Abstract: A screwing device provides an ultrasound-controlled tensioning of a screw connection. A measurement of the pre-tensioning force of the screw connection can be performed without complete fitting of a screwing tool on the screw connection. The screwing tool for this purpose is displaceable axially within a certain limit relative to the rotary drive shaft. The screwing tool is pre-tensioned by a spring in direction toward the screw connection, so that a contact pin arranged centrally inside the screwing tool for electrical contacting of a vibration body is arranged always inside the screwing tool to be protected.

Abstract: Disclosed is a device for sorting fasteners, particularly screws, wherein defective fasteners are identified by a series of mechanical and electrical gauging stations arranged one after the other on a rectilinear conveying track and controlling ejection devices for eliminating screws which are not true in size or in quality. The mechanical gauging stations precede the electrical ones operating on the eddy current principle, in order to prevent neutralization of error signals generated by the electrical gauging stations. In this manner a very high accuracy of the entire sorting device is achieved.