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).
Article from 'Autocar' magazine discussing the British S.U. carburettor, its design, and function.
| Identifier | ExFiles\Box 31\4\ Scan001 | |
| Date | 15th October 1914 | |
| Autocar 15:10:14 BRITISH CARBURETTORS. THE S.U. LIKE magnetos, certain types of automatic carburettor hitherto in much demand in this country are of continental origin, and it is now the opportunity of Great Britain to secure the huge business in this necessary component of the motor vehicle to herself, at least so far as home consumption is concerned. Unlike the case in the magneto industry, on the other hand, carburettors equal to the best from abroad have been produced in considerable quantities by two or three British manufacturers for many years past, consequently there is no lee-way to be made good in this respect, and the problem for the individual manufacturer becomes merely a question of creating a further demand for his device and of being in a position to meet this increased demand when and as it arises. We are well aware that a large proportion of home-produced motor cars are provided with British carburettors as a standard fitting, but not by any means as large a proportion as we should like to see for the honour of our own country, while the number of continental makes of car employing carburettors of British origin are few and far between, and certainly far less than is the case when the terms are reversed. It is up to each of our own carburettor manufacturers, therefore, to endeavour to make good this disparity, and no better opportunity is likely to occur than the present time, but it must not be overlooked that the demand has to come from the motoring public, and it is through this public that the manufacturer must make his efforts. One of the most popular instruments, and deservedly so, is the S.U., of entirely British conception and manufacture, the principle of which we have on more than one occasion fully described in this journal. Although the present purpose is rather to call attention to it in general terms than to describe its principle minutely, a few words of explanation, together with the accompanying sectional view, will serve to indicate its characteristic features. The fundamental idea underlying its design is to give a constant velocity of air past the jet at all times and an emission of fuel from the jet proportionate to the amount of air so passing. This is done in the following way: Suction on the induction stroke draws air through the main intake and past the jet, and also exerts a suction effect in the bellows by means of the channel shown between the latter and the main air passage. This causes the bellows to contract, which in turn raises the piston, to the base of which is a taper needle entering the orifice of the jet. Any variations in the amount of suction due to throttle movements or to speed of the engine cause similar variations in the shape of the bellows and in the position of the piston and needle. The piston, it will be seen, controls the air aperture and the taper needle the jet orifice. Constructionally, the carburettor has been so designed that the standard patterns can be readily fitted to practically every existing make of car, while a variety of special designs, all, however, embodying precisely the same characteristic features, are made to fit many of the leading makes of car without the slightest adaptation. In all other cases where unusual difficulty in fitting is present, the difficulty may be overcome by the use of special induction pipes or parts made in a large variety of forms by the S.U. Company, Ltd., of 349, Euston Road, London, W., from whom full particulars of the merits and price of this particular instrument may be obtained, together with a most convincing array of testimonials from satisfied users. [Diagram] TO ENGINE AIR BELLOWS JET Sectional view of the S.U. carburettor. [Handwritten note in left margin] X1487 | ||