OPINIONS and
Page 51
Page 52
If you've noticed an error in this article please click here to report it so we can fix it.
QUERIES
HOW TO DEAL WITH SLOW-MOVING .TRAFFIC.
The Editor, THE COMMERCIACMOTOR, 143762 Sir,—Perhaps the most interesting feature, of Mr. Scrym.geour's letter, in your issue for last week, is, that the motor industry appears to have a champion in a public position with the courage to express his private views above his public signature.
Few of your readers will quarrel with Mr. Set-yingeour's suggestion that the fitting of pneumatic tyres on cart wheels should be made compulsory, and so. remove the slow-moving horse-drawn vehicle from the tram rails, with the consequent release of faster traffic.
I offer to Mr. Scrymg-eour the suggestion that horse drivers cling to the tram rails more out of consideration for their own bodies and nerves, than for their horses— except where there are smooth road sides on gradients.
In this workaday world am afraid we shall see only a gradual substitution of steel tyres by pneumatics on horse-drawn vehicles, on account of the relatively high initial cost.
In the meantime, Councillor Scrymgeour would earn the undying gratitude of road users if he would persuade his colleagues on the Police Committee of the Dundee Corporation to visit Edinburgh to study the excellent work carried out by Chief Constable Ross, by means of mechanically mounted police, in enforcing the law as regards compelling slow-moving traffic to keep to the left.
'Thus, at one blow, would the tramway undertaking be relieved of the unfair burden of excessive upkeep costs of that portion of the road for the maintenance of which it is responsible, the trams could pursue their unchequered career, and we lesser fry would reap the benefit. H. E. HENSON, Service Manager, For THE SCOTTISH MOTOR TRACTION CO., LTD. Dundee, WORKING OUT TON-MILEAGE COSTS.
The Editor, THE COMMERCIAL MOTOR.
[4377] Sir,—What is ton-mileage, and how is it calculated? . How is cost per ton-mile worked out and how can one cost tyres per week when the ultimate mileage of the tyres before scrapping is unknown?
West Calder. j. GIRB.
.[Ton-mileage is the distance travelled per ton of weight moved, and is obtained by multiplying the weight in tons by the number of miles covered. The ton-mile serires as a useful unit for comparing the performances of vehicles of different load capacities. For example, the running cost per pay-load ton-mile, or the number of gross ton
miles per gallon, and so forth, would be ascertained. The former is calculated by obtaining the cost per mile for fuel, lubricants, tyres, maintenance and depreciation, and multiplying this total by the pay-load of the vehicle. The Commercial Motor Tables of Operating Costs give 1.68d. as the running cost per mile of a 10-cwt. machine. Thus the figure per ton-mile would be 1.68 multiplied by 0.5, which equals .84d. For a 3-tonner, the figure given is 4,29d.; therefore, per ton-mile it would be 12.87d. Tyre life varies according to size, etc. It is possible to obtain an accurate figure only by actual results. In our Tables the figures given for the cost per mile of tyres were arrived at from averages obtained from a variety of users. Pay-load ton-mileage, of course, cannot be arrived at when the vehicle is running without a load. The total cost of a return-empty journey is divided by the ton-miles to find the cost per ton-mile.—S.T.R.]
FURTHER OIL-ENGINE EXPERIENCE—THE VALUE OF LOW MAINTENANCE COSTS,
The Editor, THE COMMERCIAL MOTOR.
[4378] Sir,—The figure you quote for maintenance, viz., "over -id. per mile," means that for a yearly run of 50,000 miles (most buses do 60,000 and over) the cost would be well over RICO—or some 20 per cent, of the first cost of the engine. This is far too high and compares badly with good petrol engine results. It should not exceed id. per mile in any case. We are nowarriving at the state when we can obtain records of oil engines which have ran mileages of 150,000 up to 200,000 and even over,and therefore we are able to obtain figures and data to enable us to compare results with those of petrol engines—hitherto our standard engine. When the oil engine first made its appearance here (some six years ago), one of the major points stressed by the critics was that the maintenance costs would be so high that the fuel economy would be almost counterbalanced. It was freely stated that these engines would "knock themselves to pieces." To be quite truthful, some of them practically did so, and in sane cases the maintenance costs were truly appalling. Big-end failures, broken pistons, cracked heads, and other troubles were the order of the day.
So we have had a gradual process of "sifting out" —otherwise known as the "survival of the fittest "— and a very expensive experience in many cases has resulted in a considerable improvement generally, some examples, however, have a long way to go yet before they can boast of maintenance costs at all comparable with those of petrol engines. Quite recently a case occurred in which a well-known engine, after running only 60,000 miles (in a double-deck bus), cost some £200 to overhaul and put in order to resume work.
This is equal to 0.8d. per mile run, which is, of course, an appalling figure. On the other hand, another make
of engine doing exactly similar work—but after having
run over 80,000 miles, cost only £36—or 0.114d. per mile —to be made fit for another run of 80,000 miles. The
big-ends and mains were perfect, and were left alone-
the wear on the crankpins being only 0.001 in. It so happens that in the former case the engine was a pre
chamber design, and in the latter case of the direct-injection design, so that, in addition to the great difference in maintenance costs the latter engine showed a further considerable advantage in fuel economy.
