• Journal of the Korean Society for Precision Engineering
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• v.23 no.11 s.188
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• pp.85-92
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• 2006

For the improvement of a conventional railway speed, tilting train(Tilting Train express) is under the development aiming for a maximum speed 180km/h. Compared to the existing conventional rolling-stock, tilting train could take an advantage of speed improvement about $20{\sim}30%$ on curve sections due to the improvement of cowing performance. However, this speed increasement creates a severe load at wheels, thus it is necessary to study the safety of wheel for tilting train preferentially. On the other hand, it is under consideration that the wheel for conventional railway rolling-stock at speeds of 150km/h will be applied to tilting train at speeds of 180km/h. In this paper, we have studied the strength of wheel structure, the geometrical contact characteristics, and the dynamic performance of wheel to evaluate the safety of wheel for tilting train.

• Journal of the Korean Society for Railway
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• v.8 no.5
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• pp.490-494
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• 2005

The geometric parameters between wheel and rail change wheel/rail contact geometry characteristics, and this influence dynamic behavior of rolling stock. So, the selections of optimum geometric parameters between wheel and rail is important for planning of railway system. In this study, we have analyzed the influence of geometric parameters like wheel flange-back distance, gage, and rail inclination on the equivalent conicity relating to dynamic behavior. The analyses show the following results. The widening of wheel flange-back distanc, the decrement of gage increase the equivalent conicity and the increment of rail inclination show the sharp change of the equivalent conicity.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.31 no.7 s.262
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• pp.756-763
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• 2007

The majority of catastrophic wheel failures are caused by surface opening fatigue cracks either in the wheel tread or wheel flange areas. The inclined cracks at railway wheel tread are initiated and the cracks are caused by wheel damage-spatting after 60,000 km running. Because the failured railway wheel is reprofiled before regular wheel reprofiling, the maintenance cost for the railway wheel is increased. Therefore, it is necessary to analyze the mechanism for initiation of crack. In the present paper, the combined effect on railway wheels of a periodically varying contact pressure and an intermittent thermal braking loading is investigated. To analyze damage cause for railway wheels, the measurements for replication of wheel surface and the effect of braking application in field test are carried out. The result shows that the damages in railway wheel tread are due to combination of thermal loading and ratcheting.

• Journal of the Korean Society for Railway
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• v.15 no.6
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• pp.543-549
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• 2012

This study describes the tail vibration reduction for the next generation high speed EMU(HEMU-430X). The model of 6 cars was generated and the calculation was performed using VAMPIRE(railway vehicle dynamic software). In view of ride characteristics, HEMU-430X was expected to sway at the tail because of the yaw damper direction. The lateral acceleration of vehicle body exceeded the criteria because of hunting. To reduce this hunting motion, some methods such as wheel profile change, the change of damping coefficient for the 2nd lateral damper, the damping coefficient change of yaw damper were tested, but had little effect. Finally, the yaw damper direction was changed and the tail vibration disappeared. In real running test, the tail vibration appeared at the speed of 150km/h and the yaw damper direction change made the vehicle stable at the speed of 300km/h. The maximum test speed of HEMU-430X is 430km/h. If the tail vibration appears at higher speed, some other methods in this study may be considered to reduce it.

• Proceedings of the KSR Conference
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• 2004.06a
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• pp.664-669
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• 2004

In rolling stock, wheels are one of the most important components to run on the track in safety. Especially, it is important that wheel profile cause the variation of dynamic characteristics and running safety. The purpose of this paper is to propose the wheel profile and to know the effectiveness of improved wheel profile by using microphones. We also performed analysis of running safety to know application of improved wheel profile before the test. In result, the improved wheel profile was stable in running safety and noise level was reduced.

• Proceedings of the KSR Conference
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• 2003.05a
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• pp.663-667
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• 2003

Mechanical force acted on the rail wheel causes excessive wear and increases the maintenance cost. The present paper proposes newly designed wheel profiles in order to reduce the contact stress. Numerical analysis on the stress distribution of wheel-rail contact stress is carried out using ABAQUS, a commercial finite element code. The result of KNR1/40 conical wheel is compared to those of the proposed wheels, all of which are arc wheel profile type.

• Proceedings of the KSR Conference
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• 2003.05a
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• pp.730-733
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• 2003

In this study, it have been measured the vertical and lateral vibrations of car bodies which have an equivalent conicity of 1/20 and 1/40. Based on the measured data, it is revealed that the wheel, XP-50, which has the equivalent conicity of 1/20 causes the better riding comfort of KTX.

• Proceedings of the KSR Conference
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• 2003.05a
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• pp.641-644
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• 2003

The running safety of the rolling stock depends on the design characteristics and the contact condition between wheel and railway. In this study, it is analyzed how equivalent conicity of wheel tread or its characteristics has influence on the running safety.

• Journal of the Korean Society for Railway
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• v.8 no.5
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• pp.477-482
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• 2005

Through a year's commercial operation, Korea High Speed Railway has solved defectives from several breakages at the beginning and is going into the stage of stable operation. Among issues, wheel wear becomes a matter of primary concerns in view of vehicle's stability and maintenance. It was understood as above that wear status has been improved in the test by which railway system including vehicles and tracks was stabilized during a year's commercial operation, comparing to that with excessive wear in the trial operation prior to opening to the public. To make out wheel's wear status and characteristics of equivalent conicity at present when the service has been introduced a year ago and the average cumulative mileage of vehicles reach almost 500,000km, wheel's wear types were analyzed with the current vehicles in service.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.934-939
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• 2004

Railway wheel/rail contact conditions have an influence on dynamic behavior of rolling stock. If there are problems of incompatibility between wheel and rail, damages like wheel wear, wheel spalling, rail wear, etc are occurred. Especially wheel and rail profiles are important factor of vehicle curving performance, so compatibility study between wheel and rail has to be carried out preferentially, In this study, we have analyzed the compatibility between wheel and rail of KNR conventional line to improve the maintenance efficiency of wheel and rail. Thus we showed the results relating to wheel/rail geometric contact, vehicle running performances as the change of wheel/rail combination.