Maritime History of the Great Lakes

Marine Review (Cleveland, OH), 18 Jun 1896, p. 13

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MARINE REVIEW. is High Power Boilers and Five-Crank Engines. Ina recent issue the REviEW referred to the freight steamer Inch- mona, which has engines arranged on five cranks, and which was recently built by Messrs. Wm. Gray & Co. of West Hartlepool, Eng. We are now enabled to present an engraving of these engines and some facts regard- ing trials of the steamer, in which an unusual amount of interest has been exhibited. The Inchmona is owned by Hamilton, Fraser & Co. of Liverpool and is an ordinary cargo carrier of very full model, being 335 feet in length, by 46 feet Ginches beam, and carries 5,000 tons dead- weight on 20 feet 6inches draught. The new departure in the engine room consists generally in the adoption of a number of details tending towards the economy of fuel, with a view to arriving at once ata sub- stantial reduction in coal consumption. The boilers, although of the ordinary multitubular type, are suited to a working pressure as high as 225 pounds per square inch, having been tested by Lloyds to 510 pounds per square iach. Then the five-crank engines, built by the Central En- gine Works, West Hartlepool, are the first of their kind ever fitted toa ship, and they are regarded as highly advantageous in themselves and as specially applicable in the case of large powers for the use of high pressure steam. But these are not the only marked changes involved in the scheme of getting down to the ideal consumption of one pound of such relatively light reciprocating parts, and such rapid reversals of the up-and-down initial stresses, as to enable the engines to run almost noiselessly and entirely to obviate vibration of the ship, even when light. All the valves are on the center line of the ship, and are driven by ordi- nary link motion, the work on the valve gear being unusually light, owing to the smallness of the valves, and the power passing through each crank being only one-fifth of the total instead of one-third, as in the three-crank engine. The smallness of the low pressure cylinders enables the centers of the engines to be closer than usual, and the en- gines altogether gointo an engine room only one frame space longer than is usual with the three-crank engine. The trials were continued over two days, during which time the boilers and all steam joints re- mained absolutely steamtight and the engines ran in the most satisfactory manner possible. No bearing of any kind showed the slightest sign of warming, and although the engines were run for many hours at eighty revolutions per minute no difficulty of any kind arose, and at the con- clusion of the trials the vessel proceeded on her voyage. The coal used during the trials was carefully weighed for four separate runs in the presence of four separate groups of visitors, who were taken off to the vessel by tug, the results being of a character to entirely justify the pre- dictions of the builders. On the first run the consumption was 1.142 FIVE-CRANK ENGINES OF STEAMER INCHMONA, coal per horse power per hour. The Engineers' Gazette of London says of other features of the machinery: "With these engines and boilers, the builders felt confidence in holding out to the owners the expectation that the coal consumption would not be over 1.15 pounds of Welsh coal per horse power per hour, and had hopes of even bettering this. These predictions were based upon the calculations of the accumulated economies to be had from the various steps includedin the scheme. The boilers are fitted with Ellis & Eaves' system of induced draught, and also with Serve tubes, which haye the effect of increasing the heating surface without increasing the size of the boiler. On the trials steam was easily maintained at 255 pounds pressure, whilst the engines were running steadily at about eighty revolutions per minute, with the induced draught fan running at as easy a speed as 180 to 200 revolutions per minute. Combined with the induced draught system there is also an arrangement of tubular superheater for drying and slightly superheating the steam on its way to the engines. The steam is further kept in adryer state than usual throughout its progress through the engines by an exceptionally com- plete system of steam jacketing, and the feed wateris returned to the boilers at a much higher temperature than ordinarily, viz., at about 400 degrees Fahr., by a system of feed heaters. But, of course, the most in- teresting feature is the arrangement of the engines on five cranks, there being two low pressure cylinders, and the cranks being set at equal angles around the crank path. This gives so even a balance of forces, pounds of coal per horse per hour; on the second run, 1.078 pounds; on the third run, .999 pounds; and on the fourth, 1.069 pounds. The average of these is 1.07 pounds of coal per horse per hour, which will be recog- nized by all interested in the question of fuel economy at sea asa very remarkable result, andif it can be maintained in regular sea service, there can be no doubt that the machinery of the Inchmona will mark the beginning of a new and important step in advance in marine machinery," Whatever may be said of the present depressed condition of the iron industry, it is certaifl thatin no department of the trade is there any great amount of material involved in unfilled contracts. Everybody seems to be keeping close to immediate wants, buyers in all cases aiming to use up all material on hand before committing themselves to future contracts. This is even true of the ore business, in which, under ordinary circumstances, sales for the coming year would all be closed up several weeks ago. It wouldseem, therefore, that when a buying movement is ' resumed in the market generally the ore business should be specially benefitted by it. Low rate, short limit tickets between Cleveland and Lorain have been placed on sale via the Nickel Plate road at $1.00 for the round trip. 77-7-31 One dollar round trip excursion tickets between Cleveland and Lorain are on sale by agents of the Nickel Plate road. 78 July 31 ete ag a Bs wa i CS

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