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Burning New Zealand Coal on the Railways

(By A. McKay , Enginedriver, Wellington.)

Much has been said and written at different times for and against the utilisation of New Zealand coal on our Railways. As a rule enginemen do not concern themselves about the origin of the coal they use so long as its steam-raising qualities are of a satisfactory nature.

We have not been singular in our consideration of this important railway question. In Canada (which country the writer visited recently) there are vast deposits of soft coal. It was thought for a long time that the Canadian soft coal, being as it is of a very slack nature, was quite unsuitable for locomotive purposes. In consequence, most of the coal for utilisation on the Canadian Railways was imported from the United States. The Canadians, however, investigated the possibility of using their own soft coal for railway purposes, and experiments were carried out to this end. These experiments resulted in the two big railway organisations of Canada (the Canadian National and the Canadian Pacific Railways) adapting their locomotives for the purpose of burning the coal referred to, and, incidentally, of lessening the expenditure on coal.

All locomotives were therefore fitted with the butterfly air-operated fire hole door, and with the split, or bridge, exhaust. The latter consists of a piece of 3/8in. square steel fitted cornerwise across the exhaust cap. It has the effect of forcing the steam against the sides of the smoke stack, thus permitting of a less severe exhaust and reducing the back pressure. The engines (of all sizes) as they go through the workshops, are also being fitted with Feed Water Heaters and Thermic Syphons. The Feed Water Heaters are placed on top of the smoke box in front of the smoke stack—in the position of the head-lamps on our own locomotives. They are worked on the reverse principle to a surface condenser. The Westinghouse pump exhaust, the feed water pump exhaust, and part of the engine exhaust, are caught and circulated round the Feed Water Heater in the process of which they are condensed and returned to the tender. The water is put into the boiler almost at boiling point, and a saving of one gallon of water in ten is thereby effected by this arrangement.

The Thermic Syphons are fitted in the firebox. They are an improvement on the old style American water tube used on some locomotives to carry the brick arch. They are about seven inches in diameter at the point they leave the front tube plate below the tubes, after which they are split and carried up to the crown sheet, forming a water leg almost the entire length of the firebox, then forming back into a tube again where they enter the back firebox plate above the fire-hole door.

Two Thermic Syphons are placed in a firebox. The crown sheet is thus formed into three sections, the centre section and the inner ends of the side sections of the brick arch being carried on the enlarged lower portion of the Syphons. Placed as they are in that part of the firebox where they are subjected to the greatest heat, the Syphons assist materially in the production of steam, their use also conducing to coal economy. As a result of the adaptation of the engines in the way described, badly steaming engines are unknown in Canada.

The largest engine I saw was in the round-house of the Canadian National Railways, at Winnipeg. It was a 4-8-2 locomotive (used in the freight service) with 4ft. 9in. driving wheels, and it weighed 315 tons. A booster was fitted on the trailing bogie of the locomotive. (The booster is used only in starting and in ascending grades, and is cut out automatically at twenty miles per hour.) The big engine was also fitted with a mechanical stoker—a device which lifts the coal from the tender (by means of a worm conveyor), crushing it in the process and forcing it up to columns about nine inches in diameter on each side of the boiler. The pulverised coal is then blown into the firebox (below the crown sheet) by a jet of steam.

The engines of the class referred to can haul a load of 5,000 tons a distance of 235 miles with a coal consumption of only 7 1/2 tons—a great achievement.

We are our own devils. We drive ourselves out of our Edens.—Goethe.