The Claims of Resilient Wheels.
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By Henry Sturrney.
The question of resilient wheels is once again coming forward for consideration, and I think it will be generally admitted that it is a question of some real importance. _4() far as the touring car is concerned, the question has been well met by the pneumatic tire, and I do not think it nil! be possible for us to improve upon the pueumatie system, so far as perfection of insulation from vibration Nal the prevention of the effects of road shocks is concerned. But the pneumatic tire leaves much to be desired in other directions, its unreliability and expense being the main objections from the commercial-vehicle user's point of view, and it is in order to arrive at something better in these two directions that the official investigation of the resilient-wheel idea is suggested. Of course, we have the rubber tire—the solid-rubber tire. But this, although a deadener of sound, and somee hat of vibration, has but little resilience; moreover, with the only form of solid tire which is really satisfactory for heavy loads from a wearing point of view• I refer to the banded solid--when it is appruatching the last few thousand miles of its usefulness, it. is worn away to so shallow a thickness that, except for the deadening of sound, the car may, for all practical purposes, be running upoe steel. The solid-rubber tire, toe, is expensive. Contrary to the popular understanding of those who have no practical experience of the question, it is much-more expensive than the pneumatic in first cost— rubber always will be more costly than air. And it is only by reason of the fart that its effective life is substantially longer than that of the pneumatic tire, that it remains a practical commercial proposition at all.
What is Wanted.
What is wanted is something which will absorb the shocks without either pneumatic or solid-rubber tires, because, if we continue to use the solid-rubber tire, and merely substitute for the air an expensive construction of springs, or other devices, we add to our expense rather than reduce it, although we may obtain some advantage in lessened wear upon our machinery. Whether the use of a spring or other resilient wheel, with non-resilient tires, that is to say, with steel, wood, or, let us say, leather coverings for the wheels at those points where they are brought in contact with the ground, would meet with the approval of the authorities, or rather, I should say, would comply with the requirements of the Act in regard to the matter of speed. I cannot say. I am writing without a copy of the Act before me, but, if I remember right, motorcars fitted with other than " soft or elastic " tires are considerably restricted by law in the matter of pace, and, really, it is well for its that it should be so, because high pace on rough roads. under dead loads and elilinresdient wheels or I ites., w(illid be a very-stiff proposition for the mechanical parts of our chassis to stand. But, if a really-satisfactory system of resilient wheel can he arrived at, it should be able to give better results, bora as regards the lessening of elmeks to the internal economy of the car and the lessening of road wear, due to those shocks, than even the solid tire which is approved by the authorities for spew' to-day. Hence, providing a reasonably-reliable device can be secured, the user should certainly be able—unless, as indicated above, the law bars anything but resilient tires—to obtain an increased travelling rate for the car, and consequentially more-expeditious delivery of his goods, which, even were there no saving in upkeep expenditure, would in itself be an advantage worth securing to the commercial user. At the same time, it must be admitted, the problem is not an easy one, more especially in regard to that type of vehicle where it most wanted. I refer to the really heavy-load class.
Some of the Difficulties.
Not only has the designer to deal with the question of road shocks, but he also has to secure lateral stability: If he had anly the former point to deal with, the matter of the resilient wheel would be a comparatively-easy one, but it is the lateral stresses which require to be met which introduce the chief point of difficulty. In a laden vehicle imposing a direct vertical load of three or fleetons upon a. single wheel, the lateral stresses impo.sei upon that wheel when taking such weight around a curve or corner fast, or when travelling upon a heavily-cambered road, can easily be imagined. The factor of variable imposed load has also to be reckoned. The question of dealing with lateral stresses has resulted in the introduction of sliding movements, compensating lever actions and a lot of other complications in spring wheels. These have been practically fore-doomed to failure, on account of the number of working parts employed, and the necessity, combined with the extreme difficulty, of securing efficient lubrication for the same. I have seen some wheels of the spring order which have no working joints at al4, save what working there may be around the points of their respective attachments to the felloe and the hub, and it is possible that some one or other of these may ultimately
prove successful. I am personally rather inclined to favour the pneumatic type of resilient wheel, in which a cushion of compressed air is placed around the hub, or at sonic intermediate point between the axle and the felloe, n construction which, whilst securing the cushioning properties and resiliency of compressed air, removes the containing media from direct centact with the ground. and iherefore prevents that excessive wear of a delicate
dterial which results from abrasive conta,..t. with the / IA, and also removes the vital air container from likely must with puncturing objects.
Possible Trials: Vehicles Wanted.
Trials by the Royal Automobile Club are being spoken
as possibilities in the near future, and such trials, if They are carried out practically " to destruction," would andoubtedly be productive of much valuable and useful 3nformation: they might even result in putting this question of resilient wheels for commercial vehicles upon a practical and recognized footing. Even supposing, however, that any one particular wheel came through such Trials with signal success, it might not, after all, mean -that that particular construction would be equally satisfactory under universal application, so that we must not jump too rapidly to conclusions that a system satisfactory fer one branch of work will also be satisfactory for all athers. It is comparatively easy, for instance, to make a Ti-silient wheel which might give reasonable satisfaction Neter, say, 15-cwt. loads, whereas the same class of wheel might lamentably fall down if put under five tons. In airrying out the trials, it would, however, hardly be possible, I think, to stipulate any particular loads to be dealt ith. Were it a stipulation, for instance, that all cars in flie trial should carry, say, three tons, we should get an interesting and valuable line of comparison along the 'three-ton limit, but the results would hardy be applicable T. other limits. If trials are instituted, they will have te embrace all types. Owing to their length, if they are
be of value to the public, length of life and wearing ialities being points of the highest importance, they must necessarily be expensive as, first, they call for the use, not only of the competing wheels themselves, but of the cars to which they are attached, and that is where the main expense will come in. It seems to me that such trials might very possibly give some of our car manufacturers an opportunity of testing their cars as well as the patent wheels, but whether such a proposition would be acceptable to the trade is suite another matter. I do not think it would be. The reliability and dependableness of a good commercial vehicle to-day is already proved and acknowledged, and those makers who, by several years of serious and practical work, have established their positions, do not want to be put to either the trouble or expense of trials. They are not, for these reasons, likely to enter any competition on their own initiative, unless they happen to be interested in a particular resilientwheel idea. It is of course, the patentees and owners of • resilient-wheel devices who will want these trials, and who will participate in them: these parties will necessarily have to hire the. vehicles—if they do not already own them—to which their wheels can be fitted.
Expense or no expense, the public will not take any resilient wheel on trust, so the idea is to be encouraged. If any practical development is to take place, with any chance of commercial success and of really impressing the motor-vehicle-using public, such expense will have to be incurred, and I think the time is now ripe when such an expense may justifiably be incurred by all those interested, fur we know sufficient about the problems we have to deal with now to deal with them in a more-or-less practical manner, and the magnitude of the trade is to-day such that success in a public contest should be valuable.