Petrol Locomotives for Mines.
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Methods Adopted in Fire-damp Workings to Prevent Explosion from the Exhaust Gases. Interesting Safety Devices.
The lives of pit ponies are far from happy. They are daily put to work under extremely uncomfortable and arduous conditions, and, even if they be kindly treated by the boys in charge of them, their existence is not unattended with cruelty. Wilful cruelty, too, at times is inflicted upon them, and occasional instances of maltreatment are brought before the magistrates. Mechanically-propelled vehicles and tractors are now extensively employed in almost every branch of industry, and the day cannot be far distant when animal traction on our roads will be a thing of the past. Why, therefore, should not the pit pony be replaced by some more economical means of haulage— by machines which are not affected by long periods spent in darkness and in an impure atmosphere? It is the presence, in mines, of the deadly firedamp that has prevented the widespread adoption in this country of petrol engines for mine locomotives, The heat of the exhaust gases might lead to a serious explosion in the mine, or a back fire into the carbilretter might prove equally disastrous, but the difficulties in the way of the safe working of petrol lovoinotires in atmospheres of methylhydride keii4) or marsh gas, are not unsurmountable„ and many such locomotives are at present working in German fire-damp mines.
Many of our readers will possibly be surprised to learn that, of 847 locomotives, all propelled by internal-Non bustion engines, supplied by the Gasmotoren-Fabrik Deutz, 680, or over SO per cent., are at work underground, and of these nearly 50 per cent. are working in fire-damp mines. In the present stage of its develop
went, the Deutz pit locomotive embodies the results of experiments and experiences extending back to the year 1896, when this German manufactnrer first undertook the design of an engine for a milling company at Gissen. The Deutz machine is of very compact design, and it is fitted with extremely simple devices for the prevention of explosion due TO the escape of hot gases or sparks from the exhaust silencer, or from the ignition gear.
By the courtesy of the Deutz COMpany we are in a position to reproduce several scale drawings, which clearly
show -Elk, precautions that maker has taken to insure safe working in a firedamp atmosphere. In the first place. the whole machine is enclosed by a jacketing of sheet steel, and into the enclosed chamber air is admitted through fine gauze-covered ventilators. on the same principle as was adopted by Davy for his miner's lamp. A sectional view shows how the issue of flame from either the inlet or exhaust pipes is prevented. The exhaust gases are effectively cooled by water in the manner illustrated by passing through a cooler or spark arrester before they reach the silencer, and the latter component, besides being partly filled with gravel, has a -fine wire gauze covering its final outlet to the atmosphere of the mine. With these precautions it has been found that there is nothing to fear so far as the exhaust is concerned. Equally ihorough are the precautions which have been taken in connection with the inlet pipes so as to guard, against back fire Before it passes into the mixture pipe, the in rushing air must pass through a number of wire gauze discs and a gravel filter ; these are shown in the sectional drawings.
The engine is of the four-cycle type, and, has a single horizontal cylinder which is centrally disposed, and is arranged parallel to the longitudinal axis of the locomotive. The cylinder is, of course, water cooled, and cast integral with the water jacket is a large water tank and extensions for the erankshaft bearings. The manner i a which the engine is mounted allows for a certain amount of expansion of its bedplate. Both the valves are mechanically operated, the inlet valve being inverted and placed vertically over the exhaust valve. A governor k fitted, and high-tension magneto ignition is employed. The possibility of explosion due to external sparking is prevented by the interposition of gauze discs in the ventilating holes of the outer casing. Change-speed gears are not fitted as a general rule, because the gradients are never very considerable, and, as the direct drive admits of a top speed of from four to five miles an hour, this has been found quite sufficient for pit work. The
locomotive usually hauls a train of eight trucks. These locomotives are regularly worked in Germany at an inclusive cost of from 3i to 7 pfennigs per ton kilometre against a cost of from 10 to '20 pfennigs per ton kilometre formerly incurred by the employment of pony-drawn trucks in the sa Me mines.