Abstract: A railroad wheel test apparatus for sensing and mapping the subsurface of a railroad wheel tread face has a housing assembly with a holding device, a wheel transfer arrangement, a transducer assembly, a positioning and moving table for the transducer and a control apparatus for receiving evaluation signals from the transducer and also for communicating control signals to the positioning table and wheel transfer devices as well as a drive apparatus, where the wheel is positioned in a fluid bath and while the wheel is rotated the transducer imposes an ultrasonic signal on the tread face and receives the response signal therefrom to provide a map of the tread-face subsurface structure.

Abstract: A rotundity gage for measuring the roundness of a wheel tread of a railway wheel. The gage includes a measuring device and is adjustable so as to be capable of measuring different size wheels.