OPINIONS and QUERIES An Expert Opinion on Our Tables of Operating Costs.
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The Editor, THE COMMERCIAL MOTOR.
[3636] Sir,—I am under the impression that each year,, about April, you publish Tables of Operating Costs of various types of commercial vehicle. You kindly gave me several of these when I was last at your office. They related to March, 1930. Would you kindly send me half a dozen copies of the latest edition, which I expect will relate to March, 1931?
I may say that I found them extremely interesting and useful in my lecture work here. If you have them to spare I would like more than half a dozen, for which, of course, I would be willing to pay.
May I add that I greatly appreciate the work you are doing in editing The Commercial Motor, from the point of view of one responsible for building up a body of knowledge based on practical experience.
GILBERT J. PONSONBY, The London School of Economics and Political Science. (University of London.) London, W.C.2.
Coal Gas as a Vehicle Fuel.
The Editor, THE COMMERCIAL MOTOR.
[3637] Sir,—I am sure that there are many men in the transport industry who have read with interest your -leader on the above subject, published in your issue of January 12th. It is a matter of national importance,
Some 20 years ago I began research in this direction ; at that time exceedingly good results were promised, but to-day matters should be even more favourable. At that time it was proposed to compress London gas to 1,600 lb. per sq. in. and to employ my Paragon heat cycle, thus obtaining more horse-power-hours of useful work than is possible with the ordinary "petrol-gas" engine. The war interfered with these plans, but good work was done with gas at, or about, atmospheric pressure, also with gas highly compressed and subsequently reduced in pressure by means of a valve.
There is no question but that coal gas is a clean and reliable fuel which gives practically complete combustion with a resultant reduction of smell and carbonmonoxide content. It is important to employ a higher compression ratio than is usual with the normal constant-volume petrol engine ; this course saves fuel and gives a greater fuel range, or the possibility of using a lower gas pressure in the containers. The system formerly adopted, namely, that of having a high pressure in the bottle in order to counteract the lower efficiency, wak at a disadvantage in respect of fire risk in the event of collision causing a fracture of the "bottle."
In connection with the proposed London-Birmingham tests I have made some calculations of interest, presuming the use of an engine with a compression
pressure of about 80 lb. per sq. in. It would be necessary to compress the gas to at least 5,000 lb. per sq. in.; even then the vehicle would have to be carefully driven ; when throttled down the engine would not extract from the fuel the full heat value per cubic foot, in the case of gas used at just above atmospheric pressure.
This scheme is a very fascinating one and deserves encouragement from every source ; too much reliance has-been placed upon petroleum products.
My system would include a three-cylindered engine of the two-stroke-cycle type, operating on the Paragon high-compression heat cycle, running at a constant speed of from 600 r.p.m. to 800 r.p.m. ; regenerative braking would be provided. The gas would be compressed to about 200 lb. per sq. in., making use of the engine and a rotary compressor carried on the vehicle. In the London-Birmingham run one recharge would be necessary.
For town work I suggest that battery-electric buses should be used ; gas would be the fuel for the charging work. In the Midlands and Wales, I am informed, there are millions of cubic feet of gas in coke ovens being burned to waste; this might be used for 'battery charging at a cost of 4d. to 6d. per thousand cubic feet. No liquid-fuel engines could compete against power at such a price.
The Commercial Motor has done well in drawing attention to this source of still cheaper transport ; during the war it did much to advocate this most important heat-power development, which may yet be found to be the greatest forward step since Stephenson built the Rocket. WILLIAM P. DURTNALL. London, S.E.5.
Condensation on Sparking Plugs.
The Editor, THE COMMERCIAL MOTOR.
[36381 Sir,—In the letter signed by "Users," in your issue of January 12th, the writer stated that he has made certain that the condensation on the plugs is not due to leakage from the water jacket ; that being the case, the moisture is probably due to combustion. "
To cure the trouble we suggest that the following routine should be carried out when shutting down for the night.
Speed up the engine, switch off the ignition and at the same time open wide the throttle, holding it open until the engine stops. The idea being to sweep out all the burnt gas. Am° M. LODGE, Director Rugby. (For Lodge Plugs, Ltd.).
Unsatisfactory Transport Propositions.
The Editor, THE COMMERCIAL MOTOR.
[3639] Sir,—I am operating a Morris-Commercial 30-gwt. lorry, 1931 model, and would be glad to have your opinion of the following proposition, which is rather different from anything I have tackled before, as haulage work is only a side line, I am offered regular work fetching loads from a town 20 miles away, at the rate of 5s. 6d. per ton. Three journeys a day would be as much as I could do, and on this basis I do not think that the price is good enough.
I have been thinking, however, of getting a trailer to carry 30 cwt., so that I could bring three tons per journey. Would this be a paying proposition?
I have been doing work with the lorry at the rate of 4s. 3d. per hour, nine hours a day, also journey work at the rate of 6d. per mile. That is 6d. per mile for both out and return runs, a load being carried on the outward journey only. The weekly mileage averages 400, and the driver's wage is £3 per week. The truck is garaged in my workshop, so that I have no garage charges. Are these reasonable charges?
Todmorden. KNOTFORD.
[We are not enamoured of either of the two propositions that you mention in the second and third paragraphs of your letter.
The revenue, if you use a 30-cwt. lorry alone and cover three round journeys per day, will be equivalent to 2-id. per mile, as against a bare cost of operation of 3.90d. per mile. Moreover, the cost of operating would only be so low as that if you could complete three journeys per day for five days per week, covering 900 miles.
