The object of research in this article is the change in the rotor shape during the operation of hydraulic units. The subject of study in this article is the design and geometric state of the shape of a rotor with irregular geometry of hydraulic generators-engines. This study produced a three-dimensional mechanical calculation of the rotor segment for further use during strain gauge tests. Tasks: investigate the peculiarities of the rotor shape restoration technology; to describe the basic assumptions for the three-dimensional mechanical calculation of rotor deformations at the overspeed; and perform a three-dimensional calculation of rotor movements considering the main forces falling on the pole connection, which are obtained using classical methods. The methods used are: finite element method of mathematical modeling of the thermal stress state of nodes. The following results were obtained: a detailed description of the technological process of restoring the shape of the rotor using the hot wedging method is given. Three-dimensional models of the rotor segment were developed, and a three-dimensional mechanical calculation of this model was performed, as a result of which satisfactory values of the displacement of the rotor of the hydraulic generator at the overspeed were obtained, considering the recovery technology. To reconstruct the rotor rim, it is necessary to heat the rotor rim to a temperature difference between the rim and the frame of at least 60 °C. Next, the hot wedging of the rotor rim is performed with the driving of each of the driving wedges by the same amount, which ensures the creation of the necessary diametrical tension between the rim and the frame of the rotor and avoids the displacement of the rotor rim relative to the frame. The control of this process is performed using strain gauges. If necessary, it is necessary to cool the rotor rim until the temperatures of the rim and the frame of the rotor are equal. Conclusions. The scientific novelty consists of a combined approach to the evaluation of the deformation of the rotor rim after restoring its shape, which includes elements of analytical mechanical calculation and calculation in a three-dimensional setting. The presented technology for the rotor restoration process meets European requirements.