The periodic in-service inspection of railway axles with bore hole is in traditional realised with mechanical rotated probes. This needs a great technical effort for reliable electrical contact and sufficient sound coupling of the ultrasonic probes for fast scans. An adaption for different bore diameters is realised by replacement of the whole probe holder. The presented technique works with a rotationally symmetric array whose transducer elements are arranged at a cone and which is centred placed in the bore. The refracted angle is defined by the cone angle and the ratio of the sound velocities in the couplant and in the shaft body. The rotation of the sound beam is mainly realised by an electronic scan of the active aperture without a mechanical movement. Small steps of the rotational angle and the beam forming are realised by electronic control of the active element group. Thus the inspection time for a shaft is reduced and the complex and trouble-prone RF-signal transmission via a commutator ring is not required. The conical probe is applicable for a wide range of bore diameters (e.g. 30 – 70 mm). The adaption is exclusively realised by the different diameters of the blinding for the coupling area. The benefit of the new approach are the shorter inspection time, the reduced maintenance effort for the testing system and the applicability of the conical phased array probe for different bore diameters. The present paper describes the investigations, carried out during the ongoing European Project WOLAXIM. © Civil-Comp Press, 2012.
