Top Of Rail Research Articles

In situ X-ray analytical study on the alteration process of iron oxide layers at the railhead surface while under railway traffic

This paper describes an experimental investigation of in situ X-ray diffraction analysis of iron oxides on the railhead surface, which have an influence on various wheel/rail rolling contact phenomena, e.g. the adhesion between wheels and rails, which can cause rail corrugations. The X-ray analysis using portable X-ray diffractometer installing XRF called “XRDF” was carried out for the preliminary laboratory experiment and the field test. For the laboratory experiment, the rail specimen samples on which rust was generated by scattering salt water mist and moisture vapor alternately were analyzed. The different rust types generated under the different environmental conditions were identified. For the field test, XRDF analysis was applied to the corroded test rail after the test vehicle passed over it several times. As a result, it can be concluded that the decreased proportion of rusts due to passage of the vehicle depends on the track alignment, the location where rails are installed, and the positions across the rail head such as top of rail in tangent track or gauge corner of the high rail in curved track, and also depends on the vehicle running conditions, i.e. free-rolling, driving or braking. Finally, we confirmed the effectiveness of applying XRDF analysis to track site measurements to obtain some important suggestions for understanding the wheel/rail rolling contact phenomena on which rail surface substances have great influence.

Investigation of a transitional wear model for wear and wear-type rail corrugation prediction

▶ A calculation procedure for wear coefficient in frictional work wear model. ▶ The application of wear transition model for investigating wear-type rail corrugation growth rate. ▶ Results of the wear coefficient under conditions of friction modifiers and their effects on wear-type rail corrugation; and quantifying of the feasibility of friction modifiers. In this paper, a recently proposed mechanics-based model for the wear coefficient of rail steels is experimentally validated and implemented to obtain useful predictive wear models for some popular railway steels. The model is then implemented to investigate the feasibility of top of rail (TOR) friction modifiers (FMs) for wear-type rail corrugation control. The experimental results confirm the analytical prediction of the first transition (step change in value) of the wear coefficient based on known conditions of creep and load. The implementation of the model under dry and friction-modified conditions shows a substantial reduction in the wear coefficient from 1.6 × 10 −09 kg/Nm to 0.34 × 10 −09 kg/Nm, respectively. This along with an approximate 50% reduction in friction coefficient, is predicted to result in substantial decreases in corrugation growth rate and grinding costs of ∼20 times under the experimentally measured conditions of friction modifiers.

Implementation of Distributed Power and Friction Control to Minimize the Stress State and Maximize Velocity in Canadian Pacific's Heavy Haul/Heavy Grade Operations

Canadian Pacific (CP) has taken a systems approach to minimizing the stress state and maximizing velocity in high-tonnage, heavy haul western Canada mainline operations. Recognizing the interaction between wheel-rail contact mechanics, train handling, and track geometry, CP has tested and implemented a number of advanced technologies that leverage current knowledge, systems, products, and equipment in each of these areas. This includes implementation of distributed locomotive power configurations based on sophisticated track/train interaction modelling, as well as the state-of-the-art top of rail and gauge face friction control. Together, these technologies have resulted in reductions in damaging lateral forces, rail wear, and fastening system fatigue, as well as increases in velocity and network capacity. This article presents the theory, implementation, and verification of distributed power, fine tuning curve superelevation and friction control technologies within the practical operating conditions of British Columbia.

Novel Analytical Model of Mean Temperature and Experimental Research on the Rail Universal Rolling

For building the analytical model of mean temperature in rail universal rolling, the cross-section of workpieces and the profile of horizontal roll and vertical roll are simplified rationally. The mean temperature of the web of rail, the top of rail and the base of rail are considered individually. The temperature rises for plastic deformation and friction incorresponding deformation zone, the temperature drop for contact is calculated on the base of variation principle and energy conservation law. Then the mean temperature is obtained. For verifying the theoretical model, the 18 kg/m light rail universal rolling experiments are accomplished in Yanshan University Rolling Laboratory, China and the surface temperature is measured. The surface temperature is not exact enough to express the true temperature and the mean temperature can show the status of the true temperature basically. So the mean temperature can be used to express the true temperature and this theoretical model and its results can be applied as an important reference to control the temperature of rail universal rolling and the heat treatment of the rolled rail.

