Device for measuring deformations of the travel surface of the rails of a railway

Device for measuring deformations of the travel surface of the rails of a railway track of at least one wavelength contained within a selected wavelength range (.lambda..sub.1), comprising a traveling chassis (1) resting on at least one line of rails by two spaced guide rollers (3 and 4), the chassis being connected to a vehicle traveling over the track at a given speed (V) and being equipped with at least one group of measurement pickups giving off electric signals representing distances between a linear reference base defined by the position in space, of the said rolling chassis and the line of rails moved over, and also comprising a circuit for the processing of these signals intended to determine the value of the trough (H.sub.1) of the said wavelength deformation, characterized by the fact that the group of measurement pickups comprises at least one first set of two pickups (5 and 6) arranged opposite a generatrix of the line of rails moved over at a distance from each other (E.sub.1) less than the shortest wavelength (.lambda..sub.1 M) of the selected wavelenth range (.lambda..sub.1) and supplying two electric signals representing two distances respectively (h.sub.A and h.sub.C) between two points (A and C) of the base reference line (AC) of the base reference line (AC) and the said generatrix, and by the fact that these two pickups are connected to an electronic measurement circuit comprising a comparator (8) giving off an output signal representative of the difference (.DELTA..sub.1 =h.sub.A -h.sub.C) of the two said distances, an apparatus (9) for determining the effective average length (.lambda..sub.1 E) of the wave of the deformation detected, giving off an output signal representing said magnitude, and an apparatus (10) for the processing of these signals (.DELTA..sub.1 and .lambda..sub.1 E) connected to the outputs of the comparator (8) and of the determination apparatus (9) and delivering an electric output signal representative of the trough (H.sub.1) of the said deformation by processing of the said difference (.DELTA..sub.1) in accordance with a transfer coefficient (T.sub.1) established on basis of the ratio (E.sub.1 /.lambda..sub.1 E) between the distance (E.sub.1) between the two pickups (5 and 6) and the determined effective average length (.lambda..sub.1 E) of the wave of the detected deformation.