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).
Design features of new, non-expanding twin carburettors.
| Identifier | WestWitteringFiles\U\2January1930-September1930\ Scan249 | |
| Date | 21th August 1930 | |
| HS.{Lord Ernest Hives - Chair} ) FROM R.{Sir Henry Royce}, E.{Mr Elliott - Chief Engineer}, BY.{R.W. Bailey - Chief Engineer} ) & E/CLJ. Copy to SO. WOR.{Arthur Wormald - General Works Manager} [STAMP: RECEIVED ORIGINAL ACC AUG 25 1930] R1/M21.8.30. P. 2. TWIN CARBURETTERS. x7080. After several weeks of careful designing work we are just finishing the designs for the twin carburetter, non-expanding, in accordance with the experience obtained at Derby with various makes of carburetters of the Claudel-Hobson type. In the designs we have done all we know to make the very best of this type regardless of cost. Should some of the features be found unnecessary the designs can be simplified but to meet our high standard of requirements we believe that every feature we have embodied will be found to be well worth its cost. (1) We have provided 4 floats so that the petrol level in the main jet is very much less affected than usual by the tilting of the car, that is, it can give a very high level of petrol in the jet without fear of spilling. (2) We have arranged for all the jets (high and low) to be controlled from the steering column as we consider jet control to be preferable to depression control. This control also provides for the extraordinary enriching of the mixture for starting purposes (patentable) so that the auxiliary carburetter and control will (we hope) be dispensed with. (3) The throttle is controlled by the governor in the same way as the present Phantom engine but the foot accelerator actuates a single pump for instantly enriching the main jet of both carburetters when suddenly opening the throttle. This extra petrol is accurately divided between the 2 carburetters by passing small restrictions between the pump and the petrol jets (patentable.) There is a valve for closing this passage when the pump is not delivering. We have found this simpler than double pumps and we believe it will be actually better equalised. (4) It is intended that these carburetters shall shut down to a completely closed throttle as is our special RR. practice for luffing up, and for this purpose we have adopted the 2 hole arrangement of low speed edge throttle running. It is hoped that the floats as arranged will be very sensitive and capable of keeping the level of the petrol very accurate. We have made this mechanism independent of the end motion, the clearance endways not affecting the petrol needle. (1) | ||