In this article, we consider DC direct-current motors used in special responsible electric drives, for example, autonomous small-size systems operating in short-time modes, namely, their modernization and the resulting problems in calculating the strength of the collector. The solution of these tasks is required in connection with the new operating conditions of the reservoir, since modernization is associated with increased power, including through increased rotational speed. The article presents the results of the development and application of the method of strength calculation of a reservoir, which specifies the values of stresses arising as a result of tightening the conditions of the collector and the electric motor as a whole. The characteristics of the real samples produced from the results of the studies are an indicator, first, the adequacy of the proposed calculation technique, and secondly, the applicability of this technique in industry.