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2015. WARD, F. O., Hertford Street, Mayfair.
Horizontal steam engine, combined with double acting hydraulic power pumps, on cistern bed—new system.
This machine consists of a steam engine and four power pumps, horizontally disposed, the former on the top, the latter on the sides, of an elongated hollow bed, arranged to serve also as a cistern. The pumps are of a peculiar construction, which will be presently explained. Their disposition is such as to admit of a considerable increase of their length beyond that of ordinary hydraulic pumps, as will also be shown. They are worked on a plan believed to be novel and advantageous. The four pumps are coupled together in pairs, and the plungers of each pair are attached to the opposite ends of an intervening slide. This slide is moved to and fro, between horizontal guides, by one end of a connecting rod, whose opposite extremity is actuated by the crank of a driving shaft, transversely disposed across the oblique end of the cistern.
These arrangements are shown in the figure, which also exhibits the spur wheel and pinion, geared at 3 to 1, by which the pump-driving shaft just mentioned derives motion from the steam-engine shaft. The peculiar grouping of these parts upon and around the cistern is such, it will be observed, as virtually to compress two machines within the area which either would occupy alone. This valuable economy of floor space is effected by the super-position of the steam engine above the pumps; yet it is not purchased (as might be expected) by any addition to the height of the machine, which could not conveniently be diminished, even were the pumps away.
To this advantage of compactness that of lightness is added, since the same casting which serves as bed-plate for the steam engine, affords also a stiff framing to the pumps, besides answering as water cistern for their supply. One casting thus replaces three; and yet, compact as it is, its elongated form affords scope for a connecting rod of unusual length. This is a considerable advantage, enabling, as it does, pumps of increased length, to be worked with undiminished directness of thrust.
The economy hence resulting, in costly wrought-iron and brass work, is very great. For, on each side of the machine, one crank and one connecting rod are made to drive two long pumps, each equal in power to at least three ordinary short pumps, every one of which, on the old plan, would require a separate crank and connecting rod of its own.
We have therefore ten cranks and ten connecting rods saved out of twelve, and four sets of pump valves doing the work of twelve, with all the collateral advantages implied in these large economies. Thus, to take one example — whereas every set of six pumps on the old plan requires a costly 6-throw crank-shaft to work it, four long pumps, equal in power to two such sets, are driven on the new plan by one cheap, straight shaft, carrying one plain crank at each end.
Nor does this diminution in the number of cranks involve a less equable distribution of the resistance, seeing that the two cranks employed are set in such angular relation to each other, that when one pair of pumps is at dead-point, the other is at mid-stroke, and vice versd.
With reference to power, indeed, it is beyond doubt that the gearing, which in this machine applies three rapid engine strokes to produce one slow pump stroke, brings power to bear against resistance far more advantageously, than when (as in certain direct-acting hydraulic pumps recently introduced) steam and water are made to travel at equal speed.
The remaining peculiarities relate chiefly to the internal fitting of the pumps. These have their inlet and outlet valves placed at one end, instead of, as usual, at opposite ends of the barrel. The water, therefore, enters and quits the pump at the same end, so that the annular water-way heretofore left between the plunger and barrel, ceases to be requisite. The plunger is accordingly turned to fit the barrel, so that no cavity remains to harbour air as usual, to the detriment of the vacuum or suction power of the pump, of which no less than one-third is sacrificed by the ordinary disposition of these parts. As to back- slip, or the reflux of water through the valves during their fall, this must needs be small in an engine having three times fewer than the ordinary number of valves, each making three times fewer than the usual number of lifts.
To sum up — this pumping engine, taken as a whole, is believed to present a series of advantages not heretofore combined in any one machine of its class. Its parts are few, simple, and light, easy and cheap to make and fit, in disposition singularly compact, in action very direct and efficient.
Though specially designed to work hydraulic presses, this engine is equally available, with slight modifications, for other kinds of pumping work. It may be obtained of Messrs. Wren and Hopkinson, machinists, Manchester; who are appointed manufacturers under the patent.