pinion gear material and construction. 1

[jguti]

I'm a mechanic on helicopters and I'd like to know if pinion gears in main transmisions, intermediate and tail gear boxes have been hardened and how?...a friend told me that teeth have been thermically treated on the surface but I'm not sure of it and I'd like to have things clearer.

 

[FredGarvin]

They are most certainly hardened. Usually not thru hardened but most likely surface hardened. You will be hard pressed to find a metal gear that isn't hardened in a gearbox. The method of hardening will also vary quite a bit depending on the conditions the gearbox will encounter in service, i.e. loads, speeds, etc...The realm of heat treatment is a pretty broad one. If you post your question in the gear and pulley section, they might be able to give you a better idea of what state of the art is in terms of processes.