eng Science and Education Publishing American Journal of Mechanical Engineering 2014-11-11 2 7 282 285 10.12691/ajme-2-7-23 AJME20142723 article Robert Surovec 1 Jozef Bocko 2 Juraj Šarloši jurajsarlosi@gmail.com 2 ZTS VVÚ a s. Južná trieda 95, 041 24 Košice, Slovakia Faculty of Mechanical Engineering Technical University of Kosice Letná 9, 042 00 Košice, Slovakia 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. http://pubs.sciepub.com/ajme/2/7/23/ajme-2-7-23.pdf lateral vibration rotor �C dynamics damped free vibration undamped free vibration f?ppl-jeffcott rotor