The article studies the dynamics of resonant vibration machines with a variable mass of the material processed, used in vibrational transportation, screening, compaction, etc. The main purpose of the work was to substantiate the use of nonlinear elastic elements as a suspension of the working bodies of vibration machines with unbalanced vibration exciters to ensure a constant resonant excitation frequency at various system mass values. The design circuit consisted of a single-mass vibration machine in the form of a system with a concentrated mass, mounted on a nonlinear elastic spring performing rectilinear oscillations in the field of gravitational forces. The static characteristic of the unbalanced vibration exciter motor was taken into account, leading to a nonlinear interaction of the working body and the unbalanced vibrator due to the presence of an imperfect energy source in the system. The supply voltage of the electric motor was taken as the control parameter. Based on Lagrange equations of the second kind, a system of differential equations has been developed that describes respective system motion depending on the mass of the material being processed. The amplitude and frequency characteristics were established depending on the power supply voltage of the electric motor and the average rpm of the unbalance for various material mass values. A manifestation of the Sommerfeld effect was observed. The constancy of the resonance amplitude and vibration frequency of the working body of the vibration machine on an equal-frequency suspension at various load mass values has been shown.The study was carried out under grant No. 21-19-00183 issued by the Russian Science Foundation.