It would be more satisfactory to run a trailer, since in that ease, making the same assumptions, your revenue would be 5d. per mile, as against a bare operating cost of 4.30d., leaving a gross balance of 0.70d. per mile, which is £2 12s. 6d. per week.
We do not think, however, that you can maintain the average mileage with a vehicle and trailer without either breaking the law or breaking up the machine (or both), and we do not recommend you to take that course.
It is difficult to advise you on your other work, since you do not state what percentage of your week is devoted to work at 4s. 3d. per hour and what to work at 6d. per mile.
Taking first the work at 4s. 3d. per hour. Your cost is 2s. per hour plus 2td. per mile, so that if during the hour you run 10 miles, then you are operating at a loss.
If the 6d. per mile work totalling 400 per week is all the mileage that is covered, then the cost per mile is 5.60d., leaving you a gross profit of 0.4d. per mile, which is 13s. 4d. per week.
If you will let us know more exactly what your work is we should be able to help you better.-ED.]
Starting in the Haulage Business.
The Editor, THE COMMERCIAL MOTOR.
[3640] Sir, -I have been reading articles in your journal concerning the running costs of oil-engined lorries. I and some friends are thinking of buying a petrol lorry to carry about 3 tons, but we shall be much obliged if you can give us some information about the matter. Do you advise a start now trade is so bad?
What is the best way to work out prices for local runs, cost of insurance, etc.? Your advice on anything about the haulage business will be very acceptable.
Hull.
[it is impossible to answer the first of your questions. The advisability of starting in business depends more than anything on the energy and enterprise of the person concerned. Poor trade is a handicap, but it is up to you to gauge the extent of your handicap according to the conditions of the area in which you propose to work.
The best way to work out prices for local runs is to calculate them on a basis of time and mileage.
The Tables of Operating Costs should help you. You will observe that the standing charges for a 3-tonner amount to 1,398d., which is approximately 2s. 6d. per hour. If you add is. 6d. per hour for gross profit you arrive at a figure of 4s. per hour as being the charge you must make for time. You should add to that 5.11d. per mile.
As an example of the application of the foregoing. If you have a job which involves 20 miles of running and takes three hours to do, then your charge should he three hours at 4s., which is 12s., plus 20 miles at 5.11d., which is 8s. 6d.; total £1 Os. 6d.
The cost of insurance is indicated in the Tables.S.T.R.1 Responsibility for Repairs Resulting from an Accident.
The Editor, THE COMMERCIAL Moron.
[3641] Sir, -I have for many years been a reader of your journal, The Commercial Motor; it has proved very useful. I shall now be glad if you will help me., A lorry was standing by the side of the road unloading goods; another lorry came along and the stub axle broke, causing it to hit the stationary vehicle and doing damage that has cost £.30 to put right. The insurance company says that it is not liable at all as the damage was due to a mechanical defect. Both lorries are insured. Can you tell me who ought to pay?
Ilkeston. A READER.
[If the policy of the owner of the moving lorry is in the usual form and exempts the insurance company from liability for damage to the lorry which is not caused by external impact, or which does not cover mechanical defects, the owner would not be entitled to recover from his company the damage to his lorry.
The owner of the stationary lorry would be entitled to recover the cost of repairing his lorry from his own insurance company if his policy covers damage to his vehicle and is not limited to third-party risks.
The owner of the stationary lorry would be entitled to recover the cost of repairing his lorry from the owner of the moving lorry if he could prove that the breaking of the stub axle of the moving lorry was due to negligence on the part of the driver or owner of that lorry, but the mere fact of the axle having broken would not in itself be evidence of negligence.-Eo.1
A Removal Problem.
The Editor, THE COMMERCIAL MOTOR.
[3642] Sir, -In perusing the Tables we have not noticed particulars of costs for operating, say, a 5-ton petrol lorry and 3-4-ton trailer.
We have a removal business which is not of sufficient magnitude to enable us to keep a 4-ton lorry always at work, and for long-distance work we have for many months past favoured the railway-container mode of transport, on account of what appears to be economy on the one hand, and competition on the other hand. Our Leyland is getting old, and we have been hesitating as to whether we should recondition it, replace it with a 3-4-ton lorry, or purchase a Leyland and trailer.
Could you kindly give us an idea of the charges per mile which we should make to show a profit for :
(1) A 4-ton lorry with lift van, per day, within a radius of 60 miles, i.e., 120 miles for the return journey.
(2) A 5-ton lorry with 3-4-ton trailer with lift van as above.
(3) A 4-ton lorry, also 5-ton lorry and trailer, reckoning about 100 miles per day in each case. For instance, for a removal involving being away for 4-6 days.
In common with other places, we find that prices are being cut to such an extent that we begin to wonder where we stand.
We are running several vehicles of one kind and
another, but only one large lorry. REMOVERS. Bideford, [You will find information as to the extra cost and charges involved in the use of a trailer in Table HI. The figures there given are approximately the same as those you may experience in the case of a trailer used in conjunction with a petrol wagon.
Dealing with your numbered questions, the appropriate answers must inevitably turn on the daily profit you expect to make. Reference to that is made in each reply. (1) To make a gross profit of £1 per day you must charge 45s. per day, plus aid, per mile run. Add to that the wages of any man employed additional to the driver, also any unusual expenses. (2) For a gross profit of 25s. per day you will have to charge £3 per day, plus Sid. per mile. This includes provision for the wages of two men, but no other extras. (3) For 25s. per day gross profit, charge £3 5s. per day and 84. per mile. For journeys of 100 miles per day the charge would be £6 10s.-S.T.R.j