The article presents an approach to the schematization of the processes of random stationary and non-stationary loading of the vehicle structural frame from the side of the wheels and traction coupling devices, as well as deterministic loading from the operating functional systems. In order to reduce the amount of input data for calculating durability, it was proposed, first, to identify loads that are linear combinations of each other, and second, to replace the correlation table of average and amplitude values obtained by processing the original implementation with linear combinations of correlation tables of shorter sections. The expression of some components of the load through other components by multiplying by some predetermined constant allows to reduce the number of independent arguments and, therefore, the duration of the calculation. Similarly, the optimization of the correlation table of the entire record consists in finding the intervals of the same record with such correlation tables that, after applying simple transformations (summation and multiplication), are able to reproduce the original correlation table with a given error. Then the calculation of durability can be performed only for the intervals found, and with the results of the calculation to do the same operations as with the correlation tables. The calculation time can be reduced, the results of the calculation of fatigue life from the schematized realizations will be equivalent to the results of the calculation of the fatigue life from the original realizations by virtue of the theory of linear summation of damage. The approach was tested when schematizing the loading of a combine harvester (ZUK) of the sixth class, developed at Rostselmash, the errors in calculating the durability of the schematized loads were estimated. The reduction of the computation time from schematized implementations in comparison with the initial implementations is shown.