LEAVES FROM THE INSPECTOR'S NOTEBOOK.
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A Tendency in Design. Smooth Engine Exteriors and Efficiency.
pERHAPS IT IS NOT so noticeable, in connection with such new designs of commercial motor vehicles as have already appeared, as it is in connection with quite a considerable number of new models of touring cars, but, in the latter cases, most of us probably have been left with Ole impre§sion that the designer has gone a long way out of his way to secure smoothness of contour and an absence of protruding bits and pieces. He seems to have adopted the principle of consolidation as his main object, and one is left Wondering whether he has not, in so doing, tended to sacrifice mechanical and thermal efficiency. The writer is tempted to discuss this aspect of latter day designs in these pages, because, although there is much that is clearly distinctive between'tbe conception of a commercial vehicle chassis and its details, and that of the lighter and very Often more.elaborate machine intended for touring purposes solely, a broad and noticeable tendency of the kind now,mentioned is certain to have its effect on design as a whole, in connection with internal-combustion engines and the' chassis, of whatever kind; of which•they.are'units.
It was at the Paris Exhibition that this tendency was krst of all remarked, at any rate, to the extent. to which it has been carried in the present year. Big chassis such as the Isotta, the Delage, and, noticeably, the Lancia, all exhibited this tendency to a• marked. extent. The designer's of these machines appear to have had in mind an attempt to disguise the fact that the petrol engine, as we understand it to-day, consists of cylinders, crank chamber? 'combustion heads, and valves of sorts. The Lancia 'motor, for instance, 'hiding, I think it was, 12 cylinders, tc say nothing of valves, con. sods, and the other usual components, had the appearance of a rectangular . case, and obviously a very great deal of ingenuity had been expended in securing this remarkably clean cut effect. Tho writer was not alone inihis expression of wonder, at the time, as to whether effort in this direction was not almost certain to carry with it some measure of neglect of perfect efficiency in so far as the motor itself was concerned,
The same tendency, of course, is noticeable in respect of the other units of a chassis, but the engine, because it has so many more huxiliaries,-is the more difficult to tackle in this way, and when the task is effected the result is more startling. There are examples still of very highly efficient motors giving excellent thermal efficiency results ; motors with high speed capacity, great flexibility and silence as well, on which no pains appear to have been,exnendecl, even in quite recent designs, to secure this almost abnormal smoothness of finish. With some knowledge of the difficulties of securing adequate channels for gas and water, sufficient cooling areas, and room for the cooling medium ; of the elimination of sharp corners and tortuousvassages and, at the same time, of securing a casting that, owing to its Minimum of complication, promises a corresponding minimum of failures and weaknesses, I find itLhard to believe that this modern tendency could be achieved satisfactorily without some sacrifice of efficiency.
There is also the question of =accessibility, and, • when one begins to box everything up and cover it in, one has to have the most perfect confidence in the efficiency of the machine so treated. Where the product is one in which-110 special care has to be taken of the cost of production and.finish, the tendencyis a' pleasing one. It probably offers first-class selling points, and, owing to the excellent workmanship that can be 'achieved, there need be-,no nervousness as to the results of the boxing up process. But it is. certainly questionable Whether designers willdo well to allow themselves to be carried away by this new tendency when they are thinking out engines, and other components which are.to be produced on quan tity production lines. It is all-important that the commercial vehicle should be get-at-able, and that replacement should be made with a minimum of trouble, for, while the high-class touring car can be reasonably expected to be treated with a deference equal to its present abnormal price compared with the value ef its services, the commercial vehicle has nowadays to work harder than ever, and very often falls into the hands of people who not only know little about the technics of the subject, but even if they did, have little enough time to display their knowledge and turn it to advantage.
We have not yet seen many oi the real post-war designs of commercial motor vehicies, and, as-I wrote not very long ago, there does not appear to be any very great reason why such models are necessary at present. .We have some excellent curreitt examples Tn. this country, and they have stood up toonarvellous tests .satisfactorily. Change, farPthe sake of change, is not necessary, at any rate at present, in the industry, for the buyer does not want tempting with novelty, indeed he rather shies at it. But it is no secret that most of the leading manufacturers, at any rate, and a. few new ones, have on their drawing boards more or less advanced designs of. new types, and the writer hopes that we shall not'irt the end'find among these designs any evidence of the present desire pn 'the part of touring car manufacturers to suggest the maximum of simplicity outside, which may, and probablyealways does, result in a decrease of simplicity on the inside. There iis no more argument for such .a line of thought in connection with the production of the Commercial vehicle than there is in the-design of.locornotives, or-machine tools.