Piezoelectric pick-up device for measuring pressures within hollow bodies

A piezoelectric pick-up device for measuring the internal overpressure of a hollow cylindrical body on the basis of its elastic deformation, comprising a pick-up device having two opposed parts, a cavity provided in the pick-up device to enclose the measured cylindrical body therebetween, at least two opposed recesses in said pick-up device, a motion transmitting element and a piezoelectric plate arranged in each recess opposite to each other, each said motion transmitting element being arranged to provide mechanical communication between the associated piezoelectric plate and the outer surface of the measured body and being disposed symmetrically with respect to the axis of the measured body, a circular transverse groove machined in the cavity of the pick-up device, a multipart insert of a strong rigid metal fitting tightly in this circular groove, the radially inner surfaces of the motion transmitting elements and of the inserts forming circumferentially aligned segments cooperating to surround and accurately engage substantially the entire outer surface of the measured body, and means for clamping together the two parts of the pick-up device.