OPINIONS FROM OTHERS.
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The Eliter invites correspondence on all subjects connected with the use of commercial motors. Letters should be on ono side of the paper only and typewritten by preference, The right of abbreviation is reserved, and no responsibility for views expressed is accepted.
A Driver's Views on the Parade.
The Editor, THE COMMERCIAL Moron.
[1,918] Sir,—Now that the time is drawing near for the annual C.M.U.A. Parade in London, I would like to voice my opinion, and also that of others, on one or two matters connected with that competition. Some people are under the impression that the vehicles entered are not maintained in the same efficient manner all. the year round, but, having personally shown a team so far back as ten years ago, I am in a position to prove otherwise. I know from experience that all firms entering cars for the Parade do all they can to maintainitheir fleets the whole year round in the same efficient mechanical and clean condition in which they appear on the parade ground, and do not, as some people think, simpry arrange for them to be cleaned and overhauled a day or two before the show.
In my opinion, last year's was the fineSt show I can remember having seen, also the judging was excelleat, more especially when one takes into consideration the excellent condition of all vehicles present.
It has been suggested that the show cars are not inspected during the year by anyone connected with the Cl.M.U.A., but my reply to this question is that, all the show vehicles are, more or less, on the streets every day, and the judges have ampleopportunity to look round them and observe the' condition of the various firms' vehicles ; for such capable and exPeriencedacrities it does not fake long tc enable them to form an opinion as to the general maintenance of a vehicle.
There is oneamore point on which I would touch, which has been a grievance ever since I can remember, viz., that steamers and motor vehicles should never have been judged together. As everyone knows, Steamers have a much longer life than motors, whilst they do not attain the speed and are built much heavier, so they do not get the same wear and tear, especially on bad roads. To-day, one can find steamers with 15 years' service to their credit, and still doing good service, but where, in the show or out of it, will you find a motor with this record and in a comparable condition? The comparison is odious, and I feel certain this statement will be borne out by all fleet engineers, fitters and drivers, and, I say, let this be the last year that steam and petrol are judged together.
To condude I would suggest the presentation of-a shield to the best-kept and equipped garage, as I consider asmuch interest should' be taken in the place where the vehicles are housed and overhauled as in the vehicles themselves.—Yours faithfully,
London, W. MARC MEBTON.
The Railways and Their Road Transport Costs.
The Editor, THE COMMERCIAL MOTOR.
[1,919] S ,—A a constant reader of your valuable paper I should like to be allowed to correct the impression that may be made by the paragraph in your issue of February 28th, headed "The Railways Must Be Made To Keep Separate Costs." Having regard to the publication in your issue of the previous week of the official case on behalf of the railway com7 panies included in the North-Western group for the application for road powers, it is not quite understood why stress is. laid on this point, as it is distinctly explained in that article that the Bill puts upon the railway companies an obligation to keep separate accounts, which will be.open to insPection
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in respect to their road transport service as a whole, the object-being to meet the very objections which are put forward in the article in your last issue, that railway Companies will attempt to set up road transport services at uneconomical rates and recoup their loss from the revenue derived from rail transport.
Apart from the provisions in the Bill the last paragraph in clause 58, part 111, of thei Railway Act, 1921, would appear to render action such as is feared on the part of the railways impossible. "When fixing the charges necessary to produce the standard revenue, the tribunal shall take into consideration the charges in respect of any business carried on by the company ancillary or subsidiary to its railways, the eharges for which are not subject to the jurisdiction of the tribunal, and if in the opinion of the tribunal the company is not making, or has not taken reasonable steps to enable it to make, adequate charges in respect of any such business, the tribunal shall, in fixing the charges under this part of this Act, take into account the revenue which would be produced by any such business if adequate charges were in operation."—Yours faith
fully, B. F. TEE. UrOk ingham. as not "The Inspector," in the contribution referred to, laying strong emphasis upon the need to which he drew attention, in order to ensure that the necessary Clauses are retained in the Billl—En. C.M.1
The Crude Oil-engine for Vehicle Work.
The Editor, THE COMMERCIAL MOTOR.
