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444 for the more cumbersome slow speed direct connected machine. At the same time, by reason of the well known over- load capacity of a liberally proportioned turbine, there would be available a sur- plus power of about 50 per cent, .which should make possible an emergency speed of nearly 3 knots in excess of that called for in the specifications, Furthermore, the three independent shafts, each with its own self-contained turbines for going ahead and _ astern, would give the excellent maneuvering qualities 'which' are admittedly lacking THE Marine REVIEW in vessels fitted with the present con- ventional turbine equipment. I regard this invention as epoch-mak- ing in its importance. It has been my privilege to supply--the material things which were needed to transform the creature of Messrs. Melville and Mac- alpine's imaginations into an actual thing of iron and _ steel. achieved by the completed machine have fully justified my faith in its ultimate success. Gro. WESTINGHOUSE. Pitsburg, Oct, 15, 1909, Experimental Spur-Wheel Reduction-Gear: The inherent desirability of interpo- lating some form of reduction gear be- tween a marine steam turbine and the propeller it drives has long been suf- ficiently obvious. Suggestions for ef- fecting this by electrical or hydraulic means have been frequent, and in fact, we hope to illustrate shortly an hydrau- lic coupling which has given on trial really remarkable results. The straight- forward solution of the problem by means of a pinion and a spur wheel has generally been dismissed as im- practicable, although the remarkable ef- ficiency of a well constructed toothed wheel drive is known to all. The waste of energy in such a transmission gear is notably less than is commercially practicable with an electric coupling, which in turn is superior in this re- spect to the hydraulic system. Never- theless, the fact that turbines of the Laval type were not constructed to trans- mit more than some 300 horsepower con- stituted prima facie evidence that with higher powers special difficulties were to be feared. The remarkable results obtained with motor car drives, where tooth pressures at times exceed 2,000 Ib. per lin. in., were no sure indication 'that equally good results could be ob- tained in transmitting by gears some 4,000 horsepower instead of 40, since the rule of three is by no means always applicable in practical constructive en- gineering. Nevertheless, in his lectures on the steam turbine before the so- ciety of arts last spring, Gerald Stoney did suggest that the newer alloy steels and the greater accuracy of workman- ship, which have made gearing so successful in motor car practice, did hold) out a prospect that the problem of the marine steam turbine might be solved by means of ordinary toothed reduction gearing. Those interested in steam turbines have known for some months past that a solution of the problem on these lines was, with his characteristic enterprise, »,'Reprint from London Engineering. being put to a practical test by George Westinghouse, who was having con- structed for him a double helical spur gear intended to transmit 6,000 horse- power at 1,500 revolutions of the pinion per minute, the reduction ratio being about 5to1. Through the courtesy of Mr. Westinghouse we are now able to pub- lish illustrations of this remarkable ex- perimental gear, the details of which have been worked out by Rear Admiral George W.. Melville and John H. Macalpine, who have patented the novel features on which they rely for success. A perspective view of the gear, with the casing partly broken away, is repre- sented in Fig. 1, which shows the de- The results - ioveurber: 1909 right-handed helices, and the other pair left-handed, so as to eliminate end- thrust. The diameter of the pitch circle of the large wheels is about 70 in., and of the pinions 14 in. De- tails of the gear box are shown in Figs. 2, 3 and 4. These have been designed after a long and com- prehensive study of the circumstances which. tend to interfere with the proper, working of very broad teeth. A small pitch was deemed. essential if a reasonable absence of noise was to be secured, and this necessarily meant broad teeth, in view.of the fact that 6,000 horsepower was to be trans- mitted with a pitch-line speed of very nearly 100 ft. per second, and with a limiting pressure of 453 lb. per lineal inch on the teeth. In order..to. insure the..: proper working of such broad teeth, Messrs. Melville and Macalpine have adopted the plan of mounting the pinion shaft in a device which they have dubbed a "floating frame," the object of which is to cause the alignment and position of this shaft to be controlled wholly by the interaction of the teeth in con- tact, and not by the greater or lesser skill of the workman in laying out and fitting the bearings, which, more-. over, even if exactly right to start with, could not be depended on to 5 - : Fig, 1--MetvirtE & Macatprne's Repuction Grar CONNECTED To WESTINGHOUSE 'TURBINE, vice coupled to a Westinghouse double- flow turbine. The forgings for the gears were obtained from Messrs. Krupp, of Essen, the teeth being cut by Messrs. Schuchardt & Schutte, Chemnitz, whilst the standing parts were made by the Westinghouse Ma- chine Co. The pinions have 35 teeth each and the spur-wheels 176, a hunting-cog being introduced to equalize wear. The pitch is 1% in, and the pitch helices are at an angle of 30 degrees with the axis of the shaft. One wheel and pinion have, of course, maintain' permanently their alignment. The "floating frame," which is lettered Fin Figs. 2 to 4, is a heavy steel casting flexibly mounted. in the gear box and supporting in rigid bearings the pinion shaft, but in such a way as to allow of this shaft having a slight longitudinal freedom, so that it can slide axially to and fro within the frame. Fig. 2 is an elevation of the float- ing frame showing the flexible I-beams B, on which it is supported from the bed plate. The pinion, it will be seen, is supported in three bearings, the