ABSTRACT
The critical speed is the speed at which the rotating speed of the spindle with the rotor and wharve is equal to the circular natural frequency of the rotating systems. When the rotor's spindle transfers from massive to weightless, the equivalent mass is determined by the equality of the critical speed of the massive shaft with the critical speed of the weightless spindle; it has a different value due to the type of shaft bearings and their locations along the shaft length. In practice, the value of the equivalent mass is too small compared to the rotor's and the wharve's mass; therefore, when we calculate the critical speed of the rotor set, it can usually be neglected. The dynamics of the open-end spinning machine's rotor refer to three items: the critical speed of the rotor; the amplitude of the mechanical vibrations; and the dynamic reactions in the rotor's bearings.
