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Fottinger Transformer An Exhaustive Description of This Hydraulic Instal- lation on Board the Ill-Fated Steamer Konigin Luise HROUGH the courtesy of the | Engineer of London and _ the Zeitschrift des Vereines Deutsch- er Ingenieure we are enabled to give the following abstract of an exhaustive article on the Foettinger hydraulic transformer on the steamer Koenigin Luise. The article gains additional in- terest from the fact that the vessel dealt with was one of the first victims of the war at sea. She was sunk by the ill-fated Amphion and stroyers on August 5. Over eight years ago the Hamburg- Amerika Co. put into commission a direct turbine-driven steamer the S. S. Kaiser, which has fully met all expec- tations and has held its own with similar ships fitted with reciprocating engines. When recently, however, it was decided to build a sister vessel it was arranged to put in high-speed. tur- bines and reduce the speed of the pro- peller shafts by means of a Foettinger transformer. 4 As a comparison, it may be. stated that the propeller speed of the Kaiser is 560 revolutions per minute and that of the Koenigin Luise 450 revolutions per minute. The dimensions of the latter vessel are, or were: Overall length, 88.42 meters; greatest width, 11.78 meters; and displacement, 1720 tons. In determining the turbine speed, although the results of a long test with a 10,000 horsepower, installation proved that a reduction ratio of 5.3/1 'was quite satisfactory, and that the ratio of 6.5/1 would be quite safe, it was decided to be well on the safe side in this first installation and to adopt a turbine speed of 1800 revolutions per minute and a ratio of 4/1, giving a propeller speed of 450 revolutions per minute, as mentioned above. In view of the fact that the directional rotation of the turbine had not to be reversed since the reversal was affected by means of the Foettinger transformer, and thus the turbines were working under similar conditions to those obtaining with land turbines, it was decided to superheat the steam and thereby considerably in- crease the fuel economy. This decision carried with it the adoption of water- tube boilers fitted with superheaters, and it was arranged to install the type manufactured by the Vulcan company, in which the superheater is placed between the boiler proper and the air preheater, and which only gives a moderate degree of super- some de- heat. Three boilers were installed, each having 8 square metres grate area, 378.5 square metres heating sur- face, 93 square metres superheating surface, and a working pressure of 17 atmospheres. 5 The Main There were two turbines, each driv- ing a propeller shaft through a Foet- tinger transformer, as shown in the Supplement. The output of each tur- bine was 2745 horsepower at 1800 revolutions per minute, and a notable Engines . feature in the design of each set is that the casing of the turbine proper and oF the Foettinger. transformer were bolted together, and thus only three bearings were required, as will ' be seen on reference to. the Supple- ment. The advantage of this arrange- ment will be realized by contrasting it with Fig. 1, in which the number ef high speed bearings is at least doubled. Further, in order to prevent the ill effects of want of alignment between the high speed bearings of the turbine and the primary wheel of the transformer a piece of fairly flex- ible shaft had to be introduced. The separation between the casings would, no doubt, be of advantage if the Foettinger transformer were placed near the propeller, when a smaller shaft could be used from the turbine to the propeller. The erection at the works efcred no difficulties, and it was much assist- ed by the self-centering of the respec- tive turbine and Foettinger trans- former casings. It was important that the hearings of the secondary wheel of the transformer should be accurately centred with reference to the primary wheel, and this was affect- ed in the works by means of a cast iron test shaft. A small error be- tween these two was not, however, of vital importance, either as regards efficiency or reliability; first, because the glands were of small diameter and any play due to wear was of small consequence; and secondly, because rubbing did not affect the running, as had been proved by experience. The various parts. having been satisfac- torily erected at the works, they were separated and sent to the ship for re- erection, which was carried out with- out any difficulty. In fixing to the ship's frame the following points had to be attended to. The temperature expansion of the turbine case was about 3 mm. and the expansion of the transformer case was practically negligible. The exhaust portion of the turbine casing was bolted down to the frame with fitting bolts, and brackets were placed at each end of the turbine, and also at the back end of the secondary wheel of the trans- former, and to allow for the expan- sion these brackets could slide, the bolts passing through oval holes. The rotor of the primary wheel of the transformer also shifted slightly with temperature; that is to say, the cou- pling flange of the primary was dis- placed about 1 mm. from teft 'to right--see Supplement--on attaining the working temperature. This dis- placement was taken care of in the erection by fixing the bearing of the secondary so that the primary wheel stood, when cold, 1 mm. to much to the right. Inasmuch as the machine was fixed at the turbine end, the thrust of the propellers was taken at this point, and it was here, so as to speak, that the turbine and propeller thrusts met. 'The rotor of the steam turbine .consisted of a Curtis wheel of 1500 mm. mean blade diameter, followed by a drum carrying thirty- two reaction stages, divided up into seven groups. The turbine was de- signed for a 94 to 95 per cent vacuum. The mean speed of the blades in the Curtis wheel was 141.4 m. per second, and that of the last row of blades of the reaction portion 109 m._ per second. The Curtis wheel and the drum were made of forged steel and the casing was of cast steel. Owing to the favorable ratio between the steam speed and the blade speed of the Curtis wheel the steam could be expanded in the nozzles down to three atmospheres, and the tempera- ture was reduced to 135 degrees Cent. at this point. The Curtis wheel and its blades were of the usual type, and owing to the high speed of the turbine a single wheel was sufficient. This allowed of the removal of the top casing in one piece, exposing for inspection the whole of the rotor and the shaft laby- rinth packings. The turbine bearings had spherical seats and were forced lubricated. The governor and _ the safety governor, as originally de- signed, ran at the same speed as the turbine, but after the trial trip a modi- fication was made, and the detailed