Abstract: An ultrasonic railhead investigating apparatus is described wherein a side looking transducer is used with a lens to focus the beam in a manner whereby rail defects in the sides of rail head are more readily detected. In one form of the invention a side rail investigating transducer is provided with a curved emitting surface and so located as to place the focused acoustic beam between a side of the rail and the rail center. The curved emitting surface can be part of a cylindrical surface aligned parallel with the longitudinal axis of the rail or a spherically shaped emitting surface to provide a conically shaped beam for investigating the side of a rail.

Abstract: An ultrasonic rail flaw detection system and technique are described for the detection of flaws in the sides of rail heads. An ultrasonic transducer is oriented, sized, and so-located so as to produce an ultrasonic beam within the head whereby at least a portion of the beam will intersect a lower side corner independent of the curvature of the rail head running surface and the amount of head wear. The presence of premature reflections or the or absence of reflections can be used to detect flaws such as vertical fractures in the rail head. The side-looker is so oriented as to produce a beam in the rail head that lies within 45.degree. to 75.degree. of the normal to the rail surface. The side-looker can further be so located that its beam does not interfere with or be interfered by beams from other transducers used to investigate the rail and mounted in the same wheel assembly as the side-looker.