This standard presents a new basic rack, AGMA PT, which, with its full round fillet, may be preferred in many
applications of gears made from plastic materials. It also explains and illustrates the general concept of the
basic rack. It contains a description, with equations and sample calculation, of how the proportions of a spur or
helical gear may be derived from the design tooth thickness and the basic rack data. These equations and
calculations use ISO based symbols and metric units. In several annexes, there are discussions of possible
variations from this basic rack and also a procedure for defining tooth proportions without using the basic rack
concept.