• International Journal of Railway
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• v.6 no.4
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• pp.148-154
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• 2013

This article has tried to review the maximum contact stresses in the contact area of the wheel and rail as a result of lateral movement of the wheel on rail by taking advantage from Hertz theory. Since wheel movement on rail is accompanied by lateral movement due to wheel profile conisity, so the contact point of wheel and rail is not constant and the contact stresses are therefore changeable in every single moment. Since the shape of rail profile and rail inclination, wheel diameter and the mechanical properties of the wheel and rail are effective on the stresses of contact area, these parameters have been studied by applying Hertz theory. This article aims to calculate the contact stresses in different parts on the wheel surface by using Hertz theory.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.33 no.10
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• pp.1099-1107
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• 2009

Numerical simulation and experimental study to evaluate the critical speed of the railway bogie according to the tread inclination of wheel profile were conducted using 1/5 scale model. It has been shown that the results of the critical speed analysis for the scale bogie model is very close to the test results using scale bogie model and the critical speed is decreased in proportion to the increase of equivalent conicity of wheel profile. Results of this study show that the scale model could be applied to research area relating to vehicle stability as an alternative to overcome the experimental problems caused by full scale test on the roller rig.

• Proceedings of the KSR Conference
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• 2005.11a
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• pp.146-151
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• 2005

Main parameters of wheel-rail combination are investigated by profile analysis. A rolling radius difference is one of the main characteristics that describe a contact between wheelset and railway track, which in turn defines the dynamic behavior of a wheelset. This paper describes functional relation between lateral wheelset displacement and rolling radius difference or conicity on new/worn wheel of existing narrow gauge vehicle. Information about curving behavior and running stability are given by this both relations. The optimal wheel profile for railway vehicle with narrow gauge is adopted through this analysis. And, the applicable limit value of conicity which is used in order to do dynamic simulation of vehicle is presented.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2009.10a
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• pp.785-786
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• 2009

• Proceedings of the KSR Conference
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• 2002.10b
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• pp.787-792
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• 2002

This study presents the wheel wear measurement results of Saemaeul train running on the conventional line. The train set included three different cars which have different shape of wheel profile including KNR and KTX profile currently used in Saemaeul. Train set was operated on Seoul-Pusan line with fixed train set formation for commercial service. Wheel wear measurements were peformed periodically. Here, we describe some results.

• Proceedings of the KSR Conference
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• 2003.05a
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• pp.651-655
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• 2003

The rolling-stocks used in conventional line have suffered wheel problems due to lack of adaptability with track. These brought out severe wheel flange wear, these have caused unstable ride characteristics of rolling-stock. Especially, Wheel flange wear is severely influenced by wheel profile but lateral suspension characteristics. This study was started to induce wheel profile suitable for domestic railway environment. Thus, we analyzed the wear characteristics of wheel profiles that are being applied to railway rolling-stock in KNR. To analyze wheel wear characteristics, we have conducted experiment studies for passenger rolling-stock and obtained useful datum.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.854-859
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• 2008

In a railway vehicle, contact between wheel and rail is a peculiar characteristic and variations of wheel and rail profile influence on the dynamic characteristics of railway vehicle. Thus the variations of the wheel and rail profile are very important in railway dynamics. Recently a research relating to active steering to improve the curving performance of vehicle is progressing actively at home and abroad. In this field, a pre-study for the wheel/rail contact geometry is needed and especially the variation of the wheel/rail contact geometry with wheel wear is the key design parameter to develop the controller of the active steering bogie. In this paper, we have experimentally studied to analyze the variation of the wheel/rail contact geometry with wheel wear as a pre-study to develop the active steering bogie for electric multiple unit (EMU). For this, we have made an experiment with EMU operating in curving area. We have measured the wear profiles of the wheel of the test vehicle and analyzed the wheel/rail contact geometry with a mileage of the test vehicle. In experiment with test vehicle, we have got the useful data to design the steering controller of the wheelset.

• Proceedings of the KSR Conference
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• 2004.06a
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• pp.720-725
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• 2004

We proposed new arc-type wheel profiles to improve severe flange wear of conventional wheel profile coned 1:40. We designed many candidate wheel profiles and analyzed the geometric characteristics, dynamic performance and stress at contact points to draw out the final profiles. From the analysis result, we chose two cases of profiles and applied to wheels of test train. Tests carried out in service line to analyze the dynamic performance and verify the wear reduction for two cases of profiles. Test results shows the equal level of dynamic performance and the improvement of wheel flange wear compared with the conventional wheel profile.

• International Journal of Railway
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• v.1 no.3
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• pp.83-88
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• 2008

Since the 1990's the fleet of the Dutch Railways showed a dramatic decrease in wheel tyre life. This lifetime reduction led to an unacceptable increase in life cycle costs. Therefore Lloyd's Register Rail has proposed to NedTrain to investigate the possibilities of improving the wheel tyre life. Three improvements were determined as most promising and relatively easy to achieve: - Profile optimisation for Rolling Contact Fatigue (RCF) reduction - a new wheel profile has been developed with a better resistance against rolling contact fatigue of the wheel tread. The profile has been implemented on single deck intercity trains and shows an increase in wheel tyre life of 30%. - Selection of improved wheel tyre materials - combining information from literature and experiences of manufacturers five alternative wheel tyre materials have been selected and are now being tested in practice. - Optimisation of the maintenance strategy - an alternative, preventative maintenance regime has been developed. With this Scraping regime, during short term maintenance every wheel is reprofiled. Higher mileages are reached and savings on life cycle costs up to 50% and more have been achieved. Unplanned maintenance goes down with $30{\sim}60%$. The results from field tests, using a reference group for comparison, and preliminary results after implementation show that the increase in wheel tyre life that is achieved with this project is significant. The results will continue to be monitored using the asset management tool 'Wheel Watch', that was specially developed for this project and is also described in this paper.

• Journal of the Korean Society for Railway
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• v.7 no.3
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• pp.259-263
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• 2004

The running safety of a railway vehicle depends on the design parameters and contact condition between wheel and rail. In this study, the effect of the conicity of wheel tread is analyzed using ADAMS/RAIL software on running situation. Modal analysis shows in 0.6 Hz natural frequency of lateral mode in fully arranged the KTX cars. The excessive vibration of the tail cars occurs in the 17th car as the speed and the stiffness of the secondary suspension increases, and especially for 1/40 conicity of the GV40 wheel. Also, the analysis shows that combination of wheel profile, GV40 for power cars and XP55 for passenger cars can reduce the lateral vibration of the tail cars.