Solving the Problems of the Carrier
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Oil orPetrol for 30 m.p.h. Lorries?
Second Article on the Subject, in Which a Reasonably Accurate Comparison of Costs of Operation of the Two Types is Made, the Figures Showing Hou, Soon the Difference in Initial Cost Can Be Offset by Economies
IN the first article on this subject. I dealt, in the simplest possible way, with the comparison between oil and petrol engined lorries. for 6-tian loads. I arrived, by the' examination a certain quotations, at a fair difference in price between the one. type of vehicle and the other, taking ' precautions to ensure that the difference was due solely to the fact that the one vehicle had an oil unit and the other a petrol engine.
I made estimates of the saving in fuel cost and showed that, if that item of operating cost alone be taken as a basis for calculation, the difference in the initial outlay on the two types of vehicle—R250—would be completely wiped out in a mileage of 45,000 to 48,000; "which is, in the case of most oil-engined vehicles, approximately 18
months of work. .
I then pointed out that this method of assessing •the savings due to the use of an oil engine, in preference to. a petrol unit, was not altogether correct and I was in the middle of dealing with that aspect of the question at the end of the previous article. The argument is now taken up and the essential figures are set out below.
I terminated the earlier article in the middle of a discussion on maintenance, and I had pointed out that this is a somelihat difficult item to assess in the case of the oil engine, because .so, much depends on the way in which it is handled. In a' properly organized establishment, there .is no doubt that the cost of maintenance of the oil engine can be kept below that of' the petrol unit. On the other hand, where that organization is absent or inefficient, the probabilities are that the differencewill bein the other direction. In what follows I develop this theme in greater detail.
Maintenance Costs for Both Oil and Petrol 6-tonners
If I take ,the figures from " The Commercial Motor" Tables of 'Operating Costs for a 6-tonner running 400 miles per week, I find that under the heading of maintenance of a petrol-engined vehicle there is Maintenance (d) at 0.80d. per mile and Maintenance (e) • at 1.18d. per mile. In the case of the oil-enginect vehicle, the same figure is quoted for Maintenance (d), but Maintenance (e) is quoted at 1.30d. per mile.
These figures, of course, refer to the average expenditure on the maintenance of the vehicle as a whole. So far as Maintenance (a) is toncerned; this is routine work carried out at specified times irrespective of mileage. It includes washing and polishing, painting the vehicle, etc., and is not affected by the type of engine.
Obviously, therefore, according to the other item, Maintenance (e), which relates to upkeep, repairs, overhauls and so on, generally speaking, based on the number of miles covered by the vehicle, the oil engine has been debited. mere heavily than the petrol unit. It may not be that the extra expenditure is incurred in maintaining the engine. It may, possibly, be that certain additional cost is assumed to arise in the maintenance of the mechanism of thevehicle because the engine is oil driVen. However that may be, the fact remains that the oil-engined vehicle is quoted as costing more for maintenance than the petrol macli,ine. Now, in these Maintenance (e) figures 'there is 'provision for cert4n war-time difficulties. There is, in fact, allowance to cover the cost of delays in obtaining spares, in addition to the actual cost of the repairs and maintenance operatiOns. Actually, an addition of 25 per cent. was made to the average cost figures on account. of that difficulty, so fhat Avithout that addition it may be said that the net
Maintenance (e) figures are : For peiroI-engined vehicles, 0.95d., and for olleengined vehicles, 1,05d.
I would not be prepared to maintain that figure for the
oiler in all circumstances. Oil engines in the hands of bigger operators, Who have proper organization for effecting maintenance and who icisist that there shall be reasonable adherence to a proper schedule of operations, are actually less expensive to maintain than are petrol engines. Indeed, if the avera.ges in the Tableswere based on the number of ,engines in use and the cost of maintenance, instead of on -the number of operators which uses oil engine's, then the proportionate difference would, in all probability, he in favour of the oiler.
Until recently,, at any rate, I should have been almost ready to agree with any experienced operator of oil-engined lorries who claimed that the cost of maintenance was, at the least, no greater than in the case of petrol vehicles. would have accepted Id. per mile for either type, notwithstanding the fact that when anything does go wrong with an oiler and new parts are required their cost is usually greater than it is for •a corresponding part for a petrol
' engine.
War-time Influence on Maintenance of Petrol Engines
To-day, there is no doubt on which side the credit lies. The maintenance cost of petrol units now is probably in the region of double that of oil engines. Whereas at one time top overhauls were considered to be necessav after approximately 10,000 miles of running, they must now be effected at every 2,000-3,000 miles. That considerably increases the cost of maintenance for more than the obvious reasons, which are, of course, that there is the cost of the labour involved in doing the work, plus that of gaSket.,„ radiator hose, and other items that should he renewed when such an operation takes place.
