Motor Transports in War

Early History—The Industrial Motor—The Motor ’Bus and Motor Cab—Steam Lorries and Tractors—Petrol-Electric Vehicles—Daily Mileages and Fuel Consumption.

When we remember that the motor vehicle as we know it to-day is the result of a development not more than a quarter of a century old, its enormous influence upon the character of modern warfare must indeed be regarded as remarkable. Especially is this so in view of the fact that progress has not in the main been dictated by military considerations, but almost entirely by the requirements of private individuals and of peaceful trading concerns. The case is very different from that of the aeroplane and the airship, which from the very moment that they began to appear as practical possibilities, were recognised as having far greater potentialities in connection with warfare than in any other sphere. The whole science of flight has been studied to a great extent from this point of view, and the Government Departments concerned, in all civilised countries, have recognised the necessity of keeping in touch with and encouraging the movement, and have realised all along the nature of the work to be done by the flying corps.

On the other hand, the use of the motor vehicle was extended in the first instance mainly as a sport, and as a new occupation for well-to-do individuals of a mechanical turn of mind. There is an attraction about speed in all forms, and consequently, it was on this point that attention was for many years concentrated. Furthermore, developments were influenced to no slight extent by changes of fashion, and the need of satisfying the requirements of people who were not necessarily qualified to direct progress into the best possible channels. The motor vehicle was used as a luxury, and exploited as a means of bringing into being new forms of sport, for many years before it acquired sufficient reliability or worked with sufficient economy to justify its employment on economic grounds. The industrial motor industry is, in fact, at the present day only about ten years old. In the first instance, one of the principal factors in securing the occasional use of motor vans was the advertisement value of a rather unusual type of vehicle, which naturally attracted considerable attention wherever it went. A little later mechanical transport was adopted by a limited number of firms, not on account of any superiority in economy or reliability over old systems of delivery, but rather with a view to extending the area embraced, and so gaining an advantage over competing concerns more than sufficient to balance the increased cost involved by the employment of vehicles by no means cheap either as regards first cost or operating expenses. Once the industry was established, however, its rapid growth was inevitable, since it was found possible to construct vehicles the employment of which was more than justified on purely economic grounds. The line of least resistance was found in connection with public services and hackney carriages for the conveyance of passengers, while in the carriage of goods the new means of transport had to compete with cheap if slow systems of delivery by horsed vehicle, and with the railways which, if not offering a direct method, at least offered a very cheap one when a large volume of traffic had to be handled.

In the other sphere, competition was limited chiefly to the horsed ’bus, the horsed cab and the tram car, and the last named was under a disadvantage in some quarters, since conditions exist in parts of London and in various other cities extremely unfavourable to the complete employment of railed transport on the roads. The motor cab was assisted in driving the horse cab off the streets by the stupid conservatism of the old-fashioned cab driver, who refused point-blank to employ the taximeter, and so to forego the advantage which he had obtained by keeping his fare in a certain amount of ignorance as to the proper legal charges to which he was entitled. The promoters of the early motor-cab companies took advantage of this state of affairs, and introduced the motor cab and the taximeter simultaneously. The vehicle itself had the attraction of novelty and the advantage of greater speed, while its early popularity was still more directly due to the taximeter giving an accurate check of the amount payable on every journey. In this sphere, consequently, the victory of mechanical over horse transport was rapid and inevitable. Simultaneously, the motor omnibus made steady, if not quite such speedy, progress. Its advantage in speed over the horse ’bus was at first the determining factor, but after improvements in the mechanism, giving increased comfort and reliability, it was able to get the better also of the electric tram in spite of the advantage possessed by the railed vehicle of larger carrying capacity, which of course tends towards reduced operating costs per passenger carried. The inflexible nature of a tramway system has been the principal factor in securing the popularity of a free road vehicle, and at the present moment the motor omnibus is able to compete directly with great success against the electric tram car. So it came about that passenger transport was very rapidly converted to mechanical power. If London is taken as an example, we find that at the present moment over 95 per cent. of passenger transport is carried on by mechanical vehicles, while certainly not more than 15 per cent. of goods transport has yet been similarly diverted. Nevertheless, the motor vehicle for the carriage of goods has made great progress, particularly in this country.

A GROUP OF MOTORS IN THE SERVICE OF THE FLYING CORPS AT A RECENT REVIEW IN FRANCE.

Throughout its history, it has been greatly helped by the prior existence of the steam traction engine. From these heavy and slow machines, suitable only for limited use in particular spheres, have been developed two very useful classes of lighter steam-propelled machines coming under the provisions of the Motor Car Acts. The first is the steam tractor, which is merely a small edition of the traction engine, able, on account of its lighter weight, to travel at considerably higher speeds. The other is the steam lorry, which is an extremely valuable machine for the carriage of anything up to about six tons of goods at speeds of about five miles per hour. From the five-ton steam lorry there has more recently developed a lighter type of steam vehicle in the shape of the three-ton lorry, generally running on rubber tyres, and so entitled legally to travel at much higher speeds. The great economy of steam motors made it absolutely necessary for the makers of internal combustion industrial vehicles to study every possibility of reducing operating costs. They had on their side advantages as regards higher speed possibilities and more complete independence of fuel supplies. The steam motor of ordinary type cannot be conveniently designed to carry with it fuel and water supplies adequate for very long journeys. On the other hand, the steamer has the great advantage of being able to exert tremendous power at low road speeds. The steam engine is more flexible and more capable of standing a heavy overload than the internal combustion engine. Even if it is brought almost to a standstill, it can go on applying the full steam pressure behind its piston during every stroke. Given adequate supplies of fuel and water, it is an admirable and very economical machine for all sorts of rough and heavy work. Curiously enough, the steam lorry and the steam tractor have been essentially British developments, and as such they have done much to bring the British industrial petrol vehicle up to its present high standard of perfection.

