THE AGRICULTURAL HALL SHOW
Page 8
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Proves the Increasing Use of Commercial Motors.
The Exhibition at the Royal Agricultural Hall has not fallen short of the expectations of its promoters as regards the commercial motor section. The exhibits will remain on view for the rest of this week, and an examination of them serves to prove the hold which motor haulage has secured in all branches of trade and industry where the transport and distribution of loads are required. Many features are common to practically the whole of the vehicles of any one type. For example, the builders of steam wagons have appreciated the importance of boiler design to secure protection for the tube joints when the vehicle is on a steep gradient, as is seen from the increased depth of water allowed over the fire-box crown plates. Another point which has been carefully studied is tne facility with which the various boiler mountings may be removed, and the provision to examine check valves and other connections while the boiler is under steam. A couple of years ago it was not at all uncommon for a driver to have to draw his fire to make any such inspection. The automatic feed pumps are of ample dimensions to provide a surplus of water for the supply of the boilers even should they be called on continuously to supply steam to the engines for long spells of low gear running ; and it will now very seldom be necessary for the driver to require to use either an injector or a steam pump (which are fitted alternatively by most builders), except when the wagon is standing, whilst that necessity should not arise when t'the engine itself can be run free as is the practice in nine cases out of ten. There has been established the sound practice of submitting all boilers to a hydraulic test which reaches fully double their normal working pressure, whilst the equally useful custom of building them under the inspection of one of the best-known boiler insurance companies has also become accepted. These precautions certainly mean that the " bête noire " of the steam vehicle has disappeared, because the great difficulties on the road used to be with the boilers. As regards the amount of attention now required to be given to a boiler, this must vary with the nature of water which is available, but even at Burton-on-Trent, where the water is known to be exceedingly hard, washing out is found to be necessary only once a week and the removal of the boiler shell only once in three months. Such a result has been achieved by a better arrangement of wash-out holes and mud plugs, together with greater room for a free circulation of water in the boiler itself. Also the jointing of the smoke box top and the number of nuts which it is necessary to unloose in order to take off casings have been materially reduced without any sacrifice of security. Every steam vehicle has provision to lock the compensating gear, so that if one wheel should fail to get a grip on the road the sleeve on the differential shaft can be locked to the shaft itself, temporarily, whereby the two driving wheels must revolve together. Radius rods are of ample diameter and arranged for easy adjustment, whilst the steering is universally simple and under good control. Perhaps one of the hest features in steam lorry construction is the hardening and grinding of pins and all parts which are likely to wear, and there is also a very general tendency to machine the crank shafts from solid billets of high-grade steel. The engines are so disposed that the cylinder heads can be removed without fouling other parts of the system, whereby much valuable time may be saved, and cylinder lubrication has been advanced very greatly by the adoption of the Wokefield type of sight feed lubricator, or similar devices by which the risk of worn piston rings, with consequent leakage of steam past the pistons, is eliminated, and a great source of trouble removed. Engine and gear casings are more truly " oil-tight " and can be regarded as capable of working without an extravagant forcing-out of the lubricant on the road. Some of the driving wheels are of what is termed the " composite " pattern, which means that their construction is built up partly of wood and partly of metal, the use of cast-steel centres, with wooden felloes and pressed-on
weldless tyres, being one of the greatest merit, whilst another interesting wheel has metal pockets both on the inside oh the felloe and at the hub, with wooden spokes between. Troubles with wheels are now memories of the past, except for an occasional tightening in the hydraulic press, say, after the first e,000 miles and thereafter once in each to,000 mi.es. The growing use of cast-steel wheels is to be noted, the price of these having come down very considerably. They are slightly more noisy in use, but require even less attention than those of the composite type. The bolting on of axle caps has been adopted to save their loss through vibration.
f he growing use of tractors, which are really diminutive traction engines, is resulting in an increased number of builders of this type of machine. It is interesting to observe tnat these " steam horses " have been evolved by reducing the heavy traction engine, and they certainly follow traction engine practice as regards the use of a horizontal boiler, with the cylinders and gear mounted on the top, the crank shaft and gear being carried by bearings in projections of the fire box skies, and in the use of metal driving wheels of a larger diameter than is customary in motor wagon construction. The essential point of difference is that the motor wagon has been strengthened up from a lighter vehicle to a heavy one, and designed from the first to carry the principal part of the load upon its own platform, but the tractor has to pull the load behind it and can carry no load itself. It has been shown again with such tractors that metal wheels certainly are not the best for town haulage on sett pavement, owing to the noise and, in a less degree, the flowing action of the running strips or sections, and some users are experimenting with disc wheels built up of wood and other resilient materials. The advantage of a tractor is chiefly in the hauling of a number of different trailers which can be disposed of one at a time while others are loading or are otherwise detained, but this does not apply where there are no delays. These machines have much less weight on the driving wheels than has a loaded motor wagon, viz., about four tons, compared with eight tons. They are •capable of hauling a single trailer with from four to seven tons on its platform, according to the.road surface and gradients, and the new regulations wili lead to their adoption in larger numbers than ever.
The internal combustion engine section is not so representative as one could wish, but the fact that this class of vehicle has established itself for loads of two to three tons is made clear. Makers, too, seem confident that they will overcome the objections to their employment for heavier loads, and that steam will not he left to enjoy sole possession anywhere. Various devices are exhibited which seek to eliminate the risk of damage to gears by careless drivers, and this fact alone bears testimony to the practical difficulties which have been experienced in the use of the heavier machines, as compared with light cars, where ordinary sliding or planetary change-speed systems were employed. One of the vehicles, a double-deck 'bus, has all the teeth in gear and claw clutches. A two-ton lorry has friction discs ; another, the Soames transmission ; whilst a four-ton lorry has a system of cramps. The few users who carry four-ton or greater loads by petrol motors know how serious it is if the driver misses his gear, owing to the actual stoppage of the vehicle from lack of momentum ; hence the various schemes to avoid this risk are of great interest. The makers themselves agree that some form of transmission other than sliding gears is necessary to meet the driver difficulty, and there is little doubt that the teeth require to be constantly in mesh for a machine to be " fool-proof." There is now no need for anxiety over ignition, for both magneto and hightension systems are satisfactorily adapted to motor vehicle requirements. Bodies, wheels, tyres and sundries call for no special reference beyond its being noted that a considerable business is following in the wake of the sales of commercial motors.