An Ingenious Wooden Tire.
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The number of substitutes for rubber tires which is brought to our notice in the course of the year is enormous ; yet in how few of them is there any merit beyond that of novelty. The inventors of such devices too frequently, as one may prove by reference to the files at the fatent Office, are "knights of the road"--probably travellers for soft-goods firms. Such men have no mechanical training and only a vague conception of the true requirements which they set out to meet ; during the course of their travels, they probably notice vehicles in difficulties—they themselves may even be inconvenienced by the failure of a taxicab tire—and they then set out to solve the difficulty once and for all, and, incidentally, expect to make their fortunes by so doing. Poor deluded wretches ! Fortunes are not made that way. Occasionally we meet with patent non-rubber tires, or a resilient wheel, which possesses merit above that of novelty, but such inventions are not the products of soft-goods travellers ; they are the results of careful consideration by engineers or men who have given much study to the conditions which have to be encountered in actual service on the road.
We deal with one such invention, a wooden tire, in the resent article. It has been produced by Mr. J. H. Knight, of Barfield, Farnham, who may truly he called a "Knight of the road," although not in the same sense as a "commercial." Mr. J. H. Knight is one of England's pioneer motorists and motor engineers. So early as the year 1895 he designed, built and ran—and was repeatedly summoned before the magistrates for so doing—a two-seated paraffin car, which vehicle was shown running at the opening of the first motor exhibition at the Crystal Palace, in 1896, and was the first two-seated motorcar built in England. That historic vehicle was exhibited at the White City, in 1909, and at the present time it is safely housed at Mr. Knight's Surrey residence pending the completion of extensions to the South _pending the Museum, in which national institution it will find a permanent home. In other branches of engineering too, Mr. Knight has made his mark, and the Trusty oil engine—a popular and efficient type over a decade ago— \NILS one of his most profitable and practical inventions.
Ever since he built his first motorcar, Mr. j. H Knight has closely followed the progress of the mato/ movement, and at the present time he is the owner o
three cars ; one of these, a small 9 h.p. single-cylinder Darracq, he has " told off " for experimental work in connection with the trying out of his new wooden tire. The general appearance of this tire, as may be seen by the accompanying illustrations, is against its ready adoption by town-car owners, and even Mr. Knight will not claim that it is pretty, but it must be remembered that it has been devised not so much for town
carriage use, as for hard service on country roads and tracks, on the wheels of commercial vehicles.
Mr. Knight chose wood for his tire because it is one of the most elastic of materials, and it retains its elasticity for a much longer period than rubber or other substances of a like nature, provided, of course, that it is not stressed beyond its elastic limit. He quotes the archer's bow as an example of how wood will retain its elasticity for 50 years or more. This is an interesting example in a way, but the making of a successful wooden tire presents a very different proposition from the making of a bow. In the first place a wooden tire must be both cheap and reliable ; it must also resist wear to an extent comparable with rubber, must he resilient, show no tendency to part from the steel rim of the wheel, and it should not damage the road over which it travels. Time, and the tests which Mr. Knight is now conducting, can alone prove to what extent this new tire will meet those requirements. Mr. Knight produced his first wooden tire in the autumn of last year ; it was fitted to a 34 in. wheel, and without the intervention of a carriage spring between the axle and the load platform, the wheel, with a load of between 4 cwt. and 5 cwt., was run over such obstacles as bricks with perfect ease, and without damage to the tires. A pair of similar tires were then fitted to the driving wheels of the 9 h.p. Darracq car, which we have already mentioned ; they have since been driven over many hundreds of miles of country lanes, with results which give promise of great success.
It is not claimed that these tires are as resilient as pneumatics, but, from our own personal experience, we unhesitatingly state that they are more resilient than solid-rubber tires, and it would appear that their cost, will prove to be much lower than that of rubber.
When we first saw this tire, we anticipated that the wooden blocks would creak abominably, and that the tire would be noisy in use, but we were greatly surprised to note that the wood blocks male but little noise when running, and that they left no mark on an
average inacadaui road ; further, these tires have advantages which are not possessed by rubber tires, one of the most important of which is that they will pull through soft, wet ground, loose earth or shingle, when pneumatics or solid-rubber tires would fail to get any grip.
The tire, as may be seen from the photograph and sketch now reproduced, consists of two or more parallel rows of wooden blocks, each of which is shaped as shown in the sketch. The base of each block is cut to the radius of the steel rim, and ATshaped pieces are cut away at each end, near the base, and the wood above them is divided by saw-cuts into three or more layers, so as to increase the resiliency of the block. The grain runs lengthwise of the blocks, and the top surface of the wood is armoured with steel cleats or shoes, the object of which is to prevent the splitting of the upper fibres by loose stones. It is remarkable that these cleats are not torn away or flung off the wood, even at speeds well over 20 miles an hour, and should one block become damaged it may be replaced in a few minutes and at very low cost. A few spare blocks may readily be carried on the vehicle. It should be noted that betore they are bolted on to the steel rim the blocks are bent, by steaming, to a somewhat greater curve than the circumference of the wheel. In the wheels which we had the pleasure of testing there are two rows of eight narrow blocks in each wheel. In a commercial vehicle, of course, for heavy loads, larger wheels would be used, with three, or even more parallel rows of blocks, the blocks in each row being break-jointed in relation to those in the adjacent row.
We shall watch further developments of this wooden tire with great interest, as, if it proves to be a cheap one to run, its other advantages—those of ensuring a grip on the road under all conditions without damaging the road, and the complete elimination of sideslip—should place this tire far ahead of any solidrubber tire at present on the market. It should also be of immediate interest in military circles the world over, and to owners or prospective owners of tractors or lorries in sandy areas.