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14 MARINE REVIEW. Twin Quadruple Expansion Engines. THE NORTH WEST DISTINGUISHED AS THE FIRST VESSEL OF GREAT TON- NAGE TO USE ENGINES OF THIS TYPE--A COMPLETE DESCRIPTION OF MACHINERY. NGINES of the quadruple expansion type in this country, and throughout the world, in fact, were confined to yachts and other small steam craft of high power when the builders and owners of this boat decided, two years ago, to adopt them in connection with tubulous boilers. Now they are being applied to the new American line ships, being built by the Cramps at Philadelphia, but the North West is the first vessel of great tonnage thus equipped. Her twin engines are of the vertical quadruple type, and are designed to develop 3,500 horse power each and propel the vessel at an average speed of 20 statute miles an hour, with 195 pounds steam and 120 revolutions. The sizes of the cylinders are 25 inches for the high, 36 inches for the first intermediate, 51%4 inches for the second intermediate and 74 inches for the low pressure, with a stroke of 42 inches. The high pressure cylinder is forward, followed by the first and second intermediate and the low pres- sure. Piston valves are used on all the cylinders--one for the high, two for the first intermediate, two for the second intermediate and two for the low pressure, arranged outboard on the working side. All are operated by the Joy valve gear and reversed direct by steam and hydraulic gear. The reverse arms are slotted and are fitted with blocks and adjusting screws. The engine columns on the back or inboard side are of cast-iron, forked and of box section, and are braced together by cast-iron flanged distance pieces. The columns are fitted with detachable water-back guide faces. The front columns are of turned wrought iron, to which are attached by brackets the reverse shaft and link for the valve gear. The cylinders are without jackets or liners, and the valve chests are connected by faced joints and turned bolts. The low pressure and second intermediate cylinders are fitted with cone shaped, disk steel pistons, while the first intermediate and high pressure cylinders have cast-iron pistons, all of which are fitted with followers and single ring packing, set out with flat bent springs. The piston rods are of steel, but do not extend through the top of the cylinder head, and are secured to the piston head by quick taper and nut. The lower end is fitted with bolts and brasses that connect to pin in upper end of the connecting rod. The cross-head, which is of the slipper pattern, of cast iron, is fitted with adjustable brasses and bolted to the piston rod. The connecting rod is re-forged iron, the lower end T shaped and fitted with brasses, lined with babbitt, and secured to the rod by bolts and plate. In the middle of the rod, jaws are forged on and slotted out to receive the brasses, to which is connected the vibrating lever of the valve gear. The upper end of the rod is forked and fitted with the steel pin that engages the cross head, as already described. The bed plate is of cast iron in four sections, planed and bolted. 'The main journals inthe bed plate are bored out and faced at end; brass bushes without flanges, and babbitted, are fitted top and bottom alike, and secured in place by cast iron liners and bolts. The crank shaft is of wrought iron, built up in four duplicate interchangeable parts, 1314 inches diameter, and the crank pin is 14 inches diameter by 16 inches long. 'The crank shafts have solid forged couplings and are fitted with straight turned bolts. The total bearing in the bed plate is 10 feet 8 inches. The thrust block is of the horse shoe type, with cast iron shoes and is faced with bab- bitt, the sole plate being bolted to the bed plate. Intermediate bearings, lined with babbitt metal, are placed at proper intervals to support the in- termediate shaft. Propeller wheels are four bladed, sectional, 13 feet diameter and 18 feet pitch. The blades are of cast iron and have an expanded pitch. 'The wheels are right and left and fitted to the tail shaft with taper, key and nut. The engines are fitted complete with relief valves at each end of the cylinders in receiver chest; and drain valves are fitted to the bottom of cylinders and valve chests, and arranged to be handled from the workin g platform. Theair pump and condenser are detached from the main engine and are of the vertical compound and direct connected-type; size of steam cylinders, 15 inches high pressure and 30 inches low pressure, by a stroke of 18 inches. The air pumps are single acting, 38 inches bore by an 18-inch stroke. The condenser is bolted on the side of the channel plate and is fitted with cone and spray nozzle, injection valve, etc. Feed pumps are in the fire rooms, The cold water, bilge and sanitary pumps are of the ver- tical, duplex type and are located in the engine room. LARGE STEEL CASTINGS. In one of the numerous engravings on other pages one of the shaft brackets, or struts, is shown in a way that illustrates the stern construc- tion of the vessel. These brackets, as well as 74-inch pistons, 74-inch piston follower rings and 51 14-inch follower rings ofthe engines ae steel castings,and their use will tend to show the progress thatis being Made with ---- steel castings in ship construction. The government has of late _used steel castings on an extensive scale, in hulls, machinery, gun Carriages, mortars, etc., and now in this lake steamer there is