Coal-gas for Traction Purposes.
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A Clean, Economical and Practicable Substitute for Petrol.
1331 the Editor.
We are told that not a few gas engineers were greatly surprised to hear of the successful employment of coal-gas, for the propulsion of motor chars-abanes, by Messrs. Andrew Barton Bros., of 13eeston, Notts. concerning which satisfactory use of coal-gas in ordinary petrol engines, for traction on common roads, illustrations and information were given in our issue of the 21st September. It afforded us pleasure to circulate reproductions of our copyright photographs to the _Press of the country, both daily and technical, through our friends the Topical Press Agency, Ltd., in order to help to draw attention at large to this example of the commercial use of gas, at atmospheric pressure, contained in a composite collapsable holder of canvas and sheet rubber, the whole held in place by suitable lashings on the top of the canopy of each vehicle.
We may remind interested readers that the cost per mile for fuel is approximately id., the gas being taken through an ordinary meter at is. 4d. per 1000 cubic ft., the comparable figure for petrol at the present time being about 31d. per mile.
The foregoing example of the commercial use of coal-.gas for road-traction purposes has already within our knowledge brought to their senses—and we use the word with no offensive intention—several gas managers and directors of gas companies who had unreservedly scoffed at the suggestions which were put forward in our issue of the 27th July concerning the use of compressed coal-gas. That issue was widely circulated by us in co-operation with the British Commercial Gas Association. The mere fact that coalgas can be successfully employed, at atmospheric pressure, should persuade many of these critics to exhibit a readiness to revise the position which they so hurriedly took up in regard to the prospects. We hope they will keep the following fundamental and basic facts before them : (a) 1600 cubic ft. of ordinary coal-gas is in practice equal, for road-traction purposes, to three gallons of petrol ; (b) the dead weight of an installation of gas cylinders or containers, to carry 1000 cubic ft. of gas under pressure, is much lighter than the dead weight of the batteries in an electrically-propelled vehicle, or than the boiler and mean volume of water in a steam vehicle ; (c) both electrically-propelled and steam-propelled commercial motors are commercial successes, in spite of their ratios of dead to useful load ; (d) steam-propelled vehicles have to stop to take up water at intervals of distance which are on the average below 20 miles ; (e) the use of coal-gas under reasonable compression— and here we are prepared to go so low as 150 lb. on the sq. in., and not to ask for the use of so high a pressure as 1800 lb. on the sq. in., concerning which Mr. Tookey wrote in our above-mentioned issue of the 27th July last—offers considerable economies to any user of a heavy commercial vehicle once he is assured of the co-operation of the gas-supply undertakings in his district, and of their adopting a favourable attitude towards the scheme of development which we outline.
We must,. before proceeding further in our Sustained examination of this subject, protest against the apathetic reference back to the failure of gas traction for tramcars between Lytham arid Blackpool some 18 years ago. We incidentally mentioned this admitted failure, in our issue of last week, and the writer has taken the opportunity since then to pay a visit to Neath, in South Wales, and to satisfy himself al first hand upon the reasons for the failure of gas traction, in the crude application which was made of it between Lytham and Blackpool, and also at Neath. The Neath undertaking, recently acquired by the Neath Corporation, took over the plant of the Lytham-Blackpool company on its failure. Mr. J. Irrira,y, who is now the manager of the tramcars at Neath, under the direction of Mr. D. M. Jenkins, the Borough Engineer, has from the outset been identified with the work of thenow-defunct British Gas Traction Co., Ltd., and its successors. We unhesitatingly put it on record that anybody who seek to argue from the failure of the gas trams at Lythain, that gas must fail in modern petrol engines, is peculiarly illinformed, wholly unobservant, or wishful deliberately. to condemn the possibilities of modern practice on a specious and untenable pretext. Engineers will at once appreciate the relative hopelessness of the gas-tramcar practice, as applied between Lytham and Blackpool, and as now applied in Neath. We write "relative hopelessness" because, until the outbreak of war, the Neath undertaking was commercially successful ; the ,gas tramcars there, although they are now some 18 years old, still do their work fairly satisfactorily, and earn a revenue which averages about is. per mile. The horizontallyopposed two cylinders of the gas engines in them are each 71 ins, in the bore, and accommodate a pistonstroke of IAins. ; the maximum r.p.m. of the engines is 250 ; the_ maximum horse-power, when new, was 19.5. This indicates a mean effective pressure in the new engines of only 53 lb. on the sq. in., but that is not the whole story. The trains of gearing, which consist of spur-tooth reduction between crankshaft and first and second countershafts, and chain drive from the latter to the road wheels, show total. reductions of only 7 to 1 in low gear, and 21 to 1 in high gear. This combination, considered as a design, differs as radically from modern practice, with which we are at the present time concerned qua the use of coal-gas for road-traction purposes, as does a lowpressure, condensing, beam type of steam engine from one of any modern type.
