Gun′pow-der-ham′mer.
A pile-driver operated by the explosive force of gunpowder. The hammer a is, as usual, arranged to slide in guides in a vertical frame. It is bored out cylindrically in the upper central part, and has a plunger b below. The pile-cap c has a cylindrical hollow in its upper part for the reception of this piston and a cartridge, and a conical seat below to fit the head of the pile. It is also fitted to the guides d d. The lever e is connected by a rope with a trigger at the upper part of the frame, by which the hammer is held in an elevated position. A cartridge is placed in the pilecap c, and the piston allowed to drop, compressing the air contained in the cap c sufficiently to ignite a cartridge placed therein. The explosion throws up the hammer, which again drops by its gravity, and so on. The powder used is composed of 1 1/2 parts chlorate of potash and 1 bituminous coal, finely pulverized and intimately mixed. The charge is very small, one third of an ounce sufficing to operate a hammer of 675 pounds' weight. The piston, at the upper part of the machine, enters into the cavity in a and acts as a buffer, preventing injury to the machine and assisting the downward movement of the hammer. |
| Gunpowder-mill. |
