"In drives of vehicles, the torque is transmitted at a relatively large distance. When dimensioning for torsion under static and cyclic loading based on in many cases, connecting shafts long, slender, and are susceptible to bending vibrations. The shaft is therefore necessary to control not only to torsion, but also to bending in terms of modal and spectral properties of the shaft. The paper formulated a mathematical model of one-dimensional linear continuum in the state combined bending-gyratory oscillation. It is performed analytical solution of natural frequencies relative lateral oscillation and analyzed the influence of the rotation shaft to the spectrum of natural frequencies of continuum segment, which forms the basis of a physical model of the shaft when calculating own and forced vibration shaft."