DIESEL-ENGINED LORRIES.
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Will the Small Diesel Engine Find Favour when the Six-wheeler Becomes Popular ?
By" Vim."
N0 MOTOR agent nor motor manufacturer can afford to ignore the progress of the Diesel engine in marine work. To those who have concentrated on the petrol type of internalcombustion engine without taking the trouble to observe what is going on in the world of ship builders, I heartily commend a monthly dose of The Motor ,Slip. It will make them open their eyes, I fancy. I know that it had that effect on MC, when first I began to follow the career of the marine Diesel engine through its pages. At first sight, it may be hard to see any connection whatever between road vehicles and the monster engines now being constructed for propelling motor ships; engines of such a size that permanent gangways have to be placed round the cylinder heads, SO that the valves may be reached! But there is a connection, for all that, because it is not unfair to claim that the automobile engine and the Diesel had the same parent in the first internal-combustion engine, and because just as the petrol engine has steadily pushed steam backwards on the land, so is the Diesel thrusting its way against steam on the sea. Of course, the Diesel is also establishing itself ashore, in a stationary capacity, and so is the petrol engine doing useful work afloat in motor boats ; but, broadly, one may put it that at present each is developing most rapidly in that sphere of action to which circumstances and its peculiar qualities seem to have called it. Somewhere, however, the ranges of utility meet, and it is there that the line must be drawn defining which is the more suitable for any particular purpose. The " crab" of the Diesel as a power unit for road vehicle propulsion is its weight, but that this drawback can be overcome, given the incentive, is fairly well proved by the fact that M. Tartrais, the engineer of the Peugeot Motor Co., has recently built an engine operating on the semi-Diesel principle, with what are claimed to be satisfactory results.
The Spheres.of the Different Types.
It is comforting to find that car manufacturers are at last taking an interest in the Diesel, and it is to be hoped that makers of marine Diesels will take a corresponding interest in road vehicles. Sticking to one's..own last is all very well, but one is apt to lose opportunities if that last produces only a single sort of boot. The Peugeot experiment will be worth watching, but, to my mind, the petrol engine will take a great deal of beating in the field which it occupies to-day. For loads up to about four tons, experi.ence has shown that it fills the bill very satisfactorily, when its good points are set against its bad. It is when the load is four tons and over that the steam lorry meets it on equal terms, and, in the opinion of some large users of mechanical transport., excels. Steam enthusiasts maintain that.the steamer is better than the petroler for lighter loads ; but I think we may say that, ignoring special circumstances in favour of one or the other type, the four-ton mark is somewhere about where the ranges of utility of petrol alid steam engiees for road work meet and overlap.
The merit of the Diesel is its efficiency, judged by fuel cost, and the constancy of that efficiency at. different engine speeds It has. of course, other merits, which make it analogous to the steam engine in the quality of its power output, without the disalvantages that external combustion entails. Its (merits for road vehicle propulsion are its weight B28 and its inability to deal so satisfactorily as the petrol engine with the continually and enormously varying loads imposed by traffic, gradients, and road sur
faces. If I am wrong, perhaps sonic reader will correct me: as a motor trader I make no pretence of possessing more than a mere smattering of knowledge of the Diesel, gleaned from such text-books as have been available to me, and from the pages of The Moto} Ship. Primarily, then, this class of engine appears to be most suitable for purposes that demand more or lees regular output, and that do not render engine size, and therefore weight, of great importance (comparing size and weight of engine with the mass that it is propelling); in fine, it appears to be most suitable for that kind of haulage that is now generally performed by the steampropelled lorry.
The Diesel Engine for Coupled Loads
Along this .line of thought, one is led to the conclusion that the Diesel engine may at some future date step in to meet the demand for an economical power unit for those six-wheelers which this paper has so stoutly Championed. The six-wheeler is coming; nothing can stop it, for it is a logical development of transport by land. And, after the sixwheeler, will come the road train, which was conceived in France long ago, though before its time. Along the great highways of to-morrow these trains will pass, parrying their goods and passengers, shunting trucks or changing bodies at towns en route and picking up others laden with return merchandise. Stand on any of the arterial roads from London, say, at Maidenhead, and watch the flow of commercial motor vehicles. Is it, not wasteful that all these .loads should be travelling to or from common points independently, each requiring its quota of attendants and its own power unit? Given a wide concreted highway, and an enlightened legislature, how long would it be before thoseeloads were coupled together and drawn in suitable-groups by larger eng:nes, than those we are accustomed to now ? The ratoof travel of these road trains will be fairly regular; stopping places will be predetermined ; the weight of the whole will be such that that of the engine will, within limits, not matter much, although the weight per wheel may not exceed current practice. These are conditions that should suit the Diesel engine quite as well as, if not better than, the high-speed petrol engine. But, before we arrive at road trains, we shall have six-wheelers (with their great load capacity and welldistributed wheel pressure) in common use, with, pethaps, a sprinkling of eight-wheelers. These veW.cl-es will be at their best on long-distance journeys over i'egular routes known to be suitable for them. It is conceivable that the Diesel engine may ultimately prove superior to the petrol engine 'in their ease, either with its power applied through gearing to the wheels or driving them through an electric generator and motors. A special type of eneine would have to be evolved—but why not? The father of all steam engines would not recognize in the compact and light power unit of the modern steam wagon a descendant in a direct line from its own loins The question has more than an academic interest. We are on the eve of big developments in road-borne traffic, which are only delayed by the country's, temporary poverty, and its inability to construct proper highways. This state of affairs will pass away in due course, and then developments will ensue.