The article presents a complete procedure for determining the actual traction effort of a rail vehicle. The research was carried out on an industrial electric locomotive powered by a battery car. They were carried out during its normal operation. In the text, the authors drew a particular difference in the discrepancies between theoretical and measurement results. This is an important issue from the point of view of FEM calculations, because it is used as a load on the model. It is also one of the main technical parameters defining the scope of possible operation of the locomotive. For this reason, traction effort is an important aspect not only for FEM calculations but also for operation.