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Regulations Dictate Design

23rd January 1959
Page 51
Page 51, 23rd January 1959 — Regulations Dictate Design
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Which of the following most accurately describes the problem?

DESIGN of commercial vehicles in many Western European countries was dictated to a great extent by statutory regulations brought about by local economic circumstance or traffic difficulties, said Mr. A. R. J. van der Goes, manager of the service technical department of Van Doornes Autornobielfabriek N.Y., Eindhoven, in London yesterday. He was presenting a paper on "Continental Trends in the Design of Heavy Commercial Vehicles" to the Institute of Road Transport Engineers.

He quoted the heavy-vehicle regulations which came into force in Germany on January 1, 1958, as an illustration. This legislation, by limiting vehicle lengths and gross weights, made an increase in transport costs inevitable for German . hauliers and operators of other nationalities working in that country.

It was thought that this action was deliberately intended to protect the German railway system, which was in an

unsatisfactory financial position. How it could affect design was shown by the favouring of semi-trailers, as opposed to trailers, in the regulations. As semitrailers were comparatively rare in Germany and trailers numerous, it would mean a change of policy by operators and manufacturers.

Such changes would not, however. reduce the number of commercial vehicles in operation in Western Europe. In fact, it was predicted that the 75 per cent increase in cars; lorries and buses on the roads which had taken place between 1950 and 1955 was being followed by a further 50 per cent. increase between 1955 and 1460.

The limitation of vehicle length would lead to renewed interest in forwardcontrol designs to obtain the maximum body length within the regulations. The major objection to forward-control cabs, apart from the lack of space for more than one passenger, was the placing of the driver directly over the front axle, where he was subjected to more road shocks than in a normal-control cab. Much development had been carried out on seat springing, but the types of seat at present available did not completely

solve the problem of driver comfort in forward-control cabs.

More attention should be paid to the layout of controls. In Germany it was a legal requirement to fit an exhaust brake on goods vehicles with a gross weight of over 9 tons and on buses over 5 tons. This device should be operated by a pedal, preferably actuated by the left foot in order that the clutch could not be disengaged while the brake was in action.

The German regulations had also specified a minimum of 6 b.h.p. of engine output for each ton of gross weight for any vehicle. Most Continental makes could meet this stipulation and many, such as the Mercedes L333 models, which were invariably used for towing trailers, had available about 12 b.h.p. per ton in solo condition, To provide the power required without recourse to larger engines an exhaust-gas-driven turbocharger was often used.

Cost Hampers Progress

Gearbox requirements varied from one country to another, depending on the type of terrain likely to be encountered. The production of fiveand six-speed gearboxes had placed greater demands on the driver. Although synchromesh and automatic gearboxes were used by some manufacturers, particularly in buses where the gearbox was situated some distance away from the driver, increased cost hampered their universal adoption.

Limitation on axle loadings had favoured the use of third axles and many European manufacturers had recently introduced six-wheeled trucks with tandem-axle rear bogies, Power steering was thought to be essential for these models where 6 tons of the maximum permissible weight of 18 tons had, by law, to be placed on the front axle.

Air suspension was undergoing great development with Continental and particularly German vehicle producers. Buses with air suspension mentioned were Bussing, Fiat, Henschel, M.A.N. and Daimler-Benz. Henschel had also produced a tractor unit with this suspension system for the rear axle which was rated to carry 10 tons.


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