A novel nondestructive testing (NDT) system of high speed and high spatial resolution is needed to
detect small cracks on the wheels of an express train. This paper proposes a high-speed NDT system,
which uses the Hall sensors array and parallel signal processing circuits. Linearly integrated Hall
sensors are arrayed on the cross-section line of a wheel, and the Hall voltage are obtained in the
rotation direction. High-speed NDT can be carried out using analog-to-digital converters and micro-
processors. The @VH/@x value, which provides the most important information about a crack, can be
obtained by buffering and calculations. The effectiveness of the novel method was verified by applying
it in the examination of cracks on a wheel specimen model.