The Supply Department.
Page 16
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No More Creaking Bus Wheels.
In January and February of the present year, we published a number of letters from correspondents which dealt with the relative merits of grip and band pattern tires. One of the most interesting contributions to this discussion emanated from a contributor to the Drivers' and Mechanics' Columns, who wrote under the nom de plume of "A. Wheeler." In the course of this letter, the writer advocated the introduction of an improved form of wheel, in which the spokes and felloes should readily be capable of being adjusted. Our correspondent of that date, who, it now appears, is the inventor of such a wheel himself, has sent to us particulars of the Turner patent wedge wheel, and we are enabled to describe the arrangement he has adopted, and to illustrate the wheel in question by the reproduction of a photograph. The inventor, who holds a position in the coach shops of the London General Omnibus Co., Ltd., draws attention to his indebtedness to his employers for the valuable assistance which he has received from them while he has been developing this speciality. Wheels of this type have been subjected to severe tests on various types of motorbuses, over roads of different characteristics. At the present time, there are over 40 pairs of these driving wheels running in the service of the company, and we are told that the first pair, to be put into service, has now completed 30,000 miles without any trouble. There are hut few commercial-motor vehicle users who have not occasionally had their attention drawn to the " creaky " state of some makes of wooden wheels, in view of the fact that the spokes or felines have become loose; this undesirable feature is especially noticeable, of course, in dry weather. The application of wedges to force apart the various members, from which the ordinary wooden artillery wheel is built, is not new in practice. It is rather the arrangement of the wedges and their actuating screws that. is the subject of the patent under which the Turner wheels are constructed. An examination of the illustration herewith will reveal the form of construction that has been adopted. Wedges are inserted between the bases of the spokes in
• such a manner that, when they are drawn out radially, the spokes will be forced outwards into the felloes. Wedges, which are also capable of being forced outwards
• radially, are mounted • between the felloe pieces. It will be realized that, by a foi of construction of this nature, it is possible to build Tap a wheel inside a steel tire, instead of, as is more usual, shrinking the tire on to a built-up wheel. This latter practice has many disadvantages, amongst which are the gradual deterioration of the metal ring, owing to continual re-heating and the charring destruction of the outer surface of the wooden felloes. The surface of a shrunk-on tire is often uneven, and when this has to form a bed on to which a steelmounted rubber tire has to be forced, seine difficulty is .often occasioned in the proper assembling of these two tarts. The turning of the steel tire is not a process which is always unattended with detrimental results.
A "Henry Howler."
We have received a copy of the Royal Automobile Club's certificate of performance with regard to tli6 trial for accuracy of an excess-speed alarm, which has been constructed by Messrs. W. and T. Lewis, of Stanhope Works, Gloucester Gate, Regent's Park, N.W. A previous trial had been conducted in August last, and the certificate with regard to this accompanies that which refers to the later test. It is not to be supposed that an excess-speed alarm of any descripion is a device which users or manufacturers will welcome with open arms; nevertheless, it is to be presumed that, if such a mechanical tell-tale be eventually required to be fitted by the Licensing authorities, details of a practical mechanical contrivance of this nature will be of interest to many readers of this journal. It is, of course, not a difficult matter so to design a bell or other alarm which shall come into operation at a predetermined speed, and not until then. Any reliable form of centrifugal springloaded governor is likely to secure this result. Certain considerations, however, have to be studied in the manufacture of such a device, and, primarily, it is necessary so to arrange the mechanism that accidental vibration of the device will not operate the alarm. Some simple adjustment must also be provided which will allow the governor mechanism to be so regulated as to come into operation at a given speed. The Lewis device, as at present suggested, it is proposed to fit to one of the steer., ing arms in such a manner that it can be direct geared by a pair of small spur-toothed wheels with the front road wheel. The governor or clapper is rotated in a horizontal plane by a small bevel-gear-driven shaft, and a stop is provided which prevents this clapper's flying out to a greater angle than is necessary just to ring the bell at the determined speed. The clapper is controlled by a stiff piece of spring steel, which is adjusted by a small set screw. The three main component parts are exhibited in the photograph which we reproduce; it will be noticed that the gong itself is enclosed in an aluminium dome cover, in order that no tampering may take place with the alarm-operating mechanism. We understand from the makers that it is probable that the weight of this device will eventually be reduced in further models, and that other positions than that on the steering arm may be adopted for fixing the equipment. On a motorbus or a tramcar, of course, these two considerations do not apply. It will, moreover, be realized by our readers that this device may, if necessary, be readily adapted to either of these heavy types of machines. One of the principal features claimed by the inventors of the Lewis alarm is that it is constructed with a view to its fixing solely in a horizontal position.