What is • Holding Back the Heavy Oil Engine ?
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THERE IS ample evidence of over-production or oil in the United States, but there is little evidence of definite encouragement by oil interests of the use of . the _heavier ,distillates for internal-combnstion engines. Mr. A. E. Berriman, in his address to the engineering section of the British Association, showed that kero-sene at 10d. per gallon should yield practically as much road-wheel energy for the same cost as high-grade coal at 605. per ton. There has been a certain amount of experimental work on engines suitable for burning the heavy distillates, such as kerosene and gas-oil, but neither engineer nor vehicle user is encouraged to go ahead and to perfect or to secure the perfection of the type of engine reqUired, because of the uncertainty which must exist concerning future prices of these heavy oils. What is unquestionably required is a, definite guarantee, which shall operate over a long period of years, that kerosene should be marketed in bulk at not less than 9d. or 10d. per gallon, delivered anywhere in the United Kingdom, the price of gas-oil being at an appropriate figure.
With some such guarantee as this, engineers would be emboldened in their endeavours to overcome the fewremaining technical difficulties which are at present associated with the use of the heavy oils, such as imperfect combustion, involving an unnecessary waste of fuel, and the dilution of the crankcase oil, which again involves waste, and is destructive of bearings. Some light has, in the past few, months, been thrown upon the possibility of avoiding this trouble of imperfect combustion, and we are confident that, with suitable encouragement, engineers ,would, by means of experiment and careful design, quickly overcome the remaining troubles.
This encouragement must came from the oil companies, and if it were adequate in its terms the net result must be a cheapening of running costs and a development of road-borne traffic which cannot but be of service to industry and commerce.
The Gearbox for Steam Wagons and Trolley-buses.
NE NEED not be a believer in the high-speed engine—steam or internal-combustion—to be interested in the vitality of the ever to be condemned but ever triumphant reduction gear. When Leyasseur introduced his train of gears into B17 the first motor vehicle designed. to make use on the road of Daimler's engine, the gearing was regarded by him and by his contemporaries as a mere makeshift—something that was so certain quickly to be replaced by something better—.that-the shafts and pinions were left uncovered and :subjected to the inroads of dust thrown up by the ° vehicle. But . the gearbox of to-day differs merely in details ,from Levas-seur's:contrivance, and shows no sign of being succeasfully displaced, unless hydraulic transmission can be gotethrough its present infantile troubles, which seem to be worse than the teething troubles to which gearboxes at one time were prone. In recent years it has been interesting to watch the quiet adoption of reduction gear by designers of steam road vehicles, one of the most recent of such incorporations being dealt with in this issue, and now two and three-speed gearboxes are being suggested for trolley-buses to enable them to operate more satisfactorily in hilly districts. To secure sufficient tractive effort on hills there is an inevitable loss of speed on the level if direct drive be relied upon, but a multi-gearbox removes this disability. That reduction gearing is indispensable, despite the lass of energy entailed by its use, is shown by the development of its employment in connection with machine tools with marine turbine engines and their propeller shafts, and with aeroplane engines and their propellers.
Fuels for Steam Wagon Boilers.
THE POSSIBILITY of utilizing heavy-oil fuels for the • firing of steam-wagon boilers has always been an attractive one, although various causes have contributed to pievent much pro gress being made. In this connection the great strides which are being made in America with the use of pulverized coal for steam raising are of considerable interest. Briefly, this fuel consists of coal-dust, which is usually regarded as waste, intimately mixed with a heavy oil in such a way that it has but little tendency to separate out. The resulting mixture can be fedthrough piping from storage tanks, and is extremely cheap. So far, its use has been confined to large electrical supply stations, but there seems no vital objection to employing this fuel for steam wagons.
The Unknown QuantitY—Human Psychology.
ONE OF the most difficult problems facing the builders of public-service passenger vehicles is so to modify existing types, and to redesign new, in order further to promote the safety of the travelling public. . Alterations. which may at first appear to be beneficial in every respect may present unsuspected pitfalls, at least until those who travel by the vehicles become quite familiar with any differ ences in them. . lathe case of the vehicle catering for the casual traveller, the matter is considerably simplified. It is where continual association has caused certain habits to be acquired that danger may accrue. Take, for instance, the London omnibus. For many years Londoners have been accustomed to take two steps in mounting or descending. In the latest vehicles to be put into service an improvement was adopted in the shape of a rear platform the height of -which from -thee ground is so reduced that even the aged and decrepit'have no difficulty in entering.or leaving the vehicles. At first sight, it would appear that this modification would immediately tend to reduce accidents, but, curiously enough, human psychology here takes a hand in the game. What has been done for years has become almost an instinct, and, in spite of wan lug notices on the new vehicles, many passengers do not as yet realize the difference between the old BIB type platform and the new. Only a few da-ys ago, we saw two passengers fall in the road within 50 yards of each other when alighting from one of the buses with a. low platform, and we will admit that we had a very narrow escape from a similar fall only a short time ago. Such fan are, of course, caused by descending from the vehicles while they are still in motion. This procedure, again, has become a practice which it is almost impossible to circumvent. When stepping off a low platform bus when it is in motion, and without realizing that the low step is absent, the passenger automatically endeavours to stand on the step which does not exist and his legs are immediately carried from under him, in which case he has either to cling to the vehicle by his hands or to flop on to his face when he lets go.
Ackerman Steering Difficulties on Highspeed Trailers. Ackerman Steering Difficulties on Highspeed Trailers.
THE TRAILER with Ackerman steering has not quite lived up to the high claims which were made for it by its protagonists. In certain respects, it is an improvement on the old type with a turntable at the front, but considerable trouble has been experienced in overcoming difficulties which have shown themselves when these trailers operate at high speeds. Many vehicles develop a certain amount of tail wag, and this movement is transmitted via the drawbar to the steering wheels of the trailer, and is sometimes so accentuated that, in at least one case which has come to our notice, the side-swinging of a heavily-laden trailer has been sufficient to pull the back of a steam wagon across the road. It may be that the trouble in some instances is due to inherent faults in the design, but it behoves potential users of trailers who intend to operate them at fairly high speeds to have the trailers tested at such speeds, so that their behaviour in such circumstances can be ascertained.
Engine Temperature Control.
ITH THE advent of colder. weather, the necessity for providing some means for automatically controlling engine temperatures once again becomes prominent. --'Many users wit!, no doubt, aclopt the homely expedient of covering a portion of the radiator or disconnecting the fan belt, hut, whilst these palliatives are better than nothinE the lorry. manufacturers might. well follow the private car makers in the Provision of thermostats, which automatically regulate the -cooling water temperature. In the majority of engines the greatest petrol economy is obtained when the temperature ranges from 170 degrees F. to 190 degrees F. • At lower temperatures the trnechanical efficiency is lessened owing to the increased viscosity of the lubricating.oil ; in other words, the engine is stiffer. At the same time, the fuel is not carburetted so .efficiently. When it is remembered that the engine may be called upon to do its work with atmospheric temperatures of 40 degrees F. in the winter against 100 degrees F. in the summer, it is obvious that, if belling doevnot occur under the latter condition, the engine will be overcooled under the former.
Another important case is that of the vehicle used in delivery work, involving frequent stops. The engine with a normal cooling system never attaies an efficient working temperature under such conditions, and, in consequence, the consumption of petrol is much higher than it should be. An entirely new set of conditions has been introdueezl since we have been forced to use fuels of heavy specific gravity, and the thermostat is one of the 'means of meeting those conditions.