What the Overseas User Wants
Page 41
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THE' paper which Mr. H. W. Fulton, B.Sc.(Eng.), M.I.Mech.E., managing director of Albion Motors, Ltd., read at the Glasgow summer meeting of the Institution of Mechanical Engineers on Wednesday, was of such interest as to be worthy of publication in full. Entitled "Export Vehicle Design," it dealt in great detail with the specific features to which designers should give attention if their vehicles were to operate satisfactorily in
countries abroad. .
Mr. Fulton said that, above all else, the man responsible should be well acquainted with the conditions under which his vehicles would be called upon to operate. As a part of his training, he should meet customers, their maintenance men and their drivers.
In the past, said Mr. Fulton, the major demand for any article had generally been from users in this country; customers overseas had accepted products conforming with our standards. To change the balance of distribution in favour of the export market, overseas users had to be convinced that what we were offering was the most suitable for their purpose, rather than to offer them an article developed for the home market, but considered sufficiently suitable to warrant being purchased for overseas.
Uniformity in Production In cases where the demand abroad for an article which contravened home regulations justified it, the British
authorities should earnestly consider whether home regulations ought not to be altered to permit uniform production for home and overseas. In such circumstances, failure to bring home regulations into line with those obtaining over seas imposed onerous restrictions on trade.
Some of the particularly inconvenient regulations were those governing the overall width of vehicles, the length of passenger machines, taxation on the unladen weight of goods vehicles, and restrictive taxation on private cars. in some overseas areas, said the speaker, there were regulations limiting maximum weights of vehicles and axle loads, and these points must be kept in mind when producing models for them.
The left-hand rule of the road, said Mr. Fulton, penalized Britain in the export market. He thought it would be alleged that the cost of a change-over would be prohibitive, but he disputed this view.
There were about 30,000 single-deck and an equal number of double-deck buses operating. In the case of the singledeckers, the passenger entrance could be changed fairly easily, and the change could be carried out in rotation while most of the vehicles were still in service.
£6,000,004 to Change Rule of Road
A major difficulty would arise with double-deckers. To change the staircase from the right to the left would be practicable, but costly. Supposing the cost were £200 per vehicle, the outlay would be only about £6,000,000. An even more difficult problem, said Mr. Fulton, would be that of carrying on the services during the change-over. He believed that this could be done by having a half-way stage of conversion, in which passengers would leave the vehicle from the rear.
Even supposing the overall cost of converting both singledeck and double-deck vehicles amounted to £S,000.000, it would be a small amount to pay for a feature, without which our future as an exporting nation would be jeopardized. Mr. Fulton expressed his regret that vehicles now being designed for the Services, conformed to the British rule of the road, because they would probably be called upon to operate in countries where the rule did not apply. Designers were, therefore, being asked to produce new power units unsuited to the bulk of the export market. Dealing with import regulations of countries overseas, the speaker said that these were often compiled to foster local industries. A problem was to produce for the home market a finished vehicle, and for some other countries, an assembly without tyres or springs, and with a completely "knocked-down body_ In other instances, no body would be permitted. In the less developed areas, the vehicle would be acceptable in home-market condition.
Local Knowledge Essential The speaker then went on to discuss the need for having precise knowledge of the areas in which the vehicles would be called upon to operate. Road surfaces, he said, could vary from concrete, through degrees of metalline to natural soil. Vehicles that had to travel over terrain composed of large quantities of small, loose stones required a good clearance between the tyres and adjacent parts, and units such as batteries and petrol tanks must be suitably protected from flying stones. Twin tyres were not recommended, and where their use was indicated, single tyres of la= section were commonly fitted. These, however, were also of large diameter, and a correspondingly higher floor level. or objectionably large wheel-arches, were needed.
People of certain lightly built races found it physically impossible to handle large spare wheels, which suggested the need for a form of hand winch. All axles, said Mr. Fulton, must have wheels at approximately the same track spacing, in order that they might follow each other correctly in soft ground, and thus save expenditure of power in breaking down fresh tracks. This had particular significance in trailer operation,
Water splashes at creeks, where there were fords but no bridges, called for reasonable protection of ignition equipment, and because such creeks inevitably seemed to have steep approach and departure gradients, it was necessary to avoid undue front and rear overhang. Sufficient clearance to permit chains to be fitted under bad road conditions was another feature demanding attention.
Dealing With Sand and Mud It was also necessary to know the maximum gradient involved, and the rolling resistance of the road surface, before the ability of a vehicle to surmount a climb could be assessed. A rolling resistance of 80 lb. per ton was probably sufficient for normal unmetalled road surfaces, but sand or mud was liable to raise the figure to 200 lb.. or more, per ton.
The author felt that there was a tendency to pay too
much attention to the ability of a vehicle to climb in the lower gears, and too little to performance in the higher gears. In mountainous districts the choice of gear ratios would repay study. To be unable to speed up a vehicle sufficiently to permit a change to be made to a higher gear was most irritating on a long climb; a compromise had to be achieved between the close-ratio box with many steps, and the more simple form with wider steps.
To prevent front-wheel skids. a useful feature would be a
means for cutting out the front-wheel brakes tinder certain conditions. This would apply when descending roads having a surface composed of relatively slippery clay. It was necessary to know the nature of the climate in countries to which vehicles were exported, particularly with regard to maximum and minimum air temperatures.
It was helpful to know, said Mr. Fulton, the annual rainfall to be expected in an area, and the manner of its falling. Violent tropical rain-storms necessitated a waterproof vehicle.
Additional engine power was required to compensate for loss of volumetric efficiency at high altitudes. Vacuum serso-brakes also lost power under similar conditions.