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 20° angle teeth versus standard teeth in the Goshawk II gear box.
| Identifier | ExFiles\Box 180\M1\1\ img021 | |
| Date | 1st January 1921 | |
| To BY.{R.W. Bailey - Chief Engineer} from R.{Sir Henry Royce} Copy to Derby. " " " " HS.{Lord Ernest Hives - Chair} ORIGINAL. R11/CS/S./21 X4242 RE "GOSHAWK II" GEAR BOX. I cannot understand who is the author of using 20° angle teeth in the gear box of "Goshawk II". We do not appear to have done anything to suggest this. The only remark on the drawings is that the helical gears driving the lay shaft are marked 20° angle, but that refers to the angle of the helix. You will notice that all the addendums have been shewn the full height of the standard 14 1/2° angle. Most of the 20° teeth are short ones stubbed, but as I know these are generally noisy, I have never recommended their use, but have occasionally recommended the use of 20 angle teeth with a .19 addendum, which is somewhere between the usual standard addendum and the standard stub tooth. R.{Sir Henry Royce} | ||