evidence of a general demand for them where strength combined with durability and lightness These castings were made from finest quality of open hearth steel--possessing all the physical characteristics of open hearth steel forg- ings--with a tensile strain of about 70,000 pounds per square inch and an elongation of 20 per cent., while the reduction of area did not run under 25 per cent. The weight of each shaft bracket, or strut, averaged about 11,000 pounds, while the 74-inch and 51%-inch pistons and follower rings ranged in weight from 500 pounds each to 2,500 pounds respectively. The brackets were cored out inthe center for the purpose of lightening them, but this did not interfere with their strength, nor did it interfere with their being made successfully, thus demonstrating that the difficulties attend- ing castings of irregular shape, occasioned by enormous shrinkage, has been overcome. The 74-inch pistons were made of the very best material, as they are considerably lighter than a cast iron piston would be to stand the enormous strain to which they are subjected, As an accident to this particular part of the machinery would be disastrous, the best of work- manship and material was required. The castings were made by the Penn Steel Casting and Machine Company of Chester, Pa. LARGE SEAMLESS DRAWN TUBES. As demonstrating the fact that perfection was sought in all the details of the boat, reference may be made here to the material used for auxiliary steam and feed pipes, and also the main waste pipes and auxiliary exhausts and wastes. These pipes are generally made from sheets of copper formed up into tubes and the seams brazed. Tubes of this description, although far from satisfactory, have been used almost universally. The tendency of such tubes to open at the seams when subjected to pressure, thereby caus- ing incalculable annoyance and in some cases serious accidents, has induced the various governments to institute elaborate experiments. Ran- dolph & Clowes of Waterbury, Conn., were able to furnish tubes up to 16 inches inside diameter, but only in comparatively short lengths. This firm was, however, in their intercourse with ship builders, marine archi- tects and engineers, led to seriously consider the question of making large seamless tubes, and about two years ago, began the construction of a hydraulic machine, which is undoubtedly the most massive and powerful, and, with its tools and appliances, the most costly machine of its kind in the world. As they progressed in the erection of this machine, it was demonstrated that all their old appliances would be useless, owing to the extraordinary size and weight of all the parts and material used. The assembling of all this work delayed the firm very much in getting ina position to furnish large tubes, and it was not until about the time the Globe company was ready for the tubes for the North West that Randolph & Clowes were ready to make large tubes. Negotiations leading to the substitution of brazed tubes with seamless drawn tubes were entered into between the two concerns and it was demonstrated that the original cost of seamless drawn tubes would be in excess of that of brazed tubes. How- ever, being convinced of the superiority of the seamless drawn tubes and of their ultimate economy to the user, the builders, without regard to the difference in cost, placed the contract with Randolph & Clowes for the large seamless drawn tubes, so that it can be said that in the construction of this boat were used the largest and heaviest seamless drawn tubes ever used in an American-built vessel, and further, that her steam and feed pipes, as well as wastes and exhausts, are made from the very best material procurable. _ SOME ADDITIONAL, PARTICULARS OF SHAFTING. Hach crank shaft is of the quadruple type, built up of eight crank slabs, eight short collared coupling shafts and four crank pins. 'The length over all of each crank shaft is 22 feet 8 inches; pins are 14 inches diameter in the journals and.14% inches in the crank arms. 'The cranks are of the fig- ure eight or "fiddle" type, of 21 inch centers, and are 103% inches thick and 27% inches diameter across the eyes. The short sections of shafting for coupling the cranks together are 133/ inches diameter in the bearings, 25% inches diameter on the couplings and 14% inches where they go in the crank eyes. The line shafting for each set of engines consists of five pieces--a thrust shaft 13 feet 8% inches over all, 13% inches to 133 inches diameter in bearings, 20 inches diameter on the thrust portion and 25% inches diameter on the couplings. 'he first intermediate shaft is 20 feet 4 inch Over all and is of the same general diameters as the thrust shaft. The second intermediate shaft is also 20 feet % inch over all, and is practically a duplicate of the first intermediate, with the exception that one coupling 1s 32 inches in diameter. The third intermediate shaft is 25 feet 14 inch over all, 1334 inches to fourteen inches diameter in the bearings, with one coupling collar 25% inches diameter, and the other end is provided with a special coupling nut instead of the collar. 'The propeller shaft is 22 feet I inch over all, 137% inches and 13% inches diameter and is provided with the usual wrought iron propeller nut. This makes, then, the total length of crank shaft and line shafting for each of the two quadruple expansion engines, 123 feet 6 inches. 'This shafting was made by the Cleveland City is essential. Forge and Iron Company. 7