62 PROGRESS IN TURBINE SHIP PROPULSION. 



In addition to this a large number of fixed bearing gears were built, and at 

 one time during this period, with the view of reducing costs, fixed bearing gears 

 were built in sizes as large as 500 kilowatts, the results of which were not encourag- 

 ing, so that at the present time these are not built in sizes larger than 300 kilowatts, 

 which is regarded by the Westinghouse Company as the extreme limit for fixed bear- 

 ing construction. The flexibility of the floating frame, as the design was originally 

 developed by Melville and Macalpine, was obtained by the pinion frame being sup- 

 ported on a flexible steel member as indicated in Fig. i, Plate 28. This was later 

 modified by the construction shown in Fig. 2, Plate 29, by Mr. Westinghouse, for the 

 purpose of incorporating therewith a dynamometer which would measure directly 

 the reaction on the pinion bearings. Oil was taken from the film, which is at high 

 pressure within the bearings, and led to within the cylinders "B," one located be- 

 neath each of the three bearings where the pressure was regulated by letting a por- 

 tion of the oil escape by the automatic valve "C," thus balancing the pinion frame 

 upon the pistons at a fixed distance above the bed. By reading the pressure within 

 the cylinders and determining the revolutions, the horse-power being developed may 

 be at once determined. The construction, however, lacks the extreme simplicity of 

 the original design and for that reason is not employed except in cases where a dyna- 

 mometer feature is demanded, in which case the combination of the two is employed 

 as is shown in Fig. 3, Plate 30. When normally operating, the floating frame is 

 bolted to the base of the gear case and the flexibility is obtained by the flexible 

 steel member as in the inventor's original design. The bolts that secure the frame 

 to the bed may be loosened and, by means of an auxiliary oil pump, oil is admitted 

 to a single cylinder in sufficient quantities to raise the frame a slight distance and 

 the pressure observed. The power developed is calculated therefrom as in the other 

 case. Whenever desired, the horse-power may be determined in a manner not un- 

 like that of taking indicator cards of reciprocating engines. 



The essential features of the floating frame gear will be but little referred to here 

 in view of the many articles that have been written on this subject by Mr. Macalpine.* 



The point most freely discussed in connection with reduction gears is the per- 

 missible tooth pressure per lineal inch of tooth face. Unquestionably the safe load 

 which can be transmitted by the gear teeth is all-important, but unfortunately the 

 subject has been frequently regarded as entirely independent of any other feature of 

 the reduction gear design. This is a mistaken view. The ultimate limit of pres- 

 sure which the teeth can safely carry has not been determined, but the pressures 

 at present in use among designers are only possible with the most accurate align- 

 ment. No comparison of tooth pressure is therefore reliable without careful consid- 

 eration of the methods used to maintain the unit pressure within the limits for which 

 the design was made. Faulty bearing design, inadequate support or improper 

 couplings may be individually or collectively responsible for deranging the align- 



*Vide, London Enginesring, dated September 17. 1909, May 5, 12, 19, 26, and June 2, 9 and 16, 1916 ; 

 Proceedings of Engineers' Society of Western Pennsylvania dated December 18, 1917; Institution of Naval 

 Architects, London, March 29, 1917. 