Effect of moderating friction of wheel/rail interface on vehicle/track dynamic behaviour

Lubrication in sharp curves has been commonly adopted so far to decrease the friction between wheel flange and rail gauge face following wear reduction and energy consumption. Also, lubrication is focused on its effect on decreasing the possibility of wheel flange climb derailment and squealing which is a kind of rolling noise. In addition, the lubrication between wheel tread and the top of low rail is studied to prevent low-rail corrugations in sharp curves. The lubricant supplied between the top of rail and wheel tread called “friction modifier” because of its traction characteristics, the relation between traction coefficient and slip ratio, modified to be suitable for refraining negative damping or sliding between wheel and rail has recently been developed. In this study, track site measurements were carried out to identify the effects of lubrication between wheel tread and the top of low rail, and between wheel flange and the gauge face of high rail on vehicle/track interaction excited by vehicle running in sharp curves such as lateral force and the angle of attack caused by a leading axle of a bogie. Also, based on the results measured at a track site, the adequacy of vehicle dynamic simulation model was verified. Then the measured results were investigated from the aspects of interacting forces between wheel and rail obtained by vehicle dynamic simulations, and the effect of lubrication on vehicle/track dynamic behaviour was evaluated with the focus placed on the coefficient of kinetic friction and the steering performance of bogie such as lateral force and the angle of attack. This paper describes the detailed arrangements and the results of track site measurements in a sharp curve whose radius was 160 m and vehicle dynamic simulation. As a result, the significant effect of the top of low-rail lubrication on improving vehicle/track dynamic behaviour was identified. Finally the advantage of a kind of friction modifier, called as “friction moderator” in this study, and its jetting device by which the friction moderator was supplied to wheel/rail interface the authors have been developing for the top of low-rail lubrication was discussed.

Railway noise and the effect of top of rail liquid friction modifiers: changes in sound and vibration spectral distributions in curves

For railway noise in curves, both flanging and squeal noise can be environmentally significant. Rolling noise is dominant in tangent track. This paper examines the spectral sound distribution in curves for different wheel/rail system types, and compares spectra after the top of rail friction level is controlled with a special friction modifier. The friction modifier controls top of rail (TOR) friction at an intermediate level, and imparts “positive friction” attributes to the interfacial layer. A significant range of spectral characteristics was noted for the different wheel/rail system types. In all cases the friction modifier significantly reduced the sound levels at the frequencies associated with top of rail squeal, and also at the frequency bands related to flange contact noise. For some Metro systems a noticeable reduction was also recorded at the lower frequencies associated with rolling noise, possibly due to a reduction in “graunching”. There was some suggestion of reduction at low frequency vibration (frequencies down to 30 Hz) as well as in the high stick-slip oscillation frequencies.

Friction control between wheel and rail by means of on-board lubrication

The purpose of this study is to demonstrate the friction control between wheel and rail can solve wheel/rail contact problems, such as wheel-slipping, rail corrugation, squeak noises, wheel/rail wear and so on. Firstly, fundamental tests with two-roller-rigs were carried out to evaluate the friction performances of several types of friction modifiers. Then, for the purpose of realizing the friction control with them, authors developed an on-board system, which sprayed friction modifier from a bogie to the top of rail accurately. This method is very advantageous to control friction between wheel and rail. As a result of track tests, it was found that one type of friction modifier, which had proper coefficient of friction (COF) and positive creep characteristics, was very effective to reduce the lateral force and the squeak noises.

Rail heating analysis for multishot EM gun operation

This paper describes a method of analyzing potential railgun concepts for their rail heating effects in multishot mode. The method is meant to provide a quick estimate of heating effects based on the geometry of the rails and containment and the performance specifications of each shot. First, a coupled electrical-mechanical simulation is run for the railgun in which the effects of current diffusion are included to calculate the effective rail resistance and associated heating as a function of axial position and time. This analysis is then expanded with an assumed current distribution (relative amount of current on top and back of rail compared with the front) to develop a first order temperature distribution in the rail cross section at any specified axial location. This axial section is then subjected to two-dimensional finite element analysis (FEA) to determine the heat redistribution between shots. A sample set of calculations is compared with a single shot experiment incorporating temperature probes in the rails. Finally, the utility of the method for multishot analysis is shown with two simulations, one with and one without active cooling in the rails.

Motor trucks for milk transportation: (Clip Sheet No. 320, U. S. Department of Agriculture, August 11, 1924.)

The real friction coefficients between the rails and the wheels on a 360 t and 10,800 kW IORE locomotive were measured using the locomotive׳s in-built traction force measurement system. The locomotive consisted of two pair-connected locomotives had a CoCo+CoCo bogie configuration, and hauled a fully loaded set of 68 ore wagons (120 t/wagon). The measurements were performed both on rails in a dry condition and on rails lubricated with a water-based top-of-rail (ToR) friction modifier on the Iron Ore Line between the cities of Kiruna and Narvik in Northern Sweden and Norway, respectively. Since full-scale measurements like these are costly, the friction coefficients were also measured at the same time and place using a conventional hand-operated tribometer, with and without the ToR friction modifier. The most important results are that the real friction coefficient is definitely not constant and is surprisingly low (0.10–0.25) when the ToR friction modifier is used, and that it is also significantly dependent on the amount of ToR friction modifier. A large amount will reduce the friction coefficient. Furthermore, it is concluded that the real friction coefficients are in general lower than the friction coefficients measured with the hand-operated tribometer. A final remark is thus that the use of a water-based ToR friction modifier can give excessively low friction, which can result in unacceptably long braking distances.