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Stagg's Motor Wheel,

29th June 1905, Page 12
29th June 1905
Page 12
Page 13
Page 12, 29th June 1905 — Stagg's Motor Wheel,
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In our issue of April 27th, allusion was made to the new motor wagon wheel which has been put on the market by Messrs. Stagg and Robson, Limited, ol Selby. As the wheel is a distinct novelty and is the outcome of great practical experience, it merits a more lengthy description.

At the very commencement of the motor movement, Mr. Stagg was engaged in the manufacture of motor wagon bodies, wheels, and. trailers, and as the wheels then used were all of the artillery pattern, with wooden spokes and a rolled steel tyre, and, in the early days, of inadequate dimensions, he was soon struck with the necessity for an improved wheel, if the cost of wheel upkeep was not to affect prejudicially the introduction of motor wagons. The present wheel is the outcome of mane gra. d u a 1 improvements and much experiment, and is undoubtedly simple and efficient for both motor wagons and motor omnibuses.

The hub is a steel casting, so designed that the spoke ends fit into pockets in the hub, and are secured in position by a circular face plate bolted on. Fig. i is an elevation of the hub with the face plate removed, whilst Fig, 2 shows a section of the same. It should be particularly noticed that the section shows a slope on the bottom of the pocket, and, in fact, this slope occurs also on the sides of the pocket, as is evidenced by the double lines in the elevation, Fig. z. The effect of this slope is that the spokes are not only gripped tighter as they are forced home

in the pocket, but they are also pushed outwards, getting a better grip between the hub and the rim. A face plate, with a bolt through each spoke, secures the spokes in the hub.

The rim is also a steel casting, and is provided with pockets into which are fitted the outer ends of the spokes. Fig. 3, which shows the wheel almost complete, indicates clearly how the spokes are inserted into the pockets on the rims. After the spokes are forced home, a covering clip, secured by a bolt, is put over the spoke end to protect it from damage. The spokes are forced into the pockets, in both hub and rim by .a powerful hydraulic press, so that there is no possibility of a loose spoke. Half the spokes are put in from the front and half from the back, which gives the wheel greater rigidity, and takes up all side strains. It is thus clear that the wheel is a cross between t he oldfashioned wooden wheel and the cast steel wheel which is now seen on some motors. The makers contend that it possesses the advantages of both types and none of the disadvantages.

Artillery wooden wheels have wooden felloes and a rolled steel tyre, either welded or weldless. Such a tyre is ductile and slowly lengthens by the " rollingout " action of road work. As soon as it gets appreciably longer the spokes and felloes are found to be loose and working on one another as the wheel turns. In this state a wheel groans and complains noticeably, and all the joints between the numerous component parts of the wheel are wearing out of shape. If it is taken off and pressed up before the wheel loosens no serious effect is produced, but if it once begins to groan (and the groaning is often the first real indication that the wheel is loose), the wearing of joints and tangs has commenced, and no tightening can make a thoroughly good wheel of it again. Heavy Wagon Wheel. Fig. 3. But a cast-steel tyre, from the different nature of the material, can never roll out, and, if properly annealed, cannot break. The rims are cast by Messrs. 1k. G. Armstrong, Whitworth and Co., Ltd., whose name is a guarantee that they are the very best material that can be produced. In addition to this, they are subjected to an exhaustive test, which generally takes the shape of dropping the rim on to an anvil from a height of five or six feet. This is a much more severe shock than could ever be met with in practical use, but it enables any faulty rim to be immediately detected, and scrapped. The rims are strengthened on the inside by a diagonal rib, which adds but little to the weight. In fact the rim is made both lighter and stronger than could be the case without the diagonal bracing. The tread is made either smooth or with shakes conform:ty with the Heavy Motor car Order), as preferred. Steel wheels, cast all in one piece, possess the same advantage of a tyre that cannot roll out. They are, however, always liable to cooling strains, which sometimes show themselves in broken spokes. Several users have had to discard steel wheels because of broken spokes, and in some cases their experience has resulted in such complete distrust of steel wheels that they have gone to the other extreme and reverted to wooden wheels.

In Stagg's wheel, as hub and rim are separate castings, there is no possibility of cooling strains, but should any spoke be damaged in an accident, or in any other way, it can be replaced without affecting the other spokes, and by any competent wheelwright. Experience has shown that with cast steel in contact with the road surface there is less wear than with any other material, in fact, some have been measured that have run for eighteen months in and around London, on a 5-ton steam wagon, and the wear cannot be detected, whereas rolled steel tyres on similar wagons have worn down threeeighths to five-eighths of an inch in the same time.

Not only do the wooden spokes lend themselves to easy replacement, but the resilience that they give to the wheel is very valuable. Those who have ridden on motor wagons with steel wheels have always remarked on the fact that every vibration is transmitted not only to the axle, but apparently through the springs to the whole machinery and to the rider. The springs, which must be powerful enough to carry the wagon and its load, would give to any large movement, as when the wheel drops into a hole, but are necessarily too stiff to take up the small vibrations. In Stagg's wheel these vibrations are taken up and absorbed by the wooden spokes and do not reach the axle.

Messrs. Stagg and Robson are making the spokes of " curapy," a wood that is obtained from the Malay States, and is of a peculiarly tough yet springy nature. It is the most suitable timber that has yet been discovered and greatly superior to the ash and oak generally employed. This wheel is equally suitable for vehicles with rubber tyres, as it dispenses with the wooden felloes, and the rim is cast to suit the rubber tyres, whatever may be the method of tyre fastening employed. Fig. 4 shows an omnibus wheel with twin tyres, but with the face plates and clips left off, so as to expose the method of fixing the spokes, and also revealing the easy way damagea can be replaced.

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