2-11At this time, an urgent area of development in the field of railway transport is the reduction of operating costs for maintenance and repair of collector traction motors . The analysis of data from the monitoring of new rolling stock shows that one of the elements affecting the reliability during the operation of traction motors is the collector-brush unit. Failures associated with unsatisfactory operation of the collector-brush unit elements reach 30% of the total number for traction motors. At work of traction electric motors there is a continuous process of mechanical, electric and chemical interaction of electric brushes with a collector, leading to deterioration of electric brushes. During the research, the authors proposed a mathematical model to determine the intensity of wear of electric brushes. The paper provides information about developing an approach that allows using the operating data recorded by locomotive on-board parameter monitoring system to determine the service life of traction motor brushes. For elimination of the problem connected with processing of big arrays of parameter values for calculation, in mathematical model of intensity of wear of electric brushes it is offered to divide the received data into intervals with definition of average values and probability of approach for each of them, and also the technique on realization of the offered decision is resulted. The developed approach allows us to eliminate the need for long-term wear tests on traction motors in operation and reduce not only time, but also financial costs. The reliability of the developed method was assessed by comparing the wear values of different types of electric brushes installed on locomotive traction motors in operation with the calculated values.