• Title, Summary, Keyword: Derailment Coefficient

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Study of Influence of Wheel Unloading on Derailment Coefficient of Rolling Stock (철도차량의 윤중 감소가 탈선계수에 미치는 영향 연구)

  • Koo, Jeong Seo;Oh, Hyun Suk
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.37 no.2
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    • pp.177-185
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    • 2013
  • A new theoretical derailment coefficient model of wheel-climb derailment is proposed to consider the influence of wheel unloading. The derailment coefficient model is based on the theoretical derailment model of a wheelset that was developed to predict the derailment induced by train collisions. Presently, in domestic derailment regulations, a derailment coefficient of 0.8 is allowable using Nadal's formula, which is for a flange angle of $60^{\circ}$ and a friction coefficient of 0.3. However, theoretical studies focusing on different flange angles to justify the derailment coefficient of 0.8 have not been conducted. Therefore, this study theoretically explains a derailment coefficient of 0.8 using the proposed derailment coefficient model. Furthermore, wheel unloading of up to 50% is accepted without a clear basis. Accordingly, the correlation between a wheel unloading of 50% and a derailment coefficient of 0.8 is confirmed by using the proposed derailment coefficient model. Finally, the validity of the proposed derailment coefficient model is demonstrated through dynamic simulations.

Study on Mechanical Parameters of a Wheelset Influencing Derailment of Rolling Stock (철도차량탈선에 영향을 미치는 윤축의 기계적 인자에 관한 연구)

  • Oh, Hyun Sun;Koo, Jeong Seo
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.37 no.10
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    • pp.1207-1218
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    • 2013
  • It is difficult to predict derailment with the existing derailment coefficient like Nadal's formula which is based on the contact forces between one wheel and rail. A new derailment coefficient model developed on a wheelset is able to make a better estimate about the climb derailment, slip derailment, roll over derailment, and mixed derailment types of these. Moreover, not only the mechanical factors considered in the existing derailment coefficients but also other various factors affecting derailment such as wheel unloading and loading, diameter of wheel, and locations of axle-box bearings can be covered with this new derailment coefficient model. That is, the derailment patterns which couldn't be solved with the existing formulas such as Nadal's and Weinstock's models can be analyzed with this wheelset derailment coefficient model because of considering various factors causing derailment. Finally, the validity of the new derailment coefficient model is verified using dynamic model simulations.

A Study on New Measurement of Derailment Coefficient for Rolling Stocks (철도차량의 새로운 탈선계수 측정방법에 관한 연구)

  • Hong, Yong-Ki;You, Won-Hee;Lee, Hi-Sung
    • Proceedings of the KSR Conference
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    • pp.306-312
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    • 2007
  • The running safety of rolling stock is assessed by derailment coefficient. It requires lots of preparatory time, expenditure and high measurement technique to measure derailment coefficient. If derailment coefficient could be measured when track or vehicle is maintained, safety will be improved. The measurement and assessment of running safety is necessary for safety especially for the vehicles newly developed and started service. Therefore measurement of derailment coefficient is most important thing to secure running safety. In this paper, we examined new assessment method which could estimate derailment coefficient by measuring vibration acceleration and displacement of vehicle operating at actual track irrespective of time and place. The new method could be used effectively as a mean confirming running safety.

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Load test of wheel-set for derailment coefficient measurement that have plane style wheel plate (평면형 차륜 형상을 가진 탈선계수 측정용 윤축의 하중시험)

  • Ham Young-Sam;Hong Jai-Sung
    • Proceedings of the KSR Conference
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    • pp.228-233
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    • 2004
  • A derailment coefficient of railway vehicle is as one of important element that estimate running safety. Derailment coefficient is ratio of lateral load/vertical load happens in contact point between wheel and rail. Lateral load increases, dangerous of derailment can rise. There are ground and vehicle to measurement method of these derailment coefficient. Method of ground is simple, but when vehicles passes data of a point, there is shortcoming that acquire locally. Curved surface style wheel shape that use so far among vehicle method in this research wishes to be not but describe about static load test of wheel-set for derailment coefficient measurement that have plane plate shape that manufacture separate way and correction result etc. to test.

