Apparatus for measuring the profile of a railroad tunnel

摘要

A mobile apparatus for measuring the profile of a railroad tunnel comprising a car mounted for mobility on the railroad track, a beam emitter and receiver instrument capable of continuously receiving a signal corresponding to the distance of the tunnel profile from the instrument, a rotatable axle supporting the instrument on the car for pivoting about an axis extending parallel to the longitudinal track axis, and a drive arranged to pivot the instrument about the axis extending parallel to the track axis whereby the instrument may sweep the profile and continuously receive the signal.