The essential differences between a tractor and a lorry should here be noted. The tractor is designed merely to haul a load, while the lorry is primarily intended to carry its load. In the first case, the engine and the load-carrying vehicle are two separate units coupled together; in the second, they form one unit. The latter is the more convenient arrangement so far as manœuvring in enclosed spaces is concerned, since a good deal of skill is needed to back a tractor train with accuracy. Also, the steam lorry uses its load to increase the adhesive power of its driving wheels. On the other hand, the steam tractor can itself be doing useful work, while some of its load-carrying vehicles or trailers are being loaded or unloaded. By providing two sets of trailers, it can be kept usefully employed and need not waste time at its terminal points. Moreover, if it is required to work under very difficult conditions, it is a great advantage to be able to unhitch the engine from the trailer. If, for example, the bed of a river has to be crossed and the wheels sink into loose sand, the tractor is unhitched and run through without its load until it reaches solid ground. When it is brought to a standstill, its engine is employed through the medium of wire rope gear to drag the loaded trailer slowly but very surely out of its difficulty. Thus, for cross-country work, the tractor has much to recommend it, and it is not surprising that the success of the five-ton steamer has led to systematic endeavours to perfect internal combustion tractors possessing all the same advantages, and also self-contained for long journeys as regards fuel and water supplies.

Mention has already been made of the fact that, when a tractor is used, the load does not assist the adhesion of the wheels. This constitutes, as it were, an artificial limit to the tractive power, and has naturally caused some designers to consider methods by which the engine power of a tractor could be applied not only to one pair of wheels but to all the wheels, so that the whole weight of the engine itself can be used to secure adhesion.

The four-wheel drive is not common in commercial service, as it has only been found necessary under a limited number of very severe conditions. A good deal has been done, however, in this direction, particularly in France. The resulting vehicle need not be purely a tractor. In fact, we often find heavy lorries employed not only to carry a substantial load, but to haul an additional lighter load in a trailer. As a rule, these trailers have iron-tyred wheels, but for service in which economy of engine power is more important than economy of money, rubber tyres are usually fitted, since they have the effect of reducing the power absorbed in hauling the trailer by about 25 per cent.

Another development which is due mainly to the difficulties of adopting the internal combustion engine for the haulage of heavy loads without shock, is the petrol-electric system. In this system the power of the car engine is used to drive an electric dynamo. This dynamo generates current which is either supplied direct to electric motors or else stored in a battery of accumulators, the former method being the better and more likely to survive. Sometimes one electric motor is used, taking the place of an ordinary gear box, and driving the back wheels through a universally jointed shaft and a differential gear. In other cases, two balanced electric motors are employed in or near the driving wheels. In others again, two motors are used, each driving through shaft and differential gear to one axle of the vehicle, and so providing an electric four-wheel drive. Another arrangement is the provision of four electric motors, one for each wheel. The vehicle is controlled through the medium of a “controller”; that is to say, an apparatus which, by the movement of a handle, varies the electrical connections and so makes the installation suitable for providing either a big torque at low speeds, or a comparatively light torque at high speeds. Electrical machinery is also in a sense self-regulating, and consequently a well-designed petrol-electric transmission is tantamount to the provision of an infinitely variable change speed gear. One of the strongest arguments against the petrol-electric method is that, when the machine is running fairly light and fast, the electrical machinery involves certain unnecessary power losses. Consequently, systems have been devised in which mechanical and electrical drive are combined, the latter only operating the vehicle under conditions equivalent to an increase of load on the engine.

Efforts have been made for many years past to evolve a satisfactory internal combustion engine using paraffin or some other heavy and comparatively cheap oil in place of petrol. While these attempts have by no means failed, the practical results are up to the present more or less limited to the use of paraffin fuel in tropical or semi-tropical countries, where the higher temperature facilitates its employment. Among the disadvantages of paraffin are difficulties in starting up, a tendency to soot up the sparking plugs, the need of more frequent cleaning of cylinders, and a certain amount of disagreeable smell, partly due to the creeping of the liquid through every available crevice.

So far as the ordinary petrol van or lorry is concerned, various types have been developed to meet a variety of commercial needs. A certain number of light vans are run on pneumatic tyres, but the solid tyre is preferred wherever economy is more important than speed. It of course goes without saying that, if a chassis is to run on solid tyres, it must be of substantial construction, and so designed that its mechanism will not be injured by the fact that the solid tyre is not so capable as the pneumatic of absorbing small vibrations.

A very popular type of motor van is designed to carry about 25 or 30 cwt. These machines are capable of speeds up to about 25 or even 30 miles per hour in emergency, and can average comfortably 14 to 16 miles. Under reasonable conditions, they can cover daily journeys of 100 to 120 miles. Among larger types the 3-tonner predominates. This class of machine can be generally used for daily journeys of 70 to 90 miles, averaging perhaps 11 or 12 miles per hour. It usually consumes petrol at the rate of about 1 gallon to 8 miles, though better results are obtainable under good conditions. There are also a large number of 5-ton petrol lorries in commercial service. These can be advantageously used to cover 60 or 70 miles a day, consuming about 1 gallon of petrol to every 6 miles run. The motor cab runs about 20 to 25 miles on a gallon of petrol, and the motor omnibus about 7 to 10 miles. This question of fuel consumption is, of course, distinctly important in military service, when adequate supplies are only maintained at the right points with considerable difficulty.

In later chapters some account is given of the attempts made by various governments to influence the development of motor traction into the directions dictated by their military needs, but this brief sketch of the general trend of events will be sufficient to indicate the present position, and to provide the necessary knowledge for the appreciation of the facts and considerations to which we shall now turn.