"FADS AND FANCIES."
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Something About "Unsprung Weight" and Other Technical Matters Beloved of the
Semi-expert from "The Inspector's" Pen.
IHAVE often wondered whether the motor vehicle owner is peculiar in his capacity for acquiring fads and fancies with regard to his machine or other people's.The fact is, undoubtedly, that large numbers of owners are would-he experts who soak up lots of semi-technical information, and, from time to time, retail it without having that capacity to discriminate which naturally follows from a prolonged course of practical association with technical mat ters.
Large numbers of owners, and particularly owners of smaller vehicles, are undoubtedly as boring -to their friends as if they were fishermen or golfers. They talk amateur shop by the hour ; they do not hesitate to communicate their convictions as to the relative merits of overhead and side valves ; sleeve valves and mushrooms ; tee-heads and sphericalhead combustion chambers ; magnetes and c3ils ; Aut.:-.vacs and pressure feeds ; three-speeds and fourspeeds ; conntershaft brakes and back-wheel brakes ; bevel and worm final drives ; pressed-steel and wire wheels ; two-strokes and four-strokes ; air-ccoled and water-cooled eDgines ; horizontal and vertical engines ; two, four, six and eight-cylinder engines ; and so on, ad infinitum. Here. and there, of course, owing to many years of driving and amateur repairing, the owner, who may be a solicitor, a fishmonger or a dentist, becomes moderately expert, and his opinions, even on highly technical matters, are notevithout considerable 'value. But a large number of such folk are constantly broadcasting with no uncertain voice their definite conclusions as to what should be the practice to be followed by the highly paid technical experts who are engaged in the service of manufacturing concerns. Much of such advice is particularly tiresome, because, on the face of it, it is very superficial, and more often than not is parrot-like, information based on smatterings acquired from the technical Press and handbooks, or from conversations with numberless other enthusiasts who have made motor vehicle construction and operation their hobby.
One such example that has occurred to my mind on frequent occasions is the manner in which numbers of people prate of the disadvantages of " unsprung weight." This is an expression that one frequently hears used, and it concerns a factor which is almost invariably condemned—one that must be reduced to the lowest possible point consistent with safety. Yet, not one in a hundred of those who talk of unsprung weight realize the true facts and limitations of the problems involved therein. Particularly is this a subject that is dear to those who are associated with industrial vehicles of all kinds. The technical experts, who, in increasing numbers, are making the commercial vehicle industry their lifes work; are on very rare occasions at fault in this matter. But there is, undoubtedly, a good deal of loose thinking by the semi,experte. There are examples, for instance, of very heavy back axles which have given remarkable resulta so far as maintenance is concerned, whereas it is easy to quote other in, stances in which a designer has evidently tried to cut his unsprung weight down to the minimum, possibly with the result that axle shafts, bearings, axle casings and springs have over and over again given trouble.
Attempts to reduce the weight between the springs and the roads without proper regard for adequate bearing surfaces and cross-sections are, of course; not to be commended, and some of our friends would do well to remind themselves of the extensive damage that is frequently done to the heavier types of motor vehicle by long periods of running, without load at relatively high speeds. Far less damage is done to vehicles of this kind when they are running with loads that may even be somewhat in excess of those for which they were scheduled when they left the makers' works. In auY case, properly loaded machines willcertainly be 'less liable to trouble in many chassis components than will others which are. run for long periods in a condition which produces the very worst effect from excessive vibration.
Not necessarily does the best result accrue from the axle which, very flexibly sprung and of light weight in itself, bounces and jumps about at every i inequality of the road which t meets. People who are constantly harping on the evils of unsprung weight are also very liable to forget that even the solid tyre of ample section, and certainly the cushion and pneumatic, interpose adequate elastic provision between • axle eveight and road unevenness.
