ABSTRACT
A feeler is fixed on a slide which can traverse freely in a parallel direction to a tangent to the base circle. During rotation o f a gear, the flank o f a tooth causes a feeler to traverse, so that a linear moire-fringe grating mounted on the slide w i l l provide electrical pulses due to linear displacement. On the other hand, a rotary magnetic scale, fixed to the test gear, is used to provide a train o f pulses, each o f which defines a constant angular increment. The rotary magnetic scale had been developed by the authors as previously described. The pulse signals thus obtained are passed to the special-purpose digital computer, which instantaneously calcu lates departures from the theoretical relationship. The computing circuit (specialpurpose computer) was newly developed by using digital integrated circuits that had gradually been available on the market. The most remarkable advantage o f this system consisted in presetting on the panel switch wi th the base circle radii instead o f preparing the base disc for a tested gear. It should be noted that this happened before the arrival o f both the microcomputer and the personal computer.
