THE PROGRESS OF SUPERCHARGING.
IT has been prophesied that 1926 will be remembered as the “Supercharger” year, and this surmise is already being borne out by the appearance on the market of a proprietary supercharger. The firm responsible for this enterprising step is Messrs. PressureVac, Ltd., North Parade, Bradford, Yorks, and the article produced is known as the ” Berk ” Supercharger. That the makers anticipate a growing demand for superchargers on touring cars is shown by their willingness to fit the blower to existing cars, though owing to lack of space under the bonnet, in many cases this entails considerable alteration and adjustment. For touring purposes the supercharger is coupled to the engine through the medium of a clutch, thus enabling it to be thrown into and out of action as desired. For racing, the makers advise a direct drive from the crankshaft, and they can supply direct or chain driven models to fit any sports or racing car which possesses the necessary space and in which the engine has been designed with a view to withstanding the extra stresses imposed by the supercharger. Any doubts as to the ability of the makers to turn out a satisfactory article should be dispelled when it is remembered that Captain
successfully by many well-known racing men, is now supplied as a complete unit with interchangeable parts in a form which is readily adaptable to racing car engines.
Waite’s record-breaking Austin Seven, Major Halford ‘s A.M. Special, and the latest racing A.C. are all fitted with the ” Berk ” Supercharger, and manufacturers in all parts of the world are displaying great interest in the production. Large numbers of enquiries have also been received from private owners desirous of fitting superchargers to their own cars. From this it is quite el,ident that there is a big future in store for the supercharged touring car. Already a continental manufacturer has produced a car of this type, and it will be interesting to see which British manufacturer will be the first to follow suit.
As regards the actual design of the ” Berk ” Superchargers, these are of the well-known Roots-Blower type, having a patent form of three-arm rotor, these rotors being constructed of Duralumin and running on steel shafts on ball and roller bearings. The degree of supercharging necessary is a matter of great controversy, but Messrs. PressureVac, Ltd., can supply blowers capable of producing a pressure of Is or even 20 lb. to the square inch if desired. One of the latest models, which we illustrate, is designed to bolt direct to the front end of the engine and is direct driven from the crankshaft. It is complete with by-pass and relief valve, discharge bend, explosion valve, and incorporates a starting handle bracket. It is interesting to note that, even at this early stage of the manufacture, all parts of “Berk” Superchargers, including the timing gears, are interchangeable, so that spares are easily obtainable.
We understand further from Messrs. PressureVac, Ltd., that small blowers suitable for motor cycle engines are in course of preparation and will be available shortly.