Engineering Wonders of the World
Volume I

THE PROPELLING MACHINERY OF A SHIP. 39 cast iron, were firmly fixed at one end, but had to be left free to move in a longitudinal direction at the other end to provide for ex- pansion, the free end working between slipper guides. Some of the large castings which The “ Maure- tania’s ” Boilers. working at a steam pressure of 195 lbs. per square inch, and giving a total heating sur- face of about 159,000 square feet, or about 3f acres ! Each of the double-ended boilers is about 17 feet 3 inches in diam- Fig. 13.—A ROTOR FOR A GIANT CUNARDER’s LOW- PRESSURE TURBINE BEING FINISHED IN LATHE. [Photo, Sir W. G. Armstrong, Whitworth, and Company.) eter by 22 feet long, and contains eight fur- naces ; while the single-ended boilers are of the same diameter as the double-ended, but 12 feet long, and contain four furnaces, so that the total number of furnaces is 192. The boilers are arranged in four groups, the forward com- partment containing five double-ended and the two single-ended boilers, and the other three boiler-rooms each six double-ended. All the boilers of the Mauretania were arranged for inspection in two rows in the builders’ yard before being placed on board the vessel (Fig. formed the turbine casings weighed 38 tons each. Fig. 15 illustrates one set of the completed turbines in the erecting shop ready to be placed on board the vessel. The peripheral speed of the low-pressure turbine rotors when the ship is steaming at full speed is between 10,000 and 11,000 feet per minute ; and as the clearance between the guide blades of the casings and the revolving blades of the rotors is necessarily very fine, our readers will be able to form some idea of the ac- curacy in adjustment required. The rotating mass in the engine-rooms weighs about 600 tons, and this weight travels at about 200 revolutions per minute. The whole is under control and measurement to the fraction of an inch, and is balanced to an ounce. And now a few words as to the plant re- quired for generating steam for this great turbine installation. There are in all twenty- three double - ended and two single-ended boilers in both the Lusitania and Mauretania, Fig. 14.—LOW-PRESSURE TURBINE ROTOR FULLY ELADED. 16). Such an installation of boilers intended for one ship was never seen prior to the build- ing of the Mauretania and her sister vessel. The waste gases, etc., from the 192 furnaces are led into four huge funnels, which have an elliptical cross section, and r • The measure 23 feet 7 inches by 16 , , Funnels. feet 7 inches (or large enough for two locomotives of the usual type to pass each other inside), and are carried up to