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).
Propeller shaft vibration problems on Senior Range cars with different wheelbases.
| Identifier | ExFiles\Box 148\4\ scan0154 | |
| Date | 13th September 1940 | |
| Rm{William Robotham - Chief Engineer}/F.J.H. Please discuss SECRET. Rm{William Robotham - Chief Engineer} To Rm.{William Robotham - Chief Engineer} from Ev.{Ivan Evernden - coachwork} c. to Rm{William Robotham - Chief Engineer}/FJH.{Fred J. Hardy - Chief Dev. Engineer} c. to Rm{William Robotham - Chief Engineer}/GB. c. to Ev{Ivan Evernden - coachwork}/DB.{Donald Bastow - Suspensions} c. to Ev{Ivan Evernden - coachwork}/Tln. c. to Rm{William Robotham - Chief Engineer}/Wym.{G. Harold Whyman - Experimental Manager} 1262 Ev.{Ivan Evernden - coachwork}10/JH.13.9.40. JFH re Prop. Shafts - Senior Range. We wish to state the present outlook on the propeller shaft vibration problem on cars of the Senior Range. After further theoretical investigation by all the experts concerned we would welcome a free discussion to decide on suitable experiments which would be tried to prove or disprove any theoretical conclusions. It is stated by Rm.{William Robotham - Chief Engineer} and confirmed by Rm{William Robotham - Chief Engineer}/Wym.{G. Harold Whyman - Experimental Manager} that the propeller shafts of the longer wheelbase cars (10ft.-10in. and 11ft. 1 ins) when cured of propeller shaft vibrations, remain cured whilst those of the short wheelbase cars (10 ft. 4 ins.) do not do so. For the purposes of this investigation it is assumed that this is not a coincidence, and an attempt will be made to offer an explanation of the phenomenon theoretically, followed by experimental confirmation. The critical speeds on the B.V. appear to be 55 m.p.h. and 75 - 80 m.p.h. All cars have the semi-floating rear axle. We will now state all of the differences between the B.V. short wheelbase cars and those with the larger wheelbases. | | 10 ft. 4 ins. | 10 ft. 10 ins. | 11ft 1 in | | :--- | :--- | :--- | :--- | | 1. Moving Prop. shaft. | a | a * | a * | | 2. Fixed prop. shaft. | a | (a + 6) | (a + 9) | | 3. Axle shafts diam. | 40 m.m. | 40 m.m. & 45 m.m. | 45 m.m. | | 4. Axle shaft lengths | b | (b+) | (b+) | | 5. Rear springs length | 50.000 | 56.000 | 56.000 | | 6. Rear spring widths | 2.000 | 2.250 | 2.250 | | 7. Engine | 6 or 8 cyl. | 6 or 8 cyl. | 8 cyl. | | ||