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).
Two alterations for the Spectre Gearbox 1st and Reverse gears.
| Identifier | ExFiles\Box 94\1\ scan0100 | |
| Date | 25th February 1935 | |
| SECRET X328 GRY{Shadwell Grylls} To EY. from HDY.{William Hardy} HDY.{William Hardy}1/HP.25.2.35. c. Werx, E.{Mr Elliott - Chief Engineer} Hs.{Lord Ernest Hives - Chair} D.{John DeLooze - Company Secretary} RHG. SpectreCodename for Phantom III Gearbox. 1st and R.{Sir Henry Royce} Gears for .37 Ratio. Would you kindly make two alterations to these gears for permanent use as follows:- (1) The splines for the 1st speed wheel should have the same lead as the teeth. N. Sch.4326 instructs the same helical splines for the .335 1st speed in order to minimise delay in securing a trial. The thrusts are therefore not quite balanced but the friction will render the discrepancy of no consequence. However for the permanent gears the splines should be altered. (2) Further consideration of the reverse gear loads has led us to the conclusion that the end thrusts on the reverse shaft gears should balance when friction is neglected, for the best compromise. Accordingly the leads of the two gears on the shaft should be equal, as they were on the shaft for the original .335 1st speed and not as instructed on N. Sch.4326. This means that the helical angle of the wheel on the shaft will be 31° 38' approx. HDY.{William Hardy} | ||