PILCOMAYO. 18 PILE. River (q.v.). It rises in the Cordillera Real in Western liolivia, and Hows with no large devia- tions southeastward until it joins the Paraguay just below Asenncii'in (Map: Paraguay. E S). In the lower half of its course it forms the boundary between Argentina and Paraguay. After descending from the Bolivian plateau and breaking through several ridges, it flows for the remainder of its course through the great plain of the (Jran Chaco. partly through dense forests, partly through wide, marshy tracts, where the banks arc submerged, and where the river divides into several jjarallel channels. It is here a sluggish stream with an average width of thirty yards, and so shallow and obstructed as to lie almost completely unnavigable. The Pilcomayo has not yet been thoroughly explored, and its length is undetermined, but is estimated at 1200 miles. FILE (AS. pil, from Lat. pilum, javelin, pestle, from pisere. pinsere, to pound). In engi- neering and architecture, a long post generally of wood, but often of iron, driven into soft soils to support a load or to form an inclosure against the entrance of water. Piles are known by difl'erent names, according to their character or u.se, the more important being: Brnritifi pilr, one used to sustain a vertical load and the one generally meant when the word pile is employed without qualification; sheet piles, thick boards or timbers driven in close contact, often tongued and grooved, to inclose a space, to prevent leak- age, etc. ; screw pile, an iron shaft to the bottom of which is attached a broad-bladed screw with one or two turns; disk pile, an iron shaft to the bottom of which is attached a circular disk to give additional licaring power. The most ciini- nion form of pile is the bearing pile of. usually, a roughly trimmed, slender tree trunk, or. less usually, of a squared or other dressed timber shape. The woods used for piles are spruce and hemlock for soft soils, pines, elm. and beech for firmer soils, and oak for compact soil. Kngineers usually re(|iiire that piles shall not be less than METAL SBOE8 FOR WOODEX PILES. ten inches in diameter at the smaller end. Gen- erally the j)ile is shaped for driving, and some- times a pointed iron shoe is attached to the pointed end; the top is frequently bound with an iron band to prevent brooming. Piles are svink into the soil by several methods, the most common of which is driving by a ham- mer. The machines used to drive piles by a falling weight or hammer are known as pile- drivers. There are two general forms of s>ich machines known as drop-hammer pile-drivers. In a drop-hammer pile-driver a hea'y hammer of iron is pulled to the top of a lofty frame by hand or power and allowed to fall freely on to the head of the pile. The frame consists of two uprights called leaders about two feet apart and from ten feet to sixty feet long, which guide the falling weight, riicsc leaders are usually braced back to the pile-driver platform by diagonal timbers. The sides of the hanniier arc grooved to slide between the leach'rs, and it weighs from
- J00 to 4000 pounds, usually about 2000 pounds.
It is hauled to the top of the frame by a rope or chain attached to its top and passing over a pulley at the top of the frame, and thence to a hand windlass or the drum of a hoisting engine. In one kind of pile-driver the rope is attached to the hammer by a sort of tongs which is automatically opened by a trijiping device when the top of the frame is rcaclied. thus allowing the hammer to fall. In anotlicr form the rope is permanently attached to the haiiinier, which is set free by loosening a friction clutch, thus allow- ing the drum to unwind the rope which is pulled down with the hammer. The latter form of driver is the one least commonly used, and is the most expen.sive in flr.st cost, but is generally regarded as the most efficient. Drop-hammer pile-drivers are mounted on scows or cars, or may be skidded about on the platform timbers. A steam- hammer pile-driver consists of a steam cylinder in which a |)iston works, carrying a heavy weight or hammer on the end of the piston rod. This steam cylinder is vertical with the piston rod. extending downward, and is held between the tops of two or four u])riglits which serve to guide the hammer. The bottoms of these uprights are held together by a cast block pierced with a conical hole which fits over the partly sharp- ened bead of the pile. The ham- mer has a cylindrical projection which passes through the hole in the base block to strike the pile. The piston stroke is usu- ally about three feet, and the weight of the striking parts is conunonly about one and one- half tons. This whole appara- tus is swung between the leaders of a pile-driver frame by a rope exactly as is the hammer of a drop-hammer pile- driver. In operation the a|)paratus is lowered on to the pile until the pile carries its entire weight. By means of flexil)le hose connections with a steam boiler steam is admitted under the pistcm. raising it with its attached piston-rod hammer until at the top of the stroke a trip cuts oil' tlie steam and the hammer falls b.y its own weight, striking the pile a heavy blow. At the end of the down stroke the valves are automatically reversed and the stroke repeated. In this way the machine can deliver from sixty to eighty blows per min- ute, as compared with from si.x to fourteen blows for a trip drop-hannncr driver, and from twenty to thirty blows for a friction drum drop- hammer. While the steam-hammer driver strikes blows having much less energy' than those of a drop-hanniier driver, it strikes its lighter blows so much more rapidly that it compares favorably with the best friction drum drop-hammer drivers in ellicicncy. The two other forms of pile-drivers are the '■/Jet Hole f" CI. Point CONCBKTE-8TEEL PILE.
