Freight Car Wheel Research Articles

Мокрій Т. Ф., Малишева І. Ю. , Лапіна Л. Г., Пасічник С. С. Взаємодія з рейками коліс пасажирського вагона з новим профілем ободу ІТМ-73EP в криволі-нійних ділянках колії

Speeding up the integration of Ukraine into the European railway transportation is an important task in the current development of the Ukrainian railway transport. Currently, the most effective way to travel across borders between countries with different track gauges is the use of gauge-changeable wheelsets. Continuous traffic on the Ukrainian (1520 mm gauge) and European (1435 mm gauge) railways calls not only for gauge changing facilities, but also for the compatibility of the wheel-rail contact pair on both railways: R65 rails and a cant of 1/20 in Ukraine and UIC60 rails and a cant of 1/40 in Europe. At the Institute of Technical Mechanics of the National Academy of Sciences of Ukraine and the State Space Agency of Ukraine, a new wear-resistant wheel profile, ITM-73ER, was proposed. As predicted, its use in passenger cars will offer dynamic stability and a high dynamic performance throughout the range of operating speeds on the Ukrainian and European railways and acceptable indices of wheel – unworn rail interaction on both railways. In service, the shapes of the wheel and rail contact surfaces change due to wear, especially in curves. Because the Ukrainian and European railways mostly use wheel and rail profiles of their own, the use of the new wheel profile may impair the wheel–rail interaction process, enhance wheel flange wear, and shorten the wheel life. The goal of this work is to study the effect of the in-service rail head shape change in curves of the Ukrainian and European railways on the wheel–rail interaction indices of a passenger car with ITM-73ER profile wheels. The head shapes of outer rails of the Ukrainian and European railways’ circular curves were predicted for a side flange wear changing from 0 to 8 mm in 2 mm increments. The calculations were made for two circular curves of radius 300 m with UIC60 rails and a cant of 1/40 (Europe) and R65 rails and a cant of 1/20 (Ukraine). To speed up the prediction, it was assumed that the curves were traveled by four-axle fully loaded freight cars, which maximizes the rail wear. The freight car wheels were assumed to be unworn and machined to the S1002 profile (for the European railways) and to the standard profile specified by the Ukrainian State Standard GOST 10791:2016 (for the Ukrainian railways). Using the computed head shapes of R65 and UIC60 rails differing in wear degree, a study was conducted into their effect on the wheel–rail pair strain and stress field and the dynamic indices of car–track interaction for passenger cars with ITM73-ER profile wheels negotiating a circular curve of radius 300 m. It was shown that the use of the ITM-73ER wheel profile in passenger cars will offer improved indices of car–track interaction, for worn rails too, both on the Ukrainian railways and in the combined operation on the Ukrainian and European railways.

Hole boring technology improvement of the freight car wheel hub

The technological process of machining the wheel hub hole of a freight car is considered. Unreliable wheel and axle fit is one of the main reasons of rolling stock derailment. The reliability of the fit depends on several factors: interference, quality of the mating surfaces, the mechanical properties of the material. The roughness of the hole surface plays a very important role. In many ways, it determines the compressing force and fatigue strength, the roughness value should be within certain limits, which are strictly regulated by Russian National Standard GOST 4835-2013. The article describes in detail the requirements imposed in Russia and abroad to the amount of roughness of the mating surfaces provided by machining. The analysis of the chemical composition and mechanical properties of wheel steels of grades 1, 2, T and L. The article also discusses the technological process and equipment for boring holes in the wheel hub. The foreign experience of using boring technologies is analyzed. The arrangement of the cutting plates in the design of the boring head applied for boring the hub hole is considered. The application of round and prismatic carbide plates used in tools is also considered. The types of metal-cutting machines used are indicated. The main emphasis in the article is on ensuring the required roughness of Russian National Standard GOST 4835-2013 due to cutting modes that are optimal from the point of view of ensuring surface quality. Based on the production data and recommended in the reference literature on feed, speed and depth of cutting values, a full factorial experiment was carried out to determine the effect of each cutting mode on the roughness parameter. As a result of the analysis, diagrams of roughness changes were plotted and intervals of feed values, speed and cutting depth were established, ensuring minimal roughness of the machined surface. It was also found that the feed rate has the strongest effect on the surface roughness. The results obtained can be used when performing the operation of boring the hub hole at the enterprises of the railway industry.

