IDS AND NON-SKIDS.
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A Seasonable opic. A Problem Still Waiting Effective Solution. By "The Inspector.'
T WOULD BE difficult to point to any specific constructional detail or to any mechanical charac
teristic of the modern chassis which has not been improved almost out of knowledge, in most cases, during the last ten years. The mechanism is much more highly efficient .both as a whole and in detail. Complications have disappeared, designs are cleaner, and the distribution of mate ial more nearly approaches scientific perfection more appropriate selection is made of the gra4tings of the various metals • axle weights, wheelbases, frame heights, groundclearances, and spring lengths, to say nothing of engine dimensions, have all been improved and modified to the very distinct advantage of the user, whether in connection with the touring car or the commercial-vehicle chassis. Yet, with it all, there is one characteristic in which it appears to me that little or no improvement has been effected. I refer to the facility with which otherwise Well behaved vehicles will still deviate from the pas of rectitude, and, with the slightest excuse of insectuity of tyre hold, will cavort joyously across the highway.
It is a fact that, notwithstanding all the expenditure of ingenuity that has been lavished on the problem of the effective Don-skid, to this day, vehicles, particularly those with solid tyres, will, if the drivers allow them, skid and sideslip with just the same facility as they did ten or twelve years ago. This is an astonishing fact, and were it not true that drivers had reached a higher all-round grade of skill in the handling of the wheel and that such fittings as the brakes, the clutch, and the steering gear, all ready auxiliary to the question of skidding, had been unproved to such a very appreciable extent, there would be just as much actual skidding to-day as there used to be. It is not because of the adoption of any effective antidote to the skid that vehicles hold the road more effectively than they used to.
A certain amount of progress was initiated so long ago as six or eight years, so far as pneumatic-tyred vehicles were concerned. By the aid of various special-shaped protuberances on the tyre-cover surfaces, an effective grip• is maintained so long as the edges of these serrations remain sharp and unworn. The -metal-studded pneumatic cover is in these days the generally accepted safeguard on touring cars to the extent mentioned, and indeed it had been quite a number of years before the war, but further advance is not on record.
When we come, however, to examine the case for the solid tyre, we find that progress has been practic ally nil.We used to see that queer-looking contriv ance which, nevertheless, was an effective design, the "K.T." tyre, marketed, if I recall correctly, by the Commercial Tyre Co. It consisted of an equally
spaced series of rubber blobs or studs? held in position on the rim by a perforated metal rim. As a non
skid I can certainly certify that this was quite effective. As a matter of fact it has remained the only solid rubber tyre—and even that was cushion and not properly solid 1—which was efficient as a skid pre2, venter. It brought with it, however, certain definite' . disadvantages in. the Shape of increased tractive' resistance. On heavy, loose roads this factor was a very serious disadvantage indeed. I never had much use for the block-pattern tyre, a type favoured on the Continent, and of use in certain directions, but of no particular advantage in connection with skid pre vention. We are left, then, with the ordinary solid: c30 rubber tyre, either single or in pairs. Dennis's and other fire-engine builders adopt when possible a solid tyre of special moulded-tread pattern. This is effective for a time.
I happen to know a chain maker in the Black Country, who tells me that the Army uses very large quantities indeed of short chains, which he believes are used for fastening round the solid-tyre rims of Army lorries, and I believe it is a fact that military transport authorities have long ago come to the conclusion that the only effective method of preventing the lorry wheel skidding, and of securing adhesion when ditched in a slippery hole, is by the use of chains more or less corresponding to the famous Parson's non-skid. That, I believe, is a war-time expedient for active service, but such chains must surely wear out, under the heavy localized pressure, at a rate which would not render their use on heavy lorry whaels an economical proposition. For special purposes in snow, or on bad limestone roads, something of this kind is perhaps the best that-can be done in the present circumstances.
