Rotational Properties of a Motor with Resonating Crystalline Quartz

Mechanical rotations of X-Y-Z-cut crystal resonators (rectangular parallelepipeds cut perpendicular to the X, Y and Z axes) were investigated as functions of electrode gaps, ring-spacer dimensions, and acoustic streamings. The crystals of certain dimensions rotated when resonating at fundamental frequencies f X 1 of the X axis thickness vibrations and at satellite frequencies near f X 1, with use of a particular ring spacer under the crystal. Under the experimental conditions used by us, it was found that the horizontal components of the acoustic streamings (wind) play no important role in the rotation, and that there are some cases where the rotational directions change depending on the frequencies.