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 De Normanville gearbox, comparing it to the Wilson transmission and outlining its drawbacks.
| Identifier | ExFiles\Box 128\1\ scan0162 | |
| Date | 3rd November 1933 | |
| V 3631 To Wor.{Arthur Wormald - General Works Manager} from Hs{Lord Ernest Hives - Chair}/Gry.{Shadwell Grylls} C. BL. C. C. By.{R.W. Bailey - Chief Engineer} E.{Mr Elliott - Chief Engineer} C. Hay. Hs{Lord Ernest Hives - Chair}/Gry.{Shadwell Grylls}10/RT.3.11.33. DE NORMANVILLE GEARBOX. We have tried this gearbox fitted to a 24 HP. Humber car lent by Humber Ltd. of Coventry. The gearbox has a four forward speed and reverse epicyclic train. The drums for each gear are V shaped and held stationary by lead bronze balanced brakes. No wear of this part is said to be measurable after 10,000 miles. The brake for the required gear is operated by a hydraulic cylinder with about 400 lbs/sq.in. oil pressure. A control on the steering wheel connects up the oil pressure to the cylinder operating the brake of the required gear. To change gear, therefore, all that is necessary is to move this lever on the steering wheel. A normal clutch is provided in front of the gearbox. By use of this and the correct throttle opening, very quick and shockless gear changes can be effected. Use of the lever only although effecting an immediate gear change causes considerable shock to the transmission and is unpleasant for the passengers. The essential differences between this gearbox and the Wilson are that one does not pre-select a gear and that to change gear there is no necessity from a mechanical point of view to do more than move a small lever. If the clutch is used it is lighter in operation than the pedal on the Wilson transmission. The method of changing gear we prefer to the Wilson pre-selection. As is to be expected there are features of the transmission which would prevent it being fitted to a Rolls-Royce as it stands. These are :- (1) The noise while idling since all the gears are turning, some forwards and some backwards. (2) If the clutch is put out while the engine is running, allowing the gear trains in the box to come to rest, on letting the clutch in again, the car lurches forward due to the reaction on the propeller shaft of accelerating the gear trains. | ||