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° versus 14½° angle teeth in the Goshawk 11 gearbox.
| Identifier | ExFiles\Box 75\1\ scan0229 | |
| Date | 3rd September 1921 | |
| X4247 To BY.{R.W. Bailey - Chief Engineer} from R.{Sir Henry Royce} c. to CJ. c. to Wor.{Arthur Wormald - General Works Manager} c. to Hs.{Lord Ernest Hives - Chair} R11/G3.9.21. ___________ X.4247 - RE GOSHAWK 11. GEAR BOX. I cannot understand who is the author of using 20° angle teeth in the gear box of Goshawk 11. 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 14½° 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 that occasionally recommended the use of 20 angle teeth with a .9 addendum, which is somewhere between the usual standard addendum and the standard stud tooth. R.{Sir Henry Royce} R.R.236A (50T S.H. 986. 19-2-21) G.L.3008 | ||