IDENTIFICATION OF THE CAUSES OF SURFACE DEFECTS OF WHEELS OF CARS EQUIPPED WITH COMPOSITE PADS

The paper presents the results of the analysis of surface defects and faults of freight car wheels caused by frictional interaction with composite brake pads. It is established that the main influence on the thermomechanical behavior of freight car wheels is caused by thermal loads that occur during braking. In cases of thermal overloads, which arise mainly as a result of prolonged braking, the generation of stresses and deformations occurs, the consequences of which are the appearance of high-temperature local defects on the rolling surface of freight car wheels. These defects negatively affect the safety of trains and significantly increase the operating costs of railway transport. To determine the thermal stress state of the freight car wheel during braking, its calculation was carried out. As a calculation method, the finite element method was used, which is implemented in the SolidWorks Simulation software package. The temperature effect on the wheel during braking is determined to be permissible from the point of view of ensuring the strength of the wheel. The conducted research will contribute to the creation of recommendations for managing the temperature effect on the wheel, as well as improving the safety of trains and significantly reducing operating costs in railway transport.

Experience of operation of the UDP-2001SM railway wheelset bearing vibration diagnostics installation and the OMSD-02 mechanism diagnostics system

The Aim of the paper is to compare the UDP-2001SM installation for vibration diagnostics of bearings of freight, refrigerator and passenger car wheels and the OMSD-02 mechanism diagnostics system that since recently has been used in the Belarusian Railway.Methods. By way of analysis of the UDP-2001SM vibration diagnostics installation and the OMSD-02 mechanism diagnostics system, the authors considered the list of identifiable defects, method for defining threshold values (reference levels) of vibroacoustic pulses and noises for the criteria of “faulty” and “good”, statistical data for rejected axleboxes of freight and passenger car wheelsets in respect to the overall number of conducted measurements, the experience of operation in various car shops of the Belarusian Railway. Results. The paper describes the process of vibration diagnostics of wheelset bearings of freight and passenger cars using the case of stationary acquisition of vibroacoustic signals from acoustic plates that interact with the diagnosed axlebox. The authors present the diagrams of the UDP-2001SM installation and OMSD-02 system, as well as the defects of bearings that are to be identified using the above diagnostics equipment. Conclusion. The paper showed the advantages and disadvantages of the above diagnostics systems based on the experience of their application in a number of car shops of the Belarusian Railway.

ОЦЕНКА ЭФФЕКТИВНОСТИ РАБОТЫ ТОРМОЗНОГО ОБОРУДОВАНИЯ ИННОВАЦИОННЫХ ГРУЗОВЫХ ВАГОНОВ

The object of researches is brake systems of innovation freight cars. The work purpose consists in the assessment of braking system effectiveness in innovation freight cars and in standard ones at different operation modes. 
 The scientific novelty consists in the definition of the dependence of a slide block depth on the length of wheel pair skidding motion and braking distance dependence upon car speed. During the work there was carried out a retrospective analysis of cases with traffic safety violation connected with the formation of excessive sliders in freight cars in organized trains because of the violation of braking equipment normal operation. By means of the least-squares method there was obtained a linear equation defining the dependence of slider depth upon the skidding length of a wheel pair. As a result of the work there were defined parameters of defect formation on freight car wheels at their skidding, the calculations of braking system efficiency in different freight cars were carried out. 
 In the course of the analysis of freight car braking efficiency there are obtained equations of braking length in the accepted range of speeds at the beginning of braking for empty and loaded states. Minimum values of the design factor of braking block pressing in translation to a train length of 200 shafts in the empty state were 0.2256 for a speed of 40km/h, in the loaded one – 0.1781 for a speed of 120 km/h at the standard values 0.22 and 0.14 respectively. By means of calculations and experiments it is proved that composite braking block pressing force on a shaft exceeds 4tf/shaft, and that of cast-iron – 10tf. Accordingly, a car with the shaft load of 25 tf/shaft and accepted parameters of a braking system may be operated up to the speeds of 120 km/h inclusive without limitations.

Reduction of freight car wheel wear of 1520 mm gauge railways

A brief description is given of the comprehensive modernization of standard freight car trucks through the use of devices of American companies adapted for railways with a 1520 mm gauge and wheels with ITM-73 specially developed wear-resistant profile, which allows several times to increase the resource of problematic running gears. An approximate method is proposed for solving the wheel–rail interaction problem with determining the position and size of non-elliptic contact patches, including with conformal contact. Using this method, new profiles have been developed for turning worn wheels (ITM-73-01), as well as new wheels for cars with an axial load on rails of 23.5 tf (ITM-73-02) and 25 tf (ITM-73-03). The data of experimental studies showed that the average wear rate of the wheel flanges of freight cars with complex modernized trucks equipped with wheels with ITM-73-01 profile is 3.5-5 times lower than that of a standard car with a standard wheel profile. According to forecast estimates, the use of wheels with profiles ITM-73-02, ITM-73-03 will allow to achieve even greater increase in the resource indicators of wheelsets for wear of the flanges.

