The purpose of the study is to evaluate the energy parameters of tower cranes when using a frequency-controlled drive mechanism. The relevance of the study lies in the fact that existing tower cranes quickly become obsolete. However, there is an alternative to buying new cranes – the modernization of existing ones with the improvement of their parameters and the scientific justification for increasing the efficiency of work. The following methods are used for research: method of equivalent power and the methods of metal fatigue theory. The main scientific novelty is the approach to assessing the possible increase in the service life of crane elements when using a frequency drive based on the theory of fatigue. Also presented are examples of equivalent power calculations for the working cycles of the turning mechanism with various forms of speed change in acceleration and deceleration modes. Numerical estimates are given for increasing the service life of the main types of welded joints with different values of stress concentration factors. Showing ways to further improve the efficiency of tower cranes and their mechanisms due to more optimal transients. The proposed approaches can be used when choosing the type of drive for the designed crane or to evaluate the economic efficiency of replacing the drive.