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60 : MARINE REVIEW Rotary Pump Efficient (Continued from Page 29) design that attains static and dynamic balance. For if there is such balance, the design must be symmetrical, and this implies working in either direc- FIG. 3—CHART GIVING THE EFFICIENCIES tion. The economic advantage, of course, is in the avoidance of con- struction of right hand and left hand pumps; the one pump being suited for every type of installation. The need of freedom from internal lubrication finds its application in potable water, or of liquid foodstuffs other than edible oils. A rotary pump having internal bearings or moving parts must be oiled to stand up under operation at 1800 revolutions per minute. But the introduction of lubri- cating oil into potable water is high- ly objectionable. Hence internal mov- ing parts must be dispensed with, or so designed as to require no oil. The so-called “oilless’”? metallic bear- ings will not withstand service at any such speed as 1800 revolutions per minute. Freedom from packing trouble is a sore point with practically every rotary pump manufacturer. _This is the primary source of dissatisfaction with the user. Again it must be said that compromise breeds disaster. A suction lift of 20 feet or more (primed) is highly desirable. There can be no question on that score. And the ability of a pump to give several years of efficient service under Jeb gedetaldcbchibebate ts 40 oO January, 1926 the American Machine & Foundry Co. As a result, this pump approaches more nearly the theoretical ideal than any hitherto built. In a spirit of “no compromise” difficulties of design and construction have been. overcome to such a degree that the commercial go ee DISCHARGE PRESSURE LBS/IN®* CONTINUOUS RUN FOR EACH LIQUID severe operating conditions is a qual- ification every user should demand. All these considerations were held constantly in mind during several years of development work on a new and highly original rotary pump at FIG. 4—QUADRUPLE ARRANGEMENT OF CAMS ON SHAFT OF NEW ROTARY PUMP FOR A 21%4-INCH, 83-GA LLON-PER-MINUTE ROTARY PUMP—TAKEN FROM 500 HOURS possibilities of the new pump are most attractive. The design of this pump is shown in Fig. 2. The rotor is a plain drum, like the armature of a motor. Upon (Continued on Page 64) oe