OPINIONS and QUERIES An Alternative Fuel for Petrol Engines.
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The Editor, THE COMMERCIAL MOTOR.
[3922] Sir,—As the result of the recent rise in the price of petrol, the thoughts of many people have turned to alternative fuels which will show an appreciable saving in cost.
This field is, of course, not entirely new, as in the past several devices have been put on the market with a view to using substitutes for petrol. Objections of some kind or another have invariably arisen and these have usually had some solid foundation, so much so, that, sooner or later, these substitutes have been discarded. Up to recently, therefore, we can take it that this problem has not found any satisfactory solution; at any rate, no solution which has been found acceptable to the majority of operators.
Some interesting results have, however, been obtained by the use of creosote as the basis of a fuel, and these results may be of interest to operators in general.
The conversion referred to was carried out by this company, which is the Leyland distributor for Yorkshire, on a 36 h.p. engine in a Leyland R.A.F.-type chassis forming a unit in the fleet of Yorkshire Tar Distillers, Ltd. The problem was tackled in a different manner from previous attempts, in so far that no effort was made to utilize the substitute fuel under all conditions of engine speed; on the contrary, the petrol carburetter was retained for starting and slow running, and a speciql carburetter used for normal running. The controls of these carburetters were so adjusted, after experiment on the test bench, that the driver need only confine his attention to the usual pedal provided for throttle control; that is to say, a slight depression of this pedal would bring the petrol carburetter into service and further depression would bring the special Carburetter, supplying the low-grade fuel, Into action, whilst, of course, the converse would apply. This is a most important factor and one which contributes very largely to the success of the scheme, for if the engine stalled at any time the restart would automatically be made on pure petrol. It was also found to be an advantage to run the engine on petrol for a few minutes before stopping after the day's work; this had the effect of scavenging the engine and left a charge of petrol mixture in the cylinders ready for a quick start next morning.
The vehicle under review was engaged in local work carrying loads of 4-5 tons, and the general perform ance under all conditions when using the creosote mixture was as good as when using petrol, whilst the con sumption figures showed an actual improvement approximating to 15 per cent. So, having regard to the present cost of petrol, with the probability of an increase rather than a reduction, and the cost of the creosote mixture, which is 80. per gallon, the
attraction of this conversion will be apparent to all operators.
The question could reasonably be put: "Is the saving in fuel cost to be obtained at the expense of excessive wear and tear on the main working parts?" As an answer to this, it will be of interest to note the results of an examination carried out by this company on the engine which it converted, after the unit had run 6,000 miles. On the most important parts the wear proved to be :—Cylinders, .002 in.; main journals, .0005 in.; crankpins, .0005 in.
Similar wear would, no doubt, be found if the only fuel had been petrol; it was, however, noticed that the engine was very dirty, so, before reassembling, the compression ratio was increased to a considerable extent, with a view to obtaining more complete combustion. and a different grade of lubricating oil was used. When the vehicle was put on the road again an appreciable improvement was apparent in general performance, with a decrease in fuel consumption.
The approximate cost of the complete conversion for four-cylindered engine is i50 and for a six-cylindered
engine £65. J. E. It. CRAWFORD,
For the Brighouse Motor Agency, Ltd. Balliffe Bridge, Brighouse.
The Editor, THE COMM ERCLAS, MOTOR.
[39231 Sir,—I have been reading your book on Compression Ignition Engines for Road Vehicles, and would like to know if you have any information about the best way to use creosote in petrol engines. I am pretty well convinced that C.I. engines will become the main type, but the immediate problem is to use cheap coal-tar fractions in existing types of petrol engine.
According to accounts of the Belfast experiments, they find it advisable to retain about 15 per cent, of tar acids and to add about 10 per cent, of solvent naphtha "to keep the naphthalene in solution." I wish, if possible, to use creosote from which all tar acids have been extracted, but it is not essential. It would be interesting to know why they find it best to use tar acids. Apparently it is necessary, to consider two lines of experiment, namely, the chemical and the physical. I have heard about ethyl compounds as promoting complete combustion, and about the addition of aniline -to stop oxidation of lubricating oil. I shall have to study these points, which I cannot profess to be well up in, for it seems possible that " dopes" may have considerable value in using creosote.
On the physical side, I thought of trying a two-stage method; atomize the creosote forcibly by means of an atomizer of some kind, and deliver the vapour thus formed to the jets of a carburetter, where the suction would act and more air would be effectively mixed.
This would involve keeping the whole etomizing system at a fairly high temperature, but any etempt to use heavy stuff must involve a lot of pre-heating. Do you know if anything like this has been tried?
London, S.E.18. READER.
[Re tar acids, naphthalene and solvents. It is a very open question whether tar acids with the other two bodies are advisable or otherwise. The advantages of tar acids are that they have very high anti-knock values, being somewhere in the plus series compared to iso-octane. Their disadvantage, however, is that their flame rate is very low, and therefore an accelerator must be used in conjunction with them if present with the creosote.
The most suitable "speeder" is naphthalene, which occurs normally in the distillate, but as this has a tendency to separate out during cold weather a solvent must be added to keep it in solution. Therefore, some manufacturing complication is involved, as you will see.
Certain creosote distillers consider that the anti-knock Improvement which naphthalene confers is not worth the trouble and expense indirectly attendant upon its inclusion, for in their opinion the normal contents of creosote oil, being ring compounds and aromatics, which, of course, are very suitable in point of molecular construction for knock resistance, should suffice in the latter regard without courting the troubles which can result from the indiscriminate introduction of tar acids without suitably apportioning the accelerators and solvents that must accompany them.
