However excellent may be the workmanship, or however firmly an ordinary wooden wheel may be put together in the first instance, the wooden felloes thatform the periphery, being constantly exposed to the effect of wet and dry, are tontine ally expanding and contracting; consequently tbejoint or connexions between tbe ends of the spokes and the felloes, and the former, either become loose, or split the felloes ; when this takes place, the several parts of the wheel yield by Ruined little to the strain of the load, or the effects of concussions, and the whole eked becomes dislocated. As a remedy to this defect, Mr. Wm. Howard, the irmmaster of Rotherbithe, his recently proposed some new arrangements of a pre cisely opposite character to Mr. Jones's; which we proceed to describe.
Mr. Howard's invention has no reference whatever to the nave of the wheel, but is confined to an improved mode of combining a wheel at its periphery. He employs, as shown in the subjoined figure, representative of a small portion of a wheel, an iron ring is, as the outside tire; inside of this tire he has another ring of iron, b, which stands as a substitute for the ordinary felloes ; and to this, which we will call for distinction the felloe-ring, he fastens by red-hot rivets cc, a " spoke-shoe" d d, made of the shape represented, of cast-iron, and containing a central cavity or socket, for the insertion of the end of a spoke e; of mum there are as many spoke-shoes as spokes, which are arranged equidistantly around the inside of the felloe-ring ; when these have been all firmly fixed in the manner of that shown, and the spokes have been all duly fitted into the nave and driven home, and the outer ends of all the spokes have been accurately ganged, and duly fitted to the sockets of the shoes, they are put or forced into the same tideway., as seen at e; this operation is performed in such a manner as to leave a space of about half an inch between the-ends of the spokes and the ends of the sockets, for the purpose of wedging them up firmly. This is effected in the following manner :—Against the squared end of each spoke is laid a thin piece of' plate•iron y, of the same sectional area; then is driven a slightly tapered long oaken wedge A A, the foremost end passing through a hole cast in the shoe on the opposite side : and when the cavity is thus closely filled, the projecting pieces are cut off; and a sharp iron wedge i, is then driven into the middle of the oaken wedge, so as to render the force of contact as great as posaible ; a plate of wrought iron, f, is then put into the cavity represented over e A i, and riveted to the shoe by long red-hot rivets passing through the whole. All the shoes and spokes being thus fitted; the tire ring is put over the whole in a red-hot state, which, shrinking as it cools, draws the whole together in a manner that gives it extraordinary solidity.
It will be observed that the principle of construction of Mr. Howard's wheels is the same as that of the common kind, in which dependence is placed entirely upon the stability of the outer ring for its cohesion ; but it is a more finished and masterly production, is constructed of more tenacious materials, and is well calculated to obviate the leading defects before mentioned of the former. The
advocates for Mr. Jones's wheel object to Mr. Howard's, on the ground of its not being on the tension principle. On this point we would observe, that the spokes undoubtedly are not, but that it may be fairly contended that the periphery is, as this must be torn asunder by a longitudinal pull, in order to destroy the cohesion of the wheel ; and the felloe-ring alone, (which never wears,) is made of adequate strength to bear the whole strain, without any of the additional support it derives from the tire-ring; the utmost confidence may therefore be placed in the great strength and durability of Mr. Howard's wheels, however excellent may be the principle of the former invention.
A patent was recently taken out for a very strong metallic wheel, by the Messrs. Forrester, of Liverpool, consisting of a skeleton of malleable iron, im bedded or surrounded with cast iron. Such wheels are, however, necessarily very heavy, and less suited to the common road than to RAILWAYS.—For a description of them, see the latter article.
We shall, however, advert in this place to another patent,—not on account of any novelty it may be found to contain, but for the twofold purpose of eluci dating a process that we had imagined was commonly practised by iron-masters and tire-smiths, and of affording us an opportunity of noticing • the erroneous principle upon which wheels in general are constructed.
The specification of Mr. John Meaden, of Southampton's patent, (enrolled June 1828,) states his object to be the construction of the tire or hoops of iron, which surround carriage wheels, concave on the inner surface, next to the felloes, and convex on the external surface; the objects of which are to fix the tire more securely to the wheel, and to reduce the friction produced between the periphery of the wheel and the road. The specification proceeds to describe very minutely the process of making tires,—a process which we doubt not our readers of the before-mentioned callings will recognise as a " modern antique." A common fiat wrought-iron bar, of the proper width and length, is to be passed between a pair of rollers, one of which has a concave groove, and the other a corresponding convex projection, so as to compress and bend the inter vening bar into the required form. The bar thus formed is next bent round into a hoop of the required size, with the concave side inwards, and then the ends are welded together. To give the hoop the desired conical figure, ter " dishing, " it is placed over a large cast-iron mandril, like that represented in the annexed figure, where it is ham mered until it takes the required form.