The aim of the research was to find the possibilities to increase the tribological reliability of the ultrasonic motors at the contact zones of Piezoelectric transducer – rotor or slider, in which both static forces and ultrasonic two dimensional vibrations are taking place. This is important problem – ultrasonic motors offer a high potential for miniaturization, produce no magnetic fields and through their specific advantages compared to conventional electro-magnetic motors, fill a gap in certain actuator applications. They are characterized by extremely high resolution and small response time. Ultrasonic motors have several unique properties such as: high output torque, large breaking torque due to the friction force without energy consumption, low leakage of magnetic flux (1,2). Tribological investigations were performed with the stand of special design (fig. 1).figureFig.1. Schematic diagram of tribological tests of Piezoelectric ultrasonic motor (a) top view; b) side view; c) perforated disc (with 180 rips) fragment): 1 – rotor; 2 and 6 – antifrictional material; 3 – pjezoceramic element; 4 – perforatated disc; 5 – laser sensor; 7 – load hub; 8 – tangential force lever; 9 – tangential force sensor; 10 – normal force sensor; FA – normal force of motor loading; FN - normal force of piezoelectric contact loading; FT – tangential motor rotation force; PC – personal computer Rotor 1 is driven by piezoceramic element 3 through the friction element 2 which is glued to piezoceramic element. The normal force is applied to regulate the force in contact zone piezoelement-rotor surface. The rotation velocity can be measured with special device – perforated disc with 180 rips on it and laser sensor. Other device is applied for measuring of the torque. The load on the rotor is applied vertically through the load hub 7. The different weights can be used for that. Hub begins to rotate with the rotor, the lever (mounted in the hub) presses the tangential force sensor 9 and special program convert the signal to torque parameters. All the data are collected in PC. The experiments estimated the influence of surface hardness of the rotor and normal loading force FN on the variation of roughness parameters of the friction surface, on the rotation speed of rotor and the torque.