At the testing authority in Minden, strain gages are installed on a wheelset that comprises two wheels and the axle. This setup requires a total of 48 strain gages per wheel (Fig. 1). Signal lines are led into the hollow axle through a hole. The complete electronics including amplifiers and signal transmission is located at the end of the axle.
Installation of strain gages and signal lines is complex and takes several weeks per wheelset. The strain gages need to be individually installed and connected. Since the wheelset is subject to relatively high mechanical stress during the test runs, the signal lines, too, need to be completely bonded.