Rolling Stock Components Research Articles

An automatic method for detecting sliding railway wheels and hot bearings using thermal imagery

One of the most important safety-related tasks in the rail industry is an early detection of defective rolling stock components. Railway wheels and wheel bearings are the two components prone to damages due to their interactions with brakes and railway track, which makes them a high priority when the rail industry investigates improvements in the current detection processes. One of the specific wheel defects is a flat wheel, which is often caused by a sliding wheel during a heavy braking application. The main contribution of this paper is the development of a computer vision method for automatically detecting the sliding wheels from images taken by wayside thermal cameras. As a byproduct, the process will also include a method for detecting hot bearings from the same images. We first discuss our automatic detection and segmentation method, which identifies the wheel and bearing portion of the image. Then, we develop a method, using histogram of oriented gradients to extract the features of these regions. These feature descriptors are later employed by support vector machine to build a fast classifier with a good detection rate, which can detect abnormalities in the wheel. At the end, we train our algorithm using simulated images of sliding wheels and test it on several thermal images collected in a revenue service by the Union Pacific Railroad in North America.

An Improved Projection Method for Determination of Fatigue Parameters of Metal Structures Based on Spherical Direction Cosine Group Construction

The key components of railway rolling stock are almost constantly in the multiaxial stress state in service. To evaluate the fatigue strength of the structure, stress parameters should be obtained beforehand. The traditional projection method assumes that the maximum principal stress is the maximum tensile stress, and then the projection process is performed without taking the tension/compression states of principal stresses into account. To address these inadequacies, a method for fatigue parameter determination was proposed based on principal stress projection toward a spherical direction cosine group. This method can determine the direction of maximum tensile stress and preserve the tension/compression attribute of stress during calculating the maximum stress and the minimum stress. Therefore, the physical meaning of present improved method is more apparent than the traditional projection method, and its algorithm is simple and effective. The fatigue strength assessments of a welded bogie frame were performed utilizing the traditional projection method and present method, respectively. Results obtained show that maximum stresses calculated by the improved method can be 19.4% higher than those obtained by the traditional one at some nodes, while the minimum stresses and the stress ratios derived by these two methods can even be of opposite sign. The present method, which takes the tension/compression properties of principal stresses into consideration, is more reasonable, as compared with the traditional projection method, and thus, its fatigue strength assessment results are more credible.

Development of a Cutting Tool for High-performance Cutting of Railway Rolling Components

High performance cutting (HPC) is used in machining railway parts like wheel sets or axes with large depth of cut and high feeds). The process is accompanied by increased thermal loads causing high concentration of stresses in the contact areas with the tool. This paper presents a set of methods to reduce thermal stress in machining zone in HPC conditions through the use of a special tool system, consisting of carbide cutting inserts with nano-structured multilayer composite coatings and a special scheme for mounting such inserts on tool holder with the use of high heat-conducting ceramic-polymer pads. The study has revealed that the developed tool system can significantly accelerate heat transfer from the insert and increase efficiency. Production tests show that the tool and the new coating in machining rolling stock (of railway) components can improve performance by 80-100%.

SELECTION OF A DECISION MODEL FOR ROLLING STOCK MAINTENANCE SCHEDULING

Rolling stock is the most maintenance intensive part of the railway system and therefore, the most vulnerable if maintenance is neglected. It is therefore, essential to have an efficient maintenance schedule for rolling stock components. A decision support model can be used to achieve this. However, selecting the appropriate model to achieve this is vital to the success of the decision support model. In this paper a practical way of selecting the appropriate model to develop a decision support for scheduling of rolling stock maintenance, is presented. A case study is used as a numerical example for the proposed framework.

Longitudinal dynamics and energy analysis for heavy haul trains

Whole trip longitudinal dynamics and energy analysis of heavy haul trains are required by operators and manufacturers to enable optimisation of train controls and rolling stock components. A new technology named train dynamics and energy analyser/train simulator (TDEAS) has been developed by the State Key Laboratory of Traction Power in China to perform detailed whole trip longitudinal train dynamics and energy analyses. Facilitated by a controller user interface and a graphic user interface, the TDEAS can also be used as a train driving simulator. This paper elaborates the modelling of three primary parts in the TDEAS, namely wagon connection systems, air brake systems and train energy components. TDEAS uses advanced wedge-spring draft gear models that can simulate a wider spectrum of friction draft gear behaviour. An effective and efficient air brake model that can simulate air brake systems in various train configurations has been integrated. In addition, TDEAS simulates the train energy on the basis of a detailed longitudinal train dynamics simulation, which enables a further perspective of the train energy composition and the overall energy consumption. To demonstrate the validity of the TDEAS, a case study was carried out on a 120-km-long Chinese railway. The results show that the employment of electric locomotives with regenerative braking could bring considerable energy benefits. Nearly 40 % of the locomotive energy usage could be collected from the dynamic brake system. Most of tractive energy was dissipated by propulsion resistance that accounted for 42.48 % of the total energy. Only a small amount of tractive energy was dissipated by curving resistance, air brake and draft gear systems.

