Estimating Maintenance Costs
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Variations in Conditions Make This a Difficult -Task, But Our Costs Expert Gives Approximate Figures for a 2-ton Vehicle
AN operator has asked me for a detailed estimate of the cost of maintaining a2-ton vehicle. Unfortunately, it is almost impossible to give even an approxi. mately accurate. answer.
In the first place, any calculation must of necessity be based on a planned maintenance scheme which prescribes specific operations at specified periods and which .contrasts with other systems which require thatmaintenance should be carried out only when clearly necessary due to the condition of the vehicle: Even if planned maintenance be taken as a basis for costing there is still room for considerable variation in respect of the periods at which the routine should be carried Out; and there is likely to be almost a corresponding varia tion in the -cost. .
Overhaul by Rule of Thumb ?
Consider the top -overhaul, for ex-ample. I remember a discussion at a meeting of the I.R.T.E. on the question of Whether top overhaul should be undertaken at A scheduled mileage, or only whenever deterioration in the performance of the vehicle demanded it.
One experienced engineer in charge of a fleet of 40 vehicles greatly favoured the scheduled periods system. But, there was still room for discussion on the duration of the period.
This engineer said that in his experience 7,500 miles was correct for pre-war vehicles, and I2-,000 miles for post-war vehicles. Even he, however, was not dogmatic on the point. A predetermined figure of mileage was the best for engine servicing, but it need not be either of these figures. He stated that as al result of meticulous costing for maintenance over short periods and over indefinite periods until engine performance had Markedly deteriorated, it had been found that taking an average mileage had vindicated the predetermined schedule System.
It had: been 'found that decarbonizing at that period involved less valve reseating than at any other period. If the scheduled mileage be exceeded, reseating valves entails expense -and there was a possibility of cracked seatings due to blow-by whilst the carbon was hard and baked on. At the predetermined figure the carbon could be wiped off, as it was relatively soft and scratch and score marks were
not found on the top of the pistons. .
Other speakers disagreed, but pointed out that the size of the engine was a factor, as well as the method of operation and the class of 'work upon which the vehicle was engaged.
Accurate Forecast
Another discussion during a meeting of the Institute of Public Cleansing, produced interesting comments. One member stated that he could forecast accurately the time he would spend on the maintenance of a vehicle.
He was obviously thinking of planned maintenance. He arranged for certain operations to be carried out on each vehicle at the end -of stated periods. The work was carried out whether there was any obvious need for it or not and the cost of each operation, as a result of experience, was known almost: to a decimal of a penny. The only possible unknown factor was the expenditure on replacements, and even this could be estimated within a small margin of the adttial eXpense.
A further point now arises. Clearly, to obviate breakdowns, and to guard against any unexpected expenditure on maintenance not provided for in this accurate budget, it is A3ff
conceivable that the maintenance operations will be carried put'. more often Allan . really necessary. In other words, the system, in its origin, must embody what might be termed a safety factor. That is, maintenance could be one-and-ahalf _or twice as much as necessary, in order to keep a vehicle in such good condition th'at 'unekpeeted: expense on 'account of -maintenance or mechanicalattention is so rare as to be
almost • negligible.• , .
. It would seem, therefore, that, according to this theory of maintenance, the vehicle is burdened with extra costs in order to budget in advance for such eventualities and to avoid having to provide for Something not in the budget. Whether this procedure ii Wise or not, depends largely upon operational requirements---i.e., whether it would be a serious matter if the vehicle were temporarily off the road: Most people would agree with the man who is willing to pay` a little extra for routine maintenance rather than 'run the risk of having the vehicle laid up.. Such occasions naturally. arise.when it is. most, inconvenient and most expensive for, so far as the haulier is concerned, the loss of use of a Vehicle am not at the Moment thinking of the two-tonner--is likely to be equivalent to a reduction of income by not less than £5 per day. • • The speaker to whom I referred maintained that cleansing in any municipality makes it essential to take all possible precautions to prevent a vehicle being off the road. Another speaker said that cleansing departments were called upon to set an example in more ways than one. The vehicles always had to look respectable, and the department had to be infallible in the performance of its duties.
