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).
Timing gear and spring drive design, comparing Bakelite and fibre friction discs, and suggesting structural improvements.
| Identifier | ExFiles\Box 43\1\ Scan011 | |
| Date | 14th September 1927 | |
| X3942 c.Hs.{Lord Ernest Hives - Chair} BYL/H.{Arthur M. Hanbury - Head Complaints} 14.9.27. INDIA 3. TIMING GEAR AND SPRING DRIVE. Referring to El/M.7.9.27. with reference to the question of using friction discs made of red or grey fibre, in place of Bakelite as at present, we think R's proposal in this direction is based upon a misconception. The Bakelite material used has no unmodified gum in its constitution. After being soaked with the original gum and pressed, it is baked to such a temperature that the gum is completely transformed to a different chemical substance, and this change is irreversible. We would much prefer to continue with Bakelite material as it has cleared up a lot of troubles, but if R.{Sir Henry Royce} is insistent, we shall of course adopt the red fibre. In regard to timing gears, the question of the thrust of the gears ought to be reconsidered so that the thrust reactions fall upon proper thrust bases, and not, as at present, re-act upon the springs of the friction drive. Secondly, we think the ratio of lead/to circular/and pitch should not be less than 3.25 We also consider that it would be a distinct advantage to modify the crankcase in such a way that it/is stiffened up at the gear case end much more than in the original design, so that the re-action from the supporting bosses or arms is not likely to spring or distort the case as it unquestionably does at present. One further point which I covered in the scheme I got out with the object of quietening the gears was to carry the dynamo drive as a unit in the crankcase. At present the unit is supported with the bearing in the wheelcase cover, and the other in the crankcase. This cover unquestionably keeps considerably cooler than the bulk of the crankcase, with the nett result that the gears are pulled out of line. If the above features were incorporated, we think we would then be approximating very closely to the present 40/50 scheme. The latter is reasonably easily quietened, whereas the 20 HP. is not, the time-hours required being at least double for the 20 HP. over that required for the 40/50. BY.{R.W. Bailey - Chief Engineer} BM | ||