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A NEW HEAVY-DUTY SPARKING PLUG.
Page 126
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THERE is a great-deal of difference between the performance demanded from a sparking plug used in the engine of a commercial vehicle and from that utilised in the ordinary private car. Experience has shown that in the latter case perfect ignition may be expected for 20,000 miles or more, whilst with the same type of plug in commercial use this life may easily be halved.
One reason for the difference is that the engine of the commercial vehicle is running for far longer periods on full, or almost full, throttle. Then the fuels employed are usually somewhat inferior, being not so carefully refined, but according to some authorities the thief cause lies in the matter of carburation. The petrol consumption of business vehicles is watched very closely, and the engines are run on the weakest mixture c60 which will give efficient results. Owing to this the temperature of the combustion chambers is comparatively high and this has a deteriorating effect on the sparking plugs, for the greater the heat the sooner will perishing of the insulation occur, and the more the spark will burn away the sparking points.
Realizing all these conditions, Lodge Plugs, Ltd., of Rugby, has designed a special sparking plug of particularly
robust construction for use on commercial vehicles of all types. It is claimed for this type that it will outlast two ordinary plugs, as its features include a unique construction of the insulator, which is of laminated mica carried in a separate steel barrel and so arranged that in a few, moments it can be removed, together with its central electrode, for cleaning, massive and wellcooled sparking points, and a stout copper gasket ring between the insulator carrier and the plug body. The gland nut is also of substantial construction, and from the appearance of an example which has beetssent to us for trial, body and gland nut would seem to be standardized, although in this we may be mistaken.
This new commercial phis is called model C.V. and is priced at 5s,