Railway transport requires high reliability and safety in operation, which places high demands on the elements of the gear boxes. A particularly important role is played by the wheel reducers, which ensure the transmission of torque from the traction electric motor to the wheelsets of the rolling stock, as well as the braking torque during electrodynamic braking applied to the same wheelsets. In this work, a strength-deformation analysis of a wheel reducer for metro cars used in the Sofia Metropolitan is carried out. The main objective of the study is to find weak points in the structure through qualitative and quantitative analysis of the acting loads to increase the reliability and operational stability of the transmission mechanism of the bogies in the rolling stock of the Sofia Metropolitan. A review of the transmission mechanisms used in the rolling stock of the metro trains is carried out, considering their design features and operational characteristics. The operational condition of the considered node was analyzed, in which characteristic failures in the elastic membrane coupling EZK-MEM 250-1, related to stress concentrations and installation inaccuracies, were identified and analyzed. The conclusion provides recommendations for improving the design, installation, maintenance, repair and operation of this important for traffic safety node.