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Do Thin xles Pay?
Page 94
Page 95
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MANUFACTURERS may well feel that hauliers have an insatiable appetite for ever-larger carrying capacity. Now that the maximum legal gross weight for a four-wheeler has been increased from 12 to 14 tons, some operators are finding that their particular traffic movements require a vehicle permitting a genuine, legal 10-12-ton payload without misgivings about the 9-ton axle limit.
Although there must always be exceptions to any generalization, the selection of medium-weight six-wheeled rigid vehicles has remained much more limited than of other types. If articulated vehicles were not suitable for the job a haulier had in mind, there was often a wide gap between the medium-weight four-wheeler and the heavy, rigid six-wheeler, not only as regards the type of work for which they were designed but also in both the initial and subsequent operating costs.
In discussing the relative merits of various vehicles, there is often a tendency for the accepted quality of any particular make to be confused with suitability for the job on hand. Every manufacturer is naturally anxious that every model in his range should maintain the company's reputation, particularly as regards reliability.
As he sells to all kinds of operator, who themselves are engaged in every type of job, the margin of reliability which the manufacturer tries to build into his product when in use under some conditions must inevitably amount to overcautiousness. This, of course, implies no fault on the part of the maker, being a safeguard he considers he has justifiably taken in both his own and his customers' interests.
Conversely, where an operator—for example, a bus company—was sufficiently large to manufacture vehicles. it might well produce a more economic vehicle for one specific job than was available on the open market. If transferred out of its own area of operation, however, it could prove unsatisfactory.
Overseas Use It is with these factors in mind that some hauliers are finding the fitting of a third axle extension to a standard four-wheeler a practical and economic proposition where their traffic and routes do not demand the heavier class of vehicle. There has been an increase in demand for this type of vehicle and recent developments in suspension generally have been parallel with modifications in third-axle suspension. Their use is extending overseas, both in the form of built-up vehicles and completely knocked down units.
To determine the all-important factor whether fitting a third axle gives hauliers a lower overall cost per ton carried, it will first be necessary to provide a yardstick by ascertaining the operating cost of a standard four-wheeler. Taking as an example the popular 7-ton platform oiler with a 16-ft. 6-in. platform and 3 tons 9 cwt. unladen weight, the initial cost would be around £1,850.
As the annual duty would be £42 10s., the first of the five standing costs—licences—would amount to 17s. 10d. per week. Wages, in accordance with R.I-1.(62), Grade 1, would be £8 18s. 7d., including allowances for two weeks' holiday with pay and insurance contributions. Rent and rates are assessed at 10s. and insurance at £2 10s. per week. Interest, based on
F6 a nominal rate of 3 per cent. do the initial cost, would amount to £1 2s. a week, making a total standing cost for the week of £13 18s. 5d. Assuming 800 miles per week were operated, the standing costs per mile would then be 4.17d.
Based on a consumption rate of 16 m.p.g. at 4s. 2d. per gal., the fuel cost per mile would be 3.13d., whilst lubricants are assessed at 0.24d. Allowing 1200 as the cost of a set• of tyres and 30,000 as the mileage life, tyre costs per mile would amount to 1.60d,, whilst maintenance is calculated at 2.20d.
The last of the five items of running costs—depreciation--is obtained by deducting from the initial cost of the vehicle, the cost of a set of tyres (A200) and the estimated residual value (10 per cent. of the initial cost-1185), which leaves a balance of £1,465. Assuming a vehicle mileage life of 120,000 while in the operator's possession, a depreciation cost of 2.93d. per mile is incurred. The total running costs per mile amount to 10.10d., giving an operating cost of 14.27d. per mile.
Starting with the same basic chassis and cab, the initial price would be 11,750, or £100 less than when a platform body was fitted. The cost of a third-axle conversion so as to permit a 21-ft. platform and 12-ton payload would be approximately £500. Allowing a further £150 for the larger platform body, the overall cost would be £2,400.
