Page:Popular Science Monthly Volume 92.djvu/136

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��Popular Science Monthly

��How a Photograph Can Show the Efficiency of a Pumping Machine

ONE of the fin- est demon- strations of correct mechanical princi- ples in a machine is given in the ac- companying illus- tration. Although the pump and mo- tor are on a pre- carious mounting of eight glass tum- blers, and although the outfit is pump- ing away at full speed, a photo- graph of eight min- utes exposure fail- ed to detect the slightest vibration. To the experienced engineer, one look at the picture would convince him of the pump's high efficiency.

And that is what the manufacturers wanted to show. The pump, which is non-pulsating, has been designed on a new me- chanical basis. High speed pumps that are seen now- adays are crank driven. A crank drives the pump pis- tons fast at the middle of the stroke, and then slows them down at the end. The result is a violently pulsat- ing stream, the reaction of which, especially if the water is pumped to any height, is enough seriously to jar the pump.

As shown at the right, it has two pistons in the same cylinder, so recip- rocated by cams on the pump frame work that a solid, uniform flow is pro- duced. One piston sucks and lifts the water at con- stant speed during the larg- est part of its pumping

��stroke. Over the remainder of its stroke, the same piston gradually trails the load off while the other piston is assuming it. The combined flow is thus always uni- form and equal to the rated amount.

The continual stopping and start- ing of the column of water, which causes a great waste of power and which is hard on the machinery, is thus replaced by a uniform stream which doesn't as much as knock over the lead pencil at the top of the ma- chine. Compared with other pumps, the one described here is said to ef- fect a saving of The almost entire lack of vibration or jar eighty per cent of is a good indication that this non-pulsating power and fuel, pump has a wonderfully high efficiency

There Has Been a Short-

���Rollers opgratinq top piston

���Couple-

��Piston — ^

��Couple -

��Pl5ton-

��Filler

��. /t^Cams

^Rollers operating lower piston

Discharge

��»^i_51idmq r valve

��I

��Slidinq valve

��Water -entrance

��The principal parts of the pump and their relation to one another

��age of Coal in Italy Ever Since 1913

TALY is so pressed for coal that gas engineers are compelled to employ substitutes. Since the war with Turkey, in 1913, there has been a serious shortage of fuel in the country. To- day, coal costs seven times as much as it did a few years ago. Yet, strange to say, the price of coke has not risen in proportion to coal. At the m.iddle of 1916, coke was costing but two and a half times as much as before the war. Private gas works, which have made pre-war contracts with the muni- cipal authorities, are in a precarious condition and are running at enorn^ous losses, due to the exorbitant prices they are obliged to pay.

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