As regards oxidation of lubricating oil it has been found that petroleum-base lubricants are certainly rather apt to suffer from this, or, at least, from sludging, which is apparently due to partial oxidation of their resinous and wax contents by dilution of the creosotes from above.
It is, however, found that first-pressure castor oil entirely avoids any tendency to this trouble, and this lubricant, therefore, is now being exclusively used by the Belfast Omnibus Co., Ltd.; the Associated Equipment Co., Ltd. ; and the London General Omnibus Co., Ltd.
It is agreed that "dopes" may certainly be of value, provided the right kind of dope can be found, but investigators are not so much interested in doped creosote as in the possibility of raising the octane value of crude petroleum fuels by means of some anti-detonant.
As regards the physical side, in which atomizing is suggested at a high temperature, first, this is already covered by patents, but, apart from that, no advantage has been found in over-atomizing and re-fogging, as compared with direct disintegration after the same methods as those used in dealing with petrol.
Pre-heating of the fuel.is certainly an advisable course, for all liquids having a tolerably high viscosity, that is, of course, for disintegration purposes, but as this involves rather complex and therefore easily derangeable thermostatic controls, up to the present it has been avoided, although experts may agree as to its advisability.—En.] The Editor, THE COMMERCIAL MOTOR.
13924] Sir,—With reference to the article concerning the operations of the London and Southern Counties Transport Co., Ltd., in your issue dated November 11, we were very interested to notice that the writer stated he had two vehicles of the fleet running on creosote. Would you be kind enough to supply us with information regarding the conversion to this fuel, or, better still, put us in touch with the company.
C. E. CARTWRIGHT, Proprietor, Liss. The Liss and District Bus Co.
[The conversion of certain vehicles of the London and Southern Counties Transport Co., Ltd., for burning creosote has been effected by Solex, Ltd.
Briefly, it consists of casting a new manifold exhaust surrounding the inlet manifold, and fitting a patent dualcarburetter arrangement, so that, at small throttle openings, the petrol carburetter is in operation, this having a slow-running jet and, after a certain position of throttle opening, the creosote carburetter (with no slow-running jet) gradually comes into action, the petrol carburetter being slowly put out of action. In addition, the compression ratio is raised to about 6.6 to I, and the ignition is advanced to about 60 degrees before top dead centre.
Solex, Ltd., regards the arrangement as being now B30 beyond the experimental stage, for the Belfast Omnibus Co., Ltd., has had long and Successf ul experience. Solex, Ltd., will probably he producing manifolds for other popular makes, but at present it is able to sUpply them for only the Leyland and A.E.C. four-cylindered engines. —En.]
Oil versus Steam Engines.
The Editor, THE COMMERCIAL MOTOR.
[3925] Sir,—May I be allowed to reply to Mr. Bennett's letter published on October 28 and "Engineer's" letter in your issue dated November 4?
I am accused of innocence. Certainly in my innocence I threw a bomb, and apparently this has fallen right into the steamer camp at Shrewsbury. Mr. Bennett has ignored my statement that a 6-ton oiler now costs only about £250 more than a similar steamer, but we will take the 12-tonner as a better example.
A Sentinel of this capacity costs, I believe, £1,200. A 12-ton oiler can be bought for about £1,600, which is about £400 more. The figures published by the Sentinel concern show that, running 100 miles per day, the fuel costs are 20s. 3d., driver and mate 24s., oil and grease 2s. 9d. We will leave out insurance, licence, maintenance, etc., as being approximately equal, and deal first with depreciation. On this the oiler is £80 per annum to the bad, on fuel (at 12 m.p.g.) It is £263 15s. to the good, the oiler requires no mate, an thus saves £150 per year, it uses 20 gallons of oil at 3s, per gallon in 30,000 miles, and on this saves £38 5s.; totalling up these items, the saving is £372 in favour of the oiler.
I make no mention of the time occupied in loading up coal, filling the water tank, finding wood, etc., to light the fire, waiting 45 minutes to get up steam, etc., which actually, costs at least £20 per year. The oiler can carry 45 gallons of fuel, which will take it about 540 miles without refuelling, so that it requires to be filled about once a week. The oiler can be off in less than two minutes from the time the driver arrives, and when he reaches home he does not have to rake out the fire and attend to all the other paraphernalia of the steamer. The steamer has to stop every 40 or 50 miles for water, which. is a tiresome operation.
Like my brother of the Sentinel Company, I served my time amongst steam engines and am still a great admirer of them, but in the form in which we have them to-day, they are not to be compared, in economy and reliability, or in any other way, with the up-to-date oil-engined lorry. Progress has to hit somebody—this is unavoidable—and if I have hurt the feelings of Mr. Bennett and his steam-lorry associates
I am sorry. ' W. H. GonnAnn. Leeds.
Insurance for Loss of Vehicle Use.
The Editor, THE COMMERCIAL MOTOR.
[3926] Sir,—I have recently had an accident with a 6-ton lorry and the estimate for repairs amounted to £175. The lorry would have to have been completely rebuilt, so I have bought a new one to replace it. It has taken eight weeks to obtain delivery of the new lorry.
I am putting forward a claim to the insurance company for loss of work. What would you consider reasonable? My lorry was in regular work, drawing about £30 per week for 500 miles' running.
Atherton. INSURED.
[You should claim from the insurance company all those fixed charges which had to be paid while the lorry was nut of commission, plus the gross profit which you would have been earning if the lorry had been on the road. In your case the fixed charges I assess as follow;— The figures are per week. Licence, 17s. 6d.; garage rent, 12s.: insurance, 9s.; interest on first cost, 17s. 6d.—total £2 16s., to which add £10 per week, which is the gross Profit on the operation of a 6-tonner running 500 miles per week and earning £30 per week.—S.T.R.]