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).
Implementation of an overdrive, comparing an axle-based system with converting the existing gearbox.
| Identifier | ExFiles\Box 92\5\ scan0056 | |
| Date | 13th May 1936 | |
| x302 Sg.{Arthur F. Sidgreaves - MD} from E.{Mr Elliott - Chief Engineer} c. Hs.{Lord Ernest Hives - Chair} Ox. re Overdrives. Referring to your memo Sg.{Arthur F. Sidgreaves - MD}4/E.12.5.36, this confirms your views with regard to our suggestion, to include an over-drive for a Continental model. I have read the article you mention in the Motor and I note the type of overdrive applied to the Ford V.8 is one built into the back axle. This is a scheme that we do not regard with favour as it tends to interfere with the adhesion of the rear wheels owing to the increase of unsprung weight, and by making the structure of the axle somewhat unmechanical aggravates the increase of weight rendered necessary. As it is agreed that the overdrive should be under the control of the driver it is a comparatively simple matter to transform a 4 speed gearbox into a 3 speed with over-drive, by simply altering the ratios. This is a scheme that we used to have in the old days when an overdrive was fitted to our 4 cylinder chassis and early 6 cylinders, and was then known as an indirect top. Rather than purchasing an axle over-drive I would therefore suggest that we get somebody to look into the question of converting our existing box. E.{Mr Elliott - Chief Engineer} | ||