Revive The Steamer
Page 23
If you've noticed an error in this article please click here to report it so we can fix it.
To Use Solid Fuel
A Contributor, Describing Himself as an Old Steam User, Makes Practical Suggestions for the Conversion of Existing Goods Vehicles to this Source of Power
CONSIDERABLE attention is
—'being paid at the present time to the possibilities of steam as an alternative source of power to that obtained from imported liquid fuels and, moreover, to producer gas. Evidence of this is to be found in a number of recent issues of The Commercial Molar.
It may well be, indeed, that circumstances will ultimately compel the Government to recognize the merits of -the steam vehicle, and that encouragement to the type will be given by reducing to fairer proportions, in comparison with other types, the unladen-weight taxation rate that has been the major cause of the steamers' decline from favour in the past years.
The Preferable Type.
to Convert
Obviously the most attractive and practical course is to convert existing internal-combustion vehicles, and as an old steam. user I am of the opinion that this could be done. There are many factors, however, that need to be taken into consideration. Of these, probably the most important is the selection of the most suitable type of chassis. The forwardcontrol long-wheelbase maximumload four-wheeler, weighing about 4 tons and capable of carrying 7 tons, strikes me as the most promising.
With regard to the question of whether to set about converting a petrol or an oil engine, I prefer the latter. It would be better equipped to, withstand the heavy stresses which steam would impose, and the piston clearances would be about right. It should, for preference, be a four-cylindered unit.
The valve gear, of Course, would have to be altered, and this could be done only by fitting a new camshaft. Use could be made, however, of the same valves, springs, etc., although the 'inlets might be too large, in which case the heads could be turned down and new seats, of appropriate dimensions, would have to be fitted.
Naturally the unit would be of the single-acting . high-pressure type, each piston having a working stroke every revolution. 'It would operate expansively. [Mr. Cole does not suggest a different crankshaft, so presumably two cylinders would always be functioning together.—ED.] It would, of course, be glandless, like the Sentinel S model, but would differ in respect of the camshaft, as the Sentinel had two camshafts of the sliding type, giving three forward positions, reverse, and neutral or drain position, there being a set of cams for each. The object of the three forward positions was to give a range from full power to maximum economy. There was also a twospeed gear so that, in effect, six speeds were available.
It would hardly be practicable to employ sliding camshafts in the proposed conversion. Without effecting major alterations to the crankcase of the standard petrol or oil engine, one could not make a sound engineering jab of such a modification to the original design. There would be only one set of cams and the shaft would tun in the original bearings. Variations in power, other than by control of the steam supply, and reverse would be afforded by the existing gearbox, and the clutch would be retained. For cylinder drainage, cylinder cocks or release valves would be provided.
Power Output Materially Greater
Operating at 300 lb. per sq. in. boiler pressure, and using superheated steam, the b.h.p. of such an engine .would probably be increased by 33 per cent., whilst the fuel consumption would be approximately 1 cit. of coal or coke per 30 miles, with a 7-ton load. This would cost roughly 2s. 6d.
I am opposed to the use of oil fuel for firing the boiler, because if there is plenty to be had then there is no need at all for a steamer, which must always have disadvantages as compared with petrol , or oil internaleombustion vehicles. [This opinion is not universally held.—Eo.1 Solid fuel—coal or coke—must be burned.
With regard to the type of boiler, I have my doubts about the continuous coil for steam generation. I am a firm believer in the water-tube boiler for steam-lorry use, as this has proved itself in practice to be economical, quick steaming, and reliable, whilst it can give a consistent performance on any kind of road vehicle laden or empty.
My • scheme would include mounting such a boiler at the rear of the engine behind the cab, the body being shortened for the purpose. It would have to ride on the frame and be quickly detachable—by means of suitable hoisting tackle—to give access to the clutch and gearbox and for the execution of any repairs it might need itself. On one side of it would be placed a coal bunker and on the other a water tank.
Thus about a yard of chassis space would be occupied, but that is not much more than is taken up by a producer-gas plant. The boiler would be fired either automatically or by hand, in which latter case a second man would be required. • Steam would be fed direct• to the inlet ports of the cylinders, and would exhaust in the normal manner. From the manifold it would be conveyed to a nozzle discharging up the chimney for drawing up the fire. In the exhaust pipe would be a heater coil for warming the boiler feed water. For introducing this into the boiler,. I favour twin injectors, one for the wazrn water and the other for cold water when standing.
Steam Pressure and Temperature
• The working boiler pressure would have to be in the region of 275-300 lb. per sq. in., whilst superheated steam would be delivered to the engine at 600 degrees F.
Injection or ignition equipment and carburetter would be dispensed with, likewise radiator, water pump, fan, 'etc.
Although the foregoing may sound rather a big undertaking, if the scheme be compared with a producergas conversion it is clear that there are pronounced gains. First there is an' increase in power output as opposed to a decrease. Secondly, fuel costs are lower ; whereas coal or coke for boiler fuel can be bought for about Ss. per ton, producer fuel costs £.5 per ton. Thirdly, I am confident that the reliability and longevity of the steamer would surpass those of the producer-gas vehicle. W. COLE.