Subsurface Crack Propagation from Internal Defect in Rolling Contact Fatigue of Railway Wheel Steel

A rolling contact fatigue failure is one of the main fatigue damages in railway wheels due to cyclic rolling contact with rails. This fatigue failure caused by internal defects such as nonmetallic inclusions or voids might occur in heavy haul freight car wheels. Subsurface crack propagation behaviors from the internal defects are evaluated by twin disc type rolling contact fatigue tests using test specimens with artificial defects and by finite element analyses simulating the rolling contact fatigue tests. The subsurface cracks are more likely to propagate in the test specimens with larger artificial defects. In addition, the cracks initiating from the trailing side of defects propagate faster than those from the leading side. Shear mode equivalent stress intensity factors obtained from the finite element analyses correspond well to the results of rolling contact fatigue tests. The test specimen models with larger defect have larger equivalent stress intensity factor ranges than the test specimen model with smaller defect in both leading and trailing side. The results of finite element analyses also suggest that the crack propagations are affected by the deformation of artificial defects and this leads to have higher resistance to crack propagation in the test specimens with smaller internal defects.

Differential heat treatment of one-piece freight-car wheels

Differential quenching of the whole one-piece wheel is shown to be more effective than quenching of only the contact surface at the wheel rim. Hybrid strengthening by differential bulk quenching and surface plasma hardening is very promising in increasing the crack resistance of steel. The martensitic structure of the treated layer in hybrid strengthening is very disperse, thanks to decrease in size of the initial austenite grain. In bulk-quenched components, surface plasma strengthening creates a composite working layer characterized by high wear and crack resistance, whereas the core is relatively soft and plastic.

마모와 제동에 의한 화차륜의 잔류응력 변화

During the past few years, several incidents of freight car wheel failure during operation have occurred due to fatigue crack and overheating from braking. Tensile residual stress on the wheel tread creates an environment conducive to the formation of thermal cracks that may threaten the safety of train operations. It is important to investigate the residual stress on wheels in order to prevent derailment. In the present paper, the residual stress on wheels is measured using the x-ray diffraction system and the residual stress is analyzed using FEM. The result shows that the residual stress on the wheel rim is lower than that on the wheel tread center and the stress on over-braked wheels changes from compression residual stress to tensile residual stress.

Wear resistance of high-carbon steel with dry friction and abrasion

Assessment of the wear resistance in wheel–rail contact by determining the tribological characteristics of high-carbon steel in dry friction is proposed. Comparative test results are presented for such steel, as well as for hardened layers of wheel steel with optimal plasma surface hardening and different carbon and chromium contents. The wear resistance of the working surfaces of high-carbon wheel and rail steels in dry friction and abrasion is determined. The plasma hardening of locomotive wheel pairs with increased hardness of the outer wrap and one-piece freight-car wheels made from chrome steel is optimized. The change in wear resistance is confirmed in abrasive-wear tests. Test results for carbon and high-carbon steels are compared, as well as results for layers after plasma powder surfacing and plasma surface hardening.

To the question of modeling of wheels and rails wear processes

Purpose. There is a need of wear process modeling in the wheel-rail system. This is related to the fact that the wear processes in this system are absolutely different in the initial and final stages. The profile change of rail and, especially, of the wheels caused by the wear significantly affects the rolling stock dynamics, traffic safety and the resource of the wheels and rails. Wear modeling and the traffic safety evaluation requires the accounting of the low frequency component forces (including the modeling of transitional areas) affecting the wheel on the side of the rail and carriage in motion of rolling stock, so the statistical analysis is not possible. Methodology. The method of mathematical modeling of the wheel set and the rail interaction was used during the research conducting. Findings. As a result of the modeling of the wheel set motion on the rail track, the mathematic model with 19 freedom degrees was obtained. This model takes into account the axle torque and studies wheels constructions as the components of the mechanical systems, consisting of a hub and tire. Originality. The mathematic model allows evaluating the wear degree of the wheels and rails when using on the rolling stock not only all-metal wheel sets, but also compound ones with the use of spring wheels and independent rotation of semi-axes with the wheels. Practical value. The development of the improved mathematical model of freight car wheel set motion with differential rotation of the wheels and compound axles allows studying the wear processes of wheels and rails.

