Manufacturers and the War Office Transport Vehicle.
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.aE ARTICLE and specification dealing with the War Office 30-cwt. vehicle, which we published last week, have aroused a very considerable amount of interest amongst both manufacturers and users, and we have already received important opinions and criticisms of the machine. We have also, had the opportunity of chatting with several well-known manufacturers and of obtaining from them their candid views on the subject.
The consensus of opinion appears to be that it will be a .matter of difficulty to manufacture the new vehicle at a price sufficiently tempting to attract the ordinary buyer. The price, of course, depends• upon the number built, and this, again, will depend very largely on whether the War Office vehicle is also entirely suitable for ordinary trade purposes, and in this connection it has been pointed out that some of the requirements in the specification are not necessary for ordinary work.
It is hardly time to consider the possibility of any great numbers being ordered by the War Office, which has up to the present inquired for 10 only. It appears, therefore, that the manufacturers will have to look to the ordinary buyer if the vehicle is to be made a paying proposition.
Now the average business man cannot be expected to purchase special chassis at an increased cost purely from patriotic motives when he can obtain ordinary types which will meet satisfactorily all the conditions of his work, and if this proves to be the case it would appear that some sort of subsidy scheme will have to be brought into being, particularly as the .user who purchases vehicles of the W.D. type may be called upon to hand them over at a moment's notice, whereas he who has purchased vehicles suitable for his own work, but unsuitable for that of the War Office., will be able to retain them and this gain the advantage. Therefore, it may be essential to offer an adequate inducement, as otherwise the scheme will fall through, for to be of any real service to the country-in time of need there will have "to be a large number of suitable vehicles in commission.
If some subsidy scheme were to be adopted it could be made subject to the maintaining of each vehicle in perfect working order. .
Criticisms have been directed against the proviso that four speeds must be fitted, and the view is taken that, if a vehicle made by any particular manufacturer is efficient enough to pass the trials satisfac torily when fitted with three speeds only, this vehicle should be excepted from the rule.
As pointed out by one manufacturer, if a maker finds it necessary—perhaps because his engine is under-powered—to fit five speeds, then, if the whole performance of the vehicle is well witlain the specification, what objection can there be to this procedure ? On the other hand, if any maker has utilized a more powerful engine which necessitates only three speeds, why, again, should this number
be barred ? , We have been very glad to note that many designers agree with us in pointing out that there is no necessity for the compensation of brakes. Experiments which have been carried out have shown that the wear is more even when the brakes are not compensated, quite apart from the advantage of decreasing the 'number of wearing parts. The limiting of the chassis weight to 29 cwt. is a point which may antagonize many makers, some of whom have already expressed the opinion that this weight is not sufficient for a commercial vehicle chassis, as extreme lightness not only needs very careful design, hut invariably means extra expense, and who is to bear this I Certainly neither the user nor the manufacturer. , Will the Solid Tyre Be Superseded ?
MANY of those who have delved deeply into the subject of vehicle design and road maintenance believe firmly that, sooner or later— and probably the former—the ordinary type solid tyre will lose its present pre-eminent position and will retire into the background, although not entirely into obscurity, for its use in a lesser degree will, in the opinion of the majority, continue for many years, particularly on the larger types of vehicles and those not built specially to run on cushion or pneumatic tyres. The two factors which at present militate against the more general use of the pneumatic tyre are cost— both initial and of maintenance—and the very prevalent idea that the wheel drop in the event of the bursting of a large pneumatic tyre is certain to be a constant source of danger.
The factor of cost is one which is bound to continue a difficulty for some considerable time to come, but if it be possible to use smaller tyres on the large vehicles by spreading the load over a larger number of wheels and thus decreasing the actual load per wheel, the cost of the tyres, their maintenance, and, incidentally, the wear on the roads will be reduced, except that, in the matter of cost only, the saving may be somewhat circumvented by the fact that more tyres will be required.
The use of smaller tyres will also reduce the possible wheel drop which can occur between the inflated and deflated conditions, although, in our opinion, the importance of this matter of wheel drop is very much exaggerated. Those who ought to know better speak of a drop of 9 ins, in a 10-in. tyre, whereas the maximum drop in a tyre of this size is probably nearer 6 ins., as quite apart from the thickness of the tread, which in the larger tyres is appreciable, the easing is so strong that it would take considerably more than the legitimate load completely to flatten on to the rim even a fully deflated tyre.
By the use of pneumatic tyres, or very resilient cushion tyres, a considerable reduction can be made in the weight . of the chassis, provided it be quite understood that the chassis must never be run on solid tyres. If an ordinary private car had to be designed to run satisfactorily on solid tyres it would have to be strengthened immensely throughout, and this is what is actually done with the commercial vehicle in similar conditions. 'The result of lightening the commercial chassis is that for a given weight it can carry a bigger propors19 tion of paying load, and this to a certain extent offsets any increase in the coat of tyre maintenance, whilst an advantage is the speed at which a vehicle fitted with Pneumatics can run.
The Use of Road Vehicles, on Rails.
THERE IS an increasing tendency in various quarters, and not only in this country, to employ petrol-propelled road vehicles for tramway or railway service, and particularly in the ease of branch line and local traffic work, where the cost of providing the electric current necessary in the first ease, or the locomotives in the seeond ease, is considerable compared with the number of passengers or the quantity of goods transported. Many of the experiments carried out with lorries on rails have proved quite successful, but much depends upon the conditions peculiar to any particular sersrice, and there is always the da.nger that overspeeding may cause rapid depreciation of the _engine and transmission, for, except where engine speeds are limited by really efficient governors which cannot be tampered with, there is always the temptation, due to the smoothness of the " iron road," to run the vehicles at too high a speed.
The changed conditions also call for more efficient braking, or, perhaps, we ought to say the spreading of the braking effort over more wheels, because the coefficient of friction between wheel and rail is usually less than that between wheel and road.
Taking everything into consideration, it would appear preferable to employ petrol vehicles specially built for the work. Such machines, examples of -which have borne the test of time and arduous service, can be built by several British manufacturers ; in fact, certain of them have been engaged in this class of production for many years, and one special feature common to almost all these vehicles of British make is the very carefully designed clutch gear, by which the smooth take-up of the drive is effected_ Careful attention is also paid to adequate cooling and braking; in fact, the vehicles are built for the work and are not merely converted or modified road vehicles.
Front-wheel Brakes for Fire-engines.
IN DEALING with the activities of the Croydon Fire Brigade (an article describing the service is published in this issue), we have unearthed the fact that all the fire-engines proper in its service are fitted with front-wheel brakes which are operated independently of the driver. This equipment, according to the chief officer, has proved most efficient and reliable during the course of a number of years, and has directly resulted in the avoidance of collisions which would, without an independently operated front brake, have been almost inevitable, whilst skidding has been materially reduced.
Some might question the desirability of the frontwheel brakes being operated independently of the driver—and perhaps for any other than a' special branch of service it is inadvisable—although, if complete understanding exists between the driver and the man on his left, the former undoubtedly feels a greater sense of security and is able to keep his hands on the job of steering in case of emergency. The driver of a heavy vehicle usually has his hands fully occupied in conteolling the steering of the machine when any untoward circumstance arises, and consequently he is sometimes only able to operate the foot brake. In such instances, the independently operated front-wheel brake has much to recommend it, particularly in such a special branch of service as fire-brigade work, where speed is an all-essential factor. The greater the speed of a heavy vehicle, the greater the need for front-wheel braking—and this remark brings within its full compass vehicles other than fire-fighting appliances.