We have been surprised, too, to discover that some gas managers apparently do not know that coal-gas can be used as a fuel in ordinary petrol engines with the greatest ease and efficiency. This is possibly explained by the fact that not every gas undertaking has the good fortune to supply gas to a motor factory, at which class of factory it is now so generally the practice to use coal-gas for running in engines on the test bench, before the final test is made on petrol. It must suffice for us to inform these gentlemen that coal-gas and petrol are virtually interchangeable as fuels in modern, high-speed, internal-combustion engines, such as are used in commercial motors.
We are inclined to be influenced very considerably by the views of our friends in the gas world, when they tell us that such high pressures as 1800 lb. on the sq. in. are inadvisable, and they have not hesitated to tell us this. We certainly do not regard the employment of gas-bottles under a pressure of 1800 lb. on the sq. in. as an essential part of the case for the use of coal-gas as a propulsive agent on common roads. We may point, for example' to the • data which have been supplied to us by the Steel Barrel Co., Ltd., of Uxbridge (page 162). The gas-holders on the Neath cars are charged to 140 lb. on the sq. in.
The proposed use of coal-gas for road-traction purposes, so far as we have put it forward, concerns only vehicles with a load capacity of two tons and upwards, and with a• margin of space, either above or below the platforms, to accommodate the gas-holders. We must repeat, hereanent, our original arguments in favour of economy to the user. Any user, who adds one ton of dead weight to his earlier practice with any petrol vehicle, must be prepared to face an additional running cost of approximately Id. per mile run, to cover extra. wear on tires, extra mechanical maintenance, and sinking fund, on the added plant. Against this, however, he has to place the saving which he effects by using coal-gas in substitution for petrol, and that saving is very much more than id.
per mile. A three-tonner wants, on the average, about 33 cubic ft. of gas per mile run, which compares with 8 m.p.g. on petrol. The saving on coal-gas is as much as id. per mile, even if the coal-gas costs the user as much as 6s. 6d. per 1000 cubic ft., in which case the user will neither save nor lose. Taking the price of coal-gas at the more-likely figure of 2s. 4d. per 1000 cubic ft. (the charge to Messrs. Andrew Barton Bros., at Beeston, is is. 4d. per 1000 cubic ft.), it is clear that the owner of a three-tonner will effect an actual saving of lid., a mile on his fuel "alone over and above the extra cost of id. per mile due to the added weight. He avoids spending 3id. on petrol ; gas costs him 9-10ths of a penny, and the extra weight, say, id. It is true that his net carrying capacity will be reduced, but the way to deal with this aspect of the problem is for every purchaser, in the future, to buy an internalcombustion-engined vehicle which is capable of taking a ton more than the actual net load which is re-, quired, thus providing the margin of strength for the dead weight of the coal-gas holders and fittings. We are confident that this scheme of working will be followed largely, and that its initial establishment will be on fixed routes. The economy that can be realized in daily working is too large to be ignored.
Demand and reasons exist, in our judgment, for commercial-motor manufacturers to make the small modifications to any transmission which the adoption of such a method of working with coal-gas involves. We particularly refer to the provision of a small compression pump, with water cooling by means of a shunt" from the ordinary radiator, to compress coal-gas to a storage pressure of, say, 150 lb. on the sq. in. The disposition of storage vessels to hold 1000 cubic ft. of coal-gas, when that pressure is adopted, presents no difficulty, and 1000 cubic ft. of coal-gas is enough to run the average three-tonner about 24 miles. This, to leave a reserve, means 20 miles in practice. One can of petrol, carried as a reserve, should be usable without difficulty in case of the exhaustion of the coal-gas on the road. We have already ascertained that, for the convenience of those users and intending purchasers of commercial motors who may not be able to arrange the necessary adaptations and fittings with the vehiclemakers, they will be able to get the work done at other engineering establishments.