A study on safety against derailment of twisted track based on EN 14363 standard
A study on safety against derailment of twisted track based on EN 14363 standard
Blog Article
When a railway vehicle is running on the track, it is inevitable that it will pass through the twisted track caused by factors such as track superelevation, twist warp, rail gaps, turnouts and geometric irregularity of track.When a vehicle passes through a twisted track on a minimum plane radius curve at low speed, the risk of derailment increases.However, there is no standard method for assessment of safety against derailment on a twisted track in China at present.Therefore, in this paper, the method for assessment of safety against derailment on a twisted track stipulated in the EN 14363 standard was researched.A city vehicle was taken as an example, and the assessment was made based on three methods specified in the standard.
For method 1, the wheel lift was required to be measured on a twisted track and a plane curve with R150 m, and the wheel lift of no more than 5 mm shall be regarded as the assessment limit.For method 2, the vertical wheel-rail force was required to be measured on the straight section of the twisted track, and the lateral wheel-rail force of the outer wheel to be measured at R150 m on a plane curve.The ratio Y/Q of the lateral wheel-rail force to the vertical wheel-rail force on the outer rail side Puzzle of the curve shall be calculated according to the formula, and the value of Y/Q not exceeding 1.2 shall be regarded as the assessment Ashtrays limit.For method 3, the slewing resistance coefficient was required to be measured on the test bench and the rate of wheel load reduction to be measured on the twisted track.
The slewing resistance coefficient not exceeding 0.1 and the rate of wheel load reduction not exceeding 0.6 shall be regarded as the assessment limit.The results show that compared with method 1 and method 2, method 3 results in the worst track twist, and the maximum vertical displacement of the wheel during the track twist is 80.1 mm.
For a vehicle, the wheel load reduction increases when the vehicle passes through the twisted track due to the fact that the vertical stiffness of the secondary system increases nearly 10 times in the deflated condition of the air spring.The deflated condition of the air spring results in a lower ability to adapt to the twisted track compared with the inflated condition, and the maximum limit ratio is 98%.For the convenience of simulation and test comparison, it is recommended that when assessing the safety against derailment on the twisted track according to EN 14363, method 2 should be used.That is, the vertical wheel-rail force shall be measured on the straight section while the lateral wheel-rail force measured at R150 m.