Engines, Gears, Carburetters and Fuels.
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• Since Herr Daimler's adaptation of the principle of internal combustion to an engine designed for running at a high rate of speed, thousands of engineers, in all parts of the world, have made farreaching and satisfactory researches with the object of producing a motor that can, at all times, be relied upon to give off power, more or less proportionally to its speed, so long as the supplies of fuel and lubricating oil are maintained, and adequate means are taken to secure the correct carburation of the charge, its subsequent inflammation, and the cooling of the walls of the cylinders. One no longer hears of the frequent breakdowns which drew a certain amount of ridicule upon the early experimenters. Many of their failures were certainly due to the employment of unsuitable materials, and to an imperfect understanding, by engineers of that period, of the working conditions, but by far the greater number of failures were due, partly to imperfect carburetters, and more particularly to the clumsy and crude ignition devices which were then in use. Progress has been rapid. Amongst other parts which have claimed the designer's attention are the inlet and exhaust valves: after being in use for some considerable time, the automatic inlet valve was displaced by the more-popular and efficient valve of the mechanically-operated type, and, at the present time, there appears to be a keen competition, amongst certain designers, for the production of a slide-valve type that will outdo the claims, for silence and efficiency, which have been advanced by the English Daimler Co. for its Daimler-Knight engine, with which it has now had over a year's experience in England, and with which that maker appears to he more than satisfied. The majority of engine builders, however, are unconvinced of the slide valve's superiority over that of the mushroom type, and such makers as Aster, Forman, Price, Thornycroft, Tylor, White and Poppe, and many others, continue to use the older type.
Amongst carburetting devices, remarkable results have been obtained by the use of the Gillet-Lehman and Polyrhoa carburetters—both most ingenious devices. The carburetters made by Brown and Barlow, Claudel-Hobaon, boherty, and White and Poppo have also met with a very large circle of supporters, whilst, for heavy fuels, Cotterell. Davis, and Thornycroft have each produced highly-interesting devices.
So far as ignition apparatus is concerned, we are no longer dependent upon the irregular working of those abominable contraptions of primary or secondary batteries, innumerable wires, coils, switches, plugs, etc., but we have available neatly-designed, highly-efficient. and sturdy magnetos by Bosch, Fuller, Hall, Simms, Vandervill, and other makers. It is only the pressure on our space that prevents our dealing fully, in this week's issue, with a new and interesting dual ignition system. which has just been introduced by the last-named maker, but we hope to deal with it in an early issue. Gone clutches, either of the leatherfaced or metal-to-metal varieties, are more frequently fitted to commercial vehicles than are those of the friction-disc type, but there are a number of makers who strongly advocate the use of the last-named type of clutch, of which the Hele-Shaw was the first to be successful, and, so long as they are well fitted, and provided with a suitable grade of lubricating oil, they give most satisfactory results, but it is probable that the morecommon cone clutch will long continue to hold the " field," 'chiefly because its action is more generally understood. Straight spur " stepped " gears (either of the always-in-mesh type, as fitted on the Albion, " Commer Car," Goodchild, Halley, or Lacre vehicles, or of the sliding-type, as employed by the majority of other makers) are those most usually embodied in the change-speed gearboxes of commercial vehicles, although there are isolated examples of the employment of special gears, such as the several petrol-electric systems which appear to be in doubtful favour with operating engineers, opicyclic gears, and various hydraulic systems of transmission of power. We are of opinion that, whilst, at present, we cannot point to any large number of applications of either of the last two classes (epicyclic and hydraulic), the trade can anticipate an extended use for both systems in the future: epicyclic gears, as mentioned in our last week's issue, have already proved their ability to stand up to heavy loads on commercial vehicles.