Please review ANSI/AGMA 2015-1-A01 in regards to tolerance diameter for internal gears.
Figure 3 implies that the standard applies to internal gears. However, the definition of tolerance diameter, as written, applies only to external gears. In addition, equation (2) needs to be changed to accommodate internal gears.
In reply to the request for interpretation, the Inspection & Handbook Committee feels that the definition of tolerance diameter may be more clearly stated as:
…tolerance diameter, dT The diameter located one normal module from the design tip diameter, thereby being approximately at mid-tooth height. For external gears, it is calculated by subtracting twice the normal module from the outside (tip) diameter. For internal gears, it is calculated by adding twice the normal module to the inside (tip) diameter.