Inventors at Work, with Chapters on Discovery

by George Iles

Compressed Air. In Effect Cold Steam for Driving Hammers, Drills, and Picks.

Hammers, drills, and picks, all working by percussion, are among the most effective tools. They may be attached to a steam piston, as are Nasmyth hammers and common quarry drills, yielding a much cheaper product than does hand labor. In many places where it is not feasible to use steam in this direct and most economical way, it is best to employ compressed air which works much as steam does, so that a motor or a drill with no change of build may be operated by one or other motive power at will. Compressed air, unlike steam, may be taken long distances without condensation; in tight receivers it may be kept without any loss as long as we like, and used in mines and tunnels where steam heat would be a nuisance, or where electricity would be unsafe. Electrical drills and cutters, moreover, are liable to have their insulation harmed by working shocks, and by surrounding grit, sand or chips. In mines after a blast of gunpowder, a direct current from the main pipe quickly freshens the air; at all times the cool, pure breeze from the exhaust pipe is a welcome aid to ventilation. Steam, one of the chief servants of industry, must be kept and used hot. When its energy is used to compress air we have at command a substance with all the working quality of steam, without having to keep it warm. As it toils at common temperatures, we can imagine compressed air to be, in effect, cold steam.

New Ingersoll Coal Cutter.
F, trunnion. B, C, piston rings. A, piston. E, wheel.

[Enlarged illustration] (68 kB)

Drill steels.

Of late years cutters driven by compressed air have been largely adopted throughout the coal mines of the United States. A cutter weighing ten pounds, with air at seventy-five pounds behind it, strikes a blow 160 to 250 times a minute, beginning at the floor and making as little slack as a hand pick intelligently wielded. Other tools, in great diversity, actuated in the same way, ask only skill in guidance instead of muscular drudgery. Air drills are used in mines, wells, tunnels, and rock foundations; at will the mechanism impels a hammer instead of a drill. Air riveters build ships and bridges, as well as fasten together the comparatively small plates of boilers and fire-boxes. With a little variation in its form we have a tool which caulks boilers, tanks, and ships. Air-hammers light and strong have revolutionized the art of cutting and carving stone, the force of a stroke being regulated by a touch. Pneumatic hammers are of two kinds: Valveless hammers in which the piston is the hammer, opening and shutting the inlet and exhaust parts; and valve hammers, in which there is a distinct moving valve. Hammers without valves are always short of stroke, and are chiefly used in caulking and chipping. Some of them yield as many as 250 strokes per minute. Valve hammers do not move at this high pace, rarely exceeding thirty-five strokes per minute, but each stroke is comparatively long and forcible for riveting and the like severe work. In the Keller hammer the valve moves longitudinally with the hammer barrel and in the same direction with the hammer piston, instead of in the opposite direction as is usually the case. A blow, therefore, tends to seat the valve all the more firmly, instead of jarring it off its seat. Another result is that the tool works efficiently even when the valve is loosened by much use. This hammer is manufactured by the Philadelphia Pneumatic Tool Co., Philadelphia.

SCULPTOR AT WORK WITH PNEUMATIC CHISEL,
Hughes Granite and Marble Co., Clyde, Ohio.

Haeseler air-hammer.
Ingersoll-Rand Co., New York.

It is interesting to learn from Mr. W. L. Saunders, of New York, how the air-tools just considered were introduced. He says:—

“Mr. McCoy is entitled to the credit of first applying pneumatic tools to heavy work, such as chipping metals, caulking boilers, cutting stone and so on. He was not, however, the originator of the broad idea, as long before he perfected the tool for heavy work it had been used as a dental plugger, a device working compressed air in a cylinder so that a piston struck the end of a tamping tool, used to insert gold into the cavities of teeth.”

Rock drill used as blacksmith’s hammer.
Ingersoll-Rand Co., New York.

A rock drill, on occasion, may serve as a blacksmith’s hammer. The drill, detached from its tripod, is fastened to a vertical support. The ram, duly supplied with compressed air, is fixed in position over the anvil, upon which it descends more frequently if less forcibly than a steam hammer. A rock drill may also serve to drive drift bolts into the timbers of caissons. This task when effected by ordinary sledge hammers is slow and costly, while with compressed air as a servant capital work is done at much lower expense. The drill is provided with handles so as to be readily managed by two men, who place the anvil, with its cupped end, on the head of the bolt to be driven. Pneumatic energy does the rest.

Little Giant wood-boring machine.
Chicago Pneumatic Tool Co.

With dimensions much enlarged an air-driven piston becomes a rammer for foundry sand, for roads and pavements, for tamping the beds of railroads. In foundries a moulder is furnished with a small sand-sifter, vibrated by compressed air; he is now free to use his shovel all the time, so that he does five times as much work as before. Hoists small and large are actuated by the same agency; in every case the mechanism is so simple that rough usage is withstood and repairs, when needed, are easily effected. If a ratchet, a pawl, a bearing, wears out, a new one can be bought at small cost and at once fitted into place. Designers have produced rotary as well as reciprocating air tools; of these a wood-borer is a capital example.

Water lifted by compressed air.

Sometimes it is well worth while to employ compressed air simply as a blast to keep a milling-cutter free from its chips; when the blast is cold, as it usually is, the cutter may turn all the quicker.

Compressed air can do much else than impel pistons of familiar type. In one remarkable device it has put pistons out of business altogether.