In addition, _however, the top overhaul of a petrol engine to-day involves, more .often than not, new valves, as well as refacing the valve seats. Sometimes the valve seats • have to he renewed, and when that is not possible a new cylinder head or even a new cylinder block is required. It has thus come about that the extra. maintenance cost of the engine itself is increased out of all recognition, Furthermore, in view of the shortage of labour, the frequency with which top overhauls are required with any fleet is absorbing so much of the mechanics' time that these men are unable to carry out routine chassis maintenance and overhaul operations at the time when those
would normally fall due. They have to be postponed, With the result that when they are finally carried out they / are much more expensiVe and ive more trouble than would otherwise be the case. In considering this aspect of the problem, I have not touched upon the much wider and more difficult problem of assessing how much extra cost.— or loss of earnings—is likely to accrue because the vehicle has broken down as the result of lack of routine, maintenance work,
Most of these troubles are arising because of -the quality of Pool petrol. None of them arises in connection tvi4h the operation of oil engines.
It follows, therefore, that to-day the oiler is well worth the extra cost to the haulier, even supposing there were no economy in fuel at all, for he would probably save in a year enough to offset that .250 which figures so 'largely in the earlier part of this article.
It may be,. however,'that this difficulty with the petrol engine will prove to be a temporary and passing phase.
Indeed, that is moie than likely,' for I understand that a thorough investigation is being made into the matter. If, as appears certain to be the case, it is proved that road transport is being seriously hampered as the result of the quality of petrol served to civilian operators, then sonte improvement will be effected and thes,e difficulties will disappear. In the figures which I am about to put forward for purposes of comparison between the two types of vehicle I propose to ignore these current difficulties and to assume that the figures for maintenance are those which I have cited above. As I have said, they are taken from the current issue of " The Commercial Motea"' Tables of Operating Costs, but corrected in order to allow for the provision made in the actual published figures for the cost of waiting for spares. On that basis, then, in order that the comparisons shall be fair, I will take the figure of 0.95d. as Maintenance (ei for petrol and 1.05d; as the corresponding figure for the oil-engined machine. At the same time, it is proper to record that, in many cases, especially those where the vehicle—and engine—are properly maintained to schedule, and particularly when proper regard is had to cleanliness of fuel and lubricating oil, this differentiation is. unfair to the oiler.
Calculating Depreciation on the Basis of 150,000 Mlles of Life
There is only one item of running costs left and that is depreciation. That is, of course, measured according to the life of the vehicle and I have already assumed that to be 150,000 miles. • _ An oil-engined machine costs, in the first place, £960. From that I propose to deduct £80 on account of tyres, giving a net figure of £880. . After the vehicle has covered 150,000 miles I shall assume that the operator; disposing of it; probably in a part-exchange transaction, obtains £80 for it. I am, therefore, left with 2800 as a net figure on which to calculate depreciation. On the basis of 150,000 miles that is 1.28d. per mile. . The petrol-engined vehicle costs. £710 new, that is £630 without tyres. If £60 be obtained for it on sale when it has covered 150,000 miles, the initial cost may be taken to be £570, in which case the depreciation for a mileage of this total is 0.91d. per mile.
It is now possible to summarize the operating costs of the two vehicles, so that the comparison between them can be made more accurate First, let us take the petrol-engined vehicle. The standing charges per week are as follosv:--s-Tax, 14s., wages, £4 7s, 6d.: garage rent, '10s.; insurance, £1; interest, 7s.; total, 26 18s: 6d, The running costs per mile are:—Petrol, 2.78d.; lubricants, 0.16d.; tyres, 1,20d.; maintenance (d), 0.30d.; maintenance (e), 0.95d.; depreciation, 0.91d.; total,, 6.30d. The corresponding figures for the oiler (standing charges per week) are:—Tax, 14s.; wages, £4 7s. 6d.; garage rent. 10s.; insurance, £1; interest, 10s.; total, £7 Is. 6d.. The running costs per mile are:—Oil fuel, 1.44d.; lubricants, 0.18d.; tyres, 1.20d.; maintenance (d), 0.30d.; maintenance (e), 1.05d.; depreciation, 1,28d.; total, 5.43d.
An Explanation of Some of the Standing Charges
For the _benefit of those who have not "The Commercial Motor" Tables of operating Costs by 'them, some further explanation of these figures is necessary. First, as to the amount for wages—£4 7s. 61 That is the current rate . of wages for a vehicle of this load capacity, according to the Road Haulage Wages Act and pamphlet 1/.1-1. (12) . It includes provision for a. week's holiday with pay and the , three employees' insurances—National Health, National Unemployment, and Workm6n's Compensation Acts.
