The article presents selected results of strength simulation tests of the load-bearing structure and coupling-buffer devices of a third-generation rail-road tractor built from the CLAAS ARION 610 agricultural tractor. Tests for the extraordinary load resistance of components of the front and rear train system were carried out in the aspect of the ability to absorb longitudinal loads and shocks in extreme conditions of tractor operation on the track. It has been shown that the tested components of coupler-buffer devices meet the strength requirements at assumed extreme loads (300 kN compression, 150 kN tensile), and after introducing a modernized front axle support they can withstand a compressive strength of up to 370 kN. The second part of the article will be published in the next issue of the quarterly journal Rail Vehicles.