The lifting mechanism of hoisting machines is presented as a compound-chain mechanism, parts of which perform different movements. In the study this mechanism is replaced by a two-tier mechanism, equivalent to the action with the real scheme. Based on the principles of theoretical mechanics, theory mechanisms and Dalamber principle, we received a model of work in three periods: start abd acceleration, steady movement, braking and stopping. The model allows to evaluate the existing static and dynamic moments and to take concrete practical solutions. Numerical examples of using the model was offered, the calculated values of moments and power in three periods of work on a particular lifting mechanism were determined. The model is convenient in practical use, because it doesn´t require cumbersome calculations.