The amount for tyres may seem rather high, that is, however, in accordance with present-day experience as tyres are coming on to the market, new ones as well as retreads.
Maintenance (d) is routine maintenance, such as washing and. polishing, repainting and lettering, and operations of that kind, which are. carried out at intervals on a time basis and are, therefore, greater or less according to the mileage per week. Maintenance (e) refers to routine rmaintenance operations, as well as repairs and overhaulswhich, under
normal ,conditions, are carried tout every so many miles. The amount, therefore, does not differ whether the mileage per week is great or small, providing it be within, reasonable limits.
We can deal with these summaries of standing charges and running costs in one of. two. ways. 'We may either ascertain the cost per mile and _draw conclusions from that, or we may ascertain the total cost per week and draw other interesting" conclusions from the figures thus obtained. To obtain the total cost per mile it is necessary to divide ' the standing charges by 500, to arrive at the incidence of the standing cha ges per mile run. Doing so in the case. of the petrol-eng ed vehicle we obtain a figure of .3.32d. ' which, added to e 6.304. for running costs, gives us 9.62d. tL
for the total cost per mile.
Proceeding similarly with the figures for the oil-engined vehicle we obtain 9.40d. as the -incidence 'of the standing ,charges to which we add 5.45d. for the running costs; giving . 8.85d, as the total cost per mile. The net difference, in favour of the oil engine, notwithstanding the fact that, In respect'of certain items (particularly maintenance and depreciation), we have been somewhat' unfair to it, is' 0.77d. ..
e per mile—rather more than id.
When the Extra Initial Cost is Finally Eliminated
According to that the vehicle will have to run 80,000 miles before the extra cost of 2250 is finally wiped out. That is, however, different from the preVious figure of 45,000, or 48,000 miles, and I must say, in my opinion, it
is more nearly what we should expect.
It is now of interest to assess the total cost per week of these two vehicles. To that end it Js is netessary to multiply the rUnning costs per mileby 500 and add the result thus obtained to the total of the standing charges per week. The result, as can quite readily be checked, is that the cost per week of a petrol-engined 6-tonner, running 500 miles per week, is £19 18s. 2d., whereai that of the oil-engined vehicle is 218 8s: 7d. The difference is seen to be 21 9s, 7d. in faVour of the oiler. That is practically 30s. per week.
Of course, there are plenty of 6-tonners which are covering 800 miles per week and, obviously, the greater the mileage the greater the economy, because it is in running costs that the oiler has the advantage. .
The running costs of a petrol-engined 6-tonner for 800 miles per week are as follow:—Petrol, 2.78d.; lubricants, 0.16d.; tyres, 1.20d.; maintenance (d), 0.19d.; `maintenance (e) , 0.954.; depreciation, 0.91d.; tota17. 6.19d . ' In the case of an oil-engined vehicle, covering an equivalent mileage, the figures are:—Oil fuel, 1.94d.; lubricants,
0.184.; tyres, 1.20dz; maintenance (d), 0-,19d.; main-. tenance (e), 1.05d.; depreciation, 1.28d.; total, 5.84d.
Total Costs Per Mile for Both Types of Vehicle .
The total cost per mile—assessed as above—for the petrolengined lorry is 8.27d. That for -the oil-engined machine is 7.46d., showing 0.81d. to the advantage of the latter. In those circumstances its original debit of £250will be wiped out in 74,000 miles.
Similarly, the cost per week of the petrol-engined vehicle is £27 .11s. 2d., as against 224 17s. 6d.., a difference of £2 13s. 8d. ' per week in favour 'of the oiler. The difference in cost of the two units would, therefore, lae ' eliminated in approximately 93 weeks. ' , Certain makers of oil engines operate schemes of engine replacement, whereby the engine is replaced a certain
.-number of times under a guarantee, equivalent to that given with a new engine. On this basis, Of course, the factor of depreciation, if not entirely ironed out, is nearly eliminated. With that in its favour, it is possible that the figures for cost would be more than ever in favour of the oiler. The difference might be as much as id. per mile, in addition to that shown -in the calculations set out above.
The real value, to the user, of any such scheme depends upon the cost of the recenditioning and the comparisons of the cost of several reconditioned engines as sompared with the provision for engine maintenance embodied in-the above figures. In the absence of any such direct comparisons I would prefer, for the time being at • least, to _leave that aspect of the matter out of the question. •