78 PROGRESS IN TURBINE SHIP PROPULSION. 



unable to compress the two springs together until the turbine reaches the speed 

 corresponding to which the governor should regulate the steam supply to the turbine. 

 Motion of the governor through the first part of its travel will, by means of the 

 relay which it operates, either relieve or impose pressure in the chamber "X" of the 

 gland control valve, Fig. 33, Plate 60, causing motion of the valve to either apply 

 water or steam, or vice versa, according to whether the turbine is accelerating or 

 retarding. 



COUPLINGS. 



An important detail is the turbine coupling. To permit free motion of the float- 

 ing pinion frame there is a flexible shaft provided between the turbine and pinion 

 which provides the necessary element of flexibility. The turbine and gear must be 

 capable of axial motion relative to one another. A coupling of the type shown in 

 Fig. 34, Plate 61, is employed. Means are provided for disassembling either tur- 

 bine or gear without reference to the other, and proper provision is made for lu- 

 bricating the driving pins. 



ELECTRIC DRIVE. 



There is much diiiference of opinion concerning the relative merits of gear and 

 electric motor drive. Discussion of this important matter is refrained from here in 

 view of certain battleship installations now being carried out. Unquestionably these 

 installations will be entirely successful, and will fulfill all expectations, but whether 

 the added complication, increased cost and weight of machinery, together with in- 

 creased steam consumption per propeller horse-power, is warranted, can be shown 

 only by the development of the future. 



One system of electric motor drive suitable for the merchant marine has been 

 proposed which has promise of economy greater than that hitherto attained. The 

 proposition is to provide a number of relatively small Diesel engines whose cylin- 

 ders shall not exceed a diameter of, say, 10 inches, or within the limits where abso- 

 lute reliability may be expected. These would be coupled to dynamos which in turn 

 would operate a motor driving the propeller. The locations of the engines may be 

 where desired without reference to the propelling motor. 



DISCUSSION. 



The President : — This paper, No. 4, entitled "Notes on Progress in Turbine Ship Pro- 

 pulsion," is now before you for discussion. We will be very glad to hear from any gentle- 

 men. It does seem as though the turbine question, and the difficulties that have come 

 out of the turbine question through various causes, should afford an ample source of discus- 

 sion of this paper, if for nothing else than for information. Is there any discussion? If not, 

 have you anything further to add, Mr. Hodgkinson? 



