The problem of finding the components of the inertia tensor of irregular solids is fundamental for effective analysis of equations of motion of the medium which is processed by the agricultural machine. That problem is important both for the cultivating and harvesting machines. The paper presents an example of indirect analysis performed based on motion pictures of the "cubicoid" cut out from the wheat grainfield by the working parts of the harvesting complex. There have been analysed the movement of the center of mass of the vertical cross-section of the "cubicoid" during deflection and cutting as well as the variability of the position of lines of the instantaneous rotation of the side of the "cubicoid" facing the knife. It has been stated that in the case of the discussed general movement a gyroscope effect occurs.