a method for converting micromotions into macromotions by providing a plurality of piezoelectric members having surface areas sufficient to change the volume of the piezoelectric members macroscopically when their lengths are changed microscopically . the members are located in a sealed chamber filled with an incompressible dielectric liquid . when the piezoelectric members are increased in their volume under the effect of an electric current , this variation of volume is transmitted through the incompressible liquid to a small - diameter piston rod which is made integrally with a piston head of a substantially greater diameter . the piston head is located in a hydraulic cylinder of a hydraulic multiplicator which transmits the pressure developed in a chamber of the hydraulic multiplicator to a piston . this piston is connected to a working tool , so that when the piezoelectric members increase in their lengths microscopically , this microscopic increase in length is converted into a macroscopic increase in volume of the piezoelectric members which via the incompressible liquid displace piston rod for a substantial length which is further increased by the hydraulic amplifier and is transmitted to the working tool . an apparatus for carrying out the above - described method is made in the form of a hermetically sealed housing divided into a first chamber and a second chamber . the second chamber is filled with the incompressible liquid and contains the above - mentioned piezoelectric members , while the first chamber forms a part of the above - mentioned hydraulic amplifier .