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Including a Letter from a Correspondent who Traverses the Claims of Our Contributor " Engineer Designer " as to the Superiority of the " Designed " Class of Construction.
"Design or Assembly." Arguments in Favour of Assembly.
The Editor, THE COMMERCIAL MOTOR.
[1588] Sir,—The article under the above title in your recent issue is of great importance at the present time and will be more so in the immediate future. Your contributor asks two questions. With regard to the first, " Is a 'Designed' Chassis better than an Assembled' onel " I shall endeavour to show that it is not, or is not necessarily so. In asking the second question, "Is Low First Cost or Economy of Maintenance to be preferred ?" he is making the assumption that an assembled" chassis is more expensive to maintain. I do not think that this assumption is stall justified as I will also endeavour to prove.
In the first place, I am inclined to quarrel with the title as I consider it a very misleading one ; it assumes that an "assembled" chassis is not designed at all and is just a collection of parts thrown together anyhow. I prefer some such titles as "assembled chassis" and "one-shop chassis" and as such I shall refer to them below. One must not take the worst of the "assembled chassis" and compare itwith the best of the other sort, nor must one take any serious notice of the British or American vehicles that have been produced simply to take. advantage of the "war rush." One hears of pleasure-car -engines going unaltered into lorries ; and light-car rear axles beiiig fitted with chain pinions instead of road wheels and serving as countershafts for chain-driven trucks. These things—and many like them—are the outcome of war and must not be allowed to confuse the issue. It is also unsafe to argue round the Ford proposition without knowing the.internal history of the firm.
Your contributor states—quite correctly—that the "
one-shop" chassis is generally "in the main the product of one brain," hut he quotes this as to the advantage of the car. Surely it is the reverse. In the same paragraph hp says that another advantage of the "one-shop" car is that "each unit is specially designed and constructed for one purpose . . . and there is no excess of weight, strength or power." Does not this apply with twice the force to the shops constructing the units themselves?
Good design is the outcome of technical knowledge combined with experience. This is where the " assembled " chassis ought to score, and actually does score, if the men responsible.ifor the assembled chassis are of the same calibre As those who build the " one-shop " ear. It all depends upon the men behind the car ; given equal capacity the assembled cur must be better because it embodies more experience. It is quite obvious that, given equal intellect, the man whose whole life is devoted to producing—let us say—engines must produce a better (or cheaper) article than the man who has to divide his attentions among,jhe many units that go to form a complete chassis.' The engine man gets more experience with engines. His motors go into many more chassis, have to satisfy a broader range of tastes and ideas,
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and are used n more varying circumstances, under wider conditions of load and speed and by vastly different classes of men, all of whom add their experience and contribute to the perfection of the article.
A further point is that the "one-shop" man has to take into account the existing plant and tools in his shop, and this often has a very serious effect upon design. Of course this also applies to the maker of the units," but to a far less extent, and it still leaves it open to the assembler to buy from whom he can get the be'st article irrespective Of any other circumstances.
To take a case ; it is conceivable that a " one-shop " maker who turns out lorries up to five tons capacity fitted with a worm-driven back axle having a spurtype differential may take a small order for six-ton wagons. If unhampered by other considerations he would probably like to fit his six-ton cars with a " double-reduction " axle having a bevel differential, but this means a very large outlay on new drawings, patterns, tools and jigs, to say nothing of the bevelgear-cutting plant, and so the probability is that he would put in his five-ton worm-drive axle and trust to luck. On the other hand, the assembler has a wide range of axles to select from and can order to suit his requirements exactly.
From these considerations the possibility is that the various units of an assembled chassis, if wisely chosen, are not only as good but even better than those made by the "one-shop " firm ; half of this is already admitted by your contributor who says that "the individual units of assembled chassis are admirably designed and constructed." If they do not come up to this standard, one must blame the particular firm, not the system.
The bought units are, for the reasons mentioned above, considerably ,cheaper to produce. The writer of your article puts the figure at 15 per cent, but as the tendency is to assemble cars more and more, the difference may become far more than that in the near future.