Railway wheel-flat and rail surface defect modelling and analysis by time–frequency techniques

Damage to the surface of railway wheels and rails commonly occurs in most railways. If not detected, it can result in the rapid deterioration and possible failure of rolling stock and infrastructure components causing higher maintenance costs. This paper presents an investigation into the modelling and simulation of wheel-flat and rail surface defects. A simplified mathematical model was developed and a series of experiments were carried out on a roller rig. The time–frequency analysis is a useful tool for identifying the content of a signal in the frequency domain without losing information about its time domain characteristics. Because of this, it is widely used for dynamic system analysis and condition monitoring and has been used in this paper for the detection of wheel flats and rail surface defects. Three commonly used time–frequency analysis techniques: Short-Time Fourier Transform, Wigner–Ville transform and wavelet transform were investigated in this work.

Effect of the structural and phase composition of complexly alloyed deposited metal on the tribotechnical characteristics of rolling stock components

The results presented are of investigations of the tribotechnical properties of the complexly alloyed deposited metal with special reference to the technology of repair of rolling stock components by arc surfacing to increase the life between repairs. The composition of the deposited metal with the structure of acicular ferrite is determined.

Rolling stock maintenance strategy selection, spares parts’ estimation, and replacements’ interval calculation

The purpose of this paper is to permit an approach for: (1) selecting a maintenance strategy for rolling stock and (2) obtaining possible spare parts’ quantities and replacement intervals for the components of rolling stock. The methodology adopts an analytic network process (ANP) technique for the strategy evaluation, because ANP considers the important interactions among evaluation factors. The ANP’s result decides upon a proper rolling stock maintenance strategy formed by various combinations of preventive maintenance (PM) and corrective maintenance (CM). The ratio PM/CM, obtained by ANP, can help to predict spare parts’ quantities of the components of rolling stock. The empirical result also indicates that preventive maintenance should be much more valued than corrective maintenance. In addition, safety is considered the most crucial factor for the selection of a rolling stock maintenance strategy. The fruit of this study serves as a reference for railway system operators when evaluating their rolling stock maintenance strategy and also when estimating their spare parts’ quantities and replacement intervals for specific components of the rolling stock.

The development and properties of a new ceramic flux used for reconditioning rolling stock components

The development and properties of a new ceramic flux used for reconditioning rolling stock components

Advanced technologies of reconditioning components of rolling stock

Advanced technologies of reconditioning components of rolling stock

Experiments of Laser Surface Engineering for the Green Remanufacturing of Railway Coupler

To achieve sustainable development and to solve the question of resource recycling and environment protection, green remanufacturing should be considered in the life cycle of the used railway rolling-stock components. These invalidated components resulting from fatigue and wear, such as coupler, could be remanufactured using laser surface hardening technology as the key processing. The objective was to harden the coupler backend pinhole interface, and to repair the layer with wear and fatigue crack on the wall of pinhole. Laser transformation hardening and laser melt-solidification hardening was used to the new manufacturing process to improve wear resistance of the surface of coupler backend pinhole. Laser surface cladding was used to repair lost material area for the reason of wear or fatigue, in order to offset the geometry size and satisfy the assembly relationship, and to increase the strength, the hardness and the wear resistance of the substrate. To the E class steel, typical coupler metal, the related laser process variables and materials were test and optimized. For the sake of verification these tests, related hardening area mechanical behaviors examinations including hardness, wear resistance, impact resistance and metallographic examinations were given. The result of the examinations show that the laser hardening area joins with the substrate being metallurgic join, and the behaviors examined were equal or best than the substrate. These means that laser surface hardening technology could be applied to the green remanufacturing of railway couplers as key processing.

Separability and Subadditivity in Australian Railways

From the mid 1990s, Australian public railways were required to provide access to their track infrastructure to third parties seeking to operate trains, and some railways were split into their below-rail (track and signalling infrastructure) and above-rail (rolling stock and locomotives) components to facilitate access. Driving the reform was the notion that it would allow competition to develop in above-rail operations. This paper assesses the policy decision, using a unique dataset for Australian railways to ascertain their separability and the subadditivity of the above-rail task.

Problems of nondestructive testing of wheel-pair components of rolling stock

Improving the effectiveness of nondestructive testing of railway rolling stock’s wheel-pair components during their manufacturing and repair is considered. The results of metallographic studies of PY-1 and PY-1III solid-rolled wheels and axles, analysis of the operating specifications, and experimental studies of the optimal methods of nondestructive testing are included.

A digital filter-based approach to the remote condition monitoring of railway turnouts

Railway operations in Europe have changed dramatically since the early 1990s, partly as a result of new European Union Directives. Performance targets have become more and more exacting, due to reductions in state support for railways and the need to increasing traffic. More intensive operations also place greater demands on the hardware of the railway. This is true for both rolling stock and infrastructure subsystems and components, particularly so in the case of the latter where the time available for maintenance is being reduced. The authors of this paper focus on the railway infrastructure, and more specifically on points. These are critical elements whose reliability is key to the operation of the whole system. Using intelligent monitoring systems, it is possible to predict problems and enable quick recovery before component failures disrupt operations. The authors have studied the application of remote condition monitoring to point mechanisms and their operation, and have identified algorithms which may be used to identify incipient failures. In this paper, the authors propose a Kalman filter for the linear discrete data filtering problem encountered when using current sensor data in a point condition monitoring system. The reason for applying Kalman filtering in this study was to increase the reliability of the model presented to the rule-based decision mechanism.

A Review of the Effects of Out-Of-Round Wheels on Track and Vehicle Components

Out-of-round rollingstock wheels are caused by skidding or spalling of the wheel tread and by dynamic motion of wheels and wheelsets in service. Out-of-round wheels generate impact forces at the wheel-rail interface, which are transferred to train and to track components including rail and both bolted and welded rail joints, prestressed concrete sleepers, ballast, wheels, and bearings.To make a rational decision about removing out-of-round wheels from service, estimation of the damage caused by an individual wheel is required. Previous studies have used analytical and numerical models to illustrate the distribution of impact into track and rolling stock components. These models are compared here. The review details mathematical models and studies of the lives of the earlier-listed components, which would provide a means of determining the damage caused by impacting wheels. In addition, studies have found that impacting wheels increase fuel consumption and increase pass-by noise levels, which are also discussed here. Further study of the effect of impacting wheels on axle bearing lives, parent rail, and bridges would improve this decision-making tool.It is envisaged that these models would be combined to determine the total cost of operating rolling stock with impacting wheels. This could be offset against the cost of wheelset maintenance to determine when an impacting wheel should be reprofiled.

Reconditioning rolling stock components by electric arc spraying

Reconditioning rolling stock components by electric arc spraying

Increasing the volume of repair of cast components of rolling stock by welding

Increasing the volume of repair of cast components of rolling stock by welding

Improving the quality and extending the life of springs for railroad rolling stock

Good experience has been accumulated with the use of steels with specified range of hardenability in combination with bulk and surface hardening in deep induction heating of heavy-duty components of rolling stock. In this work the possibility was evaluated of using such a strengthening method for extending the service life of springs used for the suspension systems of railroad wagons. Hardness and microstructure were evaluated and internal and residual stresses were measured. Endurance tests were conducted in three-point bending. The use of steels with specified range of hardenability in combination with bulk and surface hardening ensured savings of rolled metal due to increased reliability and longer life of the springs, reduced expenditure of scarce alloying elements such as Cr, Ni, and Mn in steel production, resulted in savings of fuel, natural gas, and other materials used in the heat treatment process, and led to better working conditions in heat-treatment shops.

Evaluation of the quality of industrially produced iron-graphite cermet materials

1. The main shortcoming of our investigated industrially produced cermet materials was the low stability of their mechanical properties. This prevents their wider use in railroad transportation, where the stability factor, which provides service reliability of the components of rolling stock, determines travel safety. This conclusion pertains equally to all areas of industry where high service reliability of parts which can be economically manufactured from cermets is required. 2. Tensile, shear, and bending tests on a sufficiently large number of specimens made it possible to evaluate the quality of cermet bushings. Impact tests by the proposed method are less sensitive to cermet quality.