PROGRESS IN TURBINE SHIP PROPULSION. 11 



against which the gland is designed to paclc. In service its periphery is furnished 

 with water at some 5 pounds greater pressure than the maximum pressure at which 

 the gland is to pack, thus providing a water annulus at the outer part of the gland, 

 forming a hermetic seal which is very effective. For condensing turbines a water 

 pressure of 5 pounds gauge at the periphery of the gland is satisfactory. This sim- 

 ple device rendered an exceedingly difficult detail one that could be forgotten, and 

 obviously has its application to marine installations. 



The design of this gland as applied to marine installations is shown in Fig. 30, 

 Plate 57, in which there is a combination of the water gland above described for 

 use when operating at anything above half speed, and combined therewith is a sim- 

 ple steam labyrinth for use when running at speeds below one-half or when stand- 

 ing by. This labyrinth is embryotic as compared with labyrinth glands as generally 

 understood, and no attempt is made to have it particularly steam tight because of 

 its being used only when maneuvering or standing by. 



A reliable method of furnishing water at the proper pressure to the glands is 

 important and easily arranged for in land installations by pumping all or a por- 

 tion of the condensate to an overflow at the required elevation, or providing a tank 

 with a float valve at this location. 



For merchant ships there is usually head room enough and the condensate is 

 usually elevated a sufficient height above the machinery to furnish the required 

 pressure as shown in Fig. 31, Plate 58, and the system is quite automatic, requir- 

 ing no adjustment. 



On vessels where no head room is available, it is customary, as shown in Fig. 

 32, Plate 59, to provide for taking a small quantity of water from the feed line in 

 which an orifice is provided, which will pass but little more than that required for 

 the sealing of the glands. This water is carried to the gland system and there is 

 provided a relief valve, by-passing the water not required back to the feed tank, 

 thus maintaining the proper water pressure on the gland system. 



The gland casings may be removed for cleaning or inspection without other- 

 wise dismantling the turbine. 



With this combined labyrinth and water gland, provision must be made to turn 

 sealing steam on and gland water off to the gland when reducing to below half 

 speed, and similarly to turn the steam off and the water on when accelerating above 

 this speed. For merchant ships it is entirely satisfactory to provide two valves, 

 one for the water, the other for the steam, located adjacent to the maneuvering valve, 

 which may be readily manipulated by the man handling the valve. With war ships, 

 however, which require to maneuver more frequently, an automatic valve may be 

 provided, operated in conjunction with the turbine governor shown in Fig. 2y, Plate 

 54. The turbine governor is provided with two springs and its travel is divided 

 into two zones. The inner travel of the governor weights is opposed by the light 

 spring only, the governor weights being able to compress this spring at the speed at 

 which the gland should change over from steam sealed to water sealed. The 

 heavy spring comes into engagement at this speed, but the governor weights are 