Another aspect of the same question, of course, is to consider the relative effects on the road surface of heavy-axle units which hold, and perhaps crush, the road, and of comparatively light ones, which are constantly bumping about and hammering the surface There are numberless examples, if one cares to , think for a moment, of the child-like way in which the motorist has, from time to time, been beguiled into enthusiasm over some new fad. How many times, for instance, have we heard of wonderful preparations to be used by way of addition to petrol which would ensure sensational increases in the mileage to be obtained per gallon of spirit? All sorts of wonderful pills and liquids have been retailed at highly profitable prices and in great quantities for the while that the fad lasted, ultimately to be discarded when the experiment has got down to brass tacks and disillusionment has followed, because, if some slight
in
variably may have accrued, there have almost proved tohe other considerable disadvan tages which were not so carefully scheduled in the inviting announcements of the advertisers.
Then, take the wonderful case again of the con stant procession of carburetter improvements. It only needs a brief survey of patentees' activities in this direction for a number of years past to realize that thousands and thousands of odds and ends of contrivanees have been sold to unsuspecting motorists with specious promises of remarkable additions to the mileage per gallon. I can, myself, recall dozens of such devices, all of which were in the promoters' flowery phraseology destined to revolutionize motoring and bring it within the grasp of the man of moderate means. Yet to-day we are very ninch where we were years ago so far as carburetters are concerned. The improvement in consumption has been brought about by careful technical development in the design of the engine itself, and but little by the adoption of any sensational improvement for the carburation of the spirit. We still use squirts, and we still try our best to mix the partially sprayed and partially vaporized spirit with more or less satisfactory proportions of hot or cold air.
Some of the carburetters that have been tried in the past with a view po securing improvements in
consumption by way of attempting a better range of efficiency at high and low engine speeds have had the appearance of a miniature gasworks once they have been fitted under the bonnet. And yet some of the simplest and most efficient carburetting devices have consisted of very little more than the famous jet in a length of gas-pipe.
There are many more examples of the way in which the public fancy can be tempted, and perhaps one of the most familiar is the wonderful way in which Mr. Ford's masterpiece—a compromise of supreme. skill— has been altered out of all knowledge by the addition of a thousand-and-one so-called improvements. Mr. Ford does not mind, presuinably, but he goes on in his old sweef, way, and produces the hundreds of thousands of cars much the same as they have been for years past. I often wonder whether his staff keeps for .him a record of the thousands of wellmeaning efforts that people have made to improve his " flying bedstead "; if so, his smile must be a remarkainle one when he thinks that he can still count on an income of £100,000 a week (or is it a day 1—the figure is beyond me, anyway) without indulging in any of the thousand-and-one fancies that other people feel certain are necessary to adopt if the Ford is to be a practicable vehicle,
Yet one other example—and there are many of them. Innumerable devices are produced from time to time with a view to persuading the owner to im prove the springing of a manufacturer's standard machine. All, sorts of odds and ends of things are hung on to the normal springing ofk.all kinds of ehassis—more so,on pleasure cars, of course, than on commercial vehicles. Very few of those who indulge in theni realize that many of these devices are quite unnecessary if the springing, plus reasonable shock absorption arrangements, are designed correctly to start with—and it is to he presumed that most of &mil are—nowadays, at any rate.
Another interesting example that has some relation to modern motor vehicle traffic, at any rate, may be mentioned. • Recently a large section of the public essayed to adopt the idea promoted by the Press to the effect that pedestrians should in future keep to the left, so that they should, on the footpaths, walk oppositely to the oncoming vehicular traffic. There was a tremendous trumpeting of this idea but a month or so ago. In the few short weeks the idea seems to have been dropped, solely because the public, when it came to practise what it was inclined to preach, found it irksome to be bothered to change its habits. I may not have been very observant, but it is my impression that, to-day, in spite of notices and municipal injunctions to save our skins by adopting this " Safety First." precaution, very few people indeed have changed their habits so far as walking to the right of the, footpath is concerned. Recently, in Oxford Street and other busy London thoroughfares, I found the crowds still surging along to the right.