Your May/June issue contains a letter from Edward Ubert of Rockwell International with some serious questions about specifying and measuring tooth thickness.

Much of the information in this article has been extracted from an AGMA Technical Paper, "What Single Flank Testing Can Do For You", presented in 1984 by the author

In response to Ed Uberts letter, we have come a long way in gearing since WWII. The Europeans do use long addendum pinions in many cases. This modification does improve load capacity, sliding conditions and the working life of a gearset. When modifying a pinion tooth it is necessary to modify the gear tooth or adjust the center distance accordingly but we will leave that to the designers.

This letter is in response to your article asking the readers where their interests lie. The division of Rockwell International where I work has engineering departments in Cicero.

Much information has been written on gear inspection, analytical. functional. semiautomatic and automatic. In most cases, the charts, (if you are lucky enough to have recording equipment) have been explained.

This article describes a new technique for the size determination of external Involute splines by using a span measuring method. It provides application performance information demonstrating how this method and its measurements correlate with the traditional spline ring gage sizing method.

An expression is derived, giving the optimum number of teeth over which the span measurement should be made, for profile-shifted spur and helical gears.

Presumably, everyone who would be interested in this subject is already somewhat familiar with testing of gears by traditional means. Three types of gear inspection are in common use: 1) measurement of gear elements and relationships, 2) tooth contact pattern checks and 3) rolling composite checks. Single Flank testing falls into this last category, as does the more familiar Double Flank test.