The above instances show that the inventive mind has been busy on the problem in the past, and occasionally one still hears of new patent applications for modifications of the chain types and less frequently for more fantastic designs ostensibly for the same purpose. I recall the fact that, quite a number of years ago now, it happened to be my duty to examine a large number of devices that had then been fitted to get over this skidding trouble, which, in those days, was particularly bad on account of the indifferent way in which the axle-weight distribution was effected. Some of the schemes I saw were too ren4arkable to be forgotten. Will it be believed, for instance, that one brainy contrivance, embodied an apparatus by virtue of which it was intended that a lever fitted at the end with a bath brick was pressed down on top of the tyre by mechanism operated by a pedal? The idea, of course, was that the tyre should receive a coating of grit, and would therefore have a chance to hold on the slipperiest of surfaces. In practice nothing happened with the exception that the tyres were great grooves in the brick after a few applications I Another device I remember was intended to become operative upon the first lateral movement of the chassis, and then, through an elaborate and particularly ugly system of cables and rods, jerked open. the outlet cluots-from conveniently placed receptacles for gravel and sand. The objection to this was that the vehicle to which it was attached was incapable of foreseeing the moment at which the skid would start, and, although in practice the ground around was plentifully besprinkled with nice new sand or gravel, this only happened when the skid had got well under way, and when nothing short of collision with a lamp-post or kerb would have stopped it.
Yet another case (and .this was at a later dateabout-a year or two before the war). I was shown a machine fitted with a gyroscope, driven from the transmission shaft. The,idea of this was, of course, to preserve the direction of progress of the machine, to enable it, in other -words, to resist any sudden change of direction—an excellent theory, provided that all journeys could be performed as the crow flies. I remember at the time expressing myself sceptical as to the effect the device would have—if it were effective at all, when it became necessary to turn corners quickly, or to dodge in and out of traffic. The inventor-naïvely explained to me that. neither of these evolutions should be done without great care and never by a properly trained driver. So that on the whole the gyroscope had its limitations.
These and a lot of other schemes have been tried and tested to destruction in the past, and here, in 19,0; wefare left with no better -remedy than to surround.the tyres with loosely-linked steel chains, This device serves its purpose well enough on pneumatics on which the surface wear is relatively small, but it is a more or less clumsy compromise when attached to the solid-tyred wheels of heavily-loaded lorry and van axles. Perhaps it will be found that it is best after all to rely upon the skill of the driver solely, and it is certainly remarkable that so many tens of thousands of drivers should be able to control their machines with such confidence when they are running on greasy roads with nothing better to hold the reardriven wheels of their vehicles than the smooth and perfectly lubricated surfaces of the rubber tyres. These are days when roads are getting the minimum of cleaning. The roads, given a few days of bad weather, are little short of abominable. The danger of skidding is at such times very great indeed.
• We are evidently wedded, for a while at any rate, to the rear-driven machine, be its axle live or dead, and so long as that form of drive is popular, so long will the back wheels attempt to run round and catch up the front ones, given half a chance. The fourwheel-drive machine has earned for itself golden opinions on active service. Long before the war the French and American Army authorities had made up their minds that. this type of vehicle had certain very particular advantages, and one of these undoubtedly is the improvement in the conditions which they afford in " holding up" on slippery roads.
inventors appear rather to have given up this problem, but I would plead that further efforts be made to render an effective non-skid a practicable feature for all solid-tyred machines. This, as I wrote at the beginning of this article, is one of the few, if not the only characteristic of the motor chassis Which has not been improved out of all knowledge but to this day there is nothing of 'which I know which will with certainty hold a motor vehicle, on greasy asphalt, the vilest of muggy-weather surfaces. The nearest approach of which T know to effective mastery of such conditions is the " K.T." which I have already advertised sufficiently! With the great boom coming in public road transport of all kinds, when peace is declared, and with the number of new drivers of both sexes that will be available for such employment, it appears desirable that we shall not adinit that the last word has been said in this search for an effective non-skid. There is surely prize enough to spur on the inventor. A successful design should have a sale of colossal proportions. The probable handsome reward in royalties should be enough to tempt us to further investigation. But let U.S lose no time in the futile effort to rub brick dust or garden gravel on to the offending tyres nor to spread it on the surfaces upon which they are to slide. Quite a number of devices which have been proposed in the past would have . been successful had they only contrived to embody brains in the mechanism. The time to chock a skid is before it happens, not afterwards.