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Her engines arose in a tower of bracings, wheels, gearing, pistons, steam pipes, steam valves, with a multitude of the eccentrics and trip gearings used on quadruple expansion engines. Although he had seen hundreds of steam engines, never before had Madden realized their complication until he faced the problem of running this difficult fabric.
The pistons are built up from two pieces; a dropped forged steel piston head, from which depend the piston pin bosses, is combined with a cast-iron skirt, into which the steel head is screwed. Four rings are fitted, three at the upper and one at the lower end of the piston skirt, and two lubricating oil grooves are cut in the skirt, in addition to the ring grooves.
The hammer, G, is of cast steel, bored out to fit the main piston, F, the latter being also bored out to receive an internal piston, L. A pin, M, passing freely through slots in the main piston, F, connects rigidly the internal piston, L, with the hammer, G. When the main piston is raised by the rocking lever, the air in the space, X, between the main and internal pistons, is compressed, and forms an elastic medium for lifting the hammer; when the main piston is moved down, the air in the space, Y, is compressed in its turn, and the hammer forced down to give the blow.
The pistons are of cast-iron, each fitted with three rings, and the connecting rods are of high grade steel, machined all over and fitted with bushes of phosphor bronze; these rods are connected to a central collar, carried on the crank pin by two ball-bearings.
They beat the air regularly as the pistons rose and fell back and forth, thump, thud, hiss, groan, up and down, out and in: "Six and sixpence a week!" Mysie tried to straighten herself, as Robert had advised, and immediately a pain shot through her back which seemed to snap it in two.
Penn employ for the piston packing a single metallic ring with tongue piece and indented plate behind the joint; and this ring is packed behind with hemp squeezed by the junk ring as in ordinary hemp-packed pistons. Q. Will you describe the construction of the cap for connecting the piston rod with the crank pin?
There was some talk about turbine engines, direct application of steam, and the absence of pistons, rods, and cranks, all of which was beyond me, for I was familiar only with sailing craft; but I did understand the last words of the engineer. "Four thousand horse-power and forty-five miles an hour, though you wouldn't think it," he concluded proudly. "Say it again, man! Say it again!"
When the keyboard of the grand piano has been made longer by a few keys, the composers think they are remaining "behind the times" if they do not immediately introduce these new high treble tones into their next work, and when the wind instruments have been enriched by several new valves and regulators the scores immediately grow in proportion to these keys and pistons.
The desire to make the pistons of steam-engines and air-pump buckets of condensing engines perfectly steam and water tight has led to the contrivance of many complex and costly constructions for the purpose of packing them. When we take a commonsense view of the subject, we find that in most cases the loss of power resulting from the extra friction neutralises the expected saving.
And at the thought Terence looked at his hard black hands and set himself resolutely to face a life sentence of rattling ash hoists, roaring furnaces and the soft sucking sounds of the pistons. Two hundred dollars a month and the union scale was a hundred and fifty! Ah, no, he dared not trifle with that job. He must, at all hazard, avoid friction with the skipper, for what would Mrs.
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