Piezoelectric inertia motors, also known as “stick-slip-drives”, use the inertia of a body to drive it by means of a friction contact in small steps. While these steps are classically assumed to involve stiction and sliding, the mo-tors can also operate in a “slip-slip” mode without any phase of stiction. In this contribution, a one degree of freedom model of an inertia motor is used to analyse the motor characteristics. Appropriate performance indicators for the slider motion are defined: Start-up time, steady state velocity, and smoothness of motion. Inertia motors reach their theoretical maximum velocity with ideal signals containing harmonics of very high frequencies. With frequency-limited real signals, high motor velocity can only be achieved in “slip-slip” mode. The maximum motor velocity is reached by superposition of two sinusoidal signals, other signal shapes can improve other performance criteria. The results help motor designers to choose the appropriate mode of operation and the best drive parameters for their individual applications. ************ Dieser Artikel wird im Juni 2012 in "Proceedings of ACTUATOR 12 International Conference and Exhibition on New Actuators and Drive Systems" erscheinen. Die Konferenz findet am 18. bis 20. Juni in Bremen statt.