From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Use of high helix angle gears for reducing noise in gearboxes.
Identifier | ExFiles\Box 136\5\ scan0351 | |
Date | 5th April 1940 | |
1152 Ev.{Ivan Evernden - coachwork} from Rm.{William Robotham - Chief Engineer} Rm.{William Robotham - Chief Engineer}9/ML.5.4.40. It appears that most of the Americans are now using 40 - 45 deg. helix angle gears. They would not use these angles if they did not get something out of them, in the way of silence, since big helix angles produce thrust problems. I should be interested to know what is the largest helix angle which you think we can use on the junior rationalised gear box without departing from our standard practice. The third speed is, of course, the gear where silence is most essential. Rm.{William Robotham - Chief Engineer} | ||