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An Assessment of Derailment Safety of Railway Vehicle depending on Curve Rail Condition (곡선부 선로 조건에 따른 차량의 탈선안전도평가)

  • Yoo, Hee-Sang;Park, Kwang-Soo;Lee, Hi-Sung
    • Proceedings of the KSR Conference
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    • pp.953-958
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    • 2007
  • To assess the derailment safety of the Samaeul Train, We developed a fleet analysis model and carried out sensitivity analysis of the variables related to derailment factors with ADAMS/Rail computing analysis method. Depending on the variation of the running speed in curve section, derailment coefficient and wheel load reduction rate are high at right side wheels in slow running speed section and low at left side wheel in high running speed. According to decreasing the radius of curve, derailment coefficient and wheel load decreasing rate are increased. Derailment coefficient is proportional to transition curve length and wheel load decreasing rate is constant. Cant value rising causes wheel load deduction rate rising.

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Estimation of Curving Performance and Running Safety of Gwangju Electric Multiple Unit for City Subway (광주도시철도 전동차의 곡선추종성 및 주행안전성 평가)

  • Ham, Young-Sam;Oh, Taek-Yul
    • Proceedings of the KSME Conference
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    • pp.745-750
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    • 2004
  • For the safety of railway, it should be evaluated for the running safety by measuring the derailment coefficient. Although railway has run the fixed and maintained rail, some of railway is derailed. This report shows the results that performed the static load test, wheelset manufacturing for test, main line running test on the basis of the derailment theory and experience. It is executed main line test into more than 80km/h for estimating the curving performance and running safety of Gwangju EMU. As the test results, could confirm the curving performance and running safety of Gwangju EMU from the results of the wheel unloading, lateral force, derailment coefficient etc. Derailment coefficient was less than 0.8, and lateral force allowance limit and wheel load reduction ratio were enough safe.

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A Study on the Assessment of Running Safety of Railway Vehicle passing through Curve (곡선부 통과 열차의 주행안전성 평가에 관한 연구)

  • Park, Kwang-Soo;Lee, Hi-Sung
    • Journal of the Korean Society for Railway
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    • v.10 no.5
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    • pp.492-498
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    • 2007
  • For the running safety assessment of Saemaul train passing through curves, an analysis model for multibody system has been developed. By using this model and ADAMS/Rail, sensitivity analyses depending on the variation of parameters related to the derailment coefficients have been conducted. At low speed, the derailment coefficient and the unload ratio of right wheel showed higher than left wheel, while those of left wheel showed higher than right wheel at high speed. According to decrease of curve radius, the derailment coefficient and the unload ratio were increased. When the length of transition curve was increased, the derailment coefficient was increased but there was no change on the unload ratio. According to the increase of cant, the derailment coefficient and the unload rate were increased.

Cause and Counterplan of Wheel Climb Derailment at Low Speed on Curves (곡선부 저속주행시 타오르기 탈선의 원인과 대책)

  • Ham, Young-Sam;You, Won-Hee
    • Proceedings of the KSR Conference
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    • pp.1031-1035
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    • 2007
  • When vehicles running, vertical force and lateral force act except load of vehicles to rail and wheel. This force happens by complex motion at running. If mark vertical force by P and lateral force by Q, derailment coefficient displays Q/P, most important indicator pointer of running safety judgment. If Q is grown than P from derailment coefficient, than arrived to derailment because wheel climb or jumps over rail. Wheel climb derailment among kind of derailment is when attack angle is +, wheel and rail strike and flange rides to rail. This derailment occurs much in curved line and occurs in low speed. In this study, occurred when running at low speed on curved line, analyze cause of derailment and presented the countermeasure plan.

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Finite Element Analysis of Wheel-set for Derailment Coefficient Measurement that have Plane Plate Shape (평면 플레이트 형상을 가진 탈선계수 측정용 윤축의 구조해석)

  • 함영삼;오택열
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • pp.119-122
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    • 2004
  • Since a derailment of rolling stocks results in huge losses in properties and lives, the measurement of a derailment coefficient is a very important test item to estimate the running safety of rolling stocks. For a measurement of the derailment measurement of forces between the wheel and rail a measuring wheel-set should be made first. The process to make a measuring wheel-set has some stages for correct measurement. They are as follows; a finite element analysis of a wheel to find a position of holes at which vertical force shall be measured, a finite element analysis for the position of strain gauges.

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