criterion, braking efficiency, freight train, axial load, braking distance, specific braking force, calculated coefficients, actual coefficient.

A stand for researching the dynamics and strength of a freight wagons bogie

The purpose of the study is to characterize the laboratory equipment of a new generation that meets the requirements that are imposed today on the training of specialists in the rolling stock of railways. Analytical, diagnostic and didactic methods, theory and methodology of design and mechanics of freight wagon, theory of complex systems, systems engineering, modeling, as well as methodological tools for organizing experiments were used. The scientific novelty is the constructive and technological scheme of a specialized laboratory stand; a didactic set of materials for organizing laboratory work using this stand.It has been established that the introduction of a new rolling stock with an increased carrying capacity is the main trend of modern car building and should be accompanied by appropriate training of highly qualified specialists capable of further development of new generation freight wagons. It is noted that conducting educational and research sessions involves studying not only the problems of strength, but also acquiring skills in working with digital technologies for collecting and transmitting data. A detailed description is given of a specialized stand developed at the Department of "Wagons and Carriage Facilities" of PGUPS for studying the properties of dynamics and strength of freight wagons of the laboratory stand. In particular, the device of the base trolley model 18-9855 is shown, the technology of the stand operation is described, illustrative materials are given on the structure and principle of operation of the projected stand. For practical laboratory exercises, a typical version of laboratory work with the use of this stand is proposed. It is shown that the involvement of students in the implementation of practical experiments and applied bench research increases interest in the future profession and allows the formation of strong skills in practical diagnostics of the current state of a freight wagon.

ANALYSIS OF ENSURING THE SAFETY OF FREIGHT WAGON IN MODERN CONDITIONS OF OPERATION

The current state of the freight wagon fleet is characterized by increased physical wear over time. Disproportionate renewal of rolling stock, low quality of repair due to the lack of appropriate modernization of production systems, the peculiarities of loading and unloading operations in operation make increased demands on the preservation of the wagon fleet. The issues of general management of the transport safety system deserve special attention. Control of safety of freight wagons should be carried out at all stages of operation: at freight works, at transfer in the international and domestic communication, at maintenance and repair. In this case, each stage requires the use of appropriate regulations, which ensures compliance with the conditions of storage of freight wagons in operation. The presented article analyzes the current state of the freight wagon fleet with a view to ensuring their safety during operation. The factors that are the most influential in terms of effective management of the wagon fleet are identified. Possible conservation strategies are considered. The statistical material on failures and damages of wagons is resulted. Based on this, an assessment of the most significant events in terms of the impact on ensuring the safety of wagons was made. Practical solutions for creating an effective system for preserving rolling stock in transport are proposed.

Determination of dynamic loading of bearing structures of freight wagons with actual dimensions

The determination of the dynamic loading of the bearing structures of the main types of freight wagons with the actual dimensions under the main operating conditions is carried out. The inertial coefficients of the bearing structures of the wagons are determined by constructing their spatial models in the SolidWorks software package. Two cases of loading of the bearing structures of the wagons – in the vertical and longitudinal planes – have been taken into account. The studies were carried out in a flat coordinate system. When modeling the vertical loading of the bearing structures of wagons, it was taken into account that they move in the empty state with butt unevenness of the elastic-viscous track. The bearing structures of the wagons are supported by bogies of models 18-100. The solution of differential equations of motion was carried out by the Runge-Kutta method in the MathCad software package. When determining the longitudinal loading of the bearing structures of wagons, the calculation was made for the case of a shunting collision of wagons or a "jerk" (tank wagon). The accelerations acting on the bearing structures of the wagons are determined. The research results will help to determine the possibility of extending the operation of the bearing structures of freight wagons that have exhausted their standard service life. It has been established that the indicators of the dynamics of the load-carrying structures of freight wagons with the actual dimensions of the structural elements are within the permissible limits. So, for a gondola wagon, the vertical acceleration of the bearing structure is 4.87 m/s2, for a covered wagon – 5.5 m/s2, for a flat wagon – 5.8 m/s2, for a tank wagon – 4.25 m/s2, for a hopper wagon – 4.5 m/s2. The longitudinal acceleration acting on the bearing structure of a gondola wagon is 38.25 m/s2, for a covered wagon – 38.6 m/s2, for a flat wagon – 38.9 m/s2, for a tank wagon – 27.4 m/s2, for a hopper wagon – 38.5 m/s2. This makes it possible to develop a conceptual framework for restoring the effective functioning of outdated freight wagons. The conducted research will be useful developments for clarifying the existing methods for extending the service life of the bearing structures of freight wagons that have exhausted their standard resource

The Effects of The Tanzanian Railway Network in the Performance of the Rail Freight Operations

The railway is the fundamental means of transport, especially for freight. It has a substantial contribution to the sustainable economy of the country and the region at large. However, some factors have been affecting the performance of rail operations; especially for freight, to the extent of reducing the modal share from rail to roads. This has been resulting in high road maintenance costs and underutilization of the available capacity in the railway. This research has studied the factors affecting the Tanzanian railway network in the performance of rail freight operations. The focus was on the corridor from Dar es Salaam to Isaka because it serves most of the landlocked countries such as Uganda, Burundi, Rwanda, and Eastern DRC. The study used the Performance Measurement theory with the Balanced Scorecard model. Data analysis was done by the Linear Regression statistical method with the aid of SPSS version 20. The results of the study show that derailments, washouts, and rail freight wagons maintenance capacity directly affect the performance of rail freight operations. TRC, therefore, needs to strategize measures for ensuring that derailments and washouts are very much reduced. A plan for quick recovery must be in place in case a derailment or washout happens. Also, TRC should enhance its capacity for maintaining the rail freight wagons to ensure its optimal availability. Railway should be viewed as a potential area for investment because it supports the growth of other sectors as well. If constraints are minimized in the railway system; the performance of rail freight operation will be high and many customers will be attracted to use the railway as a preferred mode of transport, hence, the modal share to the railway will increase.