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).
The testing of a concertina coupling on a Phantom III gearbox to investigate 3rd gear disengagement issues.
| Identifier | ExFiles\Box 94\2\ scan0190 | |
| Date | 15th March 1937 | |
| E.{Mr Elliott - Chief Engineer} from Rm{William Robotham - Chief Engineer}/Gry.{Shadwell Grylls} Da.{Bernard Day - Chassis Design} By.{R.W. Bailey - Chief Engineer} Hdy.{William Hardy} 328 Rm{William Robotham - Chief Engineer}/Gry{Shadwell Grylls}13/R.15.3.37. P.III GEARBOX. At Hdy{William Hardy}'s request we have tested a concertina coupling with very slack 3rd speed pinion bushes. The amount of slackness was .006 endwise and .006 diametrically made up .003 inside and outside the bush. Provided the selector springs were fitted there was no sign of 3rd gear coming out on the over-run even down our Welsh test hill. On removing the selector spring the gear would jump out in about half a mile. We, therefore, tried the more flexible concertina in which the .100 sections have been reduced to .080, but this was no improvement. We are not sending you this memo because we think the situation serious, but merely to supply the information required by Hdy.{William Hardy} Since the introduction of the concertina on production they have not had one single case of the 3rd gear coming out of mesh. Rm{William Robotham - Chief Engineer}/Gry.{Shadwell Grylls} | ||