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 advantages of a free pinion on the layshaft for the Helical 2nd Gear of the Phantom II gearbox.
| Identifier | ExFiles\Box 15\5\ Scan340 | |
| Date | 20th September 1932 | |
| 87310 To R.{Sir Henry Royce} From Ha/Gry.{Shadwell Grylls} c. to Wor.{Arthur Wormald - General Works Manager} c. to SS.{S. Smith} c. to S. c. to Da.{Bernard Day - Chassis Design} c. to By.{R.W. Bailey - Chief Engineer} c. to Hdy.{William Hardy} Ha/Gry.{Shadwell Grylls}1/MJ.20.9.32. HELICAL 2nd. GEAR - P.11. R.2/M.12.9.32. We should like to point out further advantages of having the free pinion on the layshaft. If the engine is running at 3000 R.P.M. in top gear or 77 M.P.H., the second speed side shaft pinion is doing 4150 R.P.M. on a shaft running at 2150 R.P.M. the relative rubbing speed is about 2000 R.P.M. Were the free pinion on the 3rd. motion shaft the relative rubbing speed is only reduced to 1500 R.P.M. The energy required to keep the 2nd. speed continuous gear running in the oil is provided by the rotation of the propeller shaft. No more effort is therefore required for synchromesh changes into 3rd. gear, whereas with the pinion on 3rd. motion shaft the energy to churn the oil is provided by the synchromesh cones with a consequent increase in effort at the gear lever. Our great difficulty with the P.11 gearbox has been to lessen this effort. Again if it were later decided to make the change into 2nd. synchromesh the cones could be smaller in the ratio of .717, the reduction of these two gears, since the mechanical advantage is greater. Also of course the noise from the sideshaft when idling is not increased. Ha/Gry.{Shadwell Grylls} | ||