AIA NAS727 PDF

This specification covers blank configurations, gear data and tolerances for 20-degree fine pitch spur gears having standard addendums as depicted in NAS 726 and used extensively in airborne computers and control instruments where low-inertia, low-torque characteristics are required. The specification is not intended to cover gears wherein the gear drives a pinion having less than 17 teeth which require special attention to be given to the relative length of the arc of recess to the arc of approach.

Classifications. -

Because of the transient nature of gear classification terminology resulting from rapid technical advances, this specification and its related standard aviods the use of AGMA-ASA gear quality classifications. Instead numerical values for total composite error and tooth-to-tooth composite error according to AGMA Standards are used to identify gear quality.