Development of dynamic models of wagons on models 18-9810 and 18-9855 bogies taking into account wheel wear research

Purpose. Wear parameters clarification in wear simulation is an actual goal because of absence of corresponding data for freight cars in condition of using them on Russian railways. Research is devoted to development of dynamic models of wagons on three-peace two-axle models 18-9810 and 18-9855 bogies with maximum axle-loads 23,5 ts and 25 ts, and to choice of factors, with varying which parameters in the model of wheel wear can be identified. Methodology. The problem is solved by method of mathematic simulation in «MEDYNA» software. Wear calculation is based on abrasive wear theory (Archard’s theory). Findings. Clarification of wheels’ wear model may be done with varying of friction coefficient between wheel and rail for different wheel profile areas (flange and tread), wear coefficient in Archard’s model for mild and heavy wear and transition between them. Originality. Dynamic models of universal gondola on models 18-9810 and 18-9855 bogies are developed. It is established, that rail treads irregularities size effect wheel wear insignificantly, when car is running on circle track of constant radius. Practical value. Developed dynamic models of wagons on models 18-9810 and 18-9855 bogies may be used in wear simulation, determination of car running characteristics, interaction of car and rail of different type, construction, condition and etc. Research results of some factors influence on freight car wheel wear may be interesting for people, who study this problem.

Thermal Stress Analysis of the Heavy-haul Freight Car's Wheel Web Plate under the Wheel Tread Braking

As an effective and efficient solution to enhance the capacity of the freight car transportation,the increase of axle loads may lead the wheel enduring larger heat loads and suffering more severe damage.In order to offer valuable technical supports for the operation,especially braking working condition,it is necessary and meaningful to compare the thermal stress of the wheel web plates for different axle load freight cars and reveal how the changes of the axle load affect the distribution of the temperature and stress.Basing on the thermal elasto-plastic theory,a new idea is put forward,which firstly studys the residual stress generated by the heat treatment process,and then simulates the distribution of the temperature and thermal stress for the wheels with residual strain using the time history of the heat braking power calculated from the omnidistance working conditions of the Datong-Qinhuangdao railway as a theraml load.It has been proved the residual stress generated by the heat treatment process cannot be ignored and the web plates will bear greater thermal and residual stress along with the increase of axle loads,by means of comparing the ones of the 21 t,25 t and 30 t axle load wheel web plate.

Influence of Inclusion on Crack Initiation in Wheel Rim

Speed increase and heavy haul of the railway freight car are the effective measures to raise the transport ability of railway, and they have been the new trend for railway freight car development. The increase of speed and axle load will lead to the increase of wheel-rail contact stress, which will make a great change of stress distribution in the whole wheel rim. Goodier equation was employed to analyze the stress state around inclusion and cavity. In the operation of wheel-rail contact stress, stress concentration occurred in the pole of Al 2O 3 spherical inclusion, while it appeared on the equator of cavity. The critical inclusion sizes of 250 kN axle load freight car wheel at different velocities, a certain distance away from the tread, were calculated by Murakami equation. Comparing the inclusion in cast steel wheel with that in rolled steel wheel, it is found that the inclusion in cast steel wheel has much more excellent crack resistance than that in rolled steel wheel. In the meantime, in order to reduce the probability of rim crack, some suggestions were put forward.

