THE MUIR SHOCK-SHIFTER HUB.
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Its Bearing on the Ail-important Question of Road Maintenance.
TFIE END of the war has found Great Britain, in common with all the other belligerent countries, faced with many problems of a very serious nature. Not the least of these is the question of the roads, which during the war, have had to withstand an excessive amount of traffic combined with neglect of upkeep, with the result that they have badly deteriorated and now require the expenditure of enormous sums to restore them to a reasonable condition of utility. Anything that will tend to reduce the vibration due ta road shocks is worthy of consideration at a time like this when economy is—or. should be—of such cardinal importance. Economy does not always take the form merely of reduction of expenditure; very often it proves in the long run to be more. economical to spend money than to withhold it. Often the best form of economy consists in the removal of the cause responsible for the evil that calls forth the expenditure.
Some years ago, the Muir shock-shifter hub was brought before the public and received attention in the Press. Not only so, but also was it made the subject of extensive experiment by many of the leading users of commercial vehicles ; among these, we may cite the omnibus companies of London, Paris and Brussels respectively. In the hands of these users the Muir device would appear to have given every satisfaction. It was fairly well established that the shock-shifter hub did go a long way towards fulfilling what was claimed for it, viz., that it would reduce road shock. In the period immediately preceding the war, however, it was not easy to arrange for its commercial development, and with the outbreak of war its immediate prospects became very dull indeed, due to the reluctance of the War Office and other large users to depart from their standards. In this connection, however, we were interested to learn from Mr. Muir that his shock-shifter was found to be incorporated in some artillery wagons captured from the Germans during the war.
The principle of the invention has previously been described in The Commercial Motor, but that wa,s some years ago ; a repetition of it is, therefore, not inadvisable. Briefly, the idea is to interpose between 016 the hub proper and the body of the wheel an annular chamber containing a number of steel balls which do not quite fill the chamber. The wheel is free to move, in the vertical plane, a certain distance which is limited by a number of equally spaced bolts registering in the flanges of the hub, but having considerable clearance in the wheel itself. It is intended that these bolts should constitute what practically amounts to a liquid medium, of which the motion is affected 'by the movement of the wheel due to road shocks, whereby the moving column of balls shall play " the part of an energy absorber. When the vehicle is stationary on the road, the hub tends to rest upon the balls at the bottom of the chamber, displacing some of these so that the wheel and axle are eccentric with one another. When the vehicle is in motion centrifugal action asserts itself, whereby the balls tend to dispose themselves symmetrically around the annular space, their symmetry being of necessity upset, to some extent, when the wheel is given an upward movement due to road shock. It is this change of motion of the balls (to effect which the application of force is, of course, necessary) that absorbs some, at any rate, of the shock; in actual practice the idea scorns to work out very well.
'We had the opportunity, recently, of making a trial• run with a Simms car, which weighed 2 tons and was fitted with solid tyres on MI wheels. In our own mind we resolved to adopt as our standard of comparison the average London taxicab running on pneumatic tyres, and we found that the Simms car fitted withA wheels embodying.' Muir'e invention ran very smoothly, and compared favourably with the running of the average taxi.
One great advantage of the system is that it does not involve a very high first cost. Probably it will make its appeal first of all to taxi owners, who would' be willing to use solid tyres in order to escape the trouble arising from punctures, if they could 'by some means obtain smooth running for their passengers. The usefulness of the invention, however, is not . limited to taxis only, and we are inclined to think that, especially at -a time like the present, when the motoring community has to reckon with a certain amount of public hostility due to the alleged damage done to roads by motor vehicles, this subject is well worthy of consideration. Manufacturers generally maybe inclined to disclaim all interest in the state of roads. Everyone, however; is interested in this question as a taxpayer, and it is possible that shortsightedness on the part •of the motor interests may ultimately redound to the detriment of those interests.
Arising out of this subject' is the interesting consideration of the encouragement given to inventors by the patent laws of this country. Here is an invention upon which a large sum of money has already been spent, chiefly on practical experiments in connection with motor vehicles. Due to commercial and political circumstances, of which, of course, the war is the chief; it has not been found possible fully to exploit the invention. Assuming—and we can hardly do otherwise—that Mr. Muir will obtain the necessary extension of his patent, 'then we shall have an example where the patent law is able to accommodate itself to circumstances. If the appeal were unsuccessful, however, here would-be a case of an inventor being penalized ■by circumstances over which no one could possibly have any 'control, without.being able to obtain'redress, through. legal means.