This article examines the basic design and functioning of new three-component centered piezoelectric shear accelerator ''Hexemshear'' with a single seismic mass. The instrument enjoys several advantages over similar instruments from a methodological viewpoint, such as allowing uniform measurements of all spatial components of vibration. It is shown that known measuring instruments of the same type, designed for the same purpose, do not take equal advantage of current transducer technology and do satisfy the requirement of unity of measurement among the different coordinates.