Universal equipment for wheel-pair disassembly

1285 At present, presses produced by the Odessa Press mash plant are mainly used for the disassembly of wheel pairs. These presses require strong foundations and take up considerable space. In disassembly, the wheel pair is suspended from a support in the wheel hub. In practice, the disassembly force for seamlessly rolled wheels is 6000 kN or more, in contrast to the assembly forces, which are no more than 80–100 kN. This indicates considerable additional forces due to skewing, jamming, and other consequences of visual basing of the wheel. This results in skewing, scratch ing, and fracture of the wheel pair’s axle. At OAO ENIMS in 2005, the URK1 unit was man ufactured for the disassembly of freight car wheel pairs at Troitsk Refrigerator Depot [1]. It includes a system with a floating foundation plate, so that the wheel pair may be based at the surface of the axle, without suspension. This equipment has significant benefits over the Pressmash presses: smaller size, lower drive power, and lower cost. Production measurements (more than 1000) show that the disassembly forces in the URK1 unit are considerable less than in the Pressmash presses (Fig. 1), thanks to the increased basing precision and the reduced dependence on operator skill. The large scale introduction of disk brakes on the wheel pairs of high speed trains has increased the requirements on the disassembly systems. As an exam ple, consider a wheel pair of GP200 type (Fig. 2). As is evident from Fig. 2, the space for the founda tion plate on the inside of the wheel hub is very limited (on account of the braking disk or gear). This entails the search for new designs. The table presents the dimensions of the wheel pair: D, the diameter of the brake disk; h1, the distance between the wheel hubs and the braking disk; h2, the width of the braking disk; and l, the distance between the braking disks. The URK1 unit provides the starting point for the development of the URKT1 unit (Fig. 3) [2]. The URKT1 unit includes the power system of a hydraulic press: two plates 2 and 4 connected by four pins 3. The pins are attached by external nuts. The main power cylinder 5 is mounted at rear plate 4. In front plate 2, there is a cutout for the introduction of the wheel pair, as well as two holes (in the plane of the axle) for the attachment of secondary cylinders 1. This fundamentally new configuration permits a hybrid approach to disassembly. All the hydraulic cyl inders act at once, in opposing directions. The rod of Universal Equipment for Wheel Pair Disassembly

Experience in developing and using automated laser diagnostic equipment for the contactless monitoring of the parameters of freight car wheels

The problems of obtaining high reliability in the automated contactless monitoring of the geometric parameters of freight car wheels during the motion of a train under practical operating conditions using laser equipment are discussed. The factors which influence the reduction in the monitoring reliability are analyzed, and methods of reducing this influence (by a factor of 2–10) are demonstrated. An eddy-current sensor and a subsystem based on it for detecting defects in the rolling surface of wheel pairs are described.

Comprehensive Inspection of Geometric Parameters of Running Freight Car Wheel Pairs

Ensuring the safety of running trains is the main condition of railways exploitation for transport of passengers and cargoes all over the world. This is determined by the growth of moving speed in railways and by the wear of the rolling stock. As the moving speed increases, the requirements of quality of railways and of the rolling stock become stricter. This entails the necessity of optimal use of rolling stock without decreasing the movement safety. In particular, in Russia, occurs the wear of car and locomotive stock. A similar situation exists in railways of India, Australia and some former socialist countries.

3D optical measuring technologies for dimensional inspection

The results of the R & D activity of TDI SIE SB RAS in the field of the 3D optical measuring technologies and systems for noncontact 3D optical dimensional inspection applied to atomic and railway industry safety problems are presented. This activity includes investigations of diffraction phenomena on some 3D objects, using the original constructive calculation method, development of hole inspection method on the base of diffractive optical elements. Ensuring the safety of nuclear reactors and running trains as well as their high exploitation reliability takes a noncontact inspection of geometrical parameters of their components. For this tasks we have developed methods and produced the technical vision measuring systems LMM, CONTROL, PROFILE, and technologies for non-contact 3D dimensional inspection of grid spacers and fuel elements for the nuclear reactor VVER-1000 and VVER-440, as well as automatic laser diagnostic system COMPLEX for noncontact inspection of geometrical parameters of running freight car wheel pairs. The performances of these systems and the results of the industrial testing at atomic and railway companies are presented.

Rolling contact fatigue defects in freight car wheels

Three types of rolling contact fatigue of railway wheels are prevalent for freight cars of the Russian Railways: wheel spalling, shelling and thread checking. Though all these defects and mechanisms of their formation are generally known, however, there are many particularities in the defect's appearance, formation and development that should be studied. Results of theoretic studies and modeling of the defect formation are presented and discussed. As creep and associated forces are considered as one of the most damaging mechanism for the wheel–rail interface, particular attention is given to study the influence of creep velocities and the coefficient of friction on the contact stress distribution.

Tribological interrelationship of seasonal fluctuations of freight car wheel wear, contact fatigue shelling and composition brakeshoe consumption

This paper proposes a novel theory which explains the strong linkage between brakeshoe metal pick-up and a corresponding increase in wheel tread wear and shelling during the wet winter months. The model suggests that pick-up metal forms through the tribo-reduction of oxidized wheel-rail wear debris. The presence of abundant carbonaceous residues and moisture is thought to promote this reaction. The consequent removal of carbon and wear debris from the wheel-rail interface increases friction during the dry periods to the range 0.4-0.6. This exacerbates wheel-rail wear and shelling. It is concluded that the most effective way to alleviate seasonal increases in wheel shelling and wear is to control friction in the range 0.2-0.4. This can be accomplished by inhibiting carbon depletion associated with metal pick-up or by applying commercial friction reducers.