HINTS FOR HAULIERS.
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The Workings of the Law of Averages and the Need for a Thorough Understanding of that Law by the Haulier who Desires to Quote for a Job.
THIS problem of averages to which I have been referring in my two most recent contributions is an interesting one. It is really of very wide, practically universal, application. The whole business of insurance, for example, in all its .forms, is built up on.averages. As regards life assurance, to mention but one.phase, the insurance companies, in fixing the amount of premium, base their calculations on tables which schedule the Prospect of life which every person has, according to his or her age. These tables are based on averages—averages arrived at as the result of examination of statistics collected over long periods of years."' The tables are subject to slight variation from year to year as the health of the general community improves or depreciates. Even in those far-off days when the Bible was written, the principle of averages was understood and applied in thisbconnection, and it was written that man's allotted 'span was three score and ten. Now, consideration of even that simple statement may afford us some useful ideas. For example, I shall probably exceed that age by a Considerable period before 1 tun gathered to my fathers. I shall, that is if there is anything in this latest theory about hard work making for long life. On the other hand, such as the Editor, beloved of the gods (and I never appreciated before the real significance of that quotation), will die young.
There are many things besides petrol about the motor vehicle, the average life or consumption of which must be known to us before we can estimate cost.. Tyres, for example. At one time solid band tyres used to be guaranteed for a life of 10,000 miles, which circumstance has apparently given rise to a widespread and mistaken belief that 10,000 miles is the average distance a solid tyre .runs before it wears out. There is not, as a matter of fact, any necessity for there being .a connection between these two things —the guarantee and the life of the tyre.The former might easily have been arranged in accordance with the prices of the tyres, and most likely was. The life of a tyre, except in London, does not, even now, average 10,000 miles.
The Average Life of a Solid Tyre.
It is true—perfectly true—that many solid tyres run for many more miles than 10,000 before they are done. 'Twice that distance is exceeded occasionally, and when it is we hear about it or read about it in the advertisement pages of this journal. . Naturally we do. It is something to shout about. What we are r ot told is about those tyres which burst—I am still referring to solid tyres—which fail the first time out. Not that this is a frequent occurrence, any more than is the running of a tyre for 20,000 or 30,000 miles, but it does happen, and, so far as the user is concerned, the extremes balance, and he.experiences in the long run the average. Of course, it sometimes happens that one man has • the tyre which bursts and another has that which runs 20,000 miles, which is unfortunate,. or fortunate, as the case may be. It should be stated, too, in justice to the tyre manufacturer, that the owner`of the burst tyre will most surely claim, and most Kkely obtain, compensation for his loss of mileage. No direct compensation.. however, is payable to the maker of the tyre which runs an abnormally high mileage. These, at least, are Ile things which in real life happen to tyres, and they are apt greatly to disturb the average man's.notions of their average life. Moreover, as it is chiefly the tyres which do well of which he hears, before he has much experience of his own to go upon,
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the ideas he gets are such as may affect his estimates of costs, to his own detriment, at the time when he is considering the adoption of motor vehicles as the means of earning a living.
Consider, too, the life of the motor vehicle itself. Considerable importance attaches to that if any reliable and complete estimate of probable working costs is to be made. I.generally assume an average of 125,000 miles for the regular type of chassis, in ordinary service. An American expert. has just calculated, from statistics covering 25 years, that in the States -a motor vehicle will last from five to six years. If we accept six years, and. compare with my figure of 125,000 miles, this is equivalent to an annual mileage of rather more than 20,000, approximately 400 a week, which, as I have occasionally pointed out, is seldom acCompiiehed by a haulier in the ordinary way of business, except from time to time. He does not average 400 a week.
The Vehicles' Long Period of Usefulness.
Motor vehicles in this country probably average rather more than six years, yet no one would be likely to buy a machine thinking that it was only going to last six years. People who do not know— and, more especially, people who ought to know— talk glibly of from 16 to 20 years, which, considered as an average, is pure nonsense. If we take eight years to be the average, we shall not be far out. A good driver, particularly a careful owner-driver, can easily double that period, and still have a usable machine at the end, as was shown in the interesting examples described in last week's issue of The Commercial Motor. A careless man, with a machine which may not have been too good at the start, will, in four years, have it in such a condition that it is not really worth repairing.
Cost of maintenance is another .item which, although the average is fairly well known, varies in individual cases within very wide limits. Take, for example, that case of a Commer Car which, as recently advertised in this journal, had completed 50,000 miles with hardly any expenditure on repairs, and, moreover, at the end of that time cost very little to overhaul. That is an exceptional case, although I am quite prepared to believe that there are some others of similar nature. On the other hand, instances of excessive early expenditure, due either to mishandling or as the indirect outcome of an accident, are not exceptional either. The average does not merely strike the medium between these extremes; it is the mean of a large number of results, the bulk of which do not themselves greatly differ from the average itself.
The Average Consumption of Fuel and Lubricants.
The average lubrication expenditure in connection with a chassis is practically imassessable, so greatly does it vary. It differs with the. driver, the make of the chassis, and its condition. Consumption of oil differs by hundreds per cent. as between one vehicle and another of the same type, or even as between performances of the same vehicle under seemingly similar conditions.
But I want to return again to the important question of petrol consumption. I have shown, in the two previous articles, not only haw -easy it would be to obtain resits varying; in the case of a twoetonner, from 8 to 16 miles per gallon, but how difficult. it would be for the ordinary man to avoid making errors which would vitiate his results to the extent of so much as 50 per cent. His results, however, even if ace urate would be of very little use as a basis for calculation when he had griMern, as I shall presently show. Before doing so (in my next week's contribution) I want to refer to a classical modern example of a petrol consumption test of a heavy vehicle. I mean that which was carried out about a year ago by the Royal Automobile Club, the vehicle being a 2-ton Thornyerof I. That machine, loaded to 2 tons 6 cwt. 14 lb., including the weight of three persons, so that its gross weight was 5 tons 6 cwt. 2. qrs. 14 lb., travelled a distance of 1,260 miles in 101days. It ran from London to Land's End, Land's End to Edinburgh, and back again to London. The
route was a difficult one, and was covered at an average speed Of 13.9 miles per hour (running time only) and the consumption of petrol was at the rate of one gallon per 13 miles. The performance of this vehicle was regarded by the R.A.C. as so meritorious that the Thornyeroft Co. were awarded the Dewar Cup, which is given solely in connection with performances of outstanding merit, its award being considered throughout the trade as a very high honour indeed. That Is to say, the R.A.C. considers 13 miles per gallon'as an exceptionally good performance on the part*of a 2-ton lorry, and, I may add, it is so considered by all fair
minded members of the trade. THE SKOTCH,