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).
Alternative rear axle gear ratios for the Spectre model.
| Identifier | ExFiles\Box 92\5\ scan0003 | |
| Date | 5th July 1934 | |
| [Handwritten] [illegible] 302 To BY.{R.W. Bailey - Chief Engineer} from Da.{Bernard Day - Chassis Design} Da.{Bernard Day - Chassis Design}/HP.5.7.34. c. WEP. E.Hs.{Lord Ernest Hives - Chair} Mey. NHO. SpectreCodename for Phantom III - Rear Axle Gear Ratio. We wish to put on order lower axle ratios than the 3.7 to 1 specified now. Herewith is N.Sch.4121 shewing approximately a 8/34 = 4.25 ratio which goes without difficulty into the original box. The stress is approximately 8% lower than in the 3.7 gear, but the tooth load has increased 14%. Another combination giving approximately the same ratio, viz. 9/38 is considerably more highly stressed without any reduction in the tooth load, and so, though there is no hunting tooth, we prefer the 8/34 combination shown on drawing. A further ratio, viz. 8/33 = 4.125 ratio should also be ordered, but we have not set it out, as it is intermediate between those drawn and should present no difficulty. Da.{Bernard Day - Chassis Design} | ||