ROTARY PISTON P081 tive-Pithm Pump, as built by the Ken sington Engine Works, Philadelphia, is shown in Figs. 14, 15, and 16. This pump produces suction and forcing by the rotary movement of a piston. The work is done in two annular chambers, surrounding, an internal cylinder, and separated by a central partition. In each of these chambers moves a single piston with its supporting wings, mak ing the pump duplex it) its action.
The pistons are so placed that a balance of all the parts, and of the fluid moving through them, is maintained. The suction is central, passing through the internal cylinder which is at tached to and revolves with the main shaft. This cylinder supports the pistons, and has openings be hind them, bet ween their strength ening wings. Screw shaped blades lead to these open ings, through which the fluid passes drawn by action of the pis tons, which, in their travel, cause a suction in the same manner as with a reciprocating plunger, the ends of the annular chambers be ing completely closed by the abut ment cylinder, which is in close contact and revolves in equal time with the piston cylinder, the dos ing being aided, when necessary fOr very high heads or use as a fire pump, by packing. The movement of the fluid is aided as it flows through the internal cylinder from the center out ward to the annular chambers by the suction blades, and by centrifugal force. Whilst the
suction is taking place continuously behind the pistons, the contents of the chambers before them are being continuously forced through the discharge pipe in a freely open course. and in a tangent to the action of the pis tons. The discharge is entirely unob structed (and equal tot he displacement) except while the pump is being used upon air alone as in obtaining suction, when to control the great elasticity of air, two hinged valves, one for each chamber, are dropped upon their seats iu the discharge opening ; upon the current being established, these valves are raised and held completely out of it, they being no longer necessary. The gears arc used only to secure synchro nous motion to the abutment and piston cylinders, all the power for the work accomplished being applied directly t-o the pistons through the main shaft The case is made air-tight through the use of stuffing-boxes. The moving parts have no frictional contact with the case, or with each other, and the wear is almost entirely confined to outside journals, and therefore readily controlled.
Pumps, Steam Fire : see Engines, Steam Fire,