Science and Education Publishing American Journal of Mechanical Engineering 2 7 2014 11 11 Lateral Rotor Vibration Analysis Model 282 285 EN Robert Surovec Jozef Bocko Juraj Šarloši ZTS VVÚ a s. Južná trieda 95, 041 24 Košice, Slovakia AJME20142723 10.12691/ajme-2-7-23 2014 10 7 2014 10 20 2014 11 11 In this article we examine the lateral vibrations in rotating machinery can lead to rotor unstable behaviour. In some types of rotating machinery, the angular speed is subjected to wide ranges of change. The problem is to find the range of angular speeds for which a machine exhibits stable behaviour in the presence of the coupling of dynamical modes. For determine of mathematical model for vibration we will use Föppl-Jeffcott rotor model. We will examine a undamped and damped vibration on the Föppl-Jeffcott rotor model.