Increased Payload
Detailing the 10 items of operating costs as before, licences
would amount to 6s. a week because of the extra unladen weight of 1 ton 2 cwt. Similarly, because of the increased payload, wages would now be payable in the next higher category (10-15 tons) and would cost £9 4s. 10d. Rent and rates are arbitrarily upgraded to 12s. 6d. per week and insurance to £3 per week. Because of the higher initial cost, interest would now amount to LI 85. 10d., making the total standing cost per week of £15 12s. 2d., or 4.68d. per mile, on an 800-mile week.
As higher payloads are now being carried, fuel consumption must be expected to be heavier and will be assessed at a rate of 14 m.p.g., giving a cost per mile of 3.57d., whilst lubricants are shown at the slightly higher figure of 0.26d. per mile. Allowing for the extra tyres, it is estimated a set will now cost £350, giving a tyre cost per mile of 2.80d.
Some addition to maintenance cost must naturally be expected and certain parts in the trunnion suspension may necessitate additional periodical attention. This item, is, therefore, upgraded to 2.70d. per mile.
Adopting the same procedure as before, deduction of the cost of a set of tyres, together with the residual value, will leave a balance of £1,810, which, when depreciated over 120,000 miles, gives, a depreciation cost, per mile of 3.62d. Total running costs for the 12-tonner are, therefore, 12,95d. per mile, making the total operating costs 17.63d. per mile.
Turning now to the traffic side of the business, if the haulier were to operate either of these vehicles 800 miles per week, he would probably be engaged in medium to Iong-distance work. Therefore, assuming he does three return journeys of around 250-300 miles per week, his optimum load for the week would be 42 tons for the four-wheeler and 72 tons for the _larger vehicle. If 75 per cent, is accepted as the average loading, 31 tons and 48 tons respectively will be carried during the week.
The total cost of operating the smaller vehicle 800 miles per
week would be: standing costs, £13 18s. 5d.; running costs, £33 13s. 4d.; total, £47 1 1 s. 9d. For the 12-tanner, the figures would be: standing costs, £15 12s. 2d.; running costs, £43 3s. 4d,; total, £58 15s. 6d. The resulting cost per ton would be 30s. 8d. for the 7-tanner and 24s. 6d. for the 12-tonner.
As with practically all other comparisons, some qualifications must be added. Obviously, with the same basic chassis and engine, the performance of the four-wheeled 7-tanner must be better than that of the converted six-wheeler. Where operating conditions were exceptionally arduous, this might well be a vital factor. Under easier conditions, this inbuilt reserve of power and reliability might be an unnecessary luxury. It should not be overlooked, of course, that the advantage which these figures show in favour of thc larger vehicle would apply only if extra traffic, sufficient to load the vehicle to capacity, were consistently available.
Where an operator has already standardized upon rigid fourwheeled vehicles and possibly on one particular make, the decision to convert one or more into six-wheelers to meet the growing traffic demand should not he difficult. If, however, he were starting from scratch, some thought would naturally have to be given as to whether to purchase this type of converted six-wheeler or, alternatively, an articulated vehicle.
Parallel with the strong support one sometimes finds for a particular make peculiar to one area, there are similar " schools " for or against articulation. It must be admitted, however, that for certain types of operation, such as leading agricultural produce from farms, rigid vehicles have the advantage when required to run over unmade roads or farm tracks, This also applies when operating on ice or snow.
To obtain such an advantage when operating under exceptional conditions, however, it would be necessary to ensure that when a conversion is made from a fourto a six-wheeler, due consideration is given to brakes, steering and load distribution relative to the increased payload to be carried.
With the increasing use of pallets, the benefits to be derived from the larger platform made available by such a conversion may well prove of greater relative value than the ratio between say 16 ft. 6 in. and 21 ft. Similarly, a wider selection of indivisible loads might be carried if this particular traffic were handled. Alternatively, high-gravity loads, such as concrete mixers and some types of tank, may show less tendency to roll.
For the busy operator dealing in all types of load, the greatest single benefit would be the relief from any anxiety of illegal overloading. Under such conditions the maximum intcravailability of vehicles is an essential feature of efficient fleet operation. As the combined kerb weight and regular 12-ton payload of the converted rigid six-wheeler would be around 17 tons, a legal margin of 3 tons would normally be available to meet the
emergencies that inevitably arise in traffic offices. S.D.