Abstract:Abstract: In order to ensure the unity, accuracy and reliability of the level wheel positioning measuring instrument and the portable braking performance tester, a calibration device for the level wheel positioning measuring instrument is proposed. The calibration device is designed according to the requirements of the current effective national metrological technical specifications. The sensor and incremental angle encoder for measuring displacement based on the principle of grating moire fringe are developed, which has the comprehensive calibration function of one machine. Through the use of the calibration device and the comparison and analysis of the experimental data, it is shown that the measurement results of the calibration system are accurate and reliable, and can meet the requirements of value traceability.