OPINIONS and QUERIES
Page 55
Page 56
If you've noticed an error in this article please click here to report it so we can fix it.
Road Transport for the Motor Trade. The Compression,ignition Engine Not a "Diesel!'
Railways' Illogicalness Earl Howe on Slippery Roads. Commissioners Demanding Private Info' rmation from Coach and Bus Operators
The Motor. Trade's Use of Road Transport.
The Editor, THE COMMERCIAL MOTOR.
[3689] Sir,—Your correspondent "Co-operation," writing in the issue of your journal for February 23rd, deplores the fact that there is a quantity of tyre and vehicle accessory traffic • still travelling by rail, and suggests that it is the obvious duty of traders dealing in these commodities to support road transport.
It is very difficult to reconcile an attitude of this kind with the adoption of the pen-name selected.
After all, the use of the road motor, which The Commercial Motor is doing so much to foster, cannot he developed if governed by such a narrow outlook, and I think that it is rather unfortunate if its real use in improving the nation's transport as an ally to our existing system is to be obscured by any attempt to extend its field of uneconomic competition.
The fact remains that the railways themselves are large users of motor vehicles, and consequently of tyres and accessories, and it may be taken that expedition and price probably are, or will ultimately be, the governing factors in the choice of transport.
Apart from this, there is much raw material required in the construction of these, vehicles for which the railways remain the only efficient carriers.
Glasgow. SQUARE DEAL.
The Oil Engine, Past, Present and Future.
The Editor, THE COMMERCIAL MOTOR.
[36901 Sir,—With reference to " Fairplay's" letter on " Diesel " engines, in your issue of March 1st, whilst appreciating some of his points and dates, I would like to present what I consider to be an even stronger case as to why the modern compression-ignition engine using oil fuel definitely should not he termed a "Diesel."
Dr. Rudolf Diesel's original patent specification of April 140, 1892 (or was it August 27th?) certainly covered the use of solid injection and compression Ignition. Yet in spite of this, and of his first engine of 1893, I think that it may safely be assumed, that having set out with the above ideas in view, and meeting tremendous obstacles, it was quite accidental that he ever succeeded with the constant-pressure cycle. It is equally certain that after his pulverized-coal-dust rebuff, and after his 1893 engine was built, in the development of this latter, and subsequent engines, forcefully uppermost in his mind was the employment of air-blast injection.
Above all stands unrecognized the great pioneer work accomplished by Akroyd Stuart, whose name seems inseparably bound up with hot bulbs, " semi-Diesels" and the like, and throughout the 40-odd years since the inception of the compression-ignition engine, Diesel has constantly overshadowed the name of Stuart. Yet, as far as the writer is aware, Herbert .Akroyd Stuart's original patent No. 7,146 relating to his injection engine was published on May 8th, 1890; therefore, if Diesel's
patents are to be brought up to secure him further recognition even more must the patents of Akroyd Stuart be recognized as ante-dating by two years those of Dr. Diesel.
Up to 1889 internal-combustion engines were built in which the air and fuel required for combustion were placed in the cylinder before the compression stroke was completed, therefore in all such engines the compression and dependent thermal efficiency were limited by the ignition temperature of the fuel mixture, higher compression, of course, involving pre-ignition.
The year 1890 saw the introduction of the Stuart injection engine, closely followed by his dividedcombustion-head type, and here the full significance of his discovery strikes us. His first specification was worded thus : "The induction stroke, instead of drawing into the cylinder a mixture of hydrocarbon vapour and air, simply draws in pure atmospheric air, the compression stroke compresses this air, and at the desired part of the compression stroke the liquid hydrocarbon is forced in, in a spray form combining with the heated air, automatic ignition takes place and propels the piston outwards on its working stroke," etc.
In this specification, as in Diesel's, there is no mention of air injection; furthermore, unlike Diesel, he lays stress upon solid injection by specifying "a spray form," and, most important of all, preceding Diesel's engine by two years ; we must concede that the " Diesel " engine which followed certainly falls within the scope of Stuart's specification. There is no doubt whatever, in my opinion, that the compression-ignition engine of to-day is as much attributable to Stuart as to Diesel. Improvements, conducted as they were by others, were somewhat misconstrued in the transmission, and the direct outcome of the brains of Herbert Akroyd Stuart was ignored, yet his patents, beyond any shadow of doubt, covered the use of a pure-air charge alone, the solid injection of fuel into the compressed air, through the medium of a spraying oriace(s) and automatic ignition, Yet again his second patent covered the use of the two-cell combustion chamber, thereby constituting, in the writer's opinion, the first attempt to impose an orderly turbulence within the head, and from which, I contend, emanated the numerous spray penetration, tangential and rotational swirl devices which. are in vogue to-day. Furthermore, even at that early date, he secured his turbulence without throttling the induction, which, incidentally, is a criticism the writer is inclined to level at some designs to-day.
