The Reverse as a Brake.
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Steam-wagon drivers know the value of reversing the valve-gear as a check upon pace when going down hill, and it has become something of a commonplace in steam-wagon circles for a driver to say that he usually goes down hill " on the reverse." This phrase cannot, however, be applied in petrol-vehicle circles, and it has come as a surprise to us to learn that there is any risk of the kind. A correspondent, none the less, draws our attention to the matter, and remarks inter alia : " The senselessness of this proceeding should be apparent to anyone who has the slightest knowledge of driving a petrol vehicle. Just for the sake of curiosity, I have questioned drivers as to what they would do if their car were to run away down hill, and they have almost invariably given the same answer—` Put her in reverse.' Do you not think that this ignorance on the part of some drivers of petrol vehicles is a serious .menace to the travelling public, and 4o you not think you would be doing a signal service by exposing the fallacy in your columns?" We assume, as a case in point, the correctness of the reports of the driver's evidence at. the recent Consett inquest, in the course of which that man is, as recorded in our issue of the 7th inst., stated to have said : " I reversed my engine when near the bottom of the bank, but there was just a bang. If I had tried to do so before, it might have been worse, as it was possible I might have missed the gear." We are bound, therefore, to agree with our correspondent, and to endorse his view that—extraordinary as the existence of such a risk may appear to owners with driving experience, or to any persons whose mechanical knowledge is sufficient to enable them to appreciate that the use of the reverse in a petrol-env/led system (with any transmission other than those of the epicyclic type) is necessarily useless —some words of warning from us will not be out of place. The foregoing references are sufficient for the purpose, and we suggest that owners or engineersin-charge take their own steps to remove any lurking possibility of adherence to erroneous beliefs in respect of the functions of the reverse-gear in an ordinary petrol-vehicle transmission, or to the conditions under which "the reverse" on such a vehicle can be employed. In a steam vehicle, of course, and particularly in those which have a nermanently-posiLive connection between the crankshaft and the back axle, the use of "the reverse" for braking purposes is quite admissible and practicable, as is well known, but there is no analogy between steam-wagon practice and that which obtains where standard petrol vehicles are being used.
Tire and Wheel Standardization.
Some six years ago, Mr. H. G. Burford, M.I.Mech.E., M.I.A.F.., who is now general manager of Humber, Ltd., of Coventry, initiated the rule of standardized wheel-diameters, with a view to the simplification of band-tire supplies, and he was successful in convincing several of the principal tire manufacturers of the wisdom of this course. For reasons into which we need not enter at the moment, and which may not be capable of exact definition, it, appears that this question of the standardization of band-type, solid-rubber tires, taken in conjunction with the exact diameters of the wheels on which they are fitted, remains in a partially-settled and unsatisfactory state from the standpoints of both the vehicle manufacturer and the owner. In this connection, we would direct particular attention to the points which are raised by Mr. T. Blackwood Murray, B.Sc., M.T.E.E., in this week's "Opinions from Others." His letter will no doubt attract the attention of tire-makers generally, and we shall await with interest their explanations for that lack of enthusiasm in the direction of standardization which can hardly last if a real difficulty in the way of the free use of commercial motors is to be removed.
Small differences between the supplies of various makers are unquestionably thought to tend in the direction of the retention of custom to the party who secures the first order, and to that extent are capable of explanation. On the other hand, in these days of severe competition in the tire world, the practical outcome of this want of uniformity is frequently a cause of repeated initial expense to makers who successively " push out " their rivals, at the cost of allowances for wheel and rim conversions. The time has conic, in our judgment, for the Commercial Vehicle Committee of the S.M.M.T., possibly sitting in conference with representatives of that same society's Tire and Accessories Committee, to lay down reasonable standards which shall be fair to all manufacturers, and which shall, above all, solve the problem of restricted supply for the owner. Fine economies are more and more necessary, if makers ore to secure orders in all possible directions, and factors which cause delays should not be perpetuated. From the tire side of the case, it may properly be claimed—as we expect it will be—that the lowest prices can only be given when there is some assurance of repeat orders. That is probably undeniable. The point remains : are present means to that end the only ones, or the best? Whatever the modifications in existing trade customs, which are in some respects necessarily tentative, we are confident that the leading tiremakers will not for much longer continue to offer all the allurements and enticements which, in conjunction with over-generous guarantees, gnaw away profits to alarming extents. It is, without doubt, to their ultimate advantage that " pin-pricks " for customers should be eliminated.