Experiences with Coal-gas. V.
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Some Economical Running in Grimsby.
Very considerable success—both realized and in prospect—can be named in respect of the use of coalgas, in substitution for petrol, by the Great Grimsby Street Tramways Co. The motor-vehicle department of the undertaking is located at the Tramways Offices, Cleethorpes, and the engineer, to whom we are indebted for our data, in Mr. H. 0. White.
Saving on Fuel Bill for One Vehicle More Than £6 a Week.
Two of the company's fleet of motorbuses are at present fitted with Barton gas-holders. The first vehicle to be so equipped was a single-deck Daimler motorbus with 40 h.p. sleeve-valve engine. Conversion was effected nearly four months ago, and the results throughout have been satisfactory Experience with this vehicle has shown a reduction in fuel cost per mile run from 4.30d. to 1.66d. (with petrol at 2s. 2d. per gallon, and gas at 2s. 6d. per 1000 cubic ft). This particular vehicle, which we illustrate, runs some 700 odd miles weekly on the company's short-distance routes, to Waltham and Laceby, which are 3i and 4.i miles, respectively, from Grimsby. The cash saving per week is 26 6s. 4d.
l2t, Minutes to Refill.
The holder has a capacity of 600 cubic ft. ; it is charged for each double journey. The average time required to fill the gas-holder is 12 mins., through a filler hose. 4 ins, in diameter. The local gas company has fixed an extra-large meter at the garage, in order to ensure quick filling. Slight Modification of Solex Carburetter.
Mr. White tells us he has had to make no alteration to the Solex carburetter,_ beyond fitting a butterfly valve in the air-intake pipe, in order to enable the driver to regulate the air supply as required. It is found that the best results are obtained with the valve nearly half closed. The gas is led from the holder on the top of the vehicle, through a i-in. rubber hose to a f-in. copper pipe : the latter pipe is fixed on to the air-intake pipe ofthe carburetter, as near as possible to the throttle, on the underneath side.
Mr. White originally tried leading the gas into the induction pipe, above the throttle valve, through a ?,-in. pipe, with a specially-graduated cock which was worked in conjunction with the movement of the throttle lever. He decided, after numerous tests to adopt the independent method, which he found more economical, and which, he believes, allows the engine to draw the gas in the correct quantity, according to the r.p.rn. and load.
No Loss of Power.
It will be of general interest to owners of sleeve-valve engines to note the following expert view which Mr. White has communicated to us :—" The Daimler engine runs very smoothly on gas, acceterating with the same ease as when running on petrol: its pulling powers with a full load, both on the level and on hills, are the same as when on petrol?'
Record Low-consumption Results on a Commercar.
The second vehicle is a 36 h.p. Commercar, and here, again, Mr. White is particularly pleased with the behaviour when running on coal-gas. A flexible holder with a capacity of 700 cubic ft. is accommodated on the roof, the extreme length being 24 ft. and the diameter 44 ft. The front and rear canopies have been extended in order to accommodate this holder. A rubber hose, 1 in. in diameter, is used to let the gas flow from the holder, with a suitable cock near the driver for him to control the supply. The gas enters the air-intake pipe of the carburetter, through a, pipe with a bore of is in., which pipe terminates close below the throttle valve.
Part on Gas, Part on Petrol.
The Comrnercar is working on one of the company's long-distance routes, the trip extending to 18 miles from Grimsby. It covers 23 miles of the double journey on gas, the remainder being done on petrol, as there is no gas supply at the other end of the journey. It is the practice of the company to keep a supply of petrol in the tanks of both its gas-equipped vehicles.
Comtnercar Saves 2.8d. Per Mile ,on Fuel Bill.
When the Commercar was running on petrol, the cost was 3.71d. per mile ; it is now 0.91d. on coalgas, showing a saving of 2.8d. per mile run. It uses 30.4 cubic ft. per mile, and shows for a period of three months, that 1000 cubic ft. of gas is equivalent to 4i galloits of petrol. This was, until recently, the lowest consumption to be brought to our notice ; it is equivalent, approximately, to 210 cubic ft. of coal-gas in substitution for one gallon of petrol. A better record still, also from Mr. White, receives mention at the end of this article.
May. Not Return to Petrol.
The Grimsby Co. is so well satisfied with the results on coal-gas, that it is quite possible this fuel will be retained in preference when the supply of petrol returns to nor: mal. Mr. White reckons that petrol will have to fall to 7d. per gallon, before he will be inclined to go back to it. The only disadvantage, to his mind, is the sacrifice of the top deck in order to allow the holder to be carried. He considers that, with larger single-deck bodies, this difficulty will right itself.
Simpler Working. Amongst the advantages in favour of as which strongly appeal to the Grinasby officials, are the follow ing: (1) the engine keeps cleaner than with petrol, and the valves do not require grinding so frequently ; (2) choked jets, punctured floats and, other carburetter troubles, are eliminated ; (3) the lubricating oil in the engine keeps in better condition and lasts longer. There is one trouble with the gasholder : ' the fabric is sometimes worn by its catching sharp projections. This is particularly noticeable when, as in the Daimler shown on the previous page, the container as confined within the usual topdeck guard. The additional rubbing surface rapidly impairs the container by wearing out the fabric.
Experiments with Compressed Gas.
A brief experiment was made, as far back as February last year, with compressed gas, but this was abandoned owing to the difficulty at the time of finding a suitable reducing valve. The cylinder was
borrowed from the Great Central Railway Co., and filled with gas as used for train lighting. The cost of this gas was somewhat against it, being 15s. per 25 cubic ft. as compressed to 105 lb. per sq. in. (this is. equivalent approximately to 2n0 cubic feet of free gas), and militated against' its further use. As a. set-off against this high cost, it Must be remembered that the gas used by the Great Central Railway Co. is derived from shale oil, and it isamuch richer than ordinary coalgas, having a greater heat value. The weight of the cylinder used as a container was roughly alchaut 300 lb. The necessary reduction valve piping, etc., added a further 200 lb. to this. Mr. White informs us that it is quite possible that he may further experiment in this direction, especially as he now understands that more suitable reducing valves are procurable.
A photograph of the vehicle with the rigid gas-holder on the top is reproduced herewith. Mr. White will, no doubt, read with great interest the references to compression data in the report (about to be issued) Of the British Commercial Gas Association,
A New Low Record.
Writing to us a few days ago, in regard to some further observed performances with the Commercar motorbus while running on coalgas, Mr. White has found that, on a charge of 660 cubic ft. of gas, it accomplished 27 miles on a, giveand-take noad before it had to stop • for want of gas. This is equivalent to 190 cubic ft. of gas in substitution for one gallon of petrol, under the same load and road conditions, but it is only fair to point out that the Grimsby Gas Co. is delivering gas with a calorific value of 540 • British thermal units per cubic ft., the average for the countrei, at the moment, probably being not more than 480.