Research on the principle of railway wheel out-ofroundness on-line dynamic detecting system based on Laser measurement

Out-of-roundness of wheel-set is one of the main reasons which will cause the significant damaging effects to the rail for high-speed train, and quantities measuring out-of- roundness on line is a worldwide problem today. To solve the problem, a system module of `Laser-PSD´ is presented, which uses the track dynamics and detecting displacement of light spot in PSD to calculate the tortuosity of steel rail to get the size of out-of-roundness. The amplitude change of different sensors for the same wheel in the curves is found to be something to do with the wheel out-of-roundness. The system module has an enlightening function to raise the detection accuracy in the quality of railway wheel-set, and play a significant role in the safe operation of trains.