Efficiency and Economy
It is doubtful, -however, whether commercial undertakings and more particularly haulage concerns could afford to spend so much on this insurance against loss of time. Their operations, whilst they may be almost as important as those of the cleansing department of a municipality are, nevertheless, judged by two standards: by the efficiency and the economy with which the work is done.
It probably would not pay a commercial concern to organize its maintenance according to the somewhat extravaigant plan already outlined. As a matter of fact, the usual procedure is to go to the other extreme and to postpone maintenance operations until the vehicle cannot safely be run any farther. The adoption of this method may also result in unnecessarily high maintenance costs. The tendency to-day is undoubtedly towards the adoption of some form of routine maintenance, although the factor of safety is not usually so high as the one-andkt-half or two which I have mentioned.
Mid-way between the extremes comes the average maintenance system. This requires the operator to find out for himself what maintenance needs to be carried out in order to keep the vehicle in reasonable condition. It is kept to a minimum because he does not usually spend any more on the vehicle than he must. As a matter of fact, I frequently recommend that an operator should start a maintenance routine based, so far as possible, on the vehicle manufacturer's instruction book. As time goes on and his knowledge and experience, of the vehicle become more extensive he Should vary the periods until he arrives at a schedule which satisfies his needs.
But to return to my original inquiry. I shall attempt to outline only the important maintenance for costing purposes, leaving something at the end for miscellaneous items. In
calculating labour costs I shall assume, first, that the work is done by a retail motor trader and that the charges are at the rate of 7s. per hour, which, I believe, is an average figure to-day. That, of course, includes. acttial cost of labour, overheads and profit.
First come the operations most frequently required,
namely, washing, polishing and greasing. I am going to consider the matter on the assumption that the driver of the vehicle has nothing whatever to do with its maintenance, his sole occupation being that of driving. It will take one man 1-2 hours to wash and polish a van, the time depending upon the type and state of the Vehicle. If 1 take the time as 11, hours, the labour costs will be 10s, 6d.
Greasing, to be done properly, should take about half an hour and labour charges for that job would be 3s. 6d. This has to be done not less than -Once per week. The frequency with which greasing should be done depends upon the mileage, but once per week is the prevailing practise. Assuming a mileage of 240 per week, then the cost per mile of these two operations is 03d. Ifthe weekly mileage is 480 the cost is reduced accordingly to 0.35d. and it will be appreciated that the cost per mile must vary in inVerse proportion to the weekly mileage.
At 7,200-mile Intervals Turning now to some of the items of mechanical maintenance, I shall assume that it is necessary to decarbonize the engine every 7.200 miles. At the same time, other related maintenance operations are carried out, such as adjusting tappets, cleaning electrical equipment, cleaning and adjusting sparking plugs, contact breaker points, and the
carburetter, filters and fuel supply system generally. The approximate cost will be £5, excluding materials. As a rule new gaskets are required, and the valves may need grinding. On alternative occasions a new set of plugs should be fitted. The cost of these materials cannot be less than 12 10s., so that the total cost is £7 10s. Over 7.200 miles the cost per mile is 0.25d.
Another series of minor operations can conveniently be carried out at the seine time, which if omitted for any undue period can cause serious trouble. The cost of preventing such developments will be considerably less than putting the trouble right. I have in mind such work as checking spring bolts, tightening loose nuts, flushing out the radiator, oiling minor body fittings (this is very important, although often overlooked), adjusting the brakes and topping up the battery. The total cost of these operations, excluding cost of materials (which is generally negligible unless one or two new bolts are found to be necessary); can he taken as averaging 24s. or 0.04d. per mile.
Cost of Changing Oil Next comes the changing of engine oil. In the ordinary way the cost of the change, including a gallon of thin oil for swilling out the crankcase, and the time spent in doing the job, is about 10s. Oil ought to be changed at least every 3,000 miles, and every 12,000 Miles thesump ought to be taken down and thoroughly cleaned. Over a period of 12,000 miles there would, therefore, be four ordinary cleanings at 10s, each, plus the cost of removing and replacing the sump, a further 16s., Say, totalling 96s. per 12.000 miles. That is another 0.96d.—say 0.10d. per mile. I make no provision in this calculation for the cost of the lubricating oil because that is properly covered in the relevant column of operating costs.
