12.1 Normal module

The normal module mn is only shown if metric units are selected (see 1.3.3). It is defined as mn = p∕π and standard values are usually given in millimeters and can be found in ISO 54 or DIN 780. The size of the gears is increasing with the module.

The transverse module mt is the normal module divided by the cosine of the helix angle: mt = mn cos ψ.