Methods for the determination of rail vehicle motion resistance are briefly described, with special consideration given to the gravitational method of movement down an incline. After a theoretical discussion, an example of the application of the gravitational motion method by scaled-down model of a T 155-EMD SD 35 rail vehicle in HO standard 1: 87 is presented in detail. Experimental imaging is accomplished by means of a digital camera. Temporal measurements are obtained by snapshot reading. Rail vehicle constant resistance in relation to velocity is determined by the gravitational method. The application of this method on a scaled-down model is proved and it can be easily used on real models.