The level of the oil in the gearbox and back axle should be checked when the engine oil is changed. As a rule, this occupies only a minute or two and I shall assume that the amount already set down for engine lubrication will cover the cost of this check.
We now come to the more expensive operations which, fortunately, do not require to be carried out so frequently. First comes the refacing of the brake shoes. How often this may be required depends upon the class of work in which the vehicle is engaged and the kind of country in which it operates. On collection and delivery work and operation in dense traffic the period may be comparatively short, and shorter still if driven by a roan who drives on his brakes. The same applies in hilly country and when, as in some northern and country towns the two are corn
bined, brakes are apt to be a heavy maintenance charge. I have found it reasonable to assume that the brakes need refacing every 20,000 miles.
The clutch facings suffer in some degree to the same extent as the brakes according to the class Of work and the kind of country. I propose to take an average of 40.000 miles for a set of facings and assume that brake and clutch refacing woold each cost 14. Every 40,000 miles there will thus be an expenditure of £12 for these two items, equivalent to 0.07d. per mile.
Bodywork ought to be revarnished once a year and repainted every other year. In fact a longer interval is often allowed between re-paints and the cost per mile will vary greatly. I am taking an actual figure averaging 115 per year. This can easily be doubled in the case of an operator who finds it profitable and wise to keep his vehicle as smart as possible. Readers and the correspondent who has asked for the estimate must therefore use their own judgment in this particular item and vary it accordingly. Taking /15 per annum as the figure for painting and 240 miles per week or 12,000 miles per annum as the vehicle mileage, the cost is 0.30d. per mile or 0.15d. if 480 miles or 24,000 per annum are covered.
The next item is even more difficult to cost. I refer to repairs to bodywork, and here I am going to make a guess and take 112 per annum as my figure, which is 0.20d. per mile at 12.000 and 0.10d. at 24,000 miles per annum.
Engine Overhaul
I now allow for an engine overhaul every 36,000 miles. Nowadays. in the case of the popular types of chassis at least, an engine overhaul usually means fitting a re-conditioned engine and a fair price for that is £.60, which is equivalent to 0.40d. per mile assuming that my figure of 36,000 between engine overhauls is correct.
Chassis overhaul, which comes next, probably costs about the same as the engine overhaul, including materials, that is £60, but as it occurs only every 72,000 miles, the cost is 0.20d. per mile. Finally, for miscellaneous items I take 0,24d, per mile as a fair figure.
We may now sum up these items. Assuming that the vehicle is doing 240 miles per week or 12,000 miles per annum, the total cost is made up as follows: Washing and polishing, 0.70d.; decarbonizing and allied operations. 0.250.; brake adjustment and tightening of bolts, etc., 0.04d.; engine oil changes and attention to gearbox and rear axle, 0.10d.; brake and clutch re-facing, 0.07d,; painting .a.nd varnishing, 0.30d.; body repairs, 0.20d.; engine overhaul, 0.40d.; chassis overhaul, 0.20d.; sundries, 0.24d. Total, 2.50d, per mile.
If the vehicle is doing 480 miles per week the corresponding figures will be as follows: Washing and polishing, 0.35d.; decarbonizing and allied operations, 0.25d.; brake adjustment and tightening of bolts, etc., 0.04d.; engine oil changes and attention to gearbox and rear axle, 0.10d.; brake and clutch refacing, 0.07d.; painting and varnishing. 0.15d.; body repairs, 0.10d.; engine overhaul, 0.40d.; chassis overhaul, -0.20d.; sundries, 0.24d. Total, 1.90d.
Comparison of 'Costs
As stated earlier in this article, these figures are for work " done out," that is, given by the operator to the local motor agent who charges 7s. per hour for labour. It is naturally more economical for the operator to do the work himself. employing his own mechanics in his own workshop, in which case he will probably not need to charge more than 4s. per hour. His overheads are not likely to be so high as those of the motor agent and there is no necessity to show a profit on the work.
In these circumstances the total cost will probably be reduced by one-quarter to one-third and may be 1.60d. in the case of a vehicle doing 240 miles per week or 1.25d. for a vehicle doing 480 miles per week. For mileages in between these figures the operator can himself strike an average. S.T.R.