106 



[Assembly 



The nature of a centrifugal pump consists in receiving water 

 by an orifice or opening at the centre, and discharging it at the 

 periphery. It has no sliding pistons or rings, like most rotary 

 pumps, but simpfy consists in having two discs united together 

 by an arm or arms, and placing these on a shaft in an air-tight 

 case, connected with a central suction orifice, and a circumferen- 

 tial discharge pipe. > A, figure 4, is the rotary piston, formed of 

 the two discs, which are constructed with radial arms, as shown 

 in figure 3, and which constitute the water passages, through 

 which the water flows from the central inlet openings in radial 

 lines to the circumference where it is discharged at tangents into 

 -the pipe D. Tlie rotary piston is secured on the shaft, C ; 3 and 



A 



Figure 3. Figure 4. 



4 are central openings into the inside of the two discs, w ich are 

 formed like two saucers united, with their concave surfaces 

 placed towards one another ; K is a stuffing box, and P is the 

 packing; L is the driving shaft, on wnich a pulley is secured to 

 drive the rotary piston by a belt ; G is the chamber in which the 

 water is gathered previous to its discharge, and F is the base of 

 the case for the pump to be secured to any proper bed, and at 

 the same time it is the suction pipe which leads down into the 

 cistern, or whtitever it may be. The water, therefore, enters up 

 through the bottom of the outside case, and passes into the inner 

 case by the central openings, 3 and 4, and into the interior of the 

 rotary piston, the two united discs, and is driven out of the pipe 

 D. H is a bearing for the journal of shaft, C. The engravings 

 exhibit what is termed a drainage pump, one built for the dis- 

 charge of large volumes of water to distances of from 6 to 20 feet. 

 For great elevations, and fire-engines, a smaller suction and dis- 

 charge pipe, and smaller issues in the rotary piston are employed. 



