“…In case of limitation of the power of the energy source, in result of strong interaction between dynamic system and engine, Somerfield effect, requiring the increase in power from the energy source (Kononenko, 1980;Alifov and Frolov, 1985), is manifested, a linear two mass system has regular vibration motion within 1 : 1 resonance passing, and the maximum amplitude increases only during passing the resonance (Tsuchida et al, 2003). Vibration in a linear with two degrees of freedom mass system with a drive and non-ideal source and nonlinear rotation moment, is regular before resonance, and irregular during and after 1 : 1 resonance passing (Tsuchida et al, 2003). In a non-ideal system with two degrees of freedom, consisting of a dumped nonlinear oscillator, connected with rotation part, manifestation of Hopf bifurcation is a common property of non-ideal problems, related to hopping phenomenon Balthazar, 2003, 2004).…”