100-ton Road Trains Envisaged
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TRAILER trains powered by petrol engines and having a capacity of 100 tons, with an earning power of £5 per route-mile, are envisaged by Mr. A. Enticknap, director and engineer of Alpha Motors, Ltd. He made this prophecy in a paper entitled "The Future of Road Transport," which he presented to the Institute of Road Transport Engineers in London last week.
The trains he described would have an overall length of about 138 ft. and consist of a 12-wheeled towing unit, 46 ft. long, hauling two 10-wheeled powered trailers, each 36 ft. long and separated by 10-ft.-long drawbars. The estimated overall operating cost per mile of such a combination would be £1 7s. 4-}d., and Mr. Enticknap suggested a delivery price of 6d. per ton-mile, 'giving a revenue of £2 10s. per mile for a 100-ton load.
Mr. Enticknap began his paper by reviewing past and present goods-carrying facilities, and pointed out that present international transport links using road, rail and sea were slow and expensive. He felt, however, that road transport would, with the advent of new roads, have adequate opportunity to expand to the Continent and even the Middle East. inter continental haulage was the obvious answer to Britain's export problem, as it would offer ways to reduce the cost of our products in the European market.
Mr. Enticknap felt that it would be necessary to have vehicles with as large a carrying capacity in ton-miles as possible. Such vehicles would be required to haul loads of between 60-100 tons at speeds of 40-50 m.p.h. They would have to be easy to service, to reduce turnround times, and simple to maintain when a long way from their base depots.
40 Tons per Unit
Loads of up to 100 tons could not be carried on single vehicles. Multi-unit outfits with up to 40 tons on each unit would be required. Each would be independently powered but controlled from the leading vehicle.
The author felt that the oil engine. although it would appear to be suitable for a development such as this, would have the disadvantage of an unfavourable power-to-weight ratio for application to such heavy vehicles. This was particularly because engines of at least 350 b.h.p. capable of operating on various grades of fuel would be needed.
Rapid acceleration, ease of maintenance and starting, smooth running and adequate engine braking would be desirable, and Mr. Enticknap believed that an air-cooled high-speed petrol engine would be ideal, such a unit being either a V8 or a horizontally opposed design running at about 6,000 r.p.m.
The dry power-to-weight ratio should be not more than 8 lb. per b.h.p. Overhead camshafts would avoid valve bounce, and gaskets would be made from austenitic stainless steels for long life. The engine should be designed for a safe working life of at least 200,000 miles, calling for care in both design and manufacture and the use of the highest quality materials. Carburetters were favoured as being more reliable and easier to maintain than petrol-injection systerhs at present, and the lubricatingoil system should incorporate intercoolers with large reservoir tanks.
Electrically or hydraulically driven cooling fans would be used. The flow could be varied by altering fan-blade pitch. Liquid cooling would not be adopted as it might prove troublesome under the wide variety of operating conditions expected for such vehicles.
A dual electrical system would be necessary to ensure adequate reliability, and the air compressor would be designed to give an ample supply to suspension, brakes, gear control and possibly brake cooling.
The power unit would be an integral part of the bogies fitted to each unit of the train and such bogies would, as in locomotive practice, be able to swing through a given radius to assist manceuvring, although they would also require steering mechanism.
Axle loading would have to be kept to about 7 tons, so, assuming that the leading vehicle had six axles, a gross weight of 42 tons would be permitted. The leading axles would be constructed with a sub-chassis frame, thus becoming a fixed bogie with each pair of wheels able to steer.
The rear bogie might have only two driven axles and the central dead axle would not have to steer. This complete assembly would also be mounted in a sub-chassis frame, carrying the engine at its leading end and gearboxes in between the side frames.
Automatic Alignment
Mr. Enticknap described in some detail the requisite steering geometry that would be necessary for the leading and trailing vehicles of such a train, and he outlined a system which would give automatic alignment of the train without complicated power-line connections between each unit, a layout which would simplify operating each unit separately.
Integral geodetic or tubular fabrication was visualized to save weight and provide strength. Such an assembly could be quite light as all the heavy running gear would be contained within the bogie units and the " chassis " frame would be required to carry only the payload, cab and supply tanks. All metal parts would have to be either treated electro-chemically or metalsprayed to be protected against corrosion and extreme temperature changes, and the frame would have to be designed to incorporate self-loading devices.
Multi-speed gearboxes giving up to 16 ratios would be needed, and hydraulic flywheels or electro-magnetic clutches would be necessary for the automatic gearboxes to allow the driver to cut in the trailer power units as required.
Adjustable air suspension would help to ensure a long vehicle life, and the air supply would be variable so that allowances could be made for altitude when operating in mountainous country. The author felt that anti-roll bars and shock absorbers would be essential because of difficult road conditions.
Disc brakes, with either compressed
air or hydraulic operation, may be used, and Mr. Enticknap thought that compressed-air operation would be preferable. Transmission brakes would be incorporated for use when descending • long inclines, and these could be electrohydraulic, air or vacuum operated, and of the disc or multi-disc type.
Because each axle loading would be 7 tons and all but one axle on each unit would be steered, twin tyres could not be employed, although they would be advantageous in respect of loading height. Single 15.00-20-in. (20-ply) tyres with a maximum rating of 94 cwt. at an inflation pressure of 90 p.s.i. would be required. and provide a tyre capacity per axle well in excess of requirements.
Large Cabs
The towing vehicle would need a large cab to provide comfort for the crew ot two under all climatic conditions. It would be divided into two compartment!, with armchair-type seats in the forward driving section, and toilet facilities, bunks and a cooker in the rear.
The cabs on the trailers need not be much different from those in use at present, as they would be used only during local deliveries and not be occupied during long-distance runs.
Painting was considered important, and Mr. Enticknap said that he would like to see "resplendent livery" and colour schemes borrowed from the days when the railways were at the height of their glory. It was suggested that each vehicle should be named after great transport engineers of the past.
The crew to be chosen to handle such vehicles would have to be of the highest calibre as their responsibility would be similar to that of a sea captain in charge of an efficient but small vessel. It was expected that a senior driver would be paid £2.000 a year and 'a co-driver £1,700, and to encourage pride in their work their names should be written on the cabs.
It was estimated that a single unit would cost about £15,000. therefore a three-unit train would cost £45,000. A life of eight years was envisaged.