The Technicians' First New Year Job EIRST amongst the technical
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problems of 1943 is to find a substitute for the rubber tyre. There are enough alternative fuels for the urgent needs of the moment, but what use are they if wheels cannot be shod?
In this problem there are two main considerations, namely, affording resilient support for the vehicle and providing running contact with the road.
Of the two resilient media, steel springs and air, the former, with certain exceptions, are universally used in current practice in the chassissuspension system, whilst the latter is confined to the tyre. The reason, in the first case, is not wholly clear, but in the second it is fairly obvious. It is because of the nature of the contact medium that stands alone owing to its frictional, cushioning and wear-resisting properties.
Rubber is almost an ideal substance for use in conjunction with pneumatic suspension. Accordingly, the air part of the system has been applied • where the rubber part is located.
It must be remembered that the tyre has two function's, which, although separate, are very dependent upon each other. In many of the early spring wheels, some of which were illustrated in a recent issue of this paper, the designers had done little more than to incorporate in wheels resilient suspension systems, paying attention to the need for supporting radial, tangential and lateral loading, but, apparently, disregarding essential tread characteristics. These engineers appear to have missed the main point, and to have attempted to build into the wheel, not the part extending the function of the old iron rim, but the part on the frame side—not the long-suffering, hard-wearing, cut-resisting, . stress-enduring, bump-absorbing, adhesion-affording and buffet-bearing, co-operative integral of cotton and rubber, that is now in perilously short supply, but just some more springs to supplement, hardly necessarily, those that were already there.
In others, the importance of tread flexibility has been appreciated, but, even then, cushioning and wear seem to have been given little attention.
That, we suggest, is the real problem. If a material can be found which is flexible, soft, durable under abrasive action, waterproof and with road-,,ripping properties, perhaps brake fabric, leather, balata, rope, or even wood blocks suitably mounted, then the rest should •be relatively easy.