Cylindrical gear failure due to tooth wear is one of the most common reasons for the decreased technical and economic indicators of various units resulting from the forced downtime for gear replacement or repair. Nowadays, the linear wear rate, an indicator that is found experimentally, is used to determine gear service life based on the statistical linear dependence of the wear on the friction forces. The determination of this indicator requires a large amount of data on the wear obtained with real transmissions or relevant laboratory samples that increases time and financial costs. Therefore, an analytical model of wear failures has been developed for project estimation of gear service life and the search for effective and lasting design solutions. The model represents a system of constitutive equations, which includes an energy equation describing the change in the current state of a pair of wear gear wheels and the conditions for their transition to the limiting state, a basic kinetic dependence of the energy-mechanical theory of stationary tribocoupling wear, and an equation for determining the transmission's expected service life. The simultaneous solution of this system of equations taking into account the dependencies that describe the initial and boundary conditions of the gear element interaction resulted in the formulation of the algorithm for calculating their average expected service life. This allowed the authors to perform a comparative analysis of the effectiveness of various design options for improving gear durability and select the most appropriate ones. A distinctive feature of the proposed calculation algorithm is that it does not involve searching for experimental parameters similar to the linear wear rate