Abstract: A shoe (1) is provided which includes two housings designed for receiving ultrasonic probes (2) of which the vertical position with respect to the track is adjustable via two pressure cylinders (9). The shoe (1) is connected via two pressure cylinders (13) to a frame (12, 22, 23) designed for mounting under a railway vehicle. The shoe (1) is guided and driven along the track by deformable rings (14). Conduits (15, 16) are arranged in the body of the shoe (1) in such a manner as to allow the supply of a fluid in front of the probes (2) and the recovery of one part of this fluid behind said probes (2). Cleaning shoes (30, 30') and high pressure sprayers (31, 31') clean the track in front of the measuring carriage.