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).
Technical memorandum discussing issues and proposed solutions for Phantom Gearboxes, specifically regarding steel hardness and spline performance.
| Identifier | ExFiles\Box 94\2\ scan0120 | |
| Date | 14th December 1936 | |
| GRY{Shadwell Grylls} 328 RHC{R. H. Coverley - Production Engineer}: C/Hs{Lord Ernest Hives - Chair}: By.{R.W. Bailey - Chief Engineer} Fm. Ba. E/HDY.{William Hardy} E.3/HP.14.12.36. Phantom Gearboxes. Referring to your memo RHC.{R. H. Coverley - Production Engineer}11/WJ.10.12.36, it will be remembered that the history of this job started with the test of the SpectreCodename for Phantom III I gearbox on the Vulture chassis. The results of the dynamometer running of this car showed indentation of the shaft and gear splines to overcome which you proposed the hardening of the splines on both gears and shafts. It was realised of course that we might have a certain amount of trouble with distortion, and it is evident that we have now had sufficient experience to weigh up the job again. Personally I think the suggestion now put forward is excellent if we can get away with it since it should give us the best possible bedding. The only point of doubt is whether the softer steel will be satisfactory on the hard shaft but this can be proved by test. We know that soft steel will pick up on hardened steel if the load is sufficient but with good bedding of the splines we may not have this trouble. The other point that occurs to me is the question of the Brinell hardness. It used to be said that the maximum possible which we could machine was 340, whereas we now propose to broach material 360 to 380. We anticipate that this increased hardness number has not been put forward without experience of the conditions. E.{Mr Elliott - Chief Engineer} | ||