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).
Suggesting a patent for an overdrive gearbox design.
| Identifier | ExFiles\Box 147\1\ scan0252 | |
| Date | 9th August 1937 | |
| To By/NW.{N. Walker - Patents} from Rm{William Robotham - Chief Engineer}/Gry.{Shadwell Grylls} 1247 Rm{William Robotham - Chief Engineer}/Gry.{Shadwell Grylls}2/AP.9.8.37 OVERDRIVE GEARBOX. By.{R.W. Bailey - Chief Engineer} agrees it would be worthwhile to try for a patent for this gearbox. In the ordinary four forward speed gearbox in which each indirect speed ratio is obtained by the reduction of two simple trains of helical gears, it is usual to have a direct drive and then three speeds giving successively lower ratios. Since the advent of quiet helical gears it is possible to run continuously on an indirect ratio without noise, particularly if the number of teeth in the two gears of each train does not differ greatly. We suggest a patent for a four forward speed gearbox in which one ratio consisting of two pairs of helical gears provides a higher speed than the direct drive. This is the lightest method of obtaining a normal three speed gearbox with an 'over-drive'. Rm{William Robotham - Chief Engineer}/Gry.{Shadwell Grylls} | ||