Potato harvesting is an important process in crop growing technology. When implementing it, it is not necessary to completely crumble the surface layer of the soil, but only to break up its clods, which is achieved by introducing a spring into the design of the ploughshare. During translational movement, a force arises directed in the opposite direction, which compresses the spring. When the force acting on the ploughshare decreases, it expands, and when it increases, it contracts. The resulting vibrations are transmitted to the soil clods and, with sufficient force, their destruction occurs. Vibrations of the share lead to a change in its kinetic energy. Instantaneous energy increases and decreases, while the average energy remains constant. More complete information about the interaction of the ploughshare with the surface layer can be obtained through mathematical modeling. The purpose of the study is to determine the compression coefficient of the spring. The simulation is based on solving Lagrange equations of the second type in the Cartesian coordinate system with initial and boundary conditions determined by the design of the ploughshare. When compiling a mathematical model, the following were taken into account: – the gravity of the ploughshare; – gravity of the soil layer; – the elastic force of the spring, which creates additional vibrations; – cutting force of the soil layer; – the friction force of the soil layer on the surface of the ploughshare, – the normal reaction of the supporting surface of the ploughshare and the angle of its entry into the surface layer. Modeling made it possible to determine changes in the instantaneous value of kinetic energy, which ranges from 0 to 3.6 J. The optimal amplitude of oscillation of the share during forward motion at a speed of 6 km/h was 0.02 m. The spring stiffness coefficient for loamy soils of the Ryazan region should be in the range of 2200…3000 N/m.