[1,920] Sir,—Your correspondent Mr.I.Morse Scott is hypercritical (The Commercial Motor, February 28th last). In my article on the Hvid-type engine, as built by the Dodge and other companies, I Spokeof " petrol " as it is generally understood—in other words, as motor spirit—and I think if Mr. Scott had thought over the matter a little further, he would not have seen anything to wonder at in petrol being stated to be dangerous to use.
The explanation is simple. The whele principle of these super-Diesel engines is high compression, and, as I explained in my article, the, compression is so great as to raise the temperature of the contained air to a point sufficiently high to vaporize the lighterccestituents of the heavy fuel. Hence, it follows that the temperature is raised to a much higher point than the flash-point of petroleum spirit, and it will be readily appreciated that the result of this would be, if petrol were used, to effect the ignition of the fuel before the piston reached the top of the dicks, which would, of course, lead to too early firing, With the result that the engine could not be run at all and considerable damage might result.
Now, with regard to my statement that, under the Dodge-Hvid system, there is no need for that excessive strength which is required with Diesel engines, my view of the matter is as follows:—
The need for strength in a, cylinder head is, of course, to withstand the pressure generated within it by the explosion. Now, in an ordinary internalcombustion engine, whilst the initial pre,ssure of corn. pression is not high, the initial pressure on combustion is, as practically the whole of the charge is ignited at once. Hence the need for sufficient strength to withstand the pressure thus created. Under the Hvid system, the initial Pressure of compression is high, but nothing like so high as the explosion pressure in an ordinary engine, and, as the ignition and combustion of the fuel is not effected all at once, but is gradual and continuous, seems to me, without actual tests, that there should not be the need for excessively heavy construction.
If the pressure at the commencement of the combustion stroke were proportionate to the compression pressure of the mixture"' then undoubtedly the pressure would be very high indeed. But, in that case, surely the power exerted on the stroke would be proportionate to this initial pressure as withan .ordinary petrol engine, and we know that, in practice, the power generated by the engine does not materially differ from that of an ordinary engine, which, according to my way of thinking, .shows that no undue pressure exists at any time within the engine, and, hence, that no extra strength of cylinder head, or very little, is necessary.
It would be exceedingly interesting, I think, if experiments were carried out with an engine of this type, using no greater wall thickness than with an
ordinary engine. have a very strong idea that no harm would result, and, in the four-cylinder engine built by the Midwest Company, to which I referred in my, article, seeing that the additional weight over an ordinary I.C. engine is not great; it would appear that the walls of the combustion chamber are .very much thinner than either the Dodge and other livid engines, or in any other Diesel system engine, although I have not the measurements by me.
In regard to the introduction of the fuel by graviiy, I have to say that the fuel pipe is of suitable size to admit the fuel, which I would point out is assisted by suction, and, in regard to the actual fuel used in these engines in practice, I can quote from the guarant.ee of the Dodge company, in which they say: " We guarantee Dodge heavy-oil engines will operate successfully on kerosene, fuel-oil, or other heavy oils, provided such 'oils are clean, free from water contents, ashes, sand or grit, contain
18,500 B.T.U. per lb. and test not lower than 28 degrees Baume. We guarantee that the Dodge heavyoil engine will consume not more than .5 lb. per b.h.p. per .hour, under full load,with constant maximum'. rating h.p., this consumption being measured in our testing room before the engine is despatched. Of course, as Mr. Morse Scott says, the Dodge.' livid engine is a Diesel type,but it is claimed to be
an advance on the Diesel, in that it is simpler, the compression of the air and the introduction of the fuel being accomplished automatically by the engine, without the use of extra air compressors and high pressure pumps for forcing the fuel into the engine ; in fact, it-is difficult to see how greater simplicity can possibly be obtained. As I said in my first article, seeing that at least a dozen makers in both the United States and Canada. are building engines
under. this system, it is a wonder to me that no
British manufacturer has yet undertaken its construction, although licences, with working drawings
and all information for manufacture, are obtainable
by those who desire them. I do not see why America should have all the good things, because of our con servative insularity—the Yankees and Canueks are not altogether fools in engineering matters.—Yours faithfully, HENRY" SITRMEY. Coventry.