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).
Application of overdrive gearboxes to P.III, Bentley, and Wraith models.
| Identifier | ExFiles\Box 99\4\ scan0280 | |
| Date | 28th May 1937 | |
| Sg.{Arthur F. Sidgreaves - MD} from Rm.{William Robotham - Chief Engineer} 200B 4 28 Rm{William Robotham - Chief Engineer}15/R.28.5.37. re: Overdrive - Sg{Arthur F. Sidgreaves - MD}10/E26.5.37. My feelings with regard to the overdrive are, that provided the power weight ratio of two cars are similar, then the same gearbox ratio will suit each chassis. The power weight ratio of the P.III and the Bentley are almost exactly similar. We do not see any reason why the same gears should not be used in both boxes. The Wraith is in a different class, and it is doubtful whether the overdrive is applicable to this car. There is no doubt that in order to get the best ratios it will be necessary to try the cars on typical Alpine passes as second speed has got to do 95% of such work. It remains to be seen how the public will take the overdrive, but if they do not want it on the Bentley, it is very easy to put normal gears in the box. For Continental work, Sr. is enthusiastic about it, and we cannot think of any feature we could add to the motor-car which would reduce wear and tear to a greater extent. Rm.{William Robotham - Chief Engineer} | ||