Abstract:In order to dig the hidden trouble of subway train’s service air braking, the following performance of cylinder volume (CV) actual pressure and CV target pressure is chosen to be the fault feature. According to the change of CV actual pressure of the running train, service air braking process is divided into three typical braking phases: decelerating phase, hold off brake phase and release phase. For each of the three phases with own characteristic a corresponding method is put forward to extract fault feature, including correlation method, mean absolute error method and direct extraction, and there are totally six fault features extracted. At last, the three kinds of typical faults are tested on the brake system reliability test. By means of the criterion of response to the faults, amplitudes of the six fault features in hazard conditions and in normal working condition are compared. And recognition ability of the six fault features are discussed. The effectiveness of the six fault features for excavating the different hidden troubles is established via the comprehensive analysis of the running data and the fault simulation data.