It is perfectly logical to follow up this comparison over a terra of five years, In the former case the overhaul costs would then amount to something like twice the original first cost of the engine, and in the latter case about 38 per cent, of the first cost. Thus it is very evident that there is a vast difference between different makes, in design, quality of materials, and in the standard of work. The figure of 0.114d. per mile is well under the average for good petrol engines, although even to-day some users have the impression that oilengine maintenance must be .higher than that of petrol engines. '
We have ample proof that at least in one case it is not so. A buyer may be offered similar-powered
engines with a: price difference of as much as £100 certainly a large and attractive sum, but if the maintenance and overhaul costs come out respectively as above, then the higher-priced engine is far and away the cheapest-the extra £100 being insignificant when compared with the heavy overhaul costs of a poor engine over a term of, say, five years.
It is, therefore, clearly up to the buyer to obtain the fullest information on reliability and maintenance costs.
There are engines now on the market which will run 150,000 miles without overhaul—a really great achievement. Although this is not either economical or to be recommended, it is a very solid proof of good design and of high-class materials and workmanship.
Referring to your leader in your issue dated August 24, the figure you quote' viz., 50,000 miles for big-ends and mains, is poor, when compared with some results being obtained to-day, as also the figure of 13,000 miles or one-thousandth of an inch of crankpin wear—as mentioned in the example of the direct-injection engine above referred to.
Big-ends and mains should run 80,000 to 100,000 miles easily and crankpin wear should not exceed 0.001-in. per 50,000 or 60,000 miles in a well-made engine.
Leeds. PIONEER.
OPERATING A BUS ON A LOW MILEAGE.
The Editor, THE COMMERCIAL MOTOR.
[4379] Sir,—I have been interested in your articles on haulage operating costs and wonder if you would help me on a bus problem. I am using a small eightseater bus and consider going in for a 20-seater.
What would it cost per mile to run this? The annual mileage would be small, perhaps only 10,000, on pleasure-party work. I have my own garage, so that could be written off, and would drive it myself.
The vehicle I propose to run would cost between £500 and £650. What would it be necessary to have coining in weekly to clear the hire-purchase instalments in, say, two years?
I have a road service licence for tours and excursions, for which my small bus is at present big enough, but I have prospects of party work for a 20-seater.
There are some operators in my neighbourhood who, a38 • to my idea, operate very cheaply, a ran of 52 miles return for 2s. each, or to Blackpool, 250 miles return for 8s. 6d. each, are some of the prices. Do they pay? A tour of 150 miles for 4s. is another case.
BUSKER.
Stocksfield-on-Tyne.
[I gather that you wish me to calculate your costs, without making any allowance either for driver's wages or garage rent. If I assume that you will tax and insure the vehicle for a year, your annual charges, including, in this case, depreciation, will be as follow :—Tax,£36 ; insurance, £30; depreciation, £100; interest, £15; total, £181, That, On the basis of 10,000 miles per annum, is 4.34d, per mile. In addition, there are the running .costs, which will be approximately as follow:— Petrol, 1.15d.; oil, 0.07d.; tyres, 0.53d.; maintenance, 1.22d.; total. 8.07d. The sum total of standing charges and running costs is thus 7.41d. per mile, which, if you like, you may take as being Thd. I do not consider that you are justified in deleting either wages or garage rent. If you take these into consideration, the total will be about 2160 per annum, which is equivalent to a further 3.84d. per mile (for a 10,000-mile year) bringing the total cost per mile to 11.25d.; that is to say, 111d. You -should realize that that is your bare operating cost and that it will not really pay you to run your vehicle and make a charge to bring in only just that revenue per mile. You ask me_what your charges would have to be in order to enable you to clear off the initial cost of the vehicle if b,ought under a hire-purchase contract to cover two years. That means that you must earn a profit of £300 per annum and use all that profit in paying off these charges.. I do not think you can expect to make such a profit. Three hundred pounds per annum • is equal to 7.2d. per mile on the mileage you are doing, which would bring your charge up to Is. Ckid. per mile, and even if you only allow £20 per annum for contingencies the total is equivalent to is, 7d, per mile. How this compares with the figures quoted by me you may judge from the following. For a 52-mile round journey you would have to charge 4s. 2d. per head. For a 250-mile journey £1 per head, and for a 150-mile journey 12s. per head.. I cannot compare these figures or give any opinion on the charges made by your competitors, since I. do not know the conditions under which they are operating, and particularly their annual mileages. Your difficulty is that your annual mileage
is so very low. S.T.R.
THE LEGAL LIMITS ON LOADING.
The Editor, THE COMMERCIAL MOTOR.
[4380] Sir.—We have a Cornmer 2-tonner the unladen weight of which is 2 tons 7 cwt. 2 qrs. We understood that there was no legal limit as to the weight that we may carry on this lorry. We have, however, been told that under the new legislation there is a limit to what may be loaded on to the -various types and sizes of vehicle.
We have read through the Act and can find no reference to it. We should, therefore, be glad if you could help us by letting us know whether we are limited to any weight that we can carry on this lorry. LIMIT.
London, W.C.1,
[At present there is no express regulation as to the limits of loading, apart from the rule that a vehicle may not be loaded dangerously, or beyond the maximum permissible gross load applicable to the type. This is 12 tons for a four-wheeler. Personally, we think that anything in excess of a 50 per cent, overload could be regarded as dangerous. There is some possibility of the method of taxation being altered so that it will be based on load carried instead of unladen weight. In those circumstances, any weight carried in excess of that for which the vehicle was registered would render the owner liable to a penalty for operating with a load above that for which the tax is paid.—E.D.1