Pneumatic Spokes Instead of Pneumatic Tyres.
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NOT SO many years ago, when the springing of commercial vehicles was less satisfactory than it is to-day, much attention was devoted by inventors to the design of resilient or cushion wheels to supplement the usual methods of absorbing road shocks. Most of these wheels were unpractical, and failed to outlive the experimental stage, although one or two more simple in design than the majority, were tried out on commercial vehicles and gave a fair measure of satisfaction.
Of late years less attention appears to have been given to resilient wheels, due largely to the lack of encouragement given to inventors of such components, although, if it were possible to obtain a wheel which, under all conditions of service, gave a cushioning effect equal to that of a pneumatic tyre, we feel sure that it would meet with favourable consideration at the hands of manufacturers, whilst encouragement would come from users if they could be convinced that the bugbear of the burst pneumatic tyre would be dispelled without being merely replaced by other troubles.
It is for this reason that we think many of our readers will be interested in the Baquie-Marshall pneumatic wheel—an 'Australian invention—which is being sold by the Baquie-Marshall pneumatic Wheel, Ltd., 274, Collins Street, Melbourne. This pneumatic wheel has an ordinary hub, to which the spokes are rigidly secured, but cylinders which function as air compressors are fitted over the spokes, and extensions on these cylinders, which are fitted with ball bearings, give a sliding fit within the inner periphery of the rim.
The general design of this pneumatic :wheel can he seen in our line illustration, which also shows a. spoke and a rim in section. The effect of this construction is that the pneumatic action, which is said to be at least as great RS that of an
inflated rubber tyre, is transferred to a protected position between the steel rim and the hub, and as the air cushions are permanently sealed in the metal " spokes," •there can, of course, be no punctures, no valve troubles, and the like. The wheel is being made for use on vehicles of the heaviest type, and will enable more resiliency to be obtained from the use of solid tyres.
Under test for side thrust., it is said that the wheel has proved stronger than
any other type, excepting the wire wheel, and will resist greatse pressure. A spoke deflation test to which it was submitted proved that it,could stand a -pressure of 24,000 lb. equal to 8,000 lb. per sq. in. The cylinder portion of the spoke was, it is stated, also tested to over 200,000 lb. pressure before crumpling.
The other illustration which we reproduce shows a cushion wheel which is being produced by the Sewell Cushion Wheel Co., of Detroit, U.S.A. This wheel, it will be seen incorporates a • rubber flange construction, which, it is claimed, doubles the resiliency of the live rubber cushion.