A measuring trolley was developed for measuring rail wear. With laser measurement and a carbide measuring beam, the rail profile and the longitudinal grooves are recorded over the entire measured network. With the measurement data the rail wear can be monitored and the maintenance can be planned much better. The measuring module was designed to be as light as possible and modular, based on aluminum profiles. Different track widths can be adjusted without tools by simple hand grips. The measuring module was designed to be charged and operated directly with the Defender. Tricky during development was the thermal expansion of the carbide measuring beam, which grinds constantly over the rails. This caused distortion and measurement errors in initial testing. The problem was solved by a solid aluminum beam, which can dissipate the heat much better.