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).
Letter from Humber Limited to S.H.Grylls discussing solutions for gearbox gear jumping issues.
| Identifier | ExFiles\Box 126\2\ scan0085 | |
| Date | 24th January 1939 | |
| 1069 TELEGRAMS & CABLES HUMBER, COVENTRY TELEPHONE:- 5041 IN REPLY KINDLY QUOTE: RCH/G BY APPOINTMENT TO THE LATE KING GEORGE V.{VIENNA} CYCLE MANUFACTURERS HUMBER LIMITED COVENTRY LONDON SERVICE STATION CHASE ROAD WILLESDEN, N.W.10 24th January, 1939 S.H.Grylls, Esq., Rolls-Royce, Ltd., D E R B Y. Dear Grylls, With reference to your letter of the 21st instant in which you ask for further information in regard to the steps we take to overcome jumping out of gear troubles, I am afraid that you must have obtained a rather incorrect impression of what we actually do. The bell "mouthing" we spoke of was a separate stunt altogether from the relieving-of-the-teeth dodge. We may have been lucky in regard to the direction in which jumping out occurred when using dog type teeth for gear engagement. In almost every case the dogs tended to jump out on the over-run, although in one persistent case where a gear jumped out on the drive, we found that this was due to mal-alignment between the gearbox and engine. The one method of relieving the dogs as described to you was perfectly effective in regard to overcoming the jumping out on the over-run, although relieving all but one-sixth of the teeth would probably not be so effective if you attempted to overcome jumping out on the drive, as excessive tip due to the one-sided drive might cause lubrication trouble. I would suggest, however, that in all probability if instead of relieving five-sixths of consecutive dogs, two sections of, say three teeth each were left full and diametrically opposite to one another, this might be quite satisfactory, as this would obviate any tendency towards lubrication troubles due to excessive tip on the gear and six teeth | ||