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 specifications and modifications required for a new high ratio gearbox for a Bentley.
| Identifier | ExFiles\Box 86\4\ scan0084 | |
| Date | 26th May 1934 | |
| X 228 RHC.{R. H. Coverley - Production Engineer} Hs{Lord Ernest Hives - Chair}/Gry.{Shadwell Grylls}5/KW.26.5.34. High Ratio Gearbox for Bentley. We wish to try a gearbox having very much higher indirect gears than at present. The required ratio can be obtained by altering the 2nd speed gears from 37/49 to 39/47 and the 1st speed gears from 18/38 to 22/34, keeping otherwise to existing pitch etc. The gear at the back end of the reverse shaft must have 23 instead of 19 teeth with a slightly reduced addendum. It will not then foul the 1st speed sliding pinion. The ratios will then be, 3rd 1.245; 2nd 1.59; and 1st 2.02. A new sideshaft centre bearing is required of increased diameter. The casting must be built up round this bearing. A larger hole in the partition is required as the reverse gear has to pass through this. We attach a blue print showing suggestions for carrying this out and also for a slight modification to the casting to allow for the larger reverse gear when in position. Reverse gear ratio will be 2.01. Hs{Lord Ernest Hives - Chair}/Gry.{Shadwell Grylls} | ||