Problems of the
Page 58
Page 59
If you've noticed an error in this article please click here to report it so we can fix it.
HAULIER and CARRIER
Diagrammatic Evidence of the Invaluable Facilities Afforded by Large-capacity Machines
IN concluding the previous article I warned readers that they should keep that issue of The Commercial Motor by them so they would have the tables embodied in that issue available for reference. This article will not be particularly intelligible without those tables, and the first thing that readers must do, therefore, is to turn up the previous article and have them available for reference.
Tables III, IV and V are essential. They show the variations in cost and charge per ton for short, medium and long hauls for a variety of vehicles, ranging in capacity from a ton to 12 tons inclusive.
There is only one thing to do with tables of data such as these and that is to preserve them for reference. It would be absurd to try to memorize them. Alternatively-and this is the sensible course-the tables should be carefully studied so that the reader understands the underlying principle that they are designed to demonstrate.
I recommend that kind of treatment of the three tables to which I have just referred, and to facilitate that study I have prepared three diagrams, Figs. 1, 2 and 3, in which the data given in the tables are set out in graph form. There may be many hauliers who are unable to absorb the figures in a complicatedlooking table, but there is no driver or user of a commercial vehicle who is not capable of reading a map, and these diagrams are, to all intents and purposes, maps which show the way the figures in the tables go.
Before reading these notes examine the diagrams and make quite sure that the purport of the different lines is understood. Referring to Fig. 1, the lowest of the four curves, shown in even dots, is a diagram of the charge for mileage. The next higher, in plain line, indicates the variation in the charge for time, whilst the third curve, a dash and two dots, shows hdw the total charge increases with the size of the vehicle. The fourth line, shown in dashes and small crosses, indicates the fall in the charge per ton with the increase in the size of vehicle.
The first point to note is that, whilst the three important items, namely, charges for mileage and time, and total charge, gradually increase with the size of the vehicle, the charge per ton decreases. That, interpreted, simply means the increase in the main charges is not so rapid as that in the capacity of the vehicle. If Figs. 1, 2 and 3 be compared in this respect it will be noted that the rise of these principal charges is not so rapid ; the upward slope of the curve from left to right is not so steep in Fig. 2 as it is in Fig. 1, or in Fig. 3 as it is in Fig. 2. The effect of that is shown in referring to the curve for the charge per ton, which falls more quickly in Fig. 2 than it does in Fig. 1, and even more quickly still in Fig. 3.
In all the diagrams there is a break between that part relating to vehicles up to and including 2 tons capacity and that for vehicles of 3 tons and over. The reason for the break is that the difference in the speed limit has a considerable effect on the cost of operation and on the corresponding charges. Consequently a line connecting those two parts of• each curve would have no real meaning.
Now, in comparing these three diagrams, a striking difference cannot fail to be noted as between Fig. 1 and Figs. 2 and 3. In the first one the dotted line demoting the charge for mileage is below that indicating the charge for time, but in the others it is above. That is worthy of note, demonstrating that in medium and long-distance hauls the mileage factor becomes more important than the time factor, whereas in short-distance hauls the converse is true. '
Another interesting feature is the way in which the cost per ton falls rapidly, at first, as the .size of vehicle increases, but not so quickly farther along the scale. In considering this particular point it IS fair to deal with vehicles. only of 3 tons and upwards, because only those are on the same basis as regards permissible speeds.
Now, confining attention to this particular aspect, it will be noticed that in Fig. 1 the fall in the charge per ton is not really so rapid on a short haul. On a haul of medium length it is fairly acute from 3 tons to 6 tons inclusive, hut not so rapid after that. In the case of the long haul, Fig. 3, the decrease in the charge per ton continues to be rapid all the way through the range of sizes, namely 3 tons to 8 tons inclusive. The point the reader should deduce from that is that on long hauls the bigger vehicles show to greater advantage.
Another point needs discussion. In this series of calculations I have taken a standard time of 20 minutes to cover the loading and unloading of a ton of goods. Any alteration to this particular item of the work involved is bound to make a considerable difference to the results and, whilst I do not think I can go into this in great detail, I have drawn up Table VI, in which I have assumed that an hour is necessary for loading and unloading a ton. The figures given in Table VI are calculated in the same way as those in III, IV and V. The result naturally is to increase the cost per ton, but—and this is more important—it decreases the advantage of the big vehicle.
This is shown by a special curve added to Fig. 2, where a line, which is differentiated from the others by being composed of dashes and double crosses, shows how, under the new conditions, the charge per ton varies with the size of vehicle. There it will he seen that the charge for the 0-Wailers, 7-tonners and 8tonners does not decrease so rapidly as in the previous case shown in the other line on the diagram. The reason for this is that a large vehicle involves the owner in increased standing charges. Excessive expenditure on Standing charges is not of great moment when idle time is small in proportion to running time. When, as in this case, the idle time is trebled, the big vehicle begins to lose some of its advantage. The same basic principle is involved in the iftereased economy of the large vehicle when it is operated over long distances. S.T.R.