 Elements of Metric Gear Technology by SDP-SI

Manufacturer technical reference, §3.1, definition of pressure angle as the angle between the line of action and a perpendicular to the line of centers. The line of action is the common tangent to the base circles. The corresponding current manufacturer page is shop.sdp-si.com/products/gears-differentials-pinions-racks/spur-gear-technical-information.html .

Elements of Metric Gear Technology, §7.3, equation(7–8), printed T-60: helical-gear axial thrust equals transmitted tangential load times the tangent of helix angle. Figure7-1 relates thrust direction to gear hand and rotation.

D815 technical section, §11, Table11-3, “Axial (Overlap) Contact Ratio”, printed T-111: helical overlap ratio is face width times sine of helix angle divided by normal circular pitch. This indexed manufacturer edition carries copyright2019.

D815 technical section, §17.2.12, printed T-164, and Table 17-11: tooth-flank load distribution depends on face-width-to-diameter ratio, shaft bearing arrangement and shaft stiffness. The manufacturer distinguishes an uncertain loaded-contact case from one whose contact is predictable.

D815 technical section, Section 19 and §19.1, printed T-221: tooth-surface contact, assembly alignment and interpretation of surface contact for spur and helical meshes.