Note to an Undercut Limit of Involute Gearing

An undercut of an involute tooth flank is a routine matter. Moreover there is no need to be concerned with an undercut if there is no problem with teeth strength. A problem occurs if undercutting strikes not only a root but an involute flank too. It even does not matter until an operational part of an involute is not cut off. In this case the size of decreasing of a transverse ratio coefficient ea is necessary to specify. This contribution deals with two approaches to the determination of start of undercut involute and performs their evaluation with possible implications. At the conclusion the contribution is highlighting to one unpublished fact.