2 edition of Surface chemical effects in wheel to rail adhesion. found in the catalog.
Surface chemical effects in wheel to rail adhesion.
Ian J. McEwen
PhD thesis, Chemistry.
A series of experiments on the wheel/rail traction coefficient were carried out with a twin disc rolling contact machine by varying the surface roughness and the temperature of the wheel and rail discs, and using sprayed water, for the purpose of obtaining fundamental knowledge about how to prevent wheels slipping during driving and wheel sliding during by: 2. Steam locomotives suffer particularly badly from adhesion issues because the traction force at the wheel rim fluctuates (especially in 2- or most 4-cylinder engines) and, on large locomotives, not all wheels are driven. The "factor of adhesion", being the weight on the driven wheels divided by the theoretical starting tractive effort, was generally designed to be a value of 4 or slightly higher, reflecting a typical wheel .
Sand has been usually used for effective increase of adhesion, but its disadvantage is abrasive effect on wheel and rail. A systematic laboratory investigation of the effect of sanding on wheel and rail has been performed using twin disk simulation facility, which consists of disk simulation of wheel and disk simulation of : D. Smejkal. This volume deals with surfaces and their significance in adhesion, friction, wear and lubrication. Rapid advances have been made in recent years in the development of surface analytical tools for better characterization and identification of species on solid : $
Materials used for Wheels on Rolling Stock Katrin Mädler, Manfred Bannasch Deutsche Bahn AG, Technical Centre, Brandenburg-Kirchmöser, GERMANY 1 Introduction In the contact area between the wheel and the rail, the materials are used in those components encounter the greatest demands. Not only is there the pure rolling motion under a constant. Adhesion is the tendency of dissimilar particles or surfaces to cling to one another (cohesion refers to the tendency of similar or identical particles/surfaces to cling to one another).. The forces that cause adhesion and cohesion can be divided into several types. The intermolecular forces responsible for the function of various kinds of stickers and sticky tape fall into the categories of.
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Rolling contact fatigue (RCF) defects such as squats or surface shellings; gauge corner cracks or head checks; gauge face wear; rail corrugations which have four types classified from the viewpoints of mechanism and occurrence location; friction/adhesion which are related to wheel flange climb derailment in sharp curves, the stability of high-speed operation and braking performance in the case of wet wheel–rail.
surface chemical effects in wheel to rail adhesion. Author: McEwen, I. ISNI: Awarding Body: University of Salford Current Institution: University of Salford Date of Award: Availability of Full Text: Access from EThOS. Purchase Surface effects in adhesion, friction, wear, and lubrication - 1st Edition.
Print Book & E-Book. ISBNBook Edition: 1. As the wheel–rail contact is an open system, the adhesion between the wheel and rail is inevitably affected by contaminants. Contaminants, which refer to foreign substances applied both intentionally and unintentionally the wheel– to rail interface, can make wheel–rail adhesion either Surface chemical effects in wheel to rail adhesion.
book high or too low and to difficult predict. With an increasing speed, the adhesion coefficient of wheel/rail decreases under oil, water and sanding conditions. However, with the increase of axle load, the adhesion coefficient of wheel/rail.
However, with the increase of axle load, the adhesion coefficient of wheel/rail increases under the conditions with mixed oil, water and sand. Sanding can increase adhesion coefficient but damage the wheel/rail surfaces. In addition, the effect of adhesion improving by sanding is. A systematic large experimental test program of wheel/rail adhesion and wear was undertaken using the IIT wheel rail simulation facility of approximately 1/4 scale.
This study was inspired due to the need of higher adhesion locomotives which are being designed and built at present. Adhesion & Friction. •Inadequate friction = poor adhesion = unsafe braking (long min stopping distance) •Less friction = poor adhesion = wheel slip in traction (loss of hauling capacity) •Rail-wheel contact zone = 1 sq cm •Exposed to dirt, high humidity, leaves, rain.
Wheel-rail interface handbook is a one-stop reference for railway engineering practitioners and academic researchers. Part one provides the fundamentals of contact mechanics, wear, fatigue and lubrication as well as state-of-the-art research and emerging technologies related to the wheel/rail.
• The contact area at each wheel tread / low rail interface is approximately circular, with a typical radius of 7mm. • The rail steel can be assumed to have a shear yield strength of k=70 ksi. • The rail surface is dry, with a nominal COF of μ= However, the influence of the oxides is also important.
Particularly in the field, iron oxides are inevitably presenting on wheel and rail surfaces affecting adhesion. A more quantitative investigation is needed in order to develop a model based on the effect of iron oxides and surface by: wheel and rail, and the adhesion database which is based on rotation with friction was established.
This paper is organized as the followings. Section 2 describes the design of the scaled adhesion test-bench for analyzing the wheel/rail contact. Section 3 deals with experimental results for measurement of adhesion coefficient.
The main File Size: KB. Poor adhesion can make the wheel to slip on the rail surface during braking or traction process, which results in serious wear and damage of wheel/rail interface, as shown in Fig.
Furthermore, a white etching layer is the metallurgical feature associated with surface damage caused by severe wheel slip on the rail surface .Cited by: The book provides a necessary grounding in the science and practice of adhesion, without which adequate surface preparation is impossible.
Surface characterization techniques are included, as is an up-to-date assessment of existing surface treatment technologies such as Atmospheric Plasma, Degreasing, Grit blasting, laser ablation and more.
High pressure water is often used to remove leaf films on the rail surface , , , , and it is usually used in combination with sanding , . Special trains equipped with sanders and high pressure washers are routinely operated on areas of track where low adhesion conditions due to leaves are by: Wear, particle emission and adhesion are all wheel-rail contact phenomena and are covered in this paper.
Wear can be defined as the loss of material from a surface, as exemplified in igure 2, while F. Keywords: Rail/wheel, adhesion, rolling contact, water lubrication, EHL 1 INTRODUCTION Adhesion between rail and wheel is one of the most important factors for the railway tribo-system, since it greatly influences the running stability of vehicle, especially the acceleration and deceleration of.
Sanding improves adhesion coefficient but aggravates the surface damage of wheel and rail materials. With the particle diameter and feed rate increasing, the adhesion coefficient is further. Rolling resistance, sometimes called rolling friction or rolling drag, is the force resisting the motion when a body (such as a ball, tire, or wheel) rolls on a is mainly caused by non-elastic effects; that is, not all the energy needed for deformation (or movement) of the wheel, roadbed, etc., is recovered when the pressure is removed.
Two forms of this are hysteresis losses (see. IMPROVEMENT OF WHEEL-RAIL ADHESION. Positive identification of "secondary conditioning" by electron microscope and further investigations relating to the elimination of oily conditions round the oxide particles formed, together with a study of the effects of applying fluids to the rail surface, offer increasing practicalities to overcoming wheel-slip induced by rail surface : H I Andrews.
Cann () studied the problem of leaf residue and loss of adhesion in the wheel–rail contact using a ball-on-disc test device.
Analysis of the black film formed by the leaves at the contact showed that it was due to a chemical reaction between water-soluble components of the leaves and the steel by: 8.•Surface temperature was found to have a significant impact on the improvement of friction; possibly ˚C could be enough to achieve the necessary friction coefficient for traction Publication arising from this project •The low adhesion problem due to leaf contamination in the wheel/rail contact: Bonding and low adhesion mechanisms.
Many of the engineering problems of particular importance to railways arise at interfaces and the safety-critical role of the wheel-rail interface is widely acknowledged. Thus better understanding of wheel-rail interfaces is critical to improving the capacity, reliability and safety of the railway system.