We propose a probabilistic and statistical method of estimating parameters of the traction units, which is the creation of acceptable modes of operation taking into account the probabilistic nature of the load, the probability ratios, and other factors that act continuously and systematically change operational characteristics of machine-tractor units. Presents the graphical dependence of the speed of the shaft of the engine SMD-62 degree load and the coefficient of its variation.

Keywords: mathematical expectation, function of communication, frequency of rotation of the motor shaft, the coefficient of variation, the degree of load probability ratio