故障现象一：治疗时间结束后，牵引床不能自动退回，按下ＥＭＳ钮，有电机转动声，但牵引仍不能退回。故障分析与检修：牵引床不能退回，有可能为电气部分的故障，也有可能为液压系统的故障引起。首先在按下ＥＭＳ钮的情况下，检测退电磁间两端是否有电压，测得其电压值为零， Symptom 1: After the treatment time is over, the traction bed cannot be returned automatically. Press the EMS button and the motor rotates, but the traction cannot be returned. Failure analysis and maintenance: traction bed can not be returned, it may be the failure of the electrical part, it may also be caused by the failure of the hydraulic system. First, in the case of pressing the EMS button, it is detected whether or not there is a voltage between the two ends of the retracting electromagnetic field, and the voltage value thereof is measured to be zero.