A Carburetter with Self-varying Choke r HIEF of a number of
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interesting %.-efeatures in the Gladwell Upthaught Carburetter (G.U.C.), a new product of Gladwell and Kell (1932) Ltd., Ampton Street Works, Gray's Inn Road, London, W.C.1, is the arrangement by which the effective crosssectional area of the choke tube is automatically controlled by gas velocity. Another noteworthy point is the incorporation of a spraying nozzle, situated at the base of this variable choke, which is fed by a main jet and a balancing jet.
The claim made for this instrument is a saving of at least 20 per cent. in petrol consumption combined with a general improvement in performance. Whilst appreciating the importance of the devices which give the carburetter its greatest interest, we feel that this ec
claim will be received with a degree of scepticism. However, in support of it, the maker quotes a specific instance in which a Ford 24 h.p. lorry, engaged in bulk petroldelivery, was operated at the rate e of 14.3 m.p.g. on a 1,000-mile test, after a G.U.C. carburetter had been installed, the previous consumption having been at the rate of 115 m.p.g. From the accompanying drawing the general layout of the carburetter can be understood. It will be observed that
the wall all of the choke tube, which tu the wall all of the choke tube, which tu
conforms with usual venri shape, there is a number of slots arranged around its inner circumference. Each slot contains a steel ball, and is so shaped that about a quarter of each hall diameter projects into the gas passage.
Free to move axially in their slots, the balls
thus are drawn upwards by the flow of vapour, and, in us moving, diminish the restriction afforded by the venturi. Accordingly, the volume of gas that can flow at a given suction is increased as the suction increases.
in other words the area of the venturi cross section is proportional to
the depression in the induction pipe. The weight of the balls would appear to give a time lag to the opening of the venturi so that rich mixture should be supplied for quick acceleration; at the same time, when the engine r.p.m. mount up the volumetric efficiency of the unit should also rise. Screwed into the base of the carburetter body and terminating in the smallest part of the choke tube, the spraying nozzle comprises a small petrol tube carrying around its orifice a concave cap, surrounding which and the petrol tube is an air sleeve. Oblique holes in the cap permit jets of air to impinge, at what may be likened to a focal point, upon the petrol stream. Thus, the liquid is broken up into a fine mist and thorough mixing with the main air supply is ensured. Adaptable for horizontal or vertical mounting, the G.U.C. instrument is Made in a number of standard sizes and costs from L6 19s. upwards. A 30-day trial scheme is in operation. We understand that, in the near future. a downdraught model is to be produced.
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