The constant-pressure cycle advocated by Diesel constitutes his initial theories of 1892, but that they were also the theories of Akroyd Stuart two whole years previously is evident by the decisive wording of the 'Eater's specification, and I think it may safely be said that the minute combustion lag which we have not succeeded in eliminating to this day was directly responsible for Stuart's hard-earned laurels going astray.
The present status of the compression-ignition engine u37 Is largely due to efficient atomization, which in turn is due to the fine limits and precision possible in the manufacture of pumps and injector nozzles to-day. The essential difference between the Stuart and Diesel engines is the timing of the injection.
Therefore to sum up, Stuart's patent No. 3,909, of 1892, describing his production engine, having a watercooled neck and injection during the suction stroke may be said to have placed him forever back in the ranks of the "constant-volume men," yet I would suggest that the tendency of engineers of to-day is to use the hottedup Stuart version of the cycle in which heat is added at constant volume, in order to secure the high speeds required and which could not be secured by rigid adherence to the constant-pressure cycle of Diesel.
Air injection held sway until about 1910, when its disadvantages began to be realized ; airless injection was first developed in this country in 1912, and it was left to the remarkable success of this type of power unit, when adopted by the Vickers concern for submarines in 1914, to focus universal attention on the promising capabilities, and from this attention has developed the compression-ignition engine . we know to-. day.'
To my mind it is singular that, whilst in 1890-92 Dr. Diesel set out to build an engine working on blastinjected coal-dust, and in which he failed, In 1932 a high-speed engine employing compression ignition and solid injection of oil fuel, is almost universally acclaimed as a "Diesel" engine.
Further, when awarding credit, not a little is due to the British Air Ministry in token of the initiative shown in instructing the carrying out of tests at Farnnorough in 1922. In these tests a properly designed petrol conversion ran at unheard-of speeds and pressures, with an efficiency surpassing all previous standards, thereby uprooting the old fallacy that the compression-ignition engine never would be capable of high speeds.
Turning to modern conditions, I would point out that, .except for a half-hearted juggle with final-drive ratios, the majority of manufacturers seems content to put a compression-ignition engine into a petrol-enginetype chassis. Yet the outstanding characteristic of the oil engine is the tremendous torque developed at low speed in comparison with the relatively high "revs." of the petrol engine. I contend that no compromise is adequate, and that the oil engine requires a gearbox designed to suit its own peculiarities, having loWer ratios and bigger bearings to accommodate the heavier stresses and torque reversals and the addition of a stronger final drive; in consequence even more miles per gallon and higher road speeds would be within
our grasp. FRANK Youxo.
• Wakefield.
Lord Strathspey's Views on the Railways' Demands.
The Editor, THE COMMERCIAL MOTOR.
r36911 Sir,—The moment when the trade tide does seem to be on the turn is surely the least fortunate to put forward a plea for a substantial increase in the costs of production. Yet in effect that is what the railways are asking from Parliament when they demand, as they are now doing, additional taxation and restrictive regulations upon commercial roadtransport.
There is no product of our factories into which the cost of transport does not enter in some degree: and if that figure is to be increased at the whim of the rival carrying agency the cost of production must be correspondingly greater.
The railways' demand might be regardel as reasonable if motor traffic were not paying its share of our annual road costs. But motor taxation more than foots that particular national bill. Indeed, I find that the memorandum just submitted to the Minister of Transport from the Conference of Motor Organizations states the case with much too great a modesty. It estimates the present annual cost of our roads at
B38
£60,000,000 as against 112,000,000 in the days before the motors came. This i12,000,000 must, however, be put at its post-war equivalent, and the railways themselves reckon that costs have gone up 96 per cent. The £12,000,000 therefore becomes £23,500,000, which reduces the extra cost to £36,500,000.
Against that figure we have a yield of £28,000,000 from motor vehicle taxation and a further £31,000,000 from petrol duty, which is, of course, a motor duty pure and simple. In short, the total proceeds of £59,000,000 from motor taxation is already £22,500,000 (and not £11,000,000 as the memorandum states) in excess of the annual cost of our roads which can be partly attributed to motor traffic.
Any addition to that taxation would therefore not only be a further burden on British industry but a gross
injustice to motor owners. STRATHSPEY. Rottingdean.
Earl Howe's Views on Slippery Roads. The Editor, THE Commerat, MOTOR.
[36921 Sir,---I see that a motorcyclist who skidded on loose chippings on a road near Bristol has sued the local authority for negligence and been awarded no less than £70 damages.
I welcome this courageous action, Far too long users have accepted slippery and badly laid roads as a matter of course.
This case may impress those responsible for the construction and maintenance of our roads and make them realize that they have a legal, as well as a moral, responsibility in rendering the roads safe for road users. It should also show motorists that they can sue for safety, and I hope that they will do so. How. Mayfair, IVA,