. The elements of railroad engineering . hree bracestogether. The iron stayrods running from heads of lead-ers to the after part of hull are two in number, and each oneinch in diameter. The hoisting sheaves on top are two in number, placedside by side. They are 12 inches in working diameter,lo|-inches from out to out, and 3^ inches wide, and the pinpassing through them is 2|^ inches in diameter at the sheavesand 2 inches in diameter in the boxes. These dimensionsare none too great to stand the severe work frequently putupon the sheaves in hoisting heavy weights and tearing outtimber. The fall
. The elements of railroad engineering . hree bracestogether. The iron stayrods running from heads of lead-ers to the after part of hull are two in number, and each oneinch in diameter. The hoisting sheaves on top are two in number, placedside by side. They are 12 inches in working diameter,lo|-inches from out to out, and 3^ inches wide, and the pinpassing through them is 2|^ inches in diameter at the sheavesand 2 inches in diameter in the boxes. These dimensionsare none too great to stand the severe work frequently putupon the sheaves in hoisting heavy weights and tearing outtimber. The fall or hammer rope is 2 inches in diameter,and the runner used in hoisting up piles is If inches indiameter. The hoisting engine is double-drummed and of nominally25 H. P. The detail of the hammer, shown at E^ gives aclear idea of its general design. The weight is 3,300 pounds. 1586. Sheet Piles. — In building cofferdams forfoundations and often in protection work, piles are drivenin close contact to prevent leakage. Such piles are called. Fig. 481. Fig. 482. sbeet piles. Sheet piles are always of sawed the water is shallow and without a current, 2-inchplanks will be sufficient. As the depth of water and pressure 1014 RAILROAD CONSTRUCTION. increase, the dimensions of sheet piles increase. Usuallythey are thinner than they are wide, but frequently theyare of square timber and as large as bearing piles, and arethen called close piles. To make sheet piles drive close together at foot, the pointsare sharpened as shown at/in Fig. 481. Any lateral move-ment is prevented by the wales o, o. To keep the edges at top .close to those already driven, adog iron, such as shown at a in Fig. 482, is often used. A cut of a standard sheet pile driver is given in A general plan of cofferdam illustrating the use of
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectrailroadengineering
