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This article presents the results of a study focused on identifying the main causes of the asymmetric (clinodual) wear of composite brake pads on freight wagons. A new scientific approach to determining the clinodual wear of composite brake pads on freight wagons is proposed. It is established that the harmful abrasion of the pad occurs during the movement of the freight train due to an imperfection in the bogie-brake lever transmission. The causes of the non-normative frictional wear of composite brake pads were investigated. This kind of wear leads to the tilting and abutting of the upper end of the brake pads against the rotating wheel during train running. The results of geometric and kinetostatic studies of the "pad–wheel" tribotechnical pair are provided to establish the causes and consequences of the accelerated clinodual frictional wear of composite brake pads on pendulum suspension in the bogies of freight wagons. The conditions of rotation of the wheels during braking "for" and "against" the clockwise direction depending on the direction of the train are considered. A new approach to brake-pad-wear prediction depending on the mileage of wagons under operational conditions is proposed. The research conducted in this study contributes to the development of the mechanical parts of freight-wagon brakes, increasing the efficiency of brake operation and improving the safety of train traffic. [ABSTRACT FROM AUTHOR]

Couples of heavy-haul freight cars are simulated, using a 62-degree-of-freedom multi-body model developed on Simpack®, running on both tangent track and circular curve under different conditions. A benchmark simulation running at a speed of 70 km/h is set up, and then, different breaking scenarios with 2.5 kN, 5 kN, 7.5 kN and 10 kN of abnormal braking force application are simulated. In this paper, the effect of forces acting on the wheel–rail interface is compared using the derailment coefficient (L/V) and the material wear, defined by energy dissipation (Tγ). For the double-wagon setup placed in various positions along the train, the simulations run under no braking and abnormal braking conditions, where the braking force acts in only one of the wheels of the wheelset. This condition leads to an increase of up to 18% in L/V in one curve and up to 17% of reduction on the curve in the other direction. The wear increases 68% and decreases 71%, depending on the direction of the curve. These effects haven't been associated with longitudinal dynamic effects in previous studies, including in-car shocks and traction forces. [ABSTRACT FROM AUTHOR]

Summary: During an excavation of a Bronze Age, Füzesabony‐culture cemetery at Encs (north‐eastern Hungary), a clay wagon model with spoked wheels (grave 1290) and three miniature solid clay wheels were found (grave 1389). Miniature wagon and wheel models in burials began to appear in the Late Copper Age and lasted until the Iron Age in Central Europe. Their presence allows of several interpretations. These spoked wheels of grave 1290 provide early evidence about the appearance of such in the Carpathian Basin. Focussing on the two graves from Encs, this article reports AMS radiocarbon dates that suggest the spoked wheels belong to the early second millennium BC. The implications of these finds are interpreted though a comparative review of both wagon models from the Füzesabony culture and the evidence for early spoked wheels in the Carpathian Basin. [ABSTRACT FROM AUTHOR]

This paper focuses on the research on regression rate of hybrid rocket motor with single-port wagon wheel fuel grain. Both experiment and numerical investigations are carried out to study the three-dimension regression rate of hybrid rocket motor on several characteristic points. A laboratory 500 N-class firing test of hybrid rocket motor with single-port wagon wheel fuel grain has been conducted on the standard ground experimental system. The 98% hydrogen peroxide oxidizer and hydroxyl terminated polybutadiene based fuel are adopted as propellants. The digital image processing of three-dimension regression rate is carried out, and a post-processing software has been developed to calculate the time-averaged three-dimension distribution of regression rate after the firing test. Three-dimensional numerical simulations with gaseous combustion considered are carried out to study the axial distribution of regression rate. The results of digital image processing manifest that the average regression rates of the middle position of wagon wheel spokes is higher than those in the slot of wagon wheel. A good agreement exists between the calculated regression rate from numerical simulation and the experimental results conducted by computed tomography scanning. The comparison results show that the digital image processing is potentially an effective tool for investigating and predicting the three-dimension regression rate of hybrid rocket motor with single-port wagon wheel fuel grain. • Firing test of HRM with single-port wagon wheel fuel grain has been carried out. • The method of CT scanning digital image processing and software are developed. • Three-dimension regression rates of HRM are characterized by simulation and test. • A good agreement exists between regression rates from simulation and CT scanning. [ABSTRACT FROM AUTHOR]

This paper analyses the parameters relevant to the operation of underground cars in traffic on straight and curved tracks with small curve radii. Current knowledge of non-linear lateral dynamics of rail vehicles and the specialist computer programme Vi-Rail were used to build models and perform simulation calculations. A solution was proposed to enable passive control of wheelsets with very high guiding stiffnesses, without the need for systems to force the axles of the wheelsets to align radially in a curved track. This effect was achieved by varying the guidance stiffness in the horizontal plane of the frame of each bogie. The adopted course of action offers simplicity of solution, low manufacturing costs, high critical speed on straight track and extended service life of the metro wagons resulting from reduced mechanical wear of wheels and rails. A multi-criteria evaluation was carried out, confirming improved bogie controllability and reduced impact of the metro wagon wheelsets on the curved track. Comparisons were made of the design volumes for metro model wagons with bogies with symmetric and unsymmetric axleguide stiffness arrangements of the wheelsets. [ABSTRACT FROM AUTHOR]

The paper presents the results of tests of a system for monitoring the tread of moving freight car wheelsets using dynamic strain gauge. The studies were carried out at a test ring under the conditions of multiple repetition of train load to evaluate the reproducibility of the results of strain gauge measurements. During each passage of the train through the measuring section, the high-speed system with a sampling frequency of 64 kHz measured the strain of the rail web caused by the impact of the wheels of the rolling stock. A specially developed software was used to automatically detect defective wheels from the obtained data and determine the dynamic force of wheel impact on the rail. The repeatability of strain gauge measurements was evaluated by comparing them with the results of visual and measuring control of the rolling stock conducted before the beginning of the tests. [ABSTRACT FROM AUTHOR]

Shear pads are devices used to improve vehicle dynamics performance on heavy haul railways wagons. In this work, we present a method to determine the elastic properties of such components using experimental/numerical approach. The final goal is to provide adequate input to multi-body analysis software commonly applied to study and design railroad vehicles. We also considered the effect of side frame compliance to primary suspension performance, a influence that is often neglected on this type of study. Our results show that the application of shear pads can indeed promote a significant reduction of wheel and rail wear by decreasing the total frictional energy T γ. We also show that, under the simulated conditions, the most important stiffness coefficient to wear is the longitudinal one. [ABSTRACT FROM AUTHOR]

The polygonal wear around the wheel circumference could pose highly adverse influences on the wheel/rail interactions and thereby the performance of the vehicle system. In this study, the effects of wheel polygonalisation on the dynamic responses of a freight wagon are investigated through development and simulations of a comprehensive coupled vehicle-track dynamic model. The model integrates flexible ballasted track and wheelsets subsystem models so as to account for elastic deformations caused by impact loads induced by the wheel polygonalisation. Subsequently, the vehicles with low-order polygonal wear, whether in empty or loaded conditions, are simulated at different speeds considering different amplitudes and harmonic orders of the wheel polygonalisation and thus the mapping relation between wheel/rail impact force and wheel polygonalisation is obtained. The results reveal that the low-order wheel polygonalisation except 1st order and 3rd order can give rise to high-frequency impact loads at the wheel/rail interface and excite 1st-bend modes of the wheelset and "P2 resonance" leading to high-magnitude wheel/rail contact force at the corresponding speed. [ABSTRACT FROM AUTHOR]

A wheel flat is a common fault in railway vehicles that may develop after incorrect brake application, or localised wheel-rail adhesion reduction. Operators detect wheel flats using wayside systems that are not capable of delivering real-time alarms. A wheel flat defect was modelled and introduced to a railway wagon multibody dynamic simulation to study the vehicle dynamic behaviour triggered by such wheel tread defect. Bogie-based and car body-based wheel flat detection was evaluated to determine eventual hardware robustness and signal processing requirements for on-board wheel flat detection devices. Various vehicle operating conditionds and wheel flat defects were simulated to analyse the wheel flat impact propagation throughout the railway vehicle bodies. Wheel defect detectability was assessed using detectability indicators (DIs) based on envelope power spectrum analysis, crest factor and RMS. It was found that bogie and car body-based wheel flat detectability is highly dependent on the track characteristics. The wheel flat signature was reduced in the wheelset-bogie and bogie-car body interfaces, indicating that advanced signal processing techniques are required for bogie-based and car body-based wheel flat detection systems. The DIs showed clear differences between healthy and faulty wheelset and bogie frame acceleration signals, which is promising for eventual on-board wheel flat detection systems. [ABSTRACT FROM AUTHOR]

Periodic deviation of the diameter of wheel across its circumference is referred to as the out-of-round (OOR) defect that can cause significant damages to wheel – rail interface, affect the service life of various components of the vehicle/track system and the safety of trains. Under braking, OOR defect may exacerbate these damages; to uncover such exacerbation, a multi-body dynamic simulation model in a fixed coordinate system for wagons containing new/ defect free or OOR wheels subject to braking torques has been formulated and validated using a dataset in the literature. Using the validated model, the effects of the repetition order (single or multiple deviations of diameter) of OOR defect and the severity of application of braking torques to wheel wear has been examined. It has been found that under constant speed, the normal contact force increased with the repetition order. The OOR defect dominated the normal contact force with a dynamic impact force factor of 1.48, whilst the new/ defect free wheels exhibited negligible impact force. It is shown that the effect of OOR defect is significant for wear of wheels under normal braking whist under wheel skid, braking torque dominates wear. Wheel unloading ratio is shown to be a better indicator for the determination of risk to derailment, than the commonly used Nadal's derailment quotient where the wheel contains OOR defect. • Out-of-round wheels under normal, severe and emergency braking investigated. • A fixed coordinate model was formulated to investigate wheel skid under braking. • Wheel-rail contact frictional power was used to determine wear depths. • Wear under skid was significantly large irrespective of presence or absence of OOR. • Unloading of OOR wheels better predict wagon derailment than Nadal's Criterion. [ABSTRACT FROM AUTHOR]

Wheel wear is of major interest in railways due to the high cost of wheel reshaping, rail wear, and safety issues in operation. Recent researches employ onboard sensors to evaluate the dynamic behavior of the wagon and determine railway running conditions. However, sensors and computing units are expensive and some maintenance scenarios are impossible to be deliberately generated. In this work, several maintenance parameters for primary suspension, friction wedge, and flange backspacing are evaluated within operational ranges in a Box-Behnken design of experiment (DoE), set in a quadratic surface model. Such a modeling approach uses few experimental points and a significantly small computational cost when compared to a full factorial method, which uses multibody dynamic models on a simulating platform, like Simpack, to determine which parameters are more influential in safety against derailment (Y/Q) and wheel and flange wear (T γ). The present work evaluates such parameters for heavy-haul gondola rail cars, with meter and broad gauge, running on tangent track and curves, with and without FRA irregularities. The analysis makes it possible to identify non-uniformities in wheel wear and to set different inputs for condition-based maintenance for freight rail wagons. Results show that the primary suspension longitudinal clearance and stiffness affect Y/Q and wear by over 100%, increasing the operational risk and maintenance cost because of wheel wear. • The primary suspension with PAD presented the highest level of sensibility. • Wheel wear and derailment parameter Y / Q are the most affected parameters. • Wear may increase 172% by shortening the primary longitudinal suspension travel. [ABSTRACT FROM AUTHOR]

Based on the analysis of data about the structure of wheels from the royal necropolis of Ur - a fragment of stone tile, mosaic “Standard” and wagon wheels from burials, as well as artifacts discovered in the other monuments, the author concludes that in the Ancient Middle East three-wheeled wagons with central lentoid plank went out of use before the turn of the 4th-3rd millennium BC. When actual wagons already used three-partite wheels, whose central section had parallel planks, wheels with central lentoid plank continued to be represented on seals and votive tiles, copying them from older samples. Wheels of actual wagons at the turn of the 4th and 3rd millennium BC, discovered in burials beneath barrows in the Pontic-Caspian steppe, had central section with straight sides, a construction from the next stage of wheel design development. Since, presumably, the first wheels were single-partite and time was needed for the development of three-partite design with central lentoid plank, and then rectilinear shape, the appearance of wheels in the Old World must be dated much more earlier than it is commonly believed - not later than the beginning of the 4th millennium BC.

In ancient Egypt, the wheel was known since the Fifth Dynasty. About sixty wagons with four to eight wheels and only a few two-wheeled carts are attested. The first wheels appear on a scaling ladder and a siege tower in military contexts. The earliest wheeled vehicle is proven to have been in use in the Thirteenth Dynasty. Most carts and wagons date to the New Kingdom, the Third Intermediate Period, and Greco-Roman times, with the majority appearing in religious transport situations. A typological course of development is apparent from the wagon of Sobeknakht to those of Siamun, Petosiris, and Petubastis. In this article, the vehicles are viewed from technological and sociocultural viewpoints and are contextualized with regard to the invention and diffusion of the wheel. [ABSTRACT FROM AUTHOR]

The aim of the research is for a reasonable choice of wear coefficients for severe and mild phases in Archard's abrasive wear theory and friction coefficients for wheel flange and tread that correspond to conditions of Russian track for wheel profile wear modelling using dynamic models of wagons. This paper considers the gondola wagon on bogies model 18-9855 that are of the three-piece Barber S-2-R design. The wagon running test results on Experimental Loop Track in Scherbinka, the results of hardness measurements of wheel flange/tread and of wheel profile wear modelling are presented in this paper. In conclusion, a comparison of wheels wear of two freight wagons’ bogies (with friction and elastic-friction links of wheel sets with side frames) on the basis of specified wear model was carried out. [ABSTRACT FROM AUTHOR]

Wheel reprofiling costs for freight vehicles are a major issue in Sweden, reducing the profitability of freight traffic operations and therefore hindering the modal shift needed for achieving reduced emissions. In order to understand the damage modes in freight vehicles, uniform wear prediction with Archard's wear law has been studied in a two-axle timber transport wagon, and simulation results have been compared to measurements. Challenges of wheel wear prediction in freight wagons are discussed, including the influence of block brakes and switches and crossings. The latter have a major influence on the profile evolution of this case study, so specific simulations are performed and a thorough discussion is carried out. [ABSTRACT FROM AUTHOR]

The objective of this work is to study transverse vibration of a passenger car body running at various speeds over the track irregularities, which are usually encountered in practice. The tasks that are addressed in this research work: perform tests at track irregularities of symmetrical sinusoidal shape running both along straight and curved paths, as well as driving over the junctions along the straight and curved paths, and compare the results. [ABSTRACT FROM AUTHOR]

Keeping wheel profiles in an acceptable condition is a major concern for both railway operators and infrastructure owners. The condition of the wheels influences both their wear and the required rail maintenance. Wheel wear affects the dynamic characteristics of vehicles and the dynamic force impact on the rail and, in the worst case scenario, can cause derailment. This paper studies the correlation of the wear rate and the wheel force to temperature and seasonal differences, monitoring eight identical wheel axles of different ages for a full life cycle. The study notes differences in wheel wear and wheel/rail forces while operating with a 30 tonne axle load and in temperatures ranging from -30°C to +30°C. At a research station near Luleå in Sweden, measurements have been performed of the speed and the vertical and lateral forces for every train passage, and the lateral-to-vertical force ratio has been calculated. The study concludes that the wheel wear is significantly greater at lower temperatures. The magnitude and variation of the lateral forces are strongly dependent on the bogie position, with the highest peak value recorded for the leading low rail. The L/V ratio is strongly seasonally dependent, with large differences within a month due to changes in friction. [ABSTRACT FROM AUTHOR]

This study offers a brief overview of the main directions in the research into prehistoric wagon models and the appearance of wheeled vehicles. A new Early Bronze Age clay model found recently in Hungary is presented as part of the study. A discussion of the analogies to the model and the interpretation of its design are followed by a review of new European finds proving the early use of wagons. The dates strongly suggest that wheeled vehicles appeared more or less simultaneously in several places. [ABSTRACT FROM AUTHOR]

A technique for testing residual stresses in the rims of solid-rolled wagon wheels with an ultrasonic method using the electromagnetic-acoustic method of exciting-receiving acoustic signals is described. An engineering solution that makes it possible to obtain trains of bottom signals using electromagnetic-acoustic transducers is proposed. The results from determining residual stresses in new and used wagon wheels are presented. [ABSTRACT FROM AUTHOR]

The bottom-up assembly of molecular building blocks, carrying specific functions, is a promising strategy for the construction of nanomachines. In this study we show how molecules with a mechanical function, i.e., being equipped with wheels, can be connected in a controlled way directly on a surface. By choosing suitable building blocks, assembled dimers and wagon trains can be formed, whereas the length of the chains can be limited by using a heterogeneous mixture of molecules. By using low temperature scanning tunneling microscopy, the chemical nature of the intermolecular connection is determined as a metal-ligand bond, which is stable enough to maintain the wagon train structure at room temperature. The intermolecular bonds can be controllably changed from trans to cis configurations thereby achieving bond angles of almost 90°. [ABSTRACT FROM AUTHOR]

In this work the task of unification of the tensometric wheel pairs and reducing of the expenses required for testing is decided. The task is developed on basis of the wheel pair of railway freight wagon as on example. The equipment allowing realization of the measurements for the monitoring of wagon or locomotive system wheel--railing using standard wheel pair is elaborated. The possibility to use the standard wheel pair with removable measurement equipment as tensometric wheel pair reduce the material and time expenses required for preparing of testing. The optimal shape of removable disc -- ellipse with the curved transverse strengthening in the middle part of disc -- is founded. [ABSTRACT FROM AUTHOR]

The main objective of this work is to study the possibilities of improving the running safety of a railway wagon with independently rotating wheels by changing their design symmetrically mounted on an axle. The article provides a discussion of the advantages and disadvantages of using the independently rotating wheels in a bogie of railway wagons. Their increasing tendency of derailment is described. The influence of a perspective constructive scheme (PKS) of railway wagon wheels in comparison with a traditional constructive scheme (TKS) on running safety due to the climbing of a wheel flange onto a rail is studied. This work introduces a conceptual proposition of a technical solution to railway wheel design as well as containing the results of both analytical calculations as well as the results of multibody simulations. A PKS wheel design for a railway wheel is designed that allows independent rotation of its tread surface and of a guiding surface (i.e., of a flange) to each other, which both are arranged symmetrically on a wheelset axle. It brings features of the distribution of friction forces generating in a flange contact when the wheel with a TKS and with PKS move on a rail. It is possible to conclude with the help of the obtained results that the use of wheels with the PKS is advisable for the reduction of the running resistance as well as for increasing the running safety of railway wagons. [ABSTRACT FROM AUTHOR]

• The evolution laws of WDD and tread wear are analyzed based on the tracking measured data. • A freight wagons model considering Non-Hertz wheel-rail contact is developed for numical simulation. • The influence of WDD with the new profile and worn profiles on tread wear are studied. • The correlation analysis of wheel tread wear and the WDD is conducted based on the field test data. Wheel wear is a fundamental problem for railway vehicles. The unequal wear rate of the two wheels of a wheelset results in the wheel diameter difference (WDD). The WDD and wheel wear not only affect the dynamic performances of rail vehicles, but also increase the maintenance cost. This paper presents an investigation of the effect of the WDD on tread wear for freight wagons based on extensive field measurements and numerical simulations. The evolution laws of the WDD and tread wear of 4 freight wagons are first analyzed based on the monitoring data in an operation period of 200,000 km. A freight wagon dynamics model considering wheel-rail non-Hertzian contact is then established to study the influence of the WDD on the wheel tread wear of a freight wagon. The correlation analysis of wheel tread wear and the WDD is conducted based on the field test data. The results show that the initial WDD significantly affects the shapes and stress distributions of wheel-rail contact patches. The WDD can lead to the asymmetric wear of the two wheels of a wheelset, which conversely aggravates the WDD in return. [ABSTRACT FROM AUTHOR]

Investigates the dynamic behavior of ore wagons in curves at Malmbanan in northern Sweden and Norway. Possibility of allowing a higher axle load on the track with wagons; Plan to understand and predict the effects on